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

[fpitas]

I started my electronic finger exercises with the construction of detector receivers.

My dad's friends gave me old stuff from an early age. So I had a collection of popular tubes, selenium rectiers etc. I had a few Heathkits growing up too, some of which were very educational.

 

[computer-audiophile]

Heathkit was always a dream as a pupil in Germany. I had the catalog to dream about. We had the company Radio RIM which made kits.

 

[mhardy6647]

A few Heathkits here.
I never built any Heathkit hifi, but I did build a whole bunch of the 400 VDC power supplies when I was in college. We used them in undergrad biochem labs for electrophoresis power supplies. Indeed, the lab in which I did my PhD had one for electrophoresis, too. That latter P/S (which I didn't build, ironically) was passed along to me years later by my thesis advisor.

 

[fpitas]

A few Heathkits here.
I never built any Heathkit hifi, but I did build a whole bunch of the 400 VDC power supplies when I was in college. We used them in undergrad biochem labs for electrophoresis power supplies. Indeed, the lab in which I did my PhD had one for electrophoresis, too. That latter P/S (which I didn't build, ironically) was passed along to me years later by my thesis advisor.

I bet those had tube series elements, at that voltage.

 

[egellings]

In Stereophile's review of the Mastersound 845 Compact integrated amplifier, which is a tube amp, editor in chief Jim Austin is once again publicly disagreeing with a reviewer; this time it's John Atkinson.

Basically, the TL;DR is that in the measurements section of the review, Atkinson (JA1) qualifies his comments by saying -- I paraphrase -- that he's commenting on its performance as a tube amp, with the recognition that tube amps don't perform as well as solid state. He adds the following explanation in the article's comments section: "When I write 'The amp performs along the lines of what one would expect for a tube amp with zero negative feedback,' the measured performance predicts departures from a neutral sonic character that will be audible."

To which Jim Austin (JA2) responds:

I just want to make it clear that the opinion expressed by JA1 here, though very well-supported, is not universally shared.

It's true--no one connected with reality can deny it--that certain features in old-school tube amps cause departures from neutrality, especially with loudspeakers with impedance curves that drop below, let us say, 4 ohms, which is most modern loudspeakers. No one can deny it because they are measurable at clearly audible levels. But there's another school of thought--embraced by certain other Stereophile writers--that believes that something less tangible is retained in some such amplifiers that is lost in demonstrably more accurate ones. Such opinions are based on subjective experience--self-perceived connection with the music. This makes them literally irrefutable-- they cannot be tested objectively, so they cannot be contradicted, which is annoying--yet (and this is my opinion, as the magazine's editor), in a magazine committed to subjective experience--to listening--above all else, such opinions must not be dismissed out of hand.

Edit: I thought I should add that the opinions/beliefs I'm referring to are held by many of the most experienced, devoted, passionate audiophiles. I do not take that lightly.

Jim Austin, Editor
Stereophile


Still sticking to the "some things can't be measured" trope.

What maybe can't be measured is a listener's impression and opinion of the S.Q. of an amplifier. Sorry to say, the amplifier's characteristics and their interaction with speaker impedance are well understood and can be accurately characterized via measurements. There's no mystery about that.

 

[SIY]

I bet those had tube series elements, at that voltage.

The one I have (IP-32) uses a pair of 6L6.

 

[computer-audiophile]

A few Heathkits here.
I never built any Heathkit hifi, but I did build a whole bunch of the 400 VDC power supplies when I was in college. We used them in undergrad biochem labs for electrophoresis power supplies. Indeed, the lab in which I did my PhD had one for electrophoresis, too. That latter P/S (which I didn't build, ironically) was passed along to me years later by my thesis advisor.

Yes, one has beautiful memories!

I didn't build Radio RIM audio stuff either. But one very early thing I have soldered together as a pupil was a Wheatstone bridge from a RIM kit, with a so-called 'magic eye' (green fluorescent indicator tube) as zero indicator. It came like this: Because I was the best in class in physics and my teacher wanted to promote it, I had the key to the physics room and was allowed to prepare the experiments for the class, make setups there and assist him.

 

[computer-audiophile]

All my amps/source equipment is in a separate room from my speakers, so I don't get to see the glowy tubes while listening. But I prefer a clean look in my listening room, with little equipment to distract.

