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#121
Posted to rec.audio.tubes
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Tube Equaliser/Tone Control
I have brought this discussion with Joyhn Byrns
over from another thread, as it has the makings of what might prove to be aninteresting project. "John Byrns" wrote in message ... In article , "Iain Churches" wrote: John wrote The LF and HF ranges of your proposed +/- 3 dB equalizer are obvious enough, but it is not so obvious what you are talking about for the MF range? Before the days of parametric EQ, many recording consoles had three band equalisers on most channels. The mid band was often termed "presence" (particularly on broadcast consoles) and was centred at 3kHz (the BBC used 2.6kHz IIRC) The BBC analogue meter is no longer in production, though I do know a source from which they can probably be obtained NOS. I did not mean to imply and actual BBC meter should be used, I assumed a peak reading meter circuit designed specifically for this project, or a clone of the BBC circuit if desired. I assume that analog meter movements are still manufactured, or am I wrong about this? The BBC type is pretty funky. Two movements on one meter face, green needle pointer for left, red needle pointer for right. White lettering on a black background. Few people outside broadcast have seen them. They are always a talking point. See: http://www.kolumbus.fi/iain.churches/Pics/BBC_PPM.jpg What do you mean by the "Peter Baxandall topology"? When I think of a "Peter Baxandall topology" I always think of his feedback tone control circuit, but today many people, at least here on this usenet group, seem to consider the "Baxandall" tone control circuit to be the standard passive tone control circuit. It is a long time since I read the Baxandall articles. IIRC the first circuit was a feedback tone control as you describe. The passive version arrived soon afterwards. The circuit was later modified for use with guitar amps in the USA, and known by the name of James. I would like to see some evidence of who actually developed the common passive tone control circuit, it is not obvious to me that it was "Peter Baxandall" was responsible for it as many today claim, although it is possible, I don't know and would like to see some evidence to settle the issue once and for all. Peter Baxandall was the author of the articles which AFAIK first described this tone control in a British journal. All the textbooks I have seen attribute it to him also. Unfortunately I don't think the passive topology, whoever may have designed it, easily accommodates the addition of a "MF" band. Agreed. I was thinking of Baxandall for a two frequency control LF and HF ( I would probably never use the mid control) but if one needs mid, then there are plenty of other options. I have been giving this idea quite a bit of thought. There are a lot of alternatives, but I have picked one as a starting point, although it is difficult to proceed very far without having a better idea what you want the "MF" equalizer to do? Could you provide some input on the specifications desired for the "MF" equalizer? Once I have had a chance to think a bit about the requirements for the "MF" equalizer, I will write up my thoughts and post them here. As mentiond before, I think it should be fairy wide Q and centred on 3kHz Personally, I could live without it. Let me do some listening tests with a parametric set up as a three band (I have some Neve modules) and I will see if I can find a compromise. I am sure there is no "one size fits all" solution. Best regards Iain |
#122
Posted to rec.audio.tubes
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Tube Equaliser/Tone Control
Iain Churches wrote: I have brought this discussion with Joyhn Byrns over from another thread, as it has the makings of what might prove to be aninteresting project. "John Byrns" wrote in message ... In article , "Iain Churches" wrote: John wrote The LF and HF ranges of your proposed +/- 3 dB equalizer are obvious enough, but it is not so obvious what you are talking about for the MF range? Before the days of parametric EQ, many recording consoles had three band equalisers on most channels. The mid band was often termed "presence" (particularly on broadcast consoles) and was centred at 3kHz (the BBC used 2.6kHz IIRC) The BBC analogue meter is no longer in production, though I do know a source from which they can probably be obtained NOS. I did not mean to imply and actual BBC meter should be used, I assumed a peak reading meter circuit designed specifically for this project, or a clone of the BBC circuit if desired. I assume that analog meter movements are still manufactured, or am I wrong about this? The BBC type is pretty funky. Two movements on one meter face, green needle pointer for left, red needle pointer for right. White lettering on a black background. Few people outside broadcast have seen them. They are always a talking point. See: http://www.kolumbus.fi/iain.churches/Pics/BBC_PPM.jpg What do you mean by the "Peter Baxandall topology"? When I think of a "Peter Baxandall topology" I always think of his feedback tone control circuit, but today many people, at least here on this usenet group, seem to consider the "Baxandall" tone control circuit to be the standard passive tone control circuit. It is a long time since I read the Baxandall articles. IIRC the first circuit was a feedback tone control as you describe. The passive version arrived soon afterwards. The circuit was later modified for use with guitar amps in the USA, and known by the name of James. I would like to see some evidence of who actually developed the common passive tone control circuit, it is not obvious to me that it was "Peter Baxandall" was responsible for it as many today claim, although it is possible, I don't know and would like to see some evidence to settle the issue once and for all. Peter Baxandall was the author of the articles which AFAIK first described this tone control in a British journal. All the textbooks I have seen attribute it to him also. Unfortunately I don't think the passive topology, whoever may have designed it, easily accommodates the addition of a "MF" band. Agreed. I was thinking of Baxandall for a two frequency control LF and HF ( I would probably never use the mid control) but if one needs mid, then there are plenty of other options. I have been giving this idea quite a bit of thought. There are a lot of alternatives, but I have picked one as a starting point, although it is difficult to proceed very far without having a better idea what you want the "MF" equalizer to do? Could you provide some input on the specifications desired for the "MF" equalizer? Once I have had a chance to think a bit about the requirements for the "MF" equalizer, I will write up my thoughts and post them here. As mentiond before, I think it should be fairy wide Q and centred on 3kHz Personally, I could live without it. Let me do some listening tests with a parametric set up as a three band (I have some Neve modules) and I will see if I can find a compromise. I am sure there is no "one size fits all" solution. Best regards Iain I use the baxandal network in a FB circuit around a µ follower stage, See Sheet 3, V4A,V4B, lhs about 60% down the page at http://www.turneraudio.com.au/preamp...ated-2006.html Its all anyone needs for hi-fi tone controls. Patrick Turner |
#123
Posted to rec.audio.tubes
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Tube Equaliser/Tone Control
In article ,
"Iain Churches" wrote: I have brought this discussion with Joyhn Byrns over from another thread, as it has the makings of what might prove to be aninteresting project. Or not, I held off on replying to see if anyone else jumped in to express interest in the project, Patrick was the only one to comment. "John Byrns" wrote in message ... In article , "Iain Churches" wrote: The LF and HF ranges of your proposed +/- 3 dB equalizer are obvious enough, but it is not so obvious what you are talking about for the MF range? Before the days of parametric EQ, many recording consoles had three band equalisers on most channels. The mid band was often termed "presence" (particularly on broadcast consoles) and was centred at 3kHz (the BBC used 2.6kHz IIRC) I have taken the time to start thinking about three different design approaches for this equalizer. The first approach, and probably the simplest is to use the Baxandall feedback tone control topology that Patrick suggested. This seems like the simplest approach because it doesn't require a gain makeup stage like the passive approach does. The problem with the Baxandall feedback approach is that adding an MF equalizer seems a bit of a kludge to me. A better feedback approach, which more easily accommodates an MF equalizer would be to use a differential amplifier as the feedback stage. This is the basis of my magnum opus design which also uses a gyrator to create a virtual inductor for the MF equalizer. Nine triodes are required for each channel with this design, 2 for an ALCF input buffer, 2 for the gyrator, 3 for the differential amplifier feedback equalizer stage, and 2 for an ALCF output buffer. The third approach, which is my favorite, is a passive network with a gain makeup stage, although I am not sure how to build a gain makeup stage with such low gain. My approach, which I have yet to simulate to see if it can meet the MF equalizer requirements, would use a normal RC LF equalizer and two cascaded RC HF equalizers whose effects start at different frequencies. The way this would work for MF equalization would be as follows. One HF equalizer would begin its boost/cut at say 1 kHz, and the second would become effective at say 7 kHz. The precise operating frequencies have yet to be determined. A MF bump around the presence region could be created by setting the 1 kHz equalizer toggle to its boost position, and setting the 7 kHz equalizer to its cut position. An MF dip would be created with the combination of a 1kHz cut and 7 kHz boost. I see two problems with this approach. First the MF region affected is going to be quite