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#1
Posted to rec.audio.tubes
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6J6 driving EL84
Hi RATs!
OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source under the shared cathode of the 6J6 Merry Christmas and Happy New Ears! Al PS, I may us 5J6 or SV572-10 ... |
#2
Posted to rec.audio.tubes
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6J6 driving EL84
In article
, tubegarden wrote: Hi RATs! OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source under the shared cathode of the 6J6 Merry Christmas and Happy New Ears! What qualities does the 6J6 possess that recommend it for this service over say an ECC81? I remember when some people considered the 6J6 to be junk for audio purposes, but times change. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#3
Posted to rec.audio.tubes
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6J6 driving EL84
On Dec 17, 12:05�pm, John Byrns wrote:
What qualities does the 6J6 possess that recommend it for this service over say an ECC81? �I remember when some people considered the 6J6 to be junk for audio purposes, but times change. Regards, John Byrns -- Surf my web pages at, �http://fmamradios.com/ Hi John, I dunno, that is what the poster used. My guess is the shared cathode, as the circuit brings the signal in on one grid and the parallel grid is gounded, giving a one stage splitter/driver. I ignore all comments on audio junk tubes A few of us get circuits to sound good. Everybody is a "Knowledgeable Critic". Sigh. Happy Ears! Al |
#4
Posted to rec.audio.tubes
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6J6 driving EL84
"John Byrns" wrote in message ... In article , tubegarden wrote: Hi RATs! OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source under the shared cathode of the 6J6 Merry Christmas and Happy New Ears! What qualities does the 6J6 possess that recommend it for this service over say an ECC81? I remember when some people considered the 6J6 to be junk for audio purposes, but times change. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ From looking at the transfer characteristics of both the 6J6 and the ECC81, I see no overwhelming reason why the 6J6 would be considered to be junk for audio purposes. The only potential "gotcha" is perhaps the maximum grid circuit return resistance of 500kohms, but I think that biasing with a CCS in the common cathode is certainly worth a try as long as the two sections are well matched at the standing current selected. As to the qualities that recommend it over an ECC81, price is the one that jumps out at me. The 6J6 is dirt cheap and many of us probably have quite a few in our collections (at least 50 new ones in my own collection). Best Regards : Doug Bannard |
#5
Posted to rec.audio.tubes
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6J6 driving EL84
On Dec 17, 4:21 pm, tubegarden wrote:
Hi RATs! OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source I suppose I could look it up, but we're short of something to discuss on RAT. So, what is an "IXYS current source"? under the shared cathode of the 6J6 Merry Christmas and Happy New Ears! Al PS, I may us 5J6 or SV572-10 ... Now you're speaking in tongues a middle-aged bovver-boy like me can understand! The SV572-10 is the real heavy metal rocker's amp out of those Svetlana SV572-xx tubes, the -3 being a vocalist's delight with one of the best midranges in the business, the -30 sounding pretty punchy, verging on crude unless you matched it carefully to very polite speakers, and the -160 being a pentode in drag (dunno what Svet was thinking of adding it -- maybe some transmitting purpose outside my ken). Andre Jute Perception is a skill that requires study and careful development over a long period of time. Few have it as a natural gift. -- Iain Churches |
#6
Posted to rec.audio.tubes
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6J6 driving EL84
On Dec 17, 9:10 pm, "Doug Bannard" wrote:
"John Byrns" wrote in message ... In article , tubegarden wrote: Hi RATs! OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source under the shared cathode of the 6J6 Merry Christmas and Happy New Ears! What qualities does the 6J6 possess that recommend it for this service over say an ECC81? I remember when some people considered the 6J6 to be junk for audio purposes, but times change. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ From looking at the transfer characteristics of both the 6J6 and the ECC81, I see no overwhelming reason why the 6J6 would be considered to be junk for audio purposes. The only potential "gotcha" is perhaps the maximum grid circuit return resistance of 500kohms, but I think that biasing with a CCS in the common cathode is certainly worth a try as long as the two sections are well matched at the standing current selected. As to the qualities that recommend it over an ECC81, price is the one that jumps out at me. The 6J6 is dirt cheap and many of us probably have quite a few in our collections (at least 50 new ones in my own collection). Best Regards : Doug Bannard Perhaps a question of tone not revealed by the transfer curves? The 12AT7, 12AU7 and 12AX7 each has a distinctive tone, for instance. Andre Jute A little inaccuracy sometimes saves tons of explanation. --H.H.Munro ("Saki")(1870-1916) |
