anders - since you have esl's on mind, try searching the posts already done on that subject right here,..might help some. Personally, I have dd servos and think they're the best. However, if you don't care to mess with high voltages and such, perhaps a lower voltage tube amp with a single OT custom wound to interface with the esl. I've never seen the point of having 2 xfmrs in the path. I don't think the single xfmr approach is widely used and you'd be among the pioneers by using such a beast. It's a valid approach IMO.
I have built a few DIY designs........
and modified a few vintage amps with best tubes & components. A SET 845 is good sounding & also triode connected PPP 6V6. The tubes & circuitry driving either the 845 or 6V6 can sonically make for a stellar performer or just average sounding amp.
A direct coupled 76 to 6SN7 for the 6V6 or 76 to a 6J5 for the 845 operated at 550 volts plate performs excellent. Tung Sol or RCA 76 round plate tubes sounded best. The Sylvania 6SN7W with T shape plates are excellent. The Sylvania 6J5GT is also great. The Shuguang 845B is excellent and the GE 6V6GTA with grey plates or older Sylvania 1940s to early 1950s era 6V6GT are excellent. Cheaper than the NOS 6V6GT are early Sylvania 7C5. Same tubes, different sockets.
Mills & Vishey are good sounding resistors. PIO coupling caps or even AuriCap are good. A Sylvania 5R4GYB or Mullard GZ34 are good sounding rectifiers. Power supply should use oil motor run caps & Solen polyproplyene caps further down the B+ circuitry are superior over any electrolytic type.
I never cathode bypass with a cap on the 76, 6J5 or 6SN7 tubes. Sounds a little distorted.
Quality output iron is important. Vintage Peerless, trannys from the Sansui 1000A, etc make for good sounding amps. The PPP 6V6 wants about 6K or higher primary to open up sonically.
You see, you can not expect a great sounding amp unless the tube types & components are specified with the circuit details. Any less then that info, and you may as well just 'shoot craps'.
Finally, build a 76 (6P5GT same tube, different socket) or 12B4 linestage preamp & you will have a great system.
and modified a few vintage amps with best tubes & components. A SET 845 is good sounding & also triode connected PPP 6V6. The tubes & circuitry driving either the 845 or 6V6 can sonically make for a stellar performer or just average sounding amp.
A direct coupled 76 to 6SN7 for the 6V6 or 76 to a 6J5 for the 845 operated at 550 volts plate performs excellent. Tung Sol or RCA 76 round plate tubes sounded best. The Sylvania 6SN7W with T shape plates are excellent. The Sylvania 6J5GT is also great. The Shuguang 845B is excellent and the GE 6V6GTA with grey plates or older Sylvania 1940s to early 1950s era 6V6GT are excellent. Cheaper than the NOS 6V6GT are early Sylvania 7C5. Same tubes, different sockets.
Mills & Vishey are good sounding resistors. PIO coupling caps or even AuriCap are good. A Sylvania 5R4GYB or Mullard GZ34 are good sounding rectifiers. Power supply should use oil motor run caps & Solen polyproplyene caps further down the B+ circuitry are superior over any electrolytic type.
I never cathode bypass with a cap on the 76, 6J5 or 6SN7 tubes. Sounds a little distorted.
Quality output iron is important. Vintage Peerless, trannys from the Sansui 1000A, etc make for good sounding amps. The PPP 6V6 wants about 6K or higher primary to open up sonically.
You see, you can not expect a great sounding amp unless the tube types & components are specified with the circuit details. Any less then that info, and you may as well just 'shoot craps'.
Finally, build a 76 (6P5GT same tube, different socket) or 12B4 linestage preamp & you will have a great system.
I agree pretty much %100 with amperex - well said. An amp is all too much system dependent and I have yet to see any manufactured amp that is built the way an amp really should be, aside from the $20,000 units out there. I got my doubts even about those too,..just high priced fleece jobs for all I see. You'll have to drill down and get very specific about parts and the functions they perform,..not many seem to really do that. Ignoring all the hype out there and staying with the basics is a good place to start. Not sure this adds much, but perhaps getting an amp that is close to what you need and modding it might be a start. Either way, you have your work cut out for you.