wide. Second since each of the individual equalizers is designed for an ultimate boost/cut of 3 dB, the combined effect at MF of the two equalizers isn't going to reach a full 3 dB due to the overlap of their curves. To fix this problem so that the full 3 dB boost/cut is available at MF, I propose linking the two HF toggles in such a way that when they are operated to opposite positions the ultimate boost/cut provided by each is increased to more than 3 dB so that the resultant effect at MF is the required 3 dB. Unfortunately there is a possibility that this would require a contact configuration on the toggle switches that isn't easily available. An added feature of this design is that an ultimate HF boost/cut of 6 dB becomes available by activating both HF switches in the same direction. I will try and do some calculations in the next couple of days to see if this approach is workable. What do you mean by the "Peter Baxandall topology"? When I think of a "Peter Baxandall topology" I always think of his feedback tone control circuit, but today many people, at least here on this usenet group, seem to consider the "Baxandall" tone control circuit to be the standard passive tone control circuit. It is a long time since I read the Baxandall articles. IIRC the first circuit was a feedback tone control as you describe. The passive version arrived soon afterwards. The circuit was later modified for use with guitar amps in the USA, and known by the name of James. I have an old Wireless World article by P.J. Baxandall which describes his feedback tone control, I don't know if this was his original disclosure of the circuit or not. I don't have any article by Baxandall that describes the passive approach, if anyone has an early article by Baxandall on the passive tone control circuit I would be interested in a copy. I also have an article by James describing the typical passive tone control circuit as used in Hi-Fi, I don't remember where this article was published, it may also have been Wireless World. I assume that the original designer of the standard passive Hi-Fi tone control network was either James or an anonymous unknown, not Baxandall, although I am open to being convinced otherwise if there is any real evidence available, for example an article by Baxandall where he actually asserts a claim that he was the original designer, or an article by Baxandall that predates any known use of the circuit in Hi-Fi sets. The standard passive Hi-Fi tone control network seems to have appeared some time in the early 1950s, it does not appear to be discussed in the 1953 edition of the famous RDH4th, although it does appear in the 1954 edition of the RCA Receiving Tube Manual. I used to assume that the typical passive Hi-Fi tone control circuit dated back to the beginning of time and was surprised when I looked for early examples and couldn't find any. The "tone stack" used in guitar amps seems to be a quite different design than the standard passive Hi-Fi tone control circuit. I would like to see some evidence of who actually developed the common passive tone control circuit, it is not obvious to me that it was "Peter Baxandall" was responsible for it as many today claim, although it is possible, I don't know and would like to see some evidence to settle the issue once and for all. Peter Baxandall was the author of the articles which AFAIK first described this tone control in a British journal. All the textbooks I have seen attribute it to him also. I would be interested in seeing those articles and textbook references. Baxandall's name has always been associated with the feedback tone control circuit in articles and textbooks, but I never saw the passive circuit attributed to him until audio groups appeared on the internet. It just has too much of the feel of an Urban Legend to me without some serious evidence to the contrary. Do you know what issue of Wireless World Baxandall's article describing the standard passive tone control circuit appeared in? I have a fair collection of Wireless World from the relevant period and might be able to find it. I have been giving this idea quite a bit of thought. There are a lot of alternatives, but I have picked one as a starting point, although it is difficult to proceed very far without having a better idea what you want the "MF" equalizer to do? Could you provide some input on the specifications desired for the "MF" equalizer? Once I have had a chance to think a bit about the requirements for the "MF" equalizer, I will write up my thoughts and post them here. As mentiond before, I think it should be fairy wide Q and centred on 3kHz Personally, I could live without it. Broad makes it easier, without an MF range of some sort the design is trivial Let me do some listening tests with a parametric set up as a three band (I have some Neve modules) and I will see if I can find a compromise. I am sure there is no "one size fits all" solution. Of course not, but with a limit of only 3, three position toggle switches one must force a single size to fit all, even if some pushing and shoving is required. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#124
Posted to rec.audio.tubes
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Tube Equaliser/Tone Control
John Byrns wrote: In article , "Iain Churches" wrote: I have brought this discussion with Joyhn Byrns over from another thread, as it has the makings of what might prove to be aninteresting project. Or not, I held off on replying to see if anyone else jumped in to express interest in the project, Patrick was the only one to comment. "John Byrns" wrote in message ... In article , "Iain Churches" wrote: The LF and HF ranges of your proposed +/- 3 dB equalizer are obvious enough, but it is not so obvious what you are talking about for the MF range? Before the days of parametric EQ, many recording consoles had three band equalisers on most channels. The mid band was often termed "presence" (particularly on broadcast consoles) and was centred at 3kHz (the BBC used 2.6kHz IIRC) I have taken the time to start thinking about three different design approaches for this equalizer. The first approach, and probably the simplest is to use the Baxandall feedback tone control topology that Patrick suggested. This seems like the simplest approach because it doesn't require a gain makeup stage like the passive approach does. The problem with the Baxandall feedback approach is that adding an MF equalizer seems a bit of a kludge to me. If you want midrange boost, just turn down both bass and treble, and then turn up the gain. You have midrange boost. But the problem with most tone controls even with Baxandal style FB networks is that when adjusted to full cut or boost, there is just a pole at about say 2kHz and beyond that the F are all cut or boosted at at 6dB per octave slope. The ideal way for hi-fi ppl to adjust the tone of their audio is to have shelving networks so that the greatest cut or boost possible is say 6dB, which will halve or double the loudness of the F involved, and so when you turn down the treble, there are two poles, one at say 1k, and then one at 2k, which is 6dB / octave. You can draw the line of the response which remains about level to 300Hz, then sways down 3dB at about 1.4kHz, then ends up going level beyond 3kHz. This shape to the cut profile means that you don't loose detail, but you change the tone, ie the balance between what is below 1kHz to what is above1kHz. if you apply the same idea to bass cut/boost, you get a nicer effect. I have never needed to have a midrange cut/boost. The only time the tone gets adjusted a lot is on the kitchen am radio because of much variable quality, and its ability for 10kHz of audio bw. I rarely ever use tone adjustments of the main hi-fi system, and nor does anyone else, so you didn't get too many replys to your post. Its become both fashionable and normal for all high end gear to NOT have any tone controls. Good recordings have it all done well for you. A better feedback approach, which more easily accommodates an MF equalizer would be to use a differential amplifier as the feedback stage. This is the basis of my magnum opus design which also uses a gyrator to create a virtual inductor for the MF equalizer. Nine triodes are required for each channel with this design, 2 for an ALCF input buffer, 2 for the gyrator, 3 for the differential amplifier feedback equalizer stage, and 2 for an ALCF output buffer. What exactly what to you want to use this all for? The third approach, which is my favorite, is a passive network with a gain makeup stage, although I am not sure how to build a gain makeup stage with such low gain. Passive tone controls are very hard to get right, ie, get the desired log pots to track correctly and have more than one channel equal. If you start with a volt, you must amplify it to say 8V then when set level the Baxandal passive produces a volt, but you have the distortions of the amplifier all present. YUK!!!! Gain is typically via one half of a 12AU7. So lets start again with a volt.... Use the same 12AU7, but this time there is a baxandal shunt FB network using linear pots, and same value R&C either side of the pots, and first tine that you set it up you will wonder why you ever bothered with a gain stage followed by a passive TC network. The FB TC stage gives say 0.93V out at low Z. The distortion of the tube is reduced by the shunt NFB, and I don't know anyone who can tell me when i have my tone stages switched in or out when in the flat position. In fact the maximum V the tube has to make is the 0.93V out, so THD is negligible without FB and when FB is used the THD is extremely low. The only trouble is that the FB network is a lower Rin than a passive set up. But Rout is less than 2k, due to FB. so I make sure when the TC stage is switched in, its driven by something with low Rout, such as the CD player, or the phono amp output. There isn't anything these days which is high Rout, only old crap which has high Rout where bean counter's said no to a CF on the output. My approach, which I have yet to simulate to see if it can meet the MF equalizer