I believe we can talk about good sound, price versus performance, space required, WAF (wife acceptance factor),
proper system integration, and the preference of the listener as to how the total system sounds, in his room, and with the music the listener plays back.
All of that the above mentions are much more complex than simply testing harmonic distortion, intermodulation distortion, frequency response, impulse respone, damping factor, and other tests.
But, as a person who has been making calibrated measurements since 1959, I do believe that good measurements and proper interpretation of those measurements can play a large part in helping to increase the accuracy of individual components and the system as a whole.
But, that is just my opinion.
proper system integration, and the preference of the listener as to how the total system sounds, in his room, and with the music the listener plays back.
All of that the above mentions are much more complex than simply testing harmonic distortion, intermodulation distortion, frequency response, impulse respone, damping factor, and other tests.
But, as a person who has been making calibrated measurements since 1959, I do believe that good measurements and proper interpretation of those measurements can play a large part in helping to increase the accuracy of individual components and the system as a whole.
But, that is just my opinion.
As I understand, in the good old days of analog sound many engineers built their custom recording, cutting, and monitoring amplifiers. I have read this in a few technical recording notes. I dont remember what pro said it that good transformers are transparent and not coloring, and you can put a number of them in amplification chain without causing sound degradation. That's where professional quality transformers, like UTC HA and LS series, ruled. Coupling capacitors were used in consumer grade equipment.
Isn't it funny that in some of his amplifiers Sakuma used two transformers back-to-back - because a single interstage transformed with required characteristics was not available? Like plate-to-line followed by line-to-grids.
Isn't it funny that in some of his amplifiers Sakuma used two transformers back-to-back - because a single interstage transformed with required characteristics was not available? Like plate-to-line followed by line-to-grids.
Hi Andy - re your prefered line up for a three stage se amp with DH first stage - have you looked at using a DH pentode followed by a type 76 or similar? I'm using an Osram Z21 as input with a 76 C/F - thoughts......
Rgds
David
I would want a triode as input tube, or a pentode in triode. The 2P29L is the easiest by far to use and sounds really nice so that's my preferred input. That means I only need a gain of 3 or so (maybe up to 5) in the driver tube, and a low anode resistance so I can use a resistor load. I did look at 76, 37, 56, 27, 6P5 and that family but they have too much gain and the anode resistance is too high. Hence looking at 1626 and 6AH4 instead.
I don't have any background in solid state so I can't design with it, but I'm open to using a Mosfet driver stage for x3 gain. Any designs I can use would be welcome!
Thanks for that but having a driver with less than 1x gain and a high gain DH input does fill the criteria surely....
Ah yes - didn't notice you meant a pentode and CF. Yes, that works, but not for me. I like triodes. Many pentode fans, though.
Unless you've heard everything that's been created before, there is no way to know if something you've created is better or not.
On another forum, my posts have a few little signature lines, one of which is: "I'm not searching for perfection so it never eludes me. If anything I build approaches perfaction, it's purely by accident."
Another is: "The most interesting tubes are not the ones that everyone else uses."
I enjoy trying different things and different combinations of things. But I'm not really even trying to create something that's better than anything I've created before. If that's the result, then great, but even if it's just a bit different, and not horrible, I can appreciate it for what it is. Everything has its own flavor.
And, just to clarify, I never said that the difference between coupling methods cannot be heard, only that some of the technical advantages you mentioned would likely not be audible in most situations.
And I never said that distortion doesn't matter.
I would say that, to me, one aspect of "rational" involves the cost and, by extension, the perceived cost / benefit ratio. Obviously, everyone sets these limits for themselves based on what they consider to be rational. I mean it's great that you have the knowledge and ability to build your own interstage transformers. But, for me, and apparently for the vast majority of DIY builders and commercial manufacturers, the costs outweigh the benefits.
I prefer to use everyday, unexceptional, readily available parts rather than ones that are essentially unobtainable, very expensive, or require exceptional fabrication skills. While some of the tubes I use are not always quite so readily available, they are not particularly expensive - and often quite cheap - because they are not so well known.
And I'm all for distortion reduction efforts, however small and incremental, that result in audible improvements. It's not about the difference between dramatically audible and incrementally audible. It's about audible vs inaudible. Once you go below a certain percentage they become inaudible, even though they are still quite measurable.
If some people feel the urge to push for even lower levels "in the name of science", even though they're inaudible, that's fine. That's certainly one way you can validly compare what you've built to what others have built even without being able to hear them both.
But, as all of us who love tube gear know, such measurements don't always mean much. If they did we would all be listening to SS gear and the little $50 Chinese preamp I described earlier, with its 0.0032% distortion would be much more pleasing to listen to than my DIY Boogie Factor 1626 preamp which, I'm quite sure, has 100x more distortion and probably much more than that.
FlaCharlie - I have to agree with you on every point.
Whether one can hear differences or not is a controversial thing. Bud Purvine of O-netics not recommended using anything better than his entry level output transformers if one has regular speakers. He said it would be a waste of money because one will not hear any difference. But sure it didn't mean that his Level 4 transformers were not worth it.
