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#201
Posted to rec.audio.tubes
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Design for a small tube/valve mixer
John Byrns wrote in
: In article , Ian Thompson-Bell wrote: Ian Iveson wrote: Ian wrote The hump is indeed caused by that cap but it is made worse by the fact that one end of the transformer is not connected to ground but directly to that cap. I can see the transformer zero would probably cancel it out in the overall response and maybe that is what the designers intended. However, the bass hump in the closed loop response will still give rise to an unnecessary increase in 1/f noise, so whilst a zero at the input fixes the response it is treating the symptoms rather than curing the disease. Simulating with a 0.22uF series cap at the input removes the hump. Yes, but a cap won't get rid of the noise hump any more than the transformer will. A cap won't give you the 20dB gain that the transformer will. Why use a cap in series when you already have an inductor in shunt? A cap is a bad idea IMO. I know, I just put it there to check that the zero worked! The noise hump is cut away by the output transformer. Indeed, but if the hump was not there, the noise would be even better. The hump is completely removed simply by connecting the lower leg of the transformer to ground. To do that, and keep the first stage bias the same you need to add a series cap to the input transformer secondary. Also, I am considering a variant of this for the RATMIXER mic pre and as this would feed the mix bus there would be no need for a transformer at this point in the circuit. Another reason for getting rid of the hump and its added noise. My version of the "RATMIXER" also uses a very similar microphone amplifier circuit, however I don't understand your comment that "this would feed the mix bus"? If the microphone amplifier feeds the mix bus, where do you put the channel fader and pan pot, or is the point simply that no transformer is needed? Regards, John Byrns The piece below has served as the catalyst for the desire to acquire my own mixer. All of my favorite recordings were produced with it. One of my favorite engineers, Jan-Eric Persson, designed it in tandem with Kjell Malmberg and has used it on virtually all Opus 3 Records releases(please check the label's recordings out..simply stunning). Jan's recording approach is simple, just mics(most of the time two, sometimes an extra mic for double bass)mixertape machine. No EQ, Compression, or anything of the sort. Just good mics, good amps, good venue, good musicians. (for the record, *I am not posting this in hopes that yall will come up with a copy of it for me*..just posting because I thought you may find the pictures interesting)..so please, no comments like "well, you said you wanted faders and those are rotaries" http://farm3.static.flickr.com/2128/...c38eeb.jpg?v=0 http://farm3.static.flickr.com/2262/...2e720f.jpg?v=0 http://farm3.static.flickr.com/2187/...ffd675.jpg?v=0 The red knobs are bass-cut filter selectors for the 4 inputs and with 5 positions. 150 & 60Hz at 12dB/oct and 450, 225 & 75 Hz at 6dB/oct. The yellow knobs are the input-level controls The red one to the the far right is the Master output control. The green one is the listening volume to the monitor amp. The yellow button is before and after tape. The actual meters are VU, plus that from -5dB and up to +5 there are peak LED“s The 0-level with the Telefunken M-28 is 514 nW/m. Total max gain is 54 dB it is not that heavy, and the power supply is a separate unit and that is connected to the 8-pole flat pin connector on the right. (to avoid hum). -Tynan |
#202
Posted to rec.audio.tubes
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Design for a small tube/valve mixer
John Byrns wrote:
My version of the "RATMIXER" also uses a very similar microphone amplifier circuit, however I don't understand your comment that "this would feed the mix bus"? If the microphone amplifier feeds the mix bus, where do you put the channel fader and pan pot, or is the point simply that no transformer is needed? I think there are two points here. First, the mic pre feeds the mix bus (via the channel fader, pan and mute controls) so any 1/f noise from unmuted channels reaches the mix bus. Secondly, as the mix bus is unbalanced there is clearly no need for a transformer at this point in the circuit. Hope that is clearer. Cheers Ian |
#203
Posted to rec.audio.tubes
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Design for a small tube/valve mixer
In article ,
