Transformer size and sound quality

[juniper]

I was wondering how the size of a transformer affects sound quality. Sometimes when I go to the local surplus, I see military transformers that are the size of a cantaloupe and have wondered if you could make an interesting amp out of them.

[willland]

The size of the transformer in itself has nothing to do with sound "quality" but the quality and size in addition to the other parts of the power supply can have an affect on sound quality and speaker driving capabilities.

Bill

[Chris A]

Try this:  https://community.klipsch.com/index.php?/topic/142049-rip-david-manley/?p=1603571

 

...and this: http://sound.westhost.com/valves/design2.html#s2

 

Perhaps the quickest way to learn about tube/valve amplifiers is by reading from those more critical than from those that  are nostalgic on some romanticized history of these type of amplifier designs. 

 

Chris

[xxJPMxx]

I was wondering how the size of a transformer affects sound quality. Sometimes when I go to the local surplus, I see military transformers that are the size of a cantaloupe and have wondered if you could make an interesting amp out of them.

 

Usually size is a good indicator of performance, the larger the core the later it will go into saturation. Output transformers need to transfer power at lower frequencies than mains so keep that in mind. Basically if you want to use a mains transformer for output finals expect a lower power output since it was originally only designed for 60Hz. Single ended designs have standing DC current and are designed differently than push pull transformers, they physically have to be larger.

 

If you do buy a used transformers feel free to PM me or post what you got that way there we can advise you on the steps to properly test it.

[juniper]

What a great read Chris, thanks, there is a lot of info in both of those links....very cool!!!!!

[xxJPMxx]

That article linked is garbage. Ambient noise? Large rooms? Is that the only defense against low power single ended amps? I agree if you need more power go with a different design but most of us don't need 50-100 watts.

 

There is no problems with a well designed single ended tube amp, most people don't need a lot of power. If you require more power than yes it can be achieved via a different topology.

 

The problem is most people don't understand how to design one properly and tend to "borrow" or "clone" old designs from the time tube amps were the only thing around. How many Klipsch Heritage speakers go down to 20Hz? None. Cornwall and Khorn go to 32Hz or something. Also how many go over 20kHz? Bandwidth limitations and lumpy frequency responses are due to speaker and crossovers not amps. A single ended tube amp can easily achieve 20Hz-20kHz. Are we dogs? Do we need an amp to produce sound to 100kHz? 

 

 

I love people that probably have heard one POS chinese SE amp and made their mind up that they don't like them.

[Chris A]

Note that if you're not trying to get much power out of the amplifier, you can get away with not paying attention to many of the things that both authors were talking about, albeit with some issues during big music peaks that go by very quickly, but that may not be heard/sensed consciously (only unconsciously),

 

This is very similar to what I find happens on music tracks that have been limited (i.e., clipped, and there is a high percentage that have had this done).  If you're only talking about a handful of peaks, then you'll probably never hear it. But if your talking about 100s of clips per second as you see in a lot of popular music produced since 1991, and particularly since 2000, I find that the listening becomes fatiguing and edgy, and you turn it down until you can't hear it as much.

 

Note also that most people running tubes outside of the Klipsch community aren't running horn loaded with sensitivities at or above 100 dB/w at 1 metre.  They're running something more like 90 or 88 dB/w-m loudspeakers, and that's a problem for tubes, especially single ended designs with output transformers.  PWK made using tubes much easier with his loudspeakers, but caveat emptor applies if you get out of bounds on the constraints mentioned above.

 

I'll let the tube hobbyists speak for themselves since this is their domain (...and I didn't pay attention to that when I responded to your post: I don't browse by subforum). 

 

Only one item to note: it isn't only about iron saturation in the output transformers.  There are other design factors to pay attention to.

 

Enjoy!

 

Chris

Edited October 29, 2015 by Chris A

[tube fanatic]

Chris, one can always find respected individuals whose points of view differ from those of equally respected colleagues.  If you read through Nelson Pass' comments on push-pull in his article on single ended amps, you will find something quite different from those of Manley (who very mistakenly attributed low level listening in small rooms with little ambient noise solely to the Japanese- he should have met some of the folks I know) and Elliott:

https://passlabs.com/articles/single-ended-class-a

To say that those who believe in single ended amps "are nostalgic on some romanticized history of these type of amplifier designs" gives a very wrong impression to those seeking information.  Single ended designs, depending on their operating parameters, can have very low distortion and a very wide bandwidth (and I totally agree with JPs comments about not needing an amp with a high frequency response approaching daylight- in fact, some of that equipment actually sounds worse because of it than others with a more limited top end).  Push-pull is far from a miraculous cure-all for tube related issues.  In fact, if you want to hear just how crappy that mode of operation can sound, listen to some with gross imbalances in either the phase inverter or output stage.  That mode of operation will only deliver decent sound if the balance is near perfect.  In the real world, that's rarely the case unless one is constantly checking both the AC and DC balance of the amp as the tubes age.  Additionally, as has been clearly demonstrated using curve tracers, tubes which are matched at only a single operating point can be grossly imbalanced over their operating range when playing music.  I also won't bother getting into the old argument about ultralinear vs. push-pull pentodes or triodes.  The former was intended to fix some of the issues, but fell far short in my opinion.  There was no consensus back then, and the matter still comes down to subjective impressions as opposed to measurable parameters.  And, as you noted in your last post above, this forum is about using tubes with Klipsch speakers (as opposed to competitors' less efficient offerings!).  It's the proverbial "marriage made in heaven" which should be experienced by any prospective purchaser of same.

Maynard

[xxJPMxx]

This is very similar to what I find happens on music tracks that have been limited (i.e., clipped, and there is a high percentage that have had this done). If you're only talking about a handful of peaks, then you'll probably never hear it. But if your talking about 100s of clips per second as you see in a lot of popular music produced since 1991, and particularly since 2000, I find that the listening becomes fatiguing and edgy, and you turn it down until you can't hear it as much.

 

Are we talking digital or Analog? Digital medium has a 0db maximum, if the recording clips at this point it won't matter what amp it's played through. I agree in that from compression and the loudness war dynamics have gone through the window these days. In my opinion it's audible on all hifi gear.

[juniper]

Discussions like this, is one of the reasons I like audio. Its so engaging to hear peoples views and passions... we always hear how some things are voiced a certain way and sound great, and some things test good but may not sound great....then we can get into the whole human ear discussion. Interesting how Jean Hiraga, who is of Japanese descent, took a pair of old speakers, there is even a pair in our garage sale section, added some tube amps, a box, and some other things and many people at the high end Munich show thought his sound was the best, just a few years back....

[Dr Morbius]

JPM is correct about larger transformers.