Stereophile's Jim Austin disagrees w Atkinson; says tubes have something that can't be measured

[Doodski]

Which one is that? I'd like to know.

I think from memory they are Conrad Johnson Premier 12 tube mono blocks. Perhaps @MattHooper can clarify this for us and give us the model number?

 

[computer-audiophile]

Those are the best ever made? Huh.

I do not know the Conrad Johnson, but for many years I prefer only SET anyway today. My last more push-pull amps were the ELV 100 (picture) about 20 years ago and a Line Magnetic LM-211IA until last year. Both I found sonically boring. No trace of the sonic charm of a tube. In comparison with these I prefer then my Yamaha SS amps.

 

[Blumlein 88]

I do not know the Conrad Johnson, but for many years I prefer only SET anyway today. My last more push-pull amps were the ELV 100 (picture) about 20 years ago and a Line Magnetic LM-211IA until last year. Both I found sonically boring. No trace of the sonic charm of a tube. In comparison with these I prefer then my Yamaha SS amps.

That is the weird and inconsistent part. I've never heard an SET that didn't create a caricature of sound of the source recording. I've listened to push-pull triodes and liked them despite their shortcomings. I'm not trying to insult anyone's opinion on what they like, just describing that it varies.

Here is a rather traditional tube power amp that has better measurements. Even it has too much FR variation. Otherwise it is pretty clean. McIntosh did have somewhat different transformers.

McIntosh MC275 power amplifier Measurements | Stereophile.com

Sidebar 3: Measurements To perform the measurements on the McIntosh MC275, I mostly used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com); for some tests, I also used my vintage Audio Precision System One Dual...

www.stereophile.com

 

[JSmith]

The MC275 is quite respectable on the test bench;

McIntosh MC275 power amplifier Measurements | Stereophile.com

Sidebar 3: Measurements To perform the measurements on the McIntosh MC275, I mostly used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com); for some tests, I also used my vintage Audio Precision System One Dual...

www.stereophile.com

Edit: ninja'd by @Blumlein 88


JSmith

 

[fpitas]

The MC275 is quite respectable on the test bench;

McIntosh MC275 power amplifier Measurements | Stereophile.com

Sidebar 3: Measurements To perform the measurements on the McIntosh MC275, I mostly used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com); for some tests, I also used my vintage Audio Precision System One Dual...

www.stereophile.com

Edit: ninja'd by @Blumlein 88


JSmith

Tube amps used to be good measuring, back in the day. It's only lately we've realized they should really be distortion boxes.

 

[SSS]

Same reason modern Corvettes, Cameros, Mustang's , Challengers, etc are so successful.
This isn't 1969 any more.

Good to hear. I like them.

 

[computer-audiophile]

I've never heard an SET that didn't create a caricature of sound

If you were my neighbor, I'd say you can come over and we'll listen and chat a bit. Provided you like classical music.
I've always had a lot of fun and a sense of accomplishment at meetings like this.
The McIntosh amp always reminds me a bit of Harley Davidson in appearance. I can't make friends with that.

 

[SSS]

Does anybody have sound experience with Futterman tube power amps which have no output transformer?

 

[fpitas]

Does anybody have sound experience with Futterman tube power amps which have no output transformer?

No; but Ralph's OTLs from Atmasphere measure pretty well, last I checked. So it can be done.

 

[Blumlein 88]

Does anybody have sound experience with Futterman tube power amps which have no output transformer?

Yes. They can be pretty clean, but in the incarnations I've used lack oomph when push comes to shove. With an efficient enough speaker not a problem.

 

[Blumlein 88]

If you were my neighbor, I'd say you can come over and we'll listen and chat a bit. Provided you like classical music.
I've always had a lot of fun and a sense of accomplishment at meetings like this.
The McIntosh amp always reminds me a bit of Harley Davidson in appearance. I can't make friends with that.

I do like classical and would gladly come listen if we were close enough.

 

[BDWoody]

I don't know why these people refer to us this way. It looks so unprofessional. Just say the site name as we are doing here with stereophile.

They probably don't say Voldemort's name either...

They are threatened by us, and have nowhere to hide. If they get upset about being called out for writing nonsense, maybe they should stop writing nonsense.

 

[SIY]

Does anybody have sound experience with Futterman tube power amps which have no output transformer?

Yes. Paired well with the Quad 57s I had at the time. It was an idiosyncratic circuit, and I suspect that Atmasphere's are quite a bit better.

 

[computer-audiophile]

I did not have an OTL yet. I also didn't want one because I had noticed that they can become unstable and shoot down the speakers. I will exclude Atmasphere, from which I have not yet heard something like that.

 

[ribonucleic]

Well, beauty is in the eye of the beholder. I wouldn't let it in the house

I rank it in the middle of the third quartile of visual attractiveness for tube amps.

Not competitive, as our host would say.

 

[Oristo]

should the frequency dependent crosstalk in a tube system follow the load curve? Or could microphonics add reverb?

My experience with audible vacuum tube microphonics are that they are usually high Q, resonating for a few relatively narrow frequency band stimuli.
While that is arguably reverb, it does not sound like conventional reverb effects.
FWIW, frequency dependent crosstalk in some tube systems can be capacitive coupling, e.g. when a single 12AX7 is used for both channels.

 

[DonH56]

Does anybody have sound experience with Futterman tube power amps which have no output transformer?

Yes. Decent sound, still not super-low output impedance so load-sensitive, pretty much every amp was a little different, and reliability was not spectacular. As others have said, the torch-bearer for OTL tube amps today is Atmas-Sphere AFAIK and Ralph @atmasphere is a member here.

I built a couple of OTL tube amps but did not have much success. The last had an auto bias circuit and output DC servo loop to maintain 0 V DC at the output all using op-amp based circuits. I was really proud of that, then it all blew up when an output tube arced and I discovered I did not have quite enough in the way of protection for the op amps (there's always another path to destruction).

 

[ahofer]

Does anybody have sound experience with Futterman tube power amps which have no output transformer?

They were in a famous blind test:


1987, Stereo Review test - go to page 80 of the pdf

 

[MAB]

They were in a famous blind test:


1987, Stereo Review test - go to page 80 of the pdf

All-time famous test. Many in this thread should read, would save 18 or more pages of nonsense...

 

[Oristo]

Futterman tube power amps

Yes, back in the day, with KLH model 9s, which I very much wanted to own.
I preferred those KLH speakers with other amplifiers in dealers' listening rooms,
but passed on the challenges of owning them.

FWIW, OTL amplifiers are inherently asymmetric; positive excursions to speakers will mismatch negatives, at least for source impedance,
even with carefully matched vacuum tubes, which do not stay matched with any amount of aging.
Non-trivial source impedances typically allow different loudspeakers to sound even more different.