"Tynan AgviŠr" wrote: John Byrns wrote in : In article , Ian Thompson-Bell wrote: Ian Iveson wrote: Ian wrote The hump is indeed caused by that cap but it is made worse by the fact that one end of the transformer is not connected to ground but directly to that cap. I can see the transformer zero would probably cancel it out in the overall response and maybe that is what the designers intended. However, the bass hump in the closed loop response will still give rise to an unnecessary increase in 1/f noise, so whilst a zero at the input fixes the response it is treating the symptoms rather than curing the disease. Simulating with a 0.22uF series cap at the input removes the hump. Yes, but a cap won't get rid of the noise hump any more than the transformer will. A cap won't give you the 20dB gain that the transformer will. Why use a cap in series when you already have an inductor in shunt? A cap is a bad idea IMO. I know, I just put it there to check that the zero worked! The noise hump is cut away by the output transformer. Indeed, but if the hump was not there, the noise would be even better. The hump is completely removed simply by connecting the lower leg of the transformer to ground. To do that, and keep the first stage bias the same you need to add a series cap to the input transformer secondary. Also, I am considering a variant of this for the RATMIXER mic pre and as this would feed the mix bus there would be no need for a transformer at this point in the circuit. Another reason for getting rid of the hump and its added noise. My version of the "RATMIXER" also uses a very similar microphone amplifier circuit, however I don't understand your comment that "this would feed the mix bus"? If the microphone amplifier feeds the mix bus, where do you put the channel fader and pan pot, or is the point simply that no transformer is needed? Regards, John Byrns The piece below has served as the catalyst for the desire to acquire my own mixer. All of my favorite recordings were produced with it. One of my favorite engineers, Jan-Eric Persson, designed it in tandem with Kjell Malmberg and has used it on virtually all Opus 3 Records releases(please check the label's recordings out..simply stunning). Jan's recording approach is simple, just mics(most of the time two, sometimes an extra mic for double bass)mixertape machine. No EQ, Compression, or anything of the sort. Just good mics, good amps, good venue, good musicians. (for the record, *I am not posting this in hopes that yall will come up with a copy of it for me*..just posting because I thought you may find the pictures interesting)..so please, no comments like "well, you said you wanted faders and those are rotaries" http://farm3.static.flickr.com/2128/...c38eeb.jpg?v=0 http://farm3.static.flickr.com/2262/...2e720f.jpg?v=0 http://farm3.static.flickr.com/2187/...ffd675.jpg?v=0 The red knobs are bass-cut filter selectors for the 4 inputs and with 5 positions. 150 & 60Hz at 12dB/oct and 450, 225 & 75 Hz at 6dB/oct. The yellow knobs are the input-level controls The red one to the the far right is the Master output control. The green one is the listening volume to the monitor amp. The yellow button is before and after tape. The actual meters are VU, plus that from -5dB and up to +5 there are peak LED“s The 0-level with the Telefunken M-28 is 514 nW/m. Total max gain is 54 dB it is not that heavy, and the power supply is a separate unit and that is connected to the 8-pole flat pin connector on the right. (to avoid hum). Hi Tynan, I don't see the peak LED's in the photo of the front panel, were are they located? Does this mixer provide balanced outputs, from the interior photo I get a gut feeling that it doesn't? You asked for pan pots, this mixer doesn't appear to include them, it isn't even obvious how the input channels are assigned to the two output tracks, do you know how that is accomplished with this mixer, there don't seem to be enough knobs/switches? Since you seem to like this mixer, why don't you simply commission someone to build a duplicate? Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#204
Posted to rec.audio.tubes
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Design for a small tube/valve mixer
John Byrns wrote in