requirements, would use a normal RC LF equalizer and two cascaded RC HF equalizers whose effects start at different frequencies. The way this would work for MF equalization would be as follows. One HF equalizer would begin its boost/cut at say 1 kHz, and the second would become effective at say 7 kHz. The precise operating frequencies have yet to be determined. A MF bump around the presence region could be created by setting the 1 kHz equalizer toggle to its boost position, and setting the 7 kHz equalizer to its cut position. An MF dip would be created with the combination of a 1kHz cut and 7 kHz boost. I see two problems with this approach. First the MF region affected is going to be quite wide. Second since each of the individual equalizers is designed for an ultimate boost/cut of 3 dB, the combined effect at MF of the two equalizers isn't going to reach a full 3 dB due to the overlap of their curves. To fix this problem so that the full 3 dB boost/cut is available at MF, I propose linking the two HF toggles in such a way that when they are operated to opposite positions the ultimate boost/cut provided by each is increased to more than 3 dB so that the resultant effect at MF is the required 3 dB. Unfortunately there is a possibility that this would require a contact configuration on the toggle switches that isn't easily available. An added feature of this design is that an ultimate HF boost/cut of 6 dB becomes available by activating both HF switches in the same direction. I will try and do some calculations in the next couple of days to see if this approach is workable. Good luck with the endless possibilities. Patrick Turner. What do you mean by the "Peter Baxandall topology"? When I think of a "Peter Baxandall topology" I always think of his feedback tone control circuit, but today many people, at least here on this usenet group, seem to consider the "Baxandall" tone control circuit to be the standard passive tone control circuit. It is a long time since I read the Baxandall articles. IIRC the first circuit was a feedback tone control as you describe. The passive version arrived soon afterwards. The circuit was later modified for use with guitar amps in the USA, and known by the name of James. I have an old Wireless World article by P.J. Baxandall which describes his feedback tone control, I don't know if this was his original disclosure of the circuit or not. I don't have any article by Baxandall that describes the passive approach, if anyone has an early article by Baxandall on the passive tone control circuit I would be interested in a copy. I also have an article by James describing the typical passive tone control circuit as used in Hi-Fi, I don't remember where this article was published, it may also have been Wireless World. I assume that the original designer of the standard passive Hi-Fi tone control network was either James or an anonymous unknown, not Baxandall, although I am open to being convinced otherwise if there is any real evidence available, for example an article by Baxandall where he actually asserts a claim that he was the original designer, or an article by Baxandall that predates any known use of the circuit in Hi-Fi sets. The standard passive Hi-Fi tone control network seems to have appeared some time in the early 1950s, it does not appear to be discussed in the 1953 edition of the famous RDH4th, although it does appear in the 1954 edition of the RCA Receiving Tube Manual. I used to assume that the typical passive Hi-Fi tone control circuit dated back to the beginning of time and was surprised when I looked for early examples and couldn't find any. The "tone stack" used in guitar amps seems to be a quite different design than the standard passive Hi-Fi tone control circuit. I would like to see some evidence of who actually developed the common passive tone control circuit, it is not obvious to me that it was "Peter Baxandall" was responsible for it as many today claim, although it is possible, I don't know and would like to see some evidence to settle the issue once and for all. Peter Baxandall was the author of the articles which AFAIK first described this tone control in a British journal. All the textbooks I have seen attribute it to him also. I would be interested in seeing those articles and textbook references. Baxandall's name has always been associated with the feedback tone control circuit in articles and textbooks, but I never saw the passive circuit attributed to him until audio groups appeared on the internet. It just has too much of the feel of an Urban Legend to me without some serious evidence to the contrary. Do you know what issue of Wireless World Baxandall's article describing the standard passive tone control circuit appeared in? I have a fair collection of Wireless World from the relevant period and might be able to find it. I have been giving this idea quite a bit of thought. There are a lot of alternatives, but I have picked one as a starting point, although it is difficult to proceed very far without having a better idea what you want the "MF" equalizer to do? Could you provide some input on the specifications desired for the "MF" equalizer? Once I have had a chance to think a bit about the requirements for the "MF" equalizer, I will write up my thoughts and post them here. As mentiond before, I think it should be fairy wide Q and centred on 3kHz Personally, I could live without it. Broad makes it easier, without an MF range of some sort the design is trivial Let me do some listening tests with a parametric set up as a three band (I have some Neve modules) and I will see if I can find a compromise. I am sure there is no "one size fits all" solution. Of course not, but with a limit of only 3, three position toggle switches one must force a single size to fit all, even if some pushing and shoving is required. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#125
Posted to rec.audio.tubes
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Tube Equaliser/Tone Control
In article ,
Patrick Turner wrote: John Byrns wrote: I have taken the time to start thinking about three different design approaches for this equalizer. The first approach, and probably the simplest is to use the Baxandall feedback tone control topology that Patrick suggested. This seems like the simplest approach because it doesn't require a gain makeup stage like the passive approach does. The problem with the Baxandall feedback approach is that adding an MF equalizer seems a bit of a kludge to me. If you want midrange boost, just turn down both bass and treble, and then turn up the gain. You have midrange boost. I thought of that, its obvious, but it is too simplistic and doesn't work if you want the MF band to be narrower than the distance between the LF and HF bands. But the problem with most tone controls even with Baxandal style FB networks is that when adjusted to full cut or boost, there is just a pole at about say 2kHz and beyond that the F are all cut or boosted at at 6dB per octave slope. Not true, if you remember, Iain's spec. called for a maximum boost and cut of 3 dB total, controlled by three position toggle switches providing -3 dB, 0 dB, and +3 dB at LF, MF, and HF. The 6 dB per octave slope doesn't get a chance to get beyond 3 dB. The ideal way for hi-fi ppl to adjust the tone of their audio is to have shelving networks so that the greatest cut or boost possible is say 6dB, which will halve or double the loudness of the F involved, and so when you turn down the treble, there are two poles, one at say 1k, and then one at 2k, which is 6dB / octave. Actually I think you have got that wrong, there are not two poles in a shelving network, there is one pole and one zero IIRC. Actually the LF and HF networks I was proposing are shelving networks with the pole and zero closely spaced to provide 3 dB shelves. You can draw the line of the response which remains about level to 300Hz, then sways down 3dB at about 1.4kHz, then ends up going level beyond 3kHz. This shape to the cut profile means that you don't loose detail, but you change the tone, ie the balance between what is below 1kHz to what is above1kHz. if you apply the same idea to bass cut/boost, you get a nicer effect. You have correctly grasped the idea, that is exactly the response the LF and HF networks I proposed have, except the shelf is limited to 3 dB. I have never needed to have a midrange cut/boost. The MF control can be used to produce some interesting effects if the MF band is not made too wide as in your proposal above. The only time the tone gets adjusted a lot is on the kitchen am radio because of much variable quality, and its ability for 10kHz of audio bw. I rarely ever use tone adjustments of the main hi-fi system, and nor does anyone else, That's not true, I for one often like to twiddle the 5 band tone controls on my preamp to suit my mood. Surely when visiting friends or relatives, or riding in their vehicles, you have noticed how they usually have their graphic equalizers set to the infamous "smile" curve. Even years ago long before automobile radios had graphic equalizers, my Father would turn the single knob tone control fully counter clockwise which boosted the bass and cut the treble. When I would ride with my Mother I would turn the knob fully clockwise which provided electrically flat response, my Father would always complain about this the next time he drove the car. so you didn't get too many replys to your post. My post was the result of a comment I made about a matching equalizer in a response to Iain's original preamp post. I didn't expect a positive response from Iain, and was surprised at his marginally positive response, although I did considered it might have been a joke on Iain's part. Since you have been the only one besides Iain to respond, I should probably drop the idea. I would however still like to locate a source for three position toggle switches with nonstandard switching configurations. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#126
Posted to rec.audio.tubes
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Tube Equaliser/Tone Control