#7
Posted to rec.audio.tubes
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6J6 driving EL84
Perhaps a question of tone not revealed by the transfer curves? The 12AT7, 12AU7 and 12AX7 each has a distinctive tone, for instance. Those do have differing curves. And the "tone" will depend on the circuit the tube is in as well. Swapping one for another will sound different. |
#8
Posted to rec.audio.tubes
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6J6 driving EL84
On Mon, 17 Dec 2007 14:03:36 -0800 (PST), Andre Jute
wrote: On Dec 17, 4:21 pm, tubegarden wrote: Hi RATs! OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source I suppose I could look it up, but we're short of something to discuss on RAT. So, what is an "IXYS current source"? http://www.pmillett.com/current_source.htm |
#9
Posted to rec.audio.tubes
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6J6 driving EL84
On Dec 17, 3:03�pm, Andre Jute wrote:
I suppose I could look it up, but we're short of something to discuss on RAT. So, what is an "IXYS current source"? Hi RATs! http://ixdev.ixys.com/DataSheet/98704.pdf Happy Ears! Al |
#10
Posted to rec.audio.tubes
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6J6 driving EL84
Al said:
http://ixdev.ixys.com/DataSheet/98704.pdf Is "9 - 900k" dynamic R OK? Seems a wide range. Just wondering. Ian |
#11
Posted to rec.audio.tubes
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6J6 driving EL84
"Ian Iveson" wrote in message . uk... Al said: http://ixdev.ixys.com/DataSheet/98704.pdf Is "9 - 900k" dynamic R OK? Seems a wide range. Just wondering. Ian Sounds like a very good current regulator to me, capable of a 100:1 dynamic range. You, as the designer, control how low the dynamic R goes in your circuit by controlling how low the dynamic voltage across the device goes during operation - the lower the instantanious voltage, the lower the instantanious R required to maintain the design current. Fred |
#12
Posted to rec.audio.tubes
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6J6 driving EL84
On Dec 18, 12:54 am, J.P. wrote:
On Mon, 17 Dec 2007 14:03:36 -0800 (PST), Andre Jute wrote: On Dec 17, 4:21 pm, tubegarden wrote: Hi RATs! OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source I suppose I could look it up, but we're short of something to discuss on RAT. So, what is an "IXYS current source"? http://www.pmillett.com/current_source.htm Thanks. Saved. -- AJ |
#13
Posted to rec.audio.tubes
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6J6 driving EL84
On Dec 18, 3:20Â*am, tubegarden wrote:
On Dec 17, 3:03�pm, Andre Jute wrote: I suppose I could look it up, but we're short of something to discuss on RAT. So, what is an "IXYS current source"? Hi RATs! http://ixdev.ixys.com/DataSheet/98704.pdf Happy Ears! Al Thanks. Of course, since the regulator is drawn as one block, some benighted person will argue that you are using ***silicon^&*()$£@! in the signal path... Andre Jute |
#14
Posted to rec.audio.tubes
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6J6 driving EL84
In article
, Andre Jute wrote: On Dec 18, 3:20Â*am, tubegarden wrote: On Dec 17, 3:03?pm, Andre Jute wrote: I suppose I could look it up, but we're short of something to discuss on RAT. So, what is an "IXYS current source"? Hi RATs! http://ixdev.ixys.com/DataSheet/98704.pdf Happy Ears! Al Thanks. Of course, since the regulator is drawn as one block, some benighted person will argue that you are using ***silicon^&*()$£@! in the signal path... Isn't he? Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#15
Posted to rec.audio.tubes
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6J6 driving EL84
John Byrns wrote: In article , tubegarden wrote: Hi RATs! OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source under the shared cathode of the 6J6 Merry Christmas and Happy New Ears! What qualities does the 6J6 possess that recommend it for this service over say an ECC81? I remember when some people considered the 6J6 to be junk for audio purposes, but times change. 6J6 is OK for the app considered in the LTP driver for EL84. But it can be microphonic. I had a few smaples that were terrible in a phono stage where I thought they'd be just great because like the 12AT7/ECC81, the GM is high so input noise would be low. Patrick Turner. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#16