You seem to be a perfectionist and an aesthete. I would like to appreciate that, even if I come to different solutions in some respects.

 

[Cbdb2]

Whoa, I've never seen 500 ohm drivers. Since nobody else tried it, there's probably a good reason.

To get 100 watts you need 220V RMS. You'ld need +/- 300v rails. Or an output transformer.

 

[fpitas]

To get 100 watts you need 220V RMS. You'ld need +/- 300v rails.

Sounds like a tube B+

 

[OldenEars]

High impedance field coil loudspeakers are found in old radio sets.

1950s fender champ?

 

[computer-audiophile]

1950s fender champ?

Yes, you are not wrong!

Because pocket money was still tight around 1963, I actually used old tube radio sets from the dump as amplifiers for a cheap department store guitar that had been given a 'Schaller' pickup. The preamp that I had designed myself was made by an early transistor powered by a small 9V battery.

 

[Oristo]

I never built any Heathkit hifi

I happened to be of age such that many tech employees at my second corporate job had bought Heathkit equipment and failed to successfully complete assembly,
and word got around that I would quietly take those off their hands. Time lurches on, but I still have a few pieces.

 

[Sal1950]

I happened to be of age such that many tech employees at my second corporate job had bought Heathkit equipment and failed to successfully complete assembly,

I wonder how many of those big complex Color TV kits ended up in second or third hands to complete or repair?
At a time when Color TV's were expensive the kit looked like a budget option, but they weren't for just any Joe Soldering Sixpack.

 

[OldenEars]

True in general.

Back in the good old days, Philips (e.g.) made high impedance speakers and matching OTL amplifiers.

Even in the older (not necessarily gooder, though) days, so did Stephens.

View attachment 285622

Stephens

I'd this from fallout ?

 

[Kal Rubinson]

But if that's true for multich, why not for stereo?

Because the most of the original 360 degrees of directional information is lost when filtered down into two frontally-placed speakers and much more of it is conveyed via multichannel playback.

 

[Oristo]

how many

One color kit sufficed for me; the monochrome kits were fairly trivial.

 

[DonH56]

I wonder how many of those big complex Color TV kits ended up in second or third hands to complete or repair?
At a time when Color TV's were expensive the kit looked like a budget option, but they weren't for just any Joe Soldering Sixpack.

I made and/or finished a few for friends and such. There were pretty good performance-wise but a bear to repair, and the modular design meant a lot of places for connections to go bad. The assembly was tedious but fairly straight-forward IIRC. Most of the modules for the later versions were pre-assembled IIRC.

 

[atmasphere]

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.

We've been building fully differential balanced OTLs for decades. If you run feedback on them (which we've done) then all of these comments are false.

To date, I've experienced nothing to suggest that tubes have an inherent "sound", but it's pretty easy to tweak tube amplifier circuits in order to achieve "sweeter, more relaxed" sonics. In some cases, the modifications can be as simple as reducing negative feedback, until frequency response starts rolling off at oh, say 5 kHz.

OMG!! Do you really think tubes have performance that poor? One wonders how color tube TVs were possible, where the chroma amplifiers had to have 10MHz response. IOW there are many tube amps which have open loop response far in excess of 20KHz, less alone 5KHz...

Bandwidth-limited square wave response has ringing. Gibbs phenomenon
Negative feedback with delay (e.g. global feedback in vacuum tube amplifiers) exacerbates it.

Nonsense. All that's needed is proper feedback loop design. Look- I get that tubes are outdated and such, but can we at least not spread outright myth while denigrating them?

 

[mhardy6647]

I would love to have a working RCA CTC-16 chassis color set -- just sayin'.
21 inch round CRT all vacuum tube color TV ... my father's single favorite. He was a TV repairman, and a rabid RCA fan.

(random internet photo of a CTC-16 in a simple "contemporary" cabinet)

I actually had an RCA CTC-15 in an early American style cabinet in my room as a teenager. It worked great, but was old enough to have had no UHF tuner and it had a broken on-off switch (i.e., had to plug it in to turn it on). Thus life as the child of a TV repair person -- sort of like the cobbler's children always needing new shoes, you know?