John Byrns wrote: In article , Patrick Turner wrote: John Byrns wrote: I have taken the time to start thinking about three different design approaches for this equalizer. The first approach, and probably the simplest is to use the Baxandall feedback tone control topology that Patrick suggested. This seems like the simplest approach because it doesn't require a gain makeup stage like the passive approach does. The problem with the Baxandall feedback approach is that adding an MF equalizer seems a bit of a kludge to me. If you want midrange boost, just turn down both bass and treble, and then turn up the gain. You have midrange boost. I thought of that, its obvious, but it is too simplistic and doesn't work if you want the MF band to be narrower than the distance between the LF and HF bands. But the problem with most tone controls even with Baxandal style FB networks is that when adjusted to full cut or boost, there is just a pole at about say 2kHz and beyond that the F are all cut or boosted at at 6dB per octave slope. Not true, if you remember, Iain's spec. called for a maximum boost and cut of 3 dB total, controlled by three position toggle switches providing -3 dB, 0 dB, and +3 dB at LF, MF, and HF. The 6 dB per octave slope doesn't get a chance to get beyond 3 dB. The ideal way for hi-fi ppl to adjust the tone of their audio is to have shelving networks so that the greatest cut or boost possible is say 6dB, which will halve or double the loudness of the F involved, and so when you turn down the treble, there are two poles, one at say 1k, and then one at 2k, which is 6dB / octave. Actually I think you have got that wrong, there are not two poles in a shelving network, there is one pole and one zero IIRC. Actually the LF and HF networks I was proposing are shelving networks with the pole and zero closely spaced to provide 3 dB shelves. Lemme just describe what i meant. Say you want to shelve F above 2k to take more edge of a harsh digital recording. Or you have a bright speaker. Then you can design an RC network with two poles, and start with horizontal line from LF to 500Hz, then draw the slope down to HF graph side at 6dB per octave, until say -6dB is achieved, which is at 1kHz, then continue horizontally to the HF. This line won't be the resoense, F begins to visibly sag at say 300Hz, then its about -3 at 700Hz, then then is levels out with a curve. At thew "poles" there actually isn't a full 3dB sag. Its an easy swayed curved line to get the shape of the shelf. You should under stand about drawing where the poles are and drawing rates of attenuration, then filling the straight lines with curces. RC filters never have an abrupt angular response curve. You can draw the line of the response which remains about level to 300Hz, then sways down 3dB at about 1.4kHz, then ends up going level beyond 3kHz. This shape to the cut profile means that you don't loose detail, but you change the tone, ie the balance between what is below 1kHz to what is above1kHz. if you apply the same idea to bass cut/boost, you get a nicer effect. You have correctly grasped the idea, that is exactly the response the LF and HF networks I proposed have, except the shelf is limited to 3 dB. 3dB is very little, I like to have minimum 6dB, max 8 dB I have never needed to have a midrange cut/boost. The MF control can be used to produce some interesting effects if the MF band is not made too wide as in your proposal above. I just have bass/treble cut & boost and have never bothered with anything else. The only time the tone gets adjusted a lot is on the kitchen am radio because of much variable quality, and its ability for 10kHz of audio bw. I rarely ever use tone adjustments of the main hi-fi system, and nor does anyone else, That's not true, I for one often like to twiddle the 5 band tone controls on my preamp to suit my mood. Surely when visiting friends or relatives, or riding in their vehicles, you have noticed how they usually have their graphic equalizers set to the infamous "smile" curve. If the system has no bass and smothers the HF, you know why. Even years ago long before automobile radios had graphic equalizers, my Father would turn the single knob tone control fully counter clockwise which boosted the bass and cut the treble. When I would ride with my Mother I would turn the knob fully clockwise which provided electrically flat response, my Father would always complain about this the next time he drove the car. People are different. so you didn't get too many replys to your post. My post was the result of a comment I made about a matching equalizer in a response to Iain's original preamp post. I didn't expect a positive response from Iain, and was surprised at his marginally positive response, although I did considered it might have been a joke on Iain's part. Since you have been the only one besides Iain to respond, I should probably drop the idea. I would however still like to locate a source for three position toggle switches with nonstandard switching configurations. Good luck finding good switches... Patrick Turner. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#127
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In article ,
Patrick Turner wrote: John Byrns wrote: In article , Patrick Turner wrote: John Byrns wrote: I have taken the time to start thinking about three different design approaches for this equalizer. The first approach, and probably the simplest is to use the Baxandall feedback tone control topology that Patrick suggested. This seems like the simplest approach because it doesn't require a gain makeup stage like the passive approach does. The problem with the Baxandall feedback approach is that adding an MF equalizer seems a bit of a kludge to me. If you want midrange boost, just turn down both bass and treble, and then turn up the gain. You have midrange boost. I thought of that, its obvious, but it is too simplistic and doesn't work if you want the MF band to be narrower than the distance between the LF and HF bands. But the problem with most tone controls even with Baxandal style FB networks is that when adjusted to full cut or boost, there is just a pole at about say 2kHz and beyond that the F are all cut or boosted at at 6dB per octave slope. Not true, if you remember, Iain's spec. called for a maximum boost and cut of 3 dB total, controlled by three position toggle switches providing -3 dB, 0 dB, and +3 dB at LF, MF, and HF. The 6 dB per octave slope doesn't get a chance to get beyond 3 dB. The ideal way for hi-fi ppl to adjust the tone of their audio is to have shelving networks so that the greatest cut or boost possible is say 6dB, which will halve or double the loudness of the F involved, and so when you turn down the treble, there are two poles, one at say 1k, and then one at 2k, which is 6dB / octave. Actually I think you have got that wrong, there are not two poles in a shelving network, there is one pole and one zero IIRC. Actually the LF and HF networks I was proposing are shelving networks with the pole and zero closely spaced to provide 3 dB shelves. Lemme just describe what i meant. You already did that in your previous post, and I understood what you meant the first time around. Say you want to shelve F above 2k to take more edge of a harsh digital recording. Or you have a bright speaker. Then you can design an RC network with two poles, This is the part where you are wrong, an RC network with the response you have described doesn't have two poles, it has one pole and one zero, that is my point. and start with horizontal line from LF to 500Hz, then draw the slope down to HF graph side at 6dB per octave, until say -6dB is achieved, which is at 1kHz, then continue horizontally to the HF. This line won't be the resoense, F begins to visibly sag at say 300Hz, then its about -3 at 700Hz, then then is levels out with a curve. At thew "poles" there actually isn't a full 3dB sag. Its an easy swayed curved line to get the shape of the shelf. You should under stand about drawing where the poles are and drawing rates of attenuration, then filling the straight lines with curces. RC filters never have an abrupt angular response curve. The thing to understand about drawing this response curve is that there is one pole and one zero, not two poles, where is Henry Pasternack when we need him? You can draw the line of the response which remains about level to 300Hz, then sways down 3dB at about 1.4kHz, then ends up going level beyond 3kHz. This shape to the cut profile means that you don't loose detail, but you change the tone, ie the balance between what is below 1kHz to what is above1kHz. if you apply the same idea to bass cut/boost, you get a nicer effect. You have correctly grasped the idea, that is exactly the response the LF and HF networks I proposed have, except the shelf is limited to 3 dB. 3dB is very little, I like to have minimum 6dB, max 8 dB I agree with you on this, I suggested a seven position switch with positions for -6 dB, -4 dB, -2 dB, 0 dB, +2 dB, +4 dB, and +6 dB, but Iain said 6 dB was too much. I have never needed to have a midrange cut/boost. Perhaps you were only trying to compensate for a speaker with weak bass or treble, then you might not have felt the need for a midrange equalizer. If you were trying equalize a recording so that it was more in line with your personal taste, then you might have found use for a midrange equalizer. My personal preference is for a semi parametric midrange equalizer where both the center frequency and the amount of boost/cut are adjustable. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#128
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Tube Equaliser/Tone Control