Posted to rec.audio.tubes
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Are all pigs...er... CCL positions equal? was 6J6 driving EL84
On Dec 19, 12:17 am, John Byrns wrote:
In article , Andre Jute wrote: On Dec 18, 3:20 am, tubegarden wrote: On Dec 17, 3:03?pm, Andre Jute wrote: I suppose I could look it up, but we're short of something to discuss on RAT. So, what is an "IXYS current source"? Hi RATs! http://ixdev.ixys.com/DataSheet/98704.pdf Happy Ears! Al Thanks. Of course, since the regulator is drawn as one block, some benighted person will argue that you are using ***silicon^&*()$£@! in the signal path... Isn't he? Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ Okay, the ultrafidelista, and others, say loosely that every component can be heard. But some can be heard more or less than others because of one or more of the intrinsic qualities of the component, the relative quality of its manufacture or materials, and its relative position in the circuit. It is this last factor, relative position in circuit we want to discuss. A notorious case is the load capacitor in parallel shunt feed SE output topologies, aka parafeed. (Abstracting for the moment whether the ungapped trx or the cap is relatively more to blame for any solecism in the sound.) Notice that I distinguish in the headline between a constant current load (CCL), which operates in the plate circuit, and a constant current source (CCS), which operates in the tail of the tube. It seems to me that the CCL might be a little more blameless, in that the signal takes a right turn to either the next tube or the output transformer before it reaches the CCL. It also seems to me that the grunge of CCS silicon might enter the signal circuit via the ground line without first being attenuated by the triode's inherent NFB. Those are certainly impressive attenuations that Pete Millett measured. Of course, any or this will become a consideration only if the residual noise of the silicon alters the quality of the noise as well as the amount, which might come down to a fine psycho-acoustic judgement; if there is no observable difference either by meter or by psychological test, then we could just accept the noise reduction as A Good Thing. I'm too old to worry about whether silicon is bad on principle just because some uncouth obsessive I have never heard of says so. Andre Jute Neutrinos seek positrinos to party with |
#17
Posted to rec.audio.tubes
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Are all pigs...er... CCL positions equal? was 6J6 driving EL84
In article
, Andre Jute wrote: On Dec 19, 12:17 am, John Byrns wrote: In article , Andre Jute wrote: On Dec 18, 3:20 am, tubegarden wrote: On Dec 17, 3:03?pm, Andre Jute wrote: I suppose I could look it up, but we're short of something to discuss on RAT. So, what is an "IXYS current source"? Hi RATs! http://ixdev.ixys.com/DataSheet/98704.pdf Happy Ears! Al Thanks. Of course, since the regulator is drawn as one block, some benighted person will argue that you are using ***silicon^&*()$£@! in the signal path... Isn't he? Okay, the ultrafidelista, and others, say loosely that every component can be heard. But some can be heard more or less than others because of one or more of the intrinsic qualities of the component, the relative quality of its manufacture or materials, and its relative position in the circuit. It is this last factor, relative position in circuit we want to discuss. A notorious case is the load capacitor in parallel shunt feed SE output topologies, aka parafeed. (Abstracting for the moment whether the ungapped trx or the cap is relatively more to blame for any solecism in the sound.) Notice that I distinguish in the headline between a constant current load (CCL), which operates in the plate circuit, and a constant current source (CCS), which operates in the tail of the tube. It seems to me that the CCL might be a little more blameless, in that the signal takes a right turn to either the next tube or the output transformer before it reaches the CCL. It also seems to me that the grunge of CCS silicon might enter the signal circuit via the ground line without first being attenuated by the triode's inherent NFB. Those are certainly impressive attenuations that Pete Millett measured. Of course, any or this will become a consideration only if the residual noise of the silicon alters the quality of the noise as well as the amount, which might come down to a fine psycho-acoustic judgement; if there is no observable difference either by meter or by psychological test, then we could just accept the noise reduction as A Good Thing. I'm too old to worry about whether silicon is bad on principle just because some uncouth obsessive I have never heard of says so. Andre, you are talking like you have lost it and gone over to the dark side, like Arnie and that guy who worked at the Scottish bank whose name escapes me. Next you will be regaling us with all the gory details on your latest solid state amplifier designs. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#18