: In article , "Tynan AgviŠr" wrote: John Byrns wrote in : In article , Ian Thompson-Bell wrote: Ian Iveson wrote: Ian wrote The hump is indeed caused by that cap but it is made worse by the fact that one end of the transformer is not connected to ground but directly to that cap. I can see the transformer zero would probably cancel it out in the overall response and maybe that is what the designers intended. However, the bass hump in the closed loop response will still give rise to an unnecessary increase in 1/f noise, so whilst a zero at the input fixes the response it is treating the symptoms rather than curing the disease. Simulating with a 0.22uF series cap at the input removes the hump. Yes, but a cap won't get rid of the noise hump any more than the transformer will. A cap won't give you the 20dB gain that the transformer will. Why use a cap in series when you already have an inductor in shunt? A cap is a bad idea IMO. I know, I just put it there to check that the zero worked! The noise hump is cut away by the output transformer. Indeed, but if the hump was not there, the noise would be even better. The hump is completely removed simply by connecting the lower leg of the transformer to ground. To do that, and keep the first stage bias the same you need to add a series cap to the input transformer secondary. Also, I am considering a variant of this for the RATMIXER mic pre and as this would feed the mix bus there would be no need for a transformer at this point in the circuit. Another reason for getting rid of the hump and its added noise. My version of the "RATMIXER" also uses a very similar microphone amplifier circuit, however I don't understand your comment that "this would feed the mix bus"? If the microphone amplifier feeds the mix bus, where do you put the channel fader and pan pot, or is the point simply that no transformer is needed? Regards, John Byrns The piece below has served as the catalyst for the desire to acquire my own mixer. All of my favorite recordings were produced with it. One of my favorite engineers, Jan-Eric Persson, designed it in tandem with Kjell Malmberg and has used it on virtually all Opus 3 Records releases(please check the label's recordings out..simply stunning). Jan's recording approach is simple, just mics(most of the time two, sometimes an extra mic for double bass)mixertape machine. No EQ, Compression, or anything of the sort. Just good mics, good amps, good venue, good musicians. (for the record, *I am not posting this in hopes that yall will come up with a copy of it for me*..just posting because I thought you may find the pictures interesting)..so please, no comments like "well, you said you wanted faders and those are rotaries" http://farm3.static.flickr.com/2128/...c38eeb.jpg?v=0 http://farm3.static.flickr.com/2262/...2e720f.jpg?v=0 http://farm3.static.flickr.com/2187/...ffd675.jpg?v=0 The red knobs are bass-cut filter selectors for the 4 inputs and with 5 positions. 150 & 60Hz at 12dB/oct and 450, 225 & 75 Hz at 6dB/oct. The yellow knobs are the input-level controls The red one to the the far right is the Master output control. The green one is the listening volume to the monitor amp. The yellow button is before and after tape. The actual meters are VU, plus that from -5dB and up to +5 there are peak LED“s The 0-level with the Telefunken M-28 is 514 nW/m. Total max gain is 54 dB it is not that heavy, and the power supply is a separate unit and that is connected to the 8-pole flat pin connector on the right. (to avoid hum). Hi Tynan, I don't see the peak LED's in the photo of the front panel, were are they located? Does this mixer provide balanced outputs, from the interior photo I get a gut feeling that it doesn't? You asked for pan pots, this mixer doesn't appear to include them, it isn't even obvious how the input channels are assigned to the two output tracks, do you know how that is accomplished with this mixer, there don't seem to be enough knobs/switches? Since you seem to like this mixer, why don't you simply commission someone to build a duplicate? Regards, John Byrns I have to ask about the LEDs.. John, as I stated many times(with this picture and others) , I was NOT posting the picture with any intent to get a duplicate!!I just thought it may be interesting I like the sound of the mixer, and the engineer that uses it is genius...but I didnt want a carbon copy. Please dont take my posting pictures as an attempt to get copies..it was just an FYI(and you have done this twice, asked "well you said you wanted this and that, but the PICTURE doesnt have it , yadda yadda") no, it does not provide balanced outputs..it was going to a tape machine. the panning was hard left, right, and center on that unit..it was fixed. again..I want a nice sounding tube mixer, but I dont want a copy of what has been done before..otherwise I would have contacted those guys...I want a design from the folks here...hence my posting here and nowhere else! John please read what I wrote in parentheses in the post above(announcing the mixer). If I cant post pictures without folks taking them literally, maybe I shouldnt post em..they are just FYI, maybe thought someone could get ideas from the pictures..but Lord...again...I do NOT want copies! |