Lemme just describe what i meant. You already did that in your previous post, and I understood what you meant the first time around. Say you want to shelve F above 2k to take more edge of a harsh digital recording. Or you have a bright speaker. Then you can design an RC network with two poles, This is the part where you are wrong, an RC network with the response you have described doesn't have two poles, it has one pole and one zero, that is my point. I see two poles, you see one. OK, but you undertsand the shelving apprach. and start with horizontal line from LF to 500Hz, then draw the slope down to HF graph side at 6dB per octave, until say -6dB is achieved, which is at 1kHz, then continue horizontally to the HF. This line won't be the resoense, F begins to visibly sag at say 300Hz, then its about -3 at 700Hz, then then is levels out with a curve. At thew "poles" there actually isn't a full 3dB sag. Its an easy swayed curved line to get the shape of the shelf. You should under stand about drawing where the poles are and drawing rates of attenuration, then filling the straight lines with curces. RC filters never have an abrupt angular response curve. The thing to understand about drawing this response curve is that there is one pole and one zero, not two poles, where is Henry Pasternack when we need him? Does anyone need Henry? I thought they he had trouble being wanted here let alone needed. Anyway, the extra series R in my Baxandal derived tone control networks make the TCN a little easier on the ears IMHO. You can draw the line of the response which remains about level to 300Hz, then sways down 3dB at about 1.4kHz, then ends up going level beyond 3kHz. This shape to the cut profile means that you don't loose detail, but you change the tone, ie the balance between what is below 1kHz to what is above1kHz. if you apply the same idea to bass cut/boost, you get a nicer effect. You have correctly grasped the idea, that is exactly the response the LF and HF networks I proposed have, except the shelf is limited to 3 dB. 3dB is very little, I like to have minimum 6dB, max 8 dB I agree with you on this, I suggested a seven position switch with positions for -6 dB, -4 dB, -2 dB, 0 dB, +2 dB, +4 dB, and +6 dB, but Iain said 6 dB was too much. Switching is OK. I have never needed to have a midrange cut/boost. Perhaps you were only trying to compensate for a speaker with weak bass or treble, then you might not have felt the need for a midrange equalizer. If you were trying equalize a recording so that it was more in line with your personal taste, then you might have found use for a midrange equalizer. My personal preference is for a semi parametric midrange equalizer where both the center frequency and the amount of boost/cut are adjustable. I have not wanted to make much else than what I have. I've never felt a need for it. Patrick Turner. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#129
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Tube Equaliser/Tone Control
"John Byrns" wrote in message ... My post was the result of a comment I made about a matching equalizer in a response to Iain's original preamp post. I didn't expect a positive response from Iain, and was surprised at his marginally positive response, although I did considered it might have been a joke on Iain's part. Since you have been the only one besides Iain to respond, I should probably drop the idea. I was positive enough to think your ideas were worthy of a new thread, which I duly started. Didn't you notice it, John? Best regards |
#130
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Tube Equaliser/Tone Control
In article ,
"Iain Churches" wrote: "John Byrns" wrote in message ... My post was the result of a comment I made about a matching equalizer in a response to Iain's original preamp post. I didn't expect a positive response from Iain, and was surprised at his marginally positive response, although I did considered it might have been a joke on Iain's part. Since you have been the only one besides Iain to respond, I should probably drop the idea. I was positive enough to think your ideas were worthy of a new thread, which I duly started. Didn't you notice it, John? Yes, I did notice your interest, but there is no missing Patrick's point, the mention of equalizers in this group always draws intense silence. I suspect people believe they will be somehow tainted by even discussing this forbidden item, much less actually using one in their system. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#131
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Tube Equaliser/Tone Control
John Byrns said:
Yes, I did notice your interest, but there is no missing Patrick's point, the mention of equalizers in this group always draws intense silence. I suspect people believe they will be somehow tainted by even discussing this forbidden item, much less actually using one in their system. Huh? We all use equalisers, in the form of RIAA networks, crossovers, tone controls or even tube amplifiers. I just don't see the point in designing an eq with tubes........... -- - Maggies are an addiction for life. - |
#132
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Tube Equaliser/Tone Control
In article ,
Patrick Turner wrote: Does anyone need Henry? I thought they he had trouble being wanted here let alone needed. Henry had a good University education, knew his theory well, and he could explain it clearly to others, except when he choose to give it some extra spin in order to advance his agenda. Anyway, the extra series R in my Baxandal derived tone control networks make the TCN a little easier on the ears IMHO. Which extra series R are you talking about, the 4k7, 11k, or another one entirely? Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#133
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Tube Equaliser/Tone Control
John Byrns wrote: In article , Patrick Turner wrote: Does anyone need Henry? I thought they he had trouble being wanted here let alone needed. Henry had a good University education, knew his theory well, and he could explain it clearly to others, except when he choose to give it some extra spin in order to advance his agenda. Anyway, the extra series R in my Baxandal derived tone control networks make the TCN a little easier on the ears IMHO. Which extra series R are you talking about, the 4k7, 11k, or another one entirely? John, go to http://www.turneraudio.com.au/preamp...ated-2006.html Then scroll down 60% to sheet 3, which has a gain stage and tone control stage schematic. See R7, R8, R9, R10. Maybe someone may like to simulate the performance in Spice or whatever. Patrick Turner. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#134
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Tube Equaliser/Tone Control
In article ,
Patrick Turner wrote: John Byrns wrote: In article , Patrick Turner wrote: Anyway, the extra series R in my Baxandal derived tone control networks make the TCN a little easier on the ears IMHO. Which extra series R are you talking about, the 4k7, 11k, or another one entirely? John, go to http://www.turneraudio.com.au/preamp...ated-2006.html Then scroll down 60% to sheet 3, which has a gain stage and tone control stage schematic. See R7, R8, R9, R10. Patrick, R7 & R9 in the schematic of your tone control stage are simply the main shunt feedback resistors and as such are nothing new, they are not an optional part of the Baxandall tone control circuit. R8 & R10 are the only series resistors that I can see you have added to the basic Baxandall tone control circuit, however I don't see how they could "make the TCN a little easier on the ears"? Their effect on the response is no different than if they weren't present in the circuit at all and you had replaced VR3, the HF pot, with a 144k pot with mechanical stops to limit the maximum amount of High Frequency boost and cut that could be applied. The mechanical stops on the pot could even be eliminated to some potential advantage if the user could keep his baser urges under control. If you want a tone control circuit that is easier on the ears I would think a better course of action than your series resisters would be to replace V4 with a 12AU7. I did however notice that you have eliminated the isolation resister that is traditionally used between the wipers of the pots in the Baxandall type of tone control circuit. If you are interested in counting beans, you could also save two capacitors by consolidating C5 & C6 into a single capacitor connected between the two ends of VR2, and replacing C7 & C8 with a single capacitor in series with the wiper of VR3. Maybe someone may like to simulate the performance in Spice or whatever. Spice is hardly necessary to determine the effect of series resistors R8 & R10 on the circuit. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#135
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Recently completed project
"Arny Krueger" wrote in message . .. "Phil Allison" wrote in message ** What a pile of masturbation fantasy CRAP !!!! Phil, regrettably, it all seems real enough - no fantasy. It may be crap, but it is gilt-edged crap. ;-) On Friday, a gentleman to whom the unit had been sent for evaluation on his home turf, sent a message to say that he would be willing to provide finance (venture capital) to fund the building of a series of these preamplifiers. This man, who is the senior partner in a high-end dealership, liked very much both what he heard and what he saw. The toolmaker starts on metalwork jigs and templates today. So he who laughs last, laughs longest, Arns, m' dear ol' tambourine basher. Cordially, Iain |
#136
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Recently completed project
"Iain Churches" wrote in message . fi... "Arny Krueger" wrote in message . .. "Phil Allison" wrote in message ** What a pile of masturbation fantasy CRAP !!!! Phil, regrettably, it all seems real enough - no fantasy. It may be crap, but it is gilt-edged crap. ;-) On Friday, a gentleman to whom the unit had been sent for evaluation on his home turf, sent a message to say that he would be willing to provide finance (venture capital) to fund the building of a series of these preamplifiers. This man, who is the senior partner in a high-end dealership, liked very much both what he heard and what he saw. The toolmaker starts on metalwork jigs and templates today. So he who laughs last, laughs longest, Arns, m' dear ol' tambourine basher. Cordially, Iain You would be wise to produce these on a ordered only basis, half the cash with the order, the remainder on delivery. many people look at something, then when the item is produced , they say they have changed there minds. Genuine people are few and far apart where money is concerned, You may not believe this, but the genuine buyers will not object to a payment with the order, and it des help with material costs, especially when your out sourcing some of the work, they all want paying on delivery of there products. But if things go well, they will sell on recommendation, and while you might not consider them a business, they just might end up supplying you with a retirement fund. You might even consider exporting downunder. Good luck with your venture, but I really doubt Patrick will offer to build for you on licence. We are all waiting for a Chinese CLONE, of some of PT's better efforts. bassett |