Posted to rec.audio.tubes
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6J6 driving EL84
Thanks Fred
Sounds like a very good current regulator to me, capable of a 100:1 dynamic range. You, as the designer, control how low the dynamic R goes in your circuit by controlling how low the dynamic voltage across the device goes during operation - the lower the instantanious voltage, the lower the instantanious R required to maintain the design current. The same would be true of a resistor. The greater the voltage you have to play with, the greater you can make the resistance for a given required current. I hadn't read far enough into the datasheet to see under what circumstances that dynamic R might vary, so thanks for the info. But is 100k OK? Fine if it were a resistor in most cases, IMO, and for most ppl maybe fine even for a non-linear device. But I would bet that some would argue that 100k is not great enough to guarantee that the sound of silicon can't seep in under the back door. OTOH, I have seen many claims that simple discreet silicon circuits achieve many Megohms, but with no mention of frequency response, as if it didn't exist or didn't matter. If the ixys device achieves 100k at all frequencies of interest, it's just about good enough, IMHO. It's certainly convenient. cheers, Ian |
#19
Posted to rec.audio.tubes
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6J6 driving EL84
"Ian Iveson" wrote in message news Thanks Fred Sounds like a very good current regulator to me, capable of a 100:1 dynamic range. You, as the designer, control how low the dynamic R goes in your circuit by controlling how low the dynamic voltage across the device goes during operation - the lower the instantanious voltage, the lower the instantanious R required to maintain the design current. The same would be true of a resistor. The greater the voltage you have to play with, the greater you can make the resistance for a given required current. I hadn't read far enough into the datasheet to see under what circumstances that dynamic R might vary, so thanks for the info. But is 100k OK? Fine if it were a resistor in most cases, IMO, and for most ppl maybe fine even for a non-linear device. But I would bet that some would argue that 100k is not great enough to guarantee that the sound of silicon can't seep in under the back door. OTOH, I have seen many claims that simple discreet silicon circuits achieve many Megohms, but with no mention of frequency response, as if it didn't exist or didn't matter. If the ixys device achieves 100k at all frequencies of interest, it's just about good enough, IMHO. It's certainly convenient. cheers, Ian The IXYS device achieves many megohms at all frequencies of interest, Ian, unless your only frequency of interest is 0 Hz. It's a current regulator, not a solid state resistor. The AC resistance, or impedance, of a current regulator is in the megohms because the current through it doesn't change when the voltage across it changes - it looks like an open circuit in that respect. But it does conduct a (fixed by the designer) DC current, so depending on the voltage across it at any given moment, one can calculate a DC resistance for that moment by ohm's law. But it still looks like an open circuit to an AC voltage because, again, the changing voltage fails to cause a changing current as it would in a resistance. DC resistance calculations have about as much bearing on current regulator performance as they do on output transformer performance, only less. This isn't rocket science, Ian, and you don't need calculus to understand it. It's covered in any modern electronics text. Fred |
#20
Posted to rec.audio.tubes
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6J6 driving EL84
"Fred" wrote in message ... "Ian Iveson" wrote in message news Thanks Fred Sounds like a very good current regulator to me, capable of a 100:1 dynamic range. You, as the designer, control how low the dynamic R goes in your circuit by controlling how low the dynamic voltage across the device goes during operation - the lower the instantanious voltage, the lower the instantanious R required to maintain the design current. The same would be true of a resistor. The greater the voltage you have to play with, the greater you can make the resistance for a given required current. I hadn't read far enough into the datasheet to see under what circumstances that dynamic R might vary, so thanks for the info. But is 100k OK? Fine if it were a resistor in most cases, IMO, and for most ppl maybe fine even