I completely agree with amperex here. I think a few of us have been very impressed by our PPP 6V6 amps, and with the same circuit, 76 no bypass DC coupled to 6SN7, no feedback. My version was all loctal - 7A4 to 7AF7 to 7C5. Same thing in different socks. That should give you enough power, hopefully. I used a 6.6K OPT from O-netics, same as Lynn Olsen mentioned in another post. The 76 could be replaced by a 6P5GT, CV1932 or - probably best of all - a 7193/2C22. This may not be absolutely the best amp available but it's close, has cheap parts (especially in loctal, where you can use 14A4, 14N7/14AF7, 14C5) and the O-netics are really good value. For parts I'd use Russian ex-military teflon coupling caps and some motor run polypropylenes in the power supply. Not 'exotic' but about as good as it gets. Two chokes a side is good. Good resistors like Holco or Dale/Vishay and good hookup wire. That's about it.
I agree that power supply chokes are almost essential in a power amp. Big and expensive, but sweet sounding.
Shoog
Shoog
I should have added...
The better PS design is an LCLC to the power tube(s), then another LC section to the other tubes in a monoblock design
In a single power transformer stereo amp, prefer a single LC section to two seperate LC sections supplying each channel, then two seperate LC (again one for each channel) to the rest of the tubes. Two smaller chokes for each section are not any more expensive than a higher current choke for both sections. The last choke in the LCLCLC can be a inexpensive Hammond choke in the $10 to $12 range for most common designs.
If I have a transformer that produces the correct high voltage, I will not disregard a capacitor input design with a 10 to 20uf motor run oil cap.
I would use a CLC to the power tubes & another LC to the rest of the tubes. In that CLC section, I want about 10 HY choke where as 5 HY chokes meet my needs in a LCLC.
The reason a good power supply is needed is the tubes modulate the B+. A good power supply performs well with low ripple, isolating amplifier sections & shunting noise to ground.
Regarding the power supply energy storage, a SET amp is more critical than a PP amp. The last cap in a SET amp feeding a power tube such as an 845 should have say a 7 HY choke feeding a 250 to 500 uF oil cap. That is a lot of energy storage, but the tube is 'swinging' a lot of current if operating into Class A2 at higher volume levels. PP is more constant as one power tube draws less current and the other power tube draws more current- ie, push-pull.
From an engineering stand-point, I am impressed with the PP power tube output design.
The better PS design is an LCLC to the power tube(s), then another LC section to the other tubes in a monoblock design
In a single power transformer stereo amp, prefer a single LC section to two seperate LC sections supplying each channel, then two seperate LC (again one for each channel) to the rest of the tubes. Two smaller chokes for each section are not any more expensive than a higher current choke for both sections. The last choke in the LCLCLC can be a inexpensive Hammond choke in the $10 to $12 range for most common designs.
If I have a transformer that produces the correct high voltage, I will not disregard a capacitor input design with a 10 to 20uf motor run oil cap.
I would use a CLC to the power tubes & another LC to the rest of the tubes. In that CLC section, I want about 10 HY choke where as 5 HY chokes meet my needs in a LCLC.
The reason a good power supply is needed is the tubes modulate the B+. A good power supply performs well with low ripple, isolating amplifier sections & shunting noise to ground.
Regarding the power supply energy storage, a SET amp is more critical than a PP amp. The last cap in a SET amp feeding a power tube such as an 845 should have say a 7 HY choke feeding a 250 to 500 uF oil cap. That is a lot of energy storage, but the tube is 'swinging' a lot of current if operating into Class A2 at higher volume levels. PP is more constant as one power tube draws less current and the other power tube draws more current- ie, push-pull.
From an engineering stand-point, I am impressed with the PP power tube output design.
"Regarding the power supply energy storage, a SET amp is more critical than a PP amp. The last cap in a SET amp feeding a power tube such as an 845 should have say a 7 HY choke feeding a 250 to 500 uF oil cap. That is a lot of energy storage, but the tube is 'swinging' a lot of current if operating into Class A2 at higher volume levels. PP is more constant as one power tube draws less current and the other power tube draws more current- ie, push-pull."
A CCS loaded output stage draws a constant current regardless of load. It can function well on tiny amounts of final capacitance. Since good high voltage caps can be the most difficult and expensive parts to source, this is something to consider as an option.
Shoog
A CCS loaded output stage draws a constant current regardless of load. It can function well on tiny amounts of final capacitance. Since good high voltage caps can be the most difficult and expensive parts to source, this is something to consider as an option.