#205
Posted to rec.audio.tubes
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Design for a small tube/valve mixer
In article ,
"Tynan AgviŠr" wrote: John Byrns wrote in : In article , "Tynan AgviŠr" wrote: The piece below has served as the catalyst for the desire to acquire my own mixer. All of my favorite recordings were produced with it. One of my favorite engineers, Jan-Eric Persson, designed it in tandem with Kjell Malmberg and has used it on virtually all Opus 3 Records releases(please check the label's recordings out..simply stunning). Jan's recording approach is simple, just mics(most of the time two, sometimes an extra mic for double bass)mixertape machine. No EQ, Compression, or anything of the sort. Just good mics, good amps, good venue, good musicians. (for the record, *I am not posting this in hopes that yall will come up with a copy of it for me*..just posting because I thought you may find the pictures interesting)..so please, no comments like "well, you said you wanted faders and those are rotaries" http://farm3.static.flickr.com/2128/...c38eeb.jpg?v=0 http://farm3.static.flickr.com/2262/...2e720f.jpg?v=0 http://farm3.static.flickr.com/2187/...ffd675.jpg?v=0 The red knobs are bass-cut filter selectors for the 4 inputs and with 5 positions. 150 & 60Hz at 12dB/oct and 450, 225 & 75 Hz at 6dB/oct. The yellow knobs are the input-level controls The red one to the the far right is the Master output control. The green one is the listening volume to the monitor amp. The yellow button is before and after tape. The actual meters are VU, plus that from -5dB and up to +5 there are peak LED“s The 0-level with the Telefunken M-28 is 514 nW/m. Total max gain is 54 dB it is not that heavy, and the power supply is a separate unit and that is connected to the 8-pole flat pin connector on the right. (to avoid hum). Hi Tynan, I don't see the peak LED's in the photo of the front panel, were are they located? Does this mixer provide balanced outputs, from the interior photo I get a gut feeling that it doesn't? You asked for pan pots, this mixer doesn't appear to include them, it isn't even obvious how the input channels are assigned to the two output tracks, do you know how that is accomplished with this mixer, there don't seem to be enough knobs/switches? Since you seem to like this mixer, why don't you simply commission someone to build a duplicate? I have to ask about the LEDs.. John, as I stated many times(with this picture and others) , I was NOT posting the picture with any intent to get a duplicate!!I just thought it may be interesting I like the sound of the mixer, and the engineer that uses it is genius...but I didnt want a carbon copy. Please dont take my posting pictures as an attempt to get copies..it was just an FYI(and you have done this twice, asked "well you said you wanted this and that, but the PICTURE doesnt have it , yadda yadda") no, it does not provide balanced outputs..it was going to a tape machine. the panning was hard left, right, and center on that unit..it was fixed. again..I want a nice sounding tube mixer, but I dont want a copy of what has been done before..otherwise I would have contacted those guys...I want a design from the folks here...hence my posting here and nowhere else! John please read what I wrote in parentheses in the post above(announcing the mixer). If I cant post pictures without folks taking them literally, maybe I shouldnt post em..they are just FYI, maybe thought someone could get ideas from the pictures..but Lord...again...I do NOT want copies! Sorry about the redundant questions, it is hard to keep track of your requirements since they are not consolidated in a single place due to the piecemeal way they have been presented. I will try to avoid future questions about your requirements and just set my ship to sail its own course. With respect to your comment in parentheses, from the beginning I completely missed your desire to have a custom one of a kind mixer, I had assumed that if there was an already existing design that meet all your desires/requirements, simply having a duplicate constructed would be a viable alternative. I now understand that one of your prime requirements is that your mixer be one of a kind. Have you had any luck yet in locating someone willing to design and construct a custom mixer for you? I am curious what the result might look like, figuratively speaking. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
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