for a non-linear device. But I would bet that some would argue that 100k is not great enough to guarantee that the sound of silicon can't seep in under the back door. OTOH, I have seen many claims that simple discreet silicon circuits achieve many Megohms, but with no mention of frequency response, as if it didn't exist or didn't matter. If the ixys device achieves 100k at all frequencies of interest, it's just about good enough, IMHO. It's certainly convenient. cheers, Ian The IXYS device achieves many megohms at all frequencies of interest, Ian, unless your only frequency of interest is 0 Hz. It's a current regulator, not a solid state resistor. The AC resistance, or impedance, of a current regulator is in the megohms because the current through it doesn't change when the voltage across it changes - it looks like an open circuit in that respect. But it does conduct a (fixed by the designer) DC current, so depending on the voltage across it at any given moment, one can calculate a DC resistance for that moment by ohm's law. But it still looks like an open circuit to an AC voltage because, again, the changing voltage fails to cause a changing current as it would in a resistance. DC resistance calculations have about as much bearing on current regulator performance as they do on output transformer performance, only less. This isn't rocket science, Ian, and you don't need calculus to understand it. It's covered in any modern electronics text. All of which appears to me as a total nonsequitur in toto, and pure nonsense in parts. You won't find understanding in books, particularly if you have difficulty reading. You need to think a bit too. I took it that "dynamic R" meant the dynamic resistance of the current source. Since it is given as 100k max, and that is very different from your "many megohms", I felt it worth discussion. I may be mistaken, but you have failed to spot where my mistake is, smart-arse. And you are wrong, but I can't now be arsed to tell you where. bye, Ian |
#21
Posted to rec.audio.tubes
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6J6 driving EL84
Hi RATs!
The amp design in question has one happy listener. I don't know if he is a Supreme Sonic Purist or anything - he posts about amps he builds that he likes The signal path is an oversimplification of the system to help relatively unschooled people fix up really dead amps. And there are stickers and knick-knacks you can put on or around stuff to fix up really dead aural imaginations. The IXYS is a sub-$2. part that makes the circuit sound better. For one guy. I like to try stuff that made someone happy. I can't remember what every circuit sounded like, but, I can always enjoy trying another one, even if it sometimes takes a year or three ... so many lovely ladies of the mind, so little time. The endless bickering on this Newsgroup has many functions, and many posters have none, apparently, only a great need to give voice to their hostilities. It is OK, no one who wants to try strange and exotic stuff and listen cares what anybody else needs ... Well, unless she insists on getting her dreams to come true right now My wife has been very sick many more years than me, her dreams are of cigarettes and yogurt. Sigh. So, is using a 6J6 with the signal going in on one grid and the other grid grounded really what a long tail pair is? The signals on the plates are both pumped up and out of phase. Wow! One of the great things about dragging one's unschooled brain through engineering texts is the wonderful ability of technical authors to hide so much useful information. It has kept me busy for years, looking for someone who can simply describe a circuit through which they enjoy listening to music. It happens, but, there are so many people eagar to share their command of the latest techno-gibberish, it ain't often. And even I often get enthusiastic talking about what fun changing a part was ... If any of you have not built a single tube amp, get busy. What you hear when there is nothing else there will be a wonderful learning experience SV-83 and 417A each do quite well, alone And for those of you who need to explain why that is a waste of time, money and effort in all the very best techno-garble, Merry Christmas! Happy Ears! Al |
#22
Posted to rec.audio.tubes
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Are all pigs...er... CCL positions equal? was 6J6 drivingEL84
John Byrns wrote:,