#137
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Recently completed project
Iain Churches wrote: "Arny Krueger" wrote in message . .. "Phil Allison" wrote in message ** What a pile of masturbation fantasy CRAP !!!! Phil, regrettably, it all seems real enough - no fantasy. It may be crap, but it is gilt-edged crap. ;-) On Friday, a gentleman to whom the unit had been sent for evaluation on his home turf, sent a message to say that he would be willing to provide finance (venture capital) to fund the building of a series of these preamplifiers. This man, who is the senior partner in a high-end dealership, liked very much both what he heard and what he saw. The toolmaker starts on metalwork jigs and templates today. So he who laughs last, laughs longest, Arns, m' dear ol' tambourine basher. Cordially, Iain I hope the financing and production all go well for you Iain. I still think you could do a little optimising to give the ALCF circuit more idle current, say 4mA minimum. Please feel free to experiment with constant current sources and the use of a negative supply so the CCS cathode load can be taken to the negative supply, and the CF is all above 0V, with the grid input at 0V right off the gain pot wiper without the additional C and R coupling. The CF can also have its cathode output directly connected to the primary of a 10K : 10k output transformer with entirely floating secondary for genuinely balanced output. The primary is grounded and its dc winding resistance is often about the right value to act asa bias resistor for the triode whose grid is at 0V off the gain pot. Anode supply need only be +150V, and no negative supply is needed. Often the 4 mA of DC in the ungapped core of a 1:1 ratio signal tranny won't cause a huge amount of dc saturation, and the tranny while slightly dc magnetised should then not produce so much 3H, and slightly more 2H. Its going to be a very tiny amount because tranny distortions become lower as the driving triode output resistance becomes lower. Electronically, the OPT driven with CF is a very simple circuit. The option for balanced is a wanted feature in pro land. Ever seen pro gear without XLR sockets on the rear panel? And BTW, a dude here rescued an old church organ with 72 12AX7 oscillators intact, but with a large number of serious problems. He gradually stripped it down and I got a couple of the oscillator chassis. In the old days, building a gyrator using tubes was BS. They'd always use a coil because it was cheaper than a tube. So for a graphic eq where you want to exploit the LC resonance once you have more than 3 bands, the tube plus LC means you don't need 18 triodes for an eq you are considering. Or, put it this way, 18 x 12AX7 will go a lot further and give more bands if you use them for gain and do the reactive part with coils of fine wire and caps. Even the Quad 22 control unit had filters based around an LC circuit for a sharp cut off noise filter for noisy records. The coils had taps and switchable cut offs, and were very nicely made. Quad 22 isn't my favourite preamp; its far too complex, has far too many switches and it tries to be able to wear every hat for every occasion, and get away with using 1 x EF86 for phono, tape or mic input, and just two halves of a 12AX7 for the line stage amp which has a large amount of open loop gain and a shirtload of NFB with tone adjustments to control THD and IMD. The remarkable thing is that the Quad 22 switches have been so reliable for so long. Patrick Turner. |
#138
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Iain Churches wrote
On Friday, a gentleman to whom the unit had been sent for evaluation on his home turf, sent a message to say that he would be willing to provide finance (venture capital) to fund the building of a series of these preamplifiers. This man, who is the senior partner in a high-end dealership, liked very much both what he heard and what he saw. The toolmaker starts on metalwork jigs and templates today. So he who laughs last, laughs longest, Arns, m' dear ol' tambourine basher. Just wondering what kind of things you laugh at. Are you sure it's not too soon? How many do you need to sell? Have you sold them yet? cheers, Ian |
#139
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Recently completed project
bassett wrote: "Iain Churches" wrote in message . fi... "Arny Krueger" wrote in message . .. "Phil Allison" wrote in message ** What a pile of masturbation fantasy CRAP !!!! Phil, regrettably, it all seems real enough - no fantasy. It may be crap, but it is gilt-edged crap. ;-) On Friday, a gentleman to whom the unit had been sent for evaluation on his home turf, sent a message to say that he would be willing to provide finance (venture capital) to fund the building of a series of these preamplifiers. This man, who is the senior partner in a high-end dealership, liked very much both what he heard and what he saw. The toolmaker starts on metalwork jigs and templates today. So he who laughs last, laughs longest, Arns, m' dear ol' tambourine basher. Cordially, Iain You would be wise to produce these on a ordered only basis, half the cash with the order, the remainder on delivery. many people look at something, then when the item is produced , they say they have changed there minds. Genuine people are few and far apart where money is concerned, You may not believe this, but the genuine buyers will not object to a payment with the order, and it des help with material costs, especially when your out sourcing some of the work, they all want paying on delivery of there products. But if things go well, they will sell on recommendation, and while you might not consider them a business, they just might end up supplying you with a retirement fund. You might even consider exporting downunder. Good luck with your venture, but I really doubt Patrick will offer to build for you on licence. We are all waiting for a Chinese CLONE, of some of PT's better efforts. The Chinese will never bother to copy any of my designs. They only know how to make something look pretty to get a sale, and would never go to all the trouble I go to when i build an amp. I am almost utterly invisible and unknown in World Audio. I have never lined up outside Stereophile magazine to buy another good review and pay squillions for a series of glossy adds after having invested a million in stock which is in the shops. After I get the rave review, the ratting really starts, and ppl think there's money in copying a brand like they copy Gucci and Rolex. Idiots buy this crap. The makers of the imitations ride on the bandwagon of someone else's fame. But in fact in the shops I see few imitations; they don't have to imitate. Cheap crummy Chinese tube amps sell well by direct order now. Ppl's dreams about what they want on their equipment stands are now more easily realised than ever before. 100 watts of tube power costs no more than a week's pay now. In 1957, such power cost a fortune in wages. Dreams can turn into nightmares sometimes, and I have had to rewire a couple of recently bought cheap Chinese tube amps to make sure the smoke does not come out. Hahso, if the smoke come out, it cannot put back in! Patrick Turner. bassett |
#140
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Recently completed project
"Ian Iveson" wrote in
message . uk Iain Churches wrote On Friday, a gentleman to whom the unit had been sent for evaluation on his home turf, sent a message to say that he would be willing to provide finance (venture capital) to fund the building of a series of these preamplifiers. This man, who is the senior partner in a high-end dealership, liked very much both what he heard and what he saw. The toolmaker starts on metalwork jigs and templates today. What are the details of the contract covering your royalties, Iain? So he who laughs last, laughs longest, Arns, m' dear ol' tambourine basher. It ain't time for last, yet. Just wondering what kind of things you laugh at. Are you sure it's not too soon? Point well taken. How many do you need to sell? Have you sold them yet? More to the point - Iain, have you cashed any checks related to this project? |
#141
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Recently completed project
"Ian Iveson" wrote in message . uk... Just wondering what kind of things you laugh at. Are you sure it's not too soon? 'Twas a turn of phrase, Ian. Our friend Arny laughed at my and my pal's efforts. But then that was to be expected. Others thought this preamp sounded and looked just as it should. How many do you need to sell? Don't really need to sell any. We are set up for a short run of 10 pcs each psu and preamp. Have you sold them yet? The dealer who is funding the production of the first batch takes them all. Iain |
#142
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Recently completed project