Lynn Olson advocated the use of vacuum tube rectification. He experienced unacceptable levels of noise with solid state rectifiers. But some believe it doesn't make any difference. The question is, whether these deniers have the same level of equipment as Lynn's?
Same Mr. Olson designed an amplifier with parafeed phase-inverting transformer. The parafeed capacitor was the only capacitor in the signal path. He said that different capacitors that he tried brought about different kinds of coloration, so he became convinced that capacitor coloration dominated the sound signature of the amplifier. The whole design was scrapped in favor of full transformer-coupled topology. But some believe that transformer coupling is not better than RC-coupling.
David Slagle makes nice transformer volume controls. Somewhat expensive, but many people are willing to pay the price. He said that 80% nickel core has the best sound. But if one swaps an $2 volume pot in a Scott or Fisher amplifier for a Slagleformer, there would be hardly any difference.
Whether one can hear differences or not is a controversial thing. Bud Purvine of O-netics not recommended using anything better than his entry level output transformers if one has regular speakers. He said it would be a waste of money because one will not hear any difference. But sure it didn't mean that his Level 4 transformers were not worth it.
Lynn Olson advocated the use of vacuum tube rectification. He experienced unacceptable levels of noise with solid state rectifiers. But some believe it doesn't make any difference. The question is, whether these deniers have the same level of equipment as Lynn's?
Same Mr. Olson designed an amplifier with parafeed phase-inverting transformer. The parafeed capacitor was the only capacitor in the signal path. He said that different capacitors that he tried brought about different kinds of coloration, so he became convinced that capacitor coloration dominated the sound signature of the amplifier. The whole design was scrapped in favor of full transformer-coupled topology. But some believe that transformer coupling is not better than RC-coupling.
David Slagle makes nice transformer volume controls. Somewhat expensive, but many people are willing to pay the price. He said that 80% nickel core has the best sound. But if one swaps an $2 volume pot in a Scott or Fisher amplifier for a Slagleformer, there would be hardly any difference.
I'm one who generally prefers RC coupling as long as the cap is teflon, even FT-2 or FT-3.
I don't know about "hardly any difference" with a Slagle autoformer, which generally comes after the stage rather than before. Users report significantly better sound.
He sure did like his Tamuras. I am also intrigued that he would sometimes put a rheostat on the low impedance end between his transformers, presumably for volume and possibly tone control. Also, and 845 in SE IT-coupled to a pair of 6V6? Gotta love that.
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What I meant was that you need a certain level of quality in your reproduction chain for TVC to make a difference.
Using low value wirewound potentiometer as volume control makes sense to me, even if it requires back-to-back step-down and step-up transformers. One might ask why TVC is better than a traditional resistive attenuator. I think the answer could be lower thermal noise of low resistance, and more transparent quality of solid metal conductor compared to semiconductor or metallization films.He sure did like his Tamuras. I am also intrigued that he would sometimes put a rheostat on the low impedance end between his transformers, presumably for volume and possibly tone control. Also, and 845 in SE IT-coupled to a pair of 6V6? Gotta love that.
Driving 6V6 with 845 is totally nuts from traditional point of view, but maybe that's the famous chef's recipe for a perfect sound flavor?
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The whole amplifier is nuts, 'Unique sound because no one in their right mind would ever build one the same'. So, then it is 'art'?.. okay, so let it be art.
Consider the output stage clips with 35Vp-p and the input tube has a voltage gain of 9.5. You could remove three interstage transformers, the DHT and its 1050V B supply, run the whole thing from 250VDC and to full output with less than 1.5vRMS input. And, if you display it in a restaurant as the result of 'trancending ego boundaries', you can still call it art ;-)
How about voltage amplification by pentode and applying about 16dB of GNF? If the idea of GNF goes against the grain one could always turn the penthode into a triode (like Tom Schlangen did with EF184 and ECL84 here http://www.audiodesignguide.com/New2A3/ETF06TS.pdf).
Good point & verified long ago as shewn in this piece lifted from RDH4. In this case the pentode connexion has better
distortion figures than the same tube as a triode up to 21 vrms. That would fully drive any power tube whose cathode bias is 30V.
At levels for normal listening the pentode driven output stage amp should perform better than it triode driven opposite.
The pentode sound thing may be something left over from the triode vs pentode sound debate resulting
from the daze of mass conversion of AM receivers to pentode output toobz. 😀
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Back just after the dust had settled from the great meteor impact while working in the research lab I often
built simpler circuits completely without a chassis during testing. We called those things 'mid air circuits'.
We often took the short walk to the local electronics parts store, Electrosonic at lunch time to pick up small parts.
Close by was an artsy store, hanging mobiles were a common gimmick. One time I took one of my mid air circuits
in, the art nut was really impressed & asked if we could do more, he would sell them.😀
Throw enough money at a project, anything is possible.
The real challenge is to create something of value that ordinary users can afford.
It is also the secret to a successful business.😀
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Like size for instance. I could build a 3 stage 2a3 amp with 2P29L input and 10Y driver. It would probably sound marvellous. I have all the parts. But with both stages in filament bias with chokes in the filament supplies, it would just be too big for me to want to build it.