Andre Jute wrote: I'm too old to worry about whether silicon is bad on principle just because some uncouth obsessive I have never heard of says so. Andre, you are talking like you have lost it and gone over to the dark side, like Arnie and that guy who worked at the Scottish bank whose name escapes me. Here's a tip: his one distinction in life is that he is the world's greatest SPAM merchant, absolutely tons of it. Next you will be regaling us with all the gory details on your latest solid state amplifier designs. Since you ask, I am just sitting here wondering whether I should resurrect my notorious Christmas Pipes (named by RdM) and play Gregorian Chant with *extra ambience*, or stick with Bach Cantata, of which I have a book of 250 discs lying open beside me (1), enough to carry me through to St Stephen's Day. If I decide on the Gregorian Chant, for an amp I'll use my miniGainBrick Zip LM675, which is described at: http://members.lycos.co.uk/fiultra/K...dre%20Jute.htm --developed to Class A in an attempt to mimic triode sound at: http://members.lycos.co.uk/fiultra/K...dre%20Jute.htm --with the schematic at: http://members.lycos.co.uk/fiultra/K...20mGBschem.jpg --and the component layout at: http://members.lycos.co.uk/fiultra/K...%20mGBmatr.jpg --and finally a piccie at: http://members.lycos.co.uk/fiultra/K...%20NoBleed.jpg (actually the pic shows why you shouldn't stick your fingers into even silicon amps...) It will probably need a rebuild because it has been sitting around for a year or two in my studio with the signal section PCB bolted to the outside of the power supply and is no doubt damaged. If I rebuild it, I'll also rename it The Pinkie Sound, in remembrance of it being built while I was waited for Pinkie to design his silicon amp that would sound like 300B that time the poor bugger challenged me to a design contest. Andre Jute (1) I used to keep my CDs standing on end in precisely right-size cardboard boxes (US: cartons) that supermarkets get their vegetables and fruit delivered in, with lips and indents for stacking. But 250-300 CDs per box weigh a lot when they are stacked to the ceiling and you want a disc from the bottommost box. Woulda been even heavier if I ever got around to making the wooden boxes I intended... Then I saw big books of CD disc pockets at a department store and bought their entire stock for a few hundred euro. The books each have enough pockets to hold up to 250 discs, booklets, and so on. A full book takes up only three inches of bookshelf space and, while heavy, is nowhere near as heavy as a big box full of CD disc cases and extraneous paperwork, nor as awkward to handle. At about seven or eight feet of shelf space for my disc collection, that's a big space saving and solves the handling problem tidily, or will as soon as I reinforce the shelves of the bookshelf I want to use... Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
#23
Posted to rec.audio.tubes
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6J6 driving EL84
On Dec 19, 10:43 am, tubegarden wrote:
Hi RATs! The amp design in question has one happy listener. I don't know if he is a Supreme Sonic Purist or anything - he posts about amps he builds that he likes If any of you have not built a single tube amp, get busy. What you hear when there is nothing else there will be a wonderful learning experience SV-83 and 417A each do quite well, alone If you choose the 417A, to save you time, here is my Type 68bis "MZ" 417A one-tube amp: http://members.lycos.co.uk/fiultra/K...0T68MZ417A.jpg Here is the circuit with component list: http://members.lycos.co.uk/fiultra/t...17acircuit.jpg And here is the layout: http://members.lycos.co.uk/fiultra/t68bismzlayout.jpg Suitable speakers are shown with the photographs referenced above; other high-sensitivity speakers I designed for this and other low- output amps are available from http://members.lycos.co.uk/fiultra/JUTE%20ON%20AMPS.htm The High Wife Acceptance Factor (HWAF) horn: http://members.lycos.co.uk/fiultra/K...20T91HWAF3.jpg is authoritative but pricey with Lowthers; ask Mick about Fostex equivalents. The Impresario, with its guitar driver, is inexpensive and easy to build and surprisingly articulate for the money: http://members.lycos.co.uk/fiultra/K...Impresario.jpg And for those of you who need to explain why that is a waste of time, money and effort in all the very best techno-garble, Merry Christmas! It could be worse. Imagine what one of those technogobblegabble guys would taste like as a turkey... Happy Ears! Al Andre Jute A public service on legs |
#24
Posted to rec.audio.tubes
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6J6 driving EL84