"Arny Krueger" wrote in message . .. "Ian Iveson" wrote in message . uk Iain Churches wrote On Friday, a gentleman to whom the unit had been sent for evaluation on his home turf, sent a message to say that he would be willing to provide finance (venture capital) to fund the building of a series of these preamplifiers. This man, who is the senior partner in a high-end dealership, liked very much both what he heard and what he saw. The toolmaker starts on metalwork jigs and templates today. What are the details of the contract covering your royalties, Iain? It is a standard venture-capital deal. This is the way that many ideas are brought to fruition and become products. The same method of finance is common in recording projects also. So he who laughs last, laughs longest, Arns, m' dear ol' tambourine basher. It ain't time for last, yet. The money was in the bank today at 1200 hrs as agreed. More to the point - Iain, have you cashed any checks related to this project? See above. Arny, we haven't used cheques in Scandinavia since 1981. Iain. |
#143
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Recently completed project
In article ,
Patrick Turner wrote: I still think you could do a little optimising to give the ALCF circuit more idle current, say 4mA minimum. Please feel free to experiment with constant current sources and the use of a negative supply so the CCS cathode load can be taken to the negative supply, and the CF is all above 0V, with the grid input at 0V right off the gain pot wiper without the additional C and R coupling. The CF can also have its cathode output directly connected to the primary of a 10K : 10k output transformer with entirely floating secondary for genuinely balanced output. I like this idea, I have considered it several times because it eliminates the need for a negative supply, and provides a floating output not referenced to ground. Unfortunately I have not found a suitable transformer designed for this service that is specified to handle DC. The primary is grounded and its dc winding resistance is often about the right value to act asa bias resistor for the triode whose grid is at 0V off the gain pot. Anode supply need only be +150V, and no negative supply is needed. Often the 4 mA of DC in the ungapped core of a 1:1 ratio signal tranny won't cause a huge amount of dc saturation, and the tranny while slightly dc magnetised should then not produce so much 3H, and slightly more 2H. Its going to be a very tiny amount because tranny distortions become lower as the driving triode output resistance becomes lower. Electronically, the OPT driven with CF is a very simple circuit. The option for balanced is a wanted feature in pro land. All very desirable features, have you tested any commercially available 10K : 10k output transformers with DC to see what the actual distortion is? Ever seen pro gear without XLR sockets on the rear panel? Yes, I have seen a lot of pro gear without XLR sockets on the rear panel, barrier screw terminal strips used to be common on equipment intended for permanent rack mount installation. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#144
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Recently completed project
"bassett" wrote in message ... You would be wise to produce these on a ordered only basis, half the cash with the order, the remainder on delivery. many people look at something, then when the item is produced , they say they have changed there minds. Genuine people are few and far apart where money is concerned, You may not believe this, but the genuine buyers will not object to a payment with the order, and it des help with material costs, especially when your out sourcing some of the work, they all want paying on delivery of there products. Hi Bassett. This is a standard venture capital deal. But if things go well, they will sell on recommendation, and while you might not consider them a business, they just might end up supplying you with a retirement fund. You might even consider exporting downunder. :-)) Our capacity is such that I think we shall only be able to turn out a small number - I prefer quality to quantity. Good luck with your venture, but I really doubt Patrick will offer to build for you on licence. We are all waiting for a Chinese CLONE, of some of PT's better efforts. No chance of the Chinese cloning anything of Patrick's. They are interested only in the cheapest of cheap solutions dressed up to look like something they are not. The Chinese prefer a generic "one size fits all" pcb which they can use for amps from 10 to 100W. Patrick is more interested in tube-craft, which is really what it is all about. Iain |
#145
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Iain Churches
How many do you need to sell? Don't really need to sell any. We are set up for a short run of 10 pcs each psu and preamp. Have you sold them yet? The dealer who is funding the production of the first batch takes them all. Crikey...nice work if you can get it. Did you cover all your own time and expenses? Does Arny get a cut for his contribution? cheers, Ian |
#146
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Iain Churches" wrote
No chance of the Chinese cloning anything of Patrick's. They are interested only in the cheapest of cheap solutions dressed up to look like something they are not. The Chinese prefer a generic "one size fits all" pcb which they can use for amps from 10 to 100W. This must surely be unfair to at least a few of the billions of Chinese in the world. Why they may not be interested in cloning Patrick's amps is a matter of conjecture. Personally, I can't see any reason why they should. Perhaps they respect his copyright? cheers, Ian |
#147
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"Ian Iveson" said:
Does Arny get a cut for his contribution? ROFL!!! ;-) -- - Maggies are an addiction for life. - |
#148
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"Iain Churches" wrote in message No chance of the Chinese cloning anything of Patrick's. They are interested only in the cheapest of cheap solutions dressed up to look like something they are not. The Chinese prefer a generic "one size fits all" pcb which they can use for amps from 10 to 100W. Patrick is more interested in tube-craft, which is really what it is all about. Iain The Chinese manafacturing machine is now at a point where the japanese where in the early 60's with there cheap and nasty models of everything, But they evolved to a point where they became a world leader in there products. But having said that, I heard a Shanling C.D. player the other day, and it did rate up with the best the world can produce. The big problem will be in a few years when all the well known manufacturers will no longer be around due to mass cloneing my the chinese, as with the established manufacturers also comes the research and development , which is needed in any product. It would seem th Chinese do nothing of this, and simply Clone, to the point where even the original manufacturers can,t tell the differance. Also Jo consummer cares not about the quality of manufacture, and is dictated in his choice by price. An example of this is el'cheapo DVD players that are flooding the market here at the moment $39.00 yes thirty nine dollars, gets you a DVD player that does everything and sometimes more then a high priced model, And as people will tell you, "So it blows, up" throw it away and buy another one. Unfortunatly, this example is apparent in just about every consumable these days. There was a progrom on some time ago, where some bright Chinese jeweller obtained Opal chips, from an Australian jeweller, The Australian operation just swept them in the garbage bin. The Chinese company bought them for practically nothing, paid people $2.00 an hour to mount the scrappings and scrap Opal on to Broaches, fiilled with an Araldite substance, and was making a small fortune. bassett |
#149
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John Byrns wrote: In article , Patrick Turner wrote: I still think you could do a little optimising to give the ALCF circuit more idle current, say 4mA minimum. Please feel free to experiment with constant current sources and the use of a negative supply so the CCS cathode load can be taken to the negative supply, and the CF is all above 0V, with the grid input at 0V right off the gain pot wiper without the additional C and R coupling. The CF can also have its cathode output directly connected to the primary of a 10K : 10k output transformer with entirely floating secondary for genuinely balanced output. I like this idea, I have considered it several times because it eliminates the need for a negative supply, and provides a floating output not referenced to ground. Unfortunately I have not found a suitable transformer designed for this service that is specified to handle DC. The DC is very low, and may not cause any problems unless it was 30mA or more. The dc magnetisation shoud be under 0.8 tesla for this app, leaving enough headroom for the small ac signal output. Sowter or Lundahl would have something suitable. If you have say 3,000 turns for each winding, and you have a core say 20mm x 30mm, then you can work out the probable dc flux density. there are formulas for all this at my website. The primary is grounded and its dc winding resistance is often about the right value to act asa bias resistor for the triode whose grid is at 0V off the gain pot. Anode supply need only be +150V, and no negative supply is needed. Often the 4 mA of DC in the ungapped core of a 1:1 ratio signal tranny won't cause a huge amount of dc saturation, and the tranny while slightly dc magnetised should then not produce so much 3H, and slightly more 2H. Its going to be a very tiny amount because tranny distortions become lower as the driving triode output resistance becomes lower. Electronically, the OPT driven with CF is a very simple circuit. The option for balanced is a wanted feature in pro land. All very desirable features, have you tested any commercially available 10K : 10k output transformers with DC to see what the actual distortion is? No, but I did once use a 5K:16 ohm tranny powered with a paralleled 12AT7 without any problem to drive a spring box in a guitar amp reverb unit where maybe 20Vrms is the primary voltage. The core was an ungapped GOSS, very small, like a speaker tranny in an old radio. But you need two equal voltage windings for maybe 1Vrms output. If the load for the CF was ideally 20k, paralleling a twin triode allows say 6mA and 10k load. The 10k impedance suggests that the primary inductance has 10k reactance at 20Hz, and shunt C reactance at 20kHz = 10k. so Lp should be at least 80H, and Csh should be no more than 800pF. In fact usually the LP will vary betwen 50H and 500H with ungapped GOSS, and Csh will easily be 300pF. Mu metal cores give much more L and less C for the same core size and turns, but are more prone to saturation with dc. Ever seen pro gear without XLR sockets on the rear panel? Yes, I have seen a lot of pro gear without XLR sockets on the rear panel, barrier screw terminal strips used to be common on equipment intended for permanent rack mount installation. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#150