Shoog
Audio nuts like to say there is no best but I have to disagree. The best would be any amp that could do everything an amp is supposed to do and nothing it is not supposed to do. I would like to add that it should be able to do this no matter what speaker it is connected to. It should be a "wire with gain". The problem is that most amps arn't designed that way and most amps can't acheive this standard yet.
Sometimes it seems that threads like "what is the best...?" deteriorate into worthlessness almost instantly but for some reason this one has had a ton of interesting information, ideas and proposals for circuits! 😀
I'm learning a lot just by reading all the responses. Thanks to the experts and more experienced "listeners" for posting their opinions.
I'm learning a lot just by reading all the responses. Thanks to the experts and more experienced "listeners" for posting their opinions.
On the 'best tube amp', let me make a comparison:
If you can convince me to change my favourite colour, with proof that another is better, there may actually exist a 'best' tube amp for you. Perhaps, it might be the inverse, if somebody can convince *YOU* to change your favourite colour...there might be a 'best' one for you out there.
Of course, you might then be convinced that there exists another 'better' amp.
Of course, it's my opinion that there cannot be a single best amp to build. I like mine, and I've had a few folks making contributions to tweaking them. Hopefully, the next ones will be better...🙂
cheers,
Douglas
If you can convince me to change my favourite colour, with proof that another is better, there may actually exist a 'best' tube amp for you. Perhaps, it might be the inverse, if somebody can convince *YOU* to change your favourite colour...there might be a 'best' one for you out there.
Of course, you might then be convinced that there exists another 'better' amp.
Of course, it's my opinion that there cannot be a single best amp to build. I like mine, and I've had a few folks making contributions to tweaking them. Hopefully, the next ones will be better...🙂
cheers,
Douglas
On the subject of "a perfect amp should be a straight wire with gain which would work into any speaker", I know this is an oft cited bit of theory, but to me it's like saying 'the perfect partner would be as beautiful as could possibly be, be wonderfully good natured and exciting and would love you forever despite your faults'. In other words, we live in the real world and we have real world choices. On the subject of perfection, I'm also reminded of the words of a doctor "Show me a drug with no side effects and I'll show you a drug that does nothing".
A few folks have cited the Peter Walker (AKA founder of Quad) quote: ‘a straight wire with gain’, but I'm firmly in Andy's camp here; after all, we're all looking for our own ideal of audio perfection which can be viewed from a number of differing perspectives. The straight wire etc. theorum is all very well if you can assume that all of the components in the chain perform in a similarly idealistic manner - but that ain't the case no matter what budget you've got. Most of us that are honest with ourselves will admit that although there are arguments for the linear & sonic purity inherent with tubes over solid state designs, all components, valves alike, do add colour to the signal. I suppose it's all down to whether your looking for a "full flavour" valve sound, or want to stay a little closer to the truth. I once tweaked around with an old army surplus open reel some years ago that acted almost like an aural exiter! - switching between the source & recorded signal revealed a more open, palpable and believable sound which was much more euphonic. Academically very interesting, but hardly HiFi - otherwise we'd all be knitting studio effects into our systems!
Perfect Amp.........
The replies more address something like 'How to avoid the mediocre amp design'.
Interesting with so many designs and few stellar performers. No mention of the best brand of tubes & components in DIY designs should be a warning to others as well. Obviously, some of the amp designs out there was not tweaked at all.
The replies more address something like 'How to avoid the mediocre amp design'.
Interesting with so many designs and few stellar performers. No mention of the best brand of tubes & components in DIY designs should be a warning to others as well. Obviously, some of the amp designs out there was not tweaked at all.
This one looks interesting: http://www.goodsoundclub.com/Melquiades.aspx
By the time I had waded thigh high through the pompous definitions of what you should/should not be as a listener, what you should/should not have for speakers, what you should/should not do with bi-amping I'd decided that whoever could digest pages of such claptrap was welcome to the product. Are these guys on drugs?
By the time I had waded thigh high through the pompous definitions of what you should/should not be as a listener, what you should/should not have for speakers, what you should/should not do with bi-amping I'd decided that whoever could digest pages of such claptrap was welcome to the product. Are these guys on drugs?
I am seriously considering building the Karna. Not cheap by any means and going to be a hard build, but I love a good challenge. 
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