"Ian Iveson" wrote in message k... "Fred" wrote in message ... "Ian Iveson" wrote in message news Thanks Fred Sounds like a very good current regulator to me, capable of a 100:1 dynamic range. You, as the designer, control how low the dynamic R goes in your circuit by controlling how low the dynamic voltage across the device goes during operation - the lower the instantanious voltage, the lower the instantanious R required to maintain the design current. The same would be true of a resistor. The greater the voltage you have to play with, the greater you can make the resistance for a given required current. I hadn't read far enough into the datasheet to see under what circumstances that dynamic R might vary, so thanks for the info. But is 100k OK? Fine if it were a resistor in most cases, IMO, and for most ppl maybe fine even for a non-linear device. But I would bet that some would argue that 100k is not great enough to guarantee that the sound of silicon can't seep in under the back door. OTOH, I have seen many claims that simple discreet silicon circuits achieve many Megohms, but with no mention of frequency response, as if it didn't exist or didn't matter. If the ixys device achieves 100k at all frequencies of interest, it's just about good enough, IMHO. It's certainly convenient. cheers, Ian The IXYS device achieves many megohms at all frequencies of interest, Ian, unless your only frequency of interest is 0 Hz. It's a current regulator, not a solid state resistor. The AC resistance, or impedance, of a current regulator is in the megohms because the current through it doesn't change when the voltage across it changes - it looks like an open circuit in that respect. But it does conduct a (fixed by the designer) DC current, so depending on the voltage across it at any given moment, one can calculate a DC resistance for that moment by ohm's law. But it still looks like an open circuit to an AC voltage because, again, the changing voltage fails to cause a changing current as it would in a resistance. DC resistance calculations have about as much bearing on current regulator performance as they do on output transformer performance, only less. This isn't rocket science, Ian, and you don't need calculus to understand it. It's covered in any modern electronics text. All of which appears to me as a total nonsequitur in toto, and pure nonsense in parts. You won't find understanding in books, particularly if you have difficulty reading. You need to think a bit too. I took it that "dynamic R" meant the dynamic resistance of the current source. Since it is given as 100k max, and that is very different from your "many megohms", I felt it worth discussion. I may be mistaken, but you have failed to spot where my mistake is, smart-arse. And you are wrong, but I can't now be arsed to tell you where. Final words of wisdom from someone without a clue. Let us know if you figure it out. Fred bye, Ian |
#25
Posted to rec.audio.tubes
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Are all pigs...er... CCL positions equal? was 6J6 driving EL84
In article
, Andre Jute wrote: Since you ask, I am just sitting here wondering whether I should resurrect my notorious Christmas Pipes (named by RdM) and play Gregorian Chant with *extra ambience*, Yes, go for it. (1) I used to keep my CDs standing on end in precisely right-size cardboard boxes (US: cartons) that supermarkets get their vegetables and fruit delivered in, with lips and indents for stacking. But 250-300 CDs per box weigh a lot when they are stacked to the ceiling and you want a disc from the bottommost box. Woulda been even heavier if I ever got around to making the wooden boxes I intended... Then I saw big books of CD disc pockets at a department store and bought their entire stock for a few hundred euro. The books each have enough pockets to hold up to 250 discs, booklets, and so on. A full book takes up only three inches of bookshelf space and, while heavy, is nowhere near as heavy as a big box full of CD disc cases and extraneous paperwork, nor as awkward to handle. How on earth do they fit 250 CDs & booklets in a book only 3 inches thick? Assuming the book is 2 CDs deep and three high, a pretty large book, that would be 40 CDs thick, or nearly 14 CDs per inch, which seems a bit much when considering that the book needs covers and internal pockets for the CDs. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#26
Posted to rec.audio.tubes
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6J6 driving EL84
snip interesting stuff...
What voltage have you got across the source, Al, and what value current-sensing resistor? There is no timing info on the datasheet. cheers, Ian |
#27
Posted to rec.audio.tubes
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6J6 driving EL84
On Dec 19, 6:48�pm, "Ian Iveson"
wrote: snip interesting stuff... What voltage have you got across the source, Al, and what value current-sensing resistor? There is no timing info on the datasheet. cheers, Ian Hi RATs! I haven't got the parts yet. The schematic just says IXYS at -66V with the current through the shared cathode set at 8 mA. I assume I will use my fabulous trial and measure to get similar values. Meanwhile, I stumbled upon a 6528 SE What a tube! Too bad Aunty Klectron Sply doest even list it anymore : ( I only have two, TungSol. Happy Ears! Al |
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