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"Ian Iveson" wrote in message . uk... Iain Churches" wrote Why they may not be interested in cloning Patrick's amps is a matter of conjecture. Personally, I can't see any reason why they should. Perhaps they respect his copyright? Hardly:-) I saw an amp not long ago with a familiar looking pot stamps "Elps" :-) Iain |
#151
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Iain wrote:
Perhaps they respect his copyright? Hardly:-) I saw an amp not long ago with a familiar looking pot stamps "Elps" :-) Iain Ha! Perfect. Genius! Every little bit Elps. I'll get by with a little Elp from my friends. etc. Wish I'd thought of it... cheers, Ian |
#152
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"Ian Iveson" wrote in message . uk... Iain Churches How many do you need to sell? Don't really need to sell any. We are set up for a short run of 10 pcs each psu and preamp. Have you sold them yet? The dealer who is funding the production of the first batch takes them all. Crikey...nice work if you can get it. Did you cover all your own time and expenses? The tooling cost is covered, but of course not the time spent in shirtcuff and table napkin doodling:-) Our return for this batch will be sufficient to fund another two batches. We are already talking about Series II, which will have an infra-red controller with a stepped motor for the attenuator, and remote input switching. Does Arny get a cut for his contribution? But of course. He is my inspiration to better things, lest I too end up as a computer repair man in SE Michigan:-) Cheers Iain |
#153
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Iain Churches wrote: "Ian Iveson" wrote in message . uk... Iain Churches How many do you need to sell? Don't really need to sell any. We are set up for a short run of 10 pcs each psu and preamp. Have you sold them yet? The dealer who is funding the production of the first batch takes them all. Crikey...nice work if you can get it. Did you cover all your own time and expenses? The tooling cost is covered, but of course not the time spent in shirtcuff and table napkin doodling:-) Our return for this batch will be sufficient to fund another two batches. We are already talking about Series II, which will have an infra-red controller with a stepped motor for the attenuator, and remote input switching. Nobody pays a cent for design/R&D work. Ppl see something they like the look of, and have no idea how long a special amp costs to make in terms of time, and you are expected to make the special for the same price someone charges for some crap mass produced item. Often low volume production costs involved in making the item as stylish looking as top brands are quite prohibitive here. And when I did invest $3,000 for extremenly well made metal work for a dozen amps 3 years ago, nobody wanted the type of amp I wanted to sell. ( Quad 40 level of finish ) They wanted SE amps on special chassis, with different features each time. So I have all these chassis stamped for tube sockets and cases for trannies and cover plates et all sitting under a bench here gathering dust. They get on Ebay to buy second hand ARC and CJ or some Chinese crap item rather than pay a lot more for the hand crafted item. So I have to repair stuff just to pay bills. This work mounts up, and it all takes lots of time nobody like paying for. And when someone does try to order something I have to say I have to finish the repairs first. Maybe I can start in 3 month's time, so they'd get their amp in 6 mths. But folks shopping on the Internet want an instant fix, and I can't do instant fixes. Have fun building a few amps, but don't be surprised if you don't do very well after selling a couple to people you know well. When you have to compete with the world its a another matter, because you have to be better than the other gear out there, and cheaper, and available when they want it, ie, right now. So you could build things speculatively, and hope you find a buyer, but often that can be very frustrating because it may take years to sell what you have made. Maybe I am cynical, but I am not part of a team who can operate together to make and then promote production. Nobody has ever said they'd provide capital. There is a company in Sth Aust who began in about 1993 who have done OK but they had millions of dollars for the capital investment. The amps they make are amoung the world's most expensive, and apparently, they are doing OK. See http://www.halcro.com/products.asp When I searched around I could never find a motor drive for remote control of a stepped attenuator switch. The circuit you'll need just for gain control will use lots of chips and about 75dB more circuitry that the triode amplifier it has to serve. I built a preamp several years ago for a guy with DACT switches for source select and gains. But DACT don't seem to have drive motors and remote controls for their swirches. http://www.dact.com/ The switches I installed have lasted OK. The only EQ the guy wanted was a shelved treble cut to reduce the harshness found in some digital recordings and reduce the top a little in his Vienna Acoustics. the wafer rotary type of switch seemed only type I thought appropriate. I wasn't ever going to use a set of toggle switches, let alone a row of pressbutton types. Rotary wafers have sliding self cleaning contacts, and good quality are available from Farnell, and are 20dB cheaper than anything from DACT. If at some future time a change is to be made to the amp topology or features, the wafer switch can be easily removed/changed/modded. Being able to do tone control from a distance would be useful for a hi-fi listener, but why would it be wanted by a pro in a studio? Don't they have to be able to alter eq of each track while monitors are set up so they can be near the desk, and listen from ideal speaker monitor speaker positioning? One can easily set out to design a puppy dog, and end up with a camel. Patrick Turner. |
#154
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Iain Churches wrote
...We are already talking about Series II, which will have an infra-red controller with a stepped motor for the attenuator, and remote input switching. Including a transmitter? Which protocol will you use? Which chip? What kind of relays? Or fet switches? cheers, Ian |
#155
Posted to rec.audio.tubes
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"Patrick Turner" wrote in message Nobody pays a cent for design/R&D work. Ppl see something they like the look of, and have no idea how long a special amp costs to make in terms of time, and you are expected to make the special for the same price someone charges for some crap mass produced item. Often low volume production costs involved in making the item as stylish looking as top brands are quite prohibitive here. And when I did invest $3,000 for extremenly well made metal work for a dozen amps 3 years ago, nobody wanted the type of amp I wanted to sell. ( Quad 40 level of finish ) They wanted SE amps on special chassis, with different features each time. So I have all these chassis stamped for tube sockets and cases for trannies and cover plates et all sitting under a bench here gathering dust. They get on Ebay to buy second hand ARC and CJ or some Chinese crap item rather than pay a lot more for the hand crafted item. So I have to repair stuff just to pay bills. This work mounts up, and it all takes lots of time nobody like paying for. And when someone does try to order something I have to say I have to finish the repairs first. Maybe I can start in 3 month's time, so they'd get their amp in 6 mths. But folks shopping on the Internet want an instant fix, and I can't do instant fixes. For ****'s sake, some send patrick a box of Tissues |
#156
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"Ian Iveson" wrote in message news Iain Churches wrote ...We are already talking about Series II, which will have an infra-red controller with a stepped motor for the attenuator, and remote input switching. Including a transmitter? Which protocol will you use? Which chip? What kind of relays? Or fet switches? cheers, Ian A pal of mine who helped me with the square wave analysis pics, works in a national research establishment as a prototype engineer. This kind of thing is just his cup of tea. Yesterday he brought me a stepped motor with a 6mm and 6.3mm sleeve which drives an attenuator nicely. We have discussed only briefly the controller board, but the idea is to incorporate four inputs plus a mute, FET switched. It will probably take him a week or two to put something together. Iain |
#157
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"Ian Iveson" wrote in message . uk... Iain Churches" wrote No chance of the Chinese cloning anything of Patrick's. They are interested only in the cheapest of cheap solutions dressed up to look like something they are not. The Chinese prefer a generic "one size fits all" pcb which they can use for amps from 10 to 100W. This must surely be unfair to at least a few of the billions of Chinese in the world. Why they may not be interested in cloning Patrick's amps is a matter of conjecture. Personally, I can't see any reason why they should. I know that you are not the brightest LED in this group Iverson, but how many Billions of Chinese do you think there are? west Perhaps they respect his copyright? cheers, Ian |
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