Objectivist or Subjectivist? Give Me a Break

[Phelonious Ponk]

btw, let's use Lamm ML2.1 for your measurement talk about SETs. As they measure well according to JA.

http://www.stereophile.com/content/lamm-ml21-monoblock-power-amplifier-measurements

and assume speakers would be 8ohm, 95+db speakers so work with the specified wattage.

Note that my comment regarding added harmonic content referred to many SETs, not all.

Tim

 

[amirm]

On the topic of distortion and THD, I like Earl Geddes' work: http://www.gedlee.com/downloads/Distortion_AES_I.pdf. And http://www.gedlee.com/downloads/Distortion_AES_II.pdf. A more layman friendly version is in this article: http://www.gedlee.com/downloads/THD_.pdf.

 

[Gregadd]

I think John K said this:

To have some chance of characterising an amplifier I have seen the following list of measurements being cited as necessary:
"S/n ratio, frequency response, IMD/multi-tone distortion (for all levels, all loads, full bandwidth), channel separation, distortion of crosstalk signal, load tolerance, output impedance, stability margin, supply rejection, EMI susceptibility, ..."

Add in phase response and you got a pretty good measurement suite. And add in if the device or distortions all null to something less than say 75 or so db on music, then dang near nobody, nowhere can humanely hear a difference. Now, we can all decide if "what" we hear is close to the real thing, but thats not measurements, measurments are simply revealing the replication of what signal is input. Tone per our ears is per our ears, and not the same thing.

That null test is very hard to argue against, just the db threshold that humans stop hearing things at is arguable.

Do "standard" tests measure everything, no, they don't. No true, educated, objectivist would say so. Is there a point where a null test can prove that one is hearing things in their imagination, yes, at what level down does the null test have to be is debatable, but IMO null testing is absolute! Notice that CARVER used that test to match two different amps to the point they sounded the same. There you have it, if you want it.

Yeah but he only used 2/3 of the amp. No bass.

 

[Gregadd]

By a certain persons logic people love digital because of its' distortions not the ones it lacks.

 

[KeithR]

I don't know that odd-order harmonic distortions are more audible, but they are more annoying when they are audible. Fortunately, in competently designed equipment they are not. And yes, that's my preference.

Tim

Isn't there an AES study from the 80s that like .005% ss distortion was clearly audible?

 

[Phelonious Ponk]

Isn't there an AES study from the 80s that like .005% ss distortion was clearly audible?

Not one I remember.

Tim

 

[Whatmore]

Ah, tautology reigns supreme!
The statement made by others is that those who prefer the sound of tube/SET amps do so because they must like distortion!


If you are just looking for an argument - try elsewhere!

I'm not commenting on the statement made by others. I have no idea whether those who like tube/SET do so because they like distortion - that would imply a causation (as well as a correlation) and as you have pointed out correlation doesn't always imply causation

 

[opus111]

By a certain persons logic people love digital because of its' distortions not the ones it lacks.

Observation would probably be enough to demonstrate that that is true for certain digital lovers yes. There are people who love the MSG of digital, the extra 'detail' that's added. When I first bought a NOS DAC, I must admit I found it rather boring compared to my previous S-D DACs - not enough 'energy' at the top of the mid. As I listened more, on and off over weeks and months I slowly realised that my earlier DAC was adding something. Sure the NOS was taking away some HF but my earlier DAC was adding too much. I found a happy medium eventually with a droop-corrected HF on NOS.

 

[DonH50]

I'd like to see that study. Really; I am not questioning that it was done, but do not recall it nor anything else claiming that level of distortion is audible. I would expect it to be swamped by the speakers and buried in the music in the real world.

 

[Robh3606]

Originally Posted by Gregadd
Yeah but he only used 2/3 of the amp. No bass.

That is BS. I already posted the recordings they used and why. So I will do it again just for fun.

Program sources were as follows, for the
following specific sonic attributes: “The
Portrait” and “Peter the Hermit,” from
Growing Up in Hollywood Town (Sheffield
CD-13 and Lab 13) for depth and perspective,
HF maturalness, bass heft and tightness;
Respighi’s Church Windows (Reference
Recordings RR-15) for breadth, depth, bass
range and control, and massed string tone;
Beethoven & Enesco Violin & Piano
Sonatas (Wilson Audio Specialties W-8315)& timbre and low-end attack, control and
range; and McBride’s “Mexican Rhapsody,”
from a badly worn copy of Fiesta In Hi-Fi
(Mercury Living Presence SR90134) for
treatment of HF stridency and mistracking.
for tonal accuracy, depth , and imaging
specificity and stability; “Improvisations”
by Jim Keltner, from The Drum Record
(Sheffield CD-14/20) for high-end openness

 

[terryj]

I'd love to visit Terry! BBQ, Music, Cars....three of my favorite things! I was in QLD for the Mercedes Trophy Asian finals (golf) we had a driving day with slaloms, a short closed road course and skid pad. My playing partner was almost mauled by a huge male Kangaroo when he got too close. LOL.

Excellent Jack, look forward to it if it ever happens.

Hmm, kangaroos and cars, not a good mix.

Esp when during a bathurst race

 

[JackD201]

Holy! LOL!

Is Bathurst a V8 supercars race? The guy who scared the bejeezus out of us flying us around in a modded C63 AMG was Tim Slade. He said he races in that category.

 

[KeithR]

I'd like to see that study. Really; I am not questioning that it was done, but do not recall it nor anything else claiming that level of distortion is audible. I would expect it to be swamped by the speakers and buried in the music in the real world.

Kevin Hayes (vac) mentions in one of his white papers the study from 1987 I believe. I think it was digital SS distortion though, although the same principals should apply?

 

[DonH50]

Hmmm... I need to find the paper. SS distortion is not neccesarily "digital", and "digital" circuits generate "digital" distortion tube or SS. Not enough info. Either way, 0.005% (-86 dB) is well below any threshold of audibility I recall, and would be swamped by the nonlinearity of any speaker I have ever heard/seen/read about/measured.

 

[Gregadd]

Originally Posted by tomelex
Originally Posted by Gregadd
The null hypothesis is different from the null test.

Here what JA had to say;
Quote:
Where is that original modified Carver amp today?

Bob Carver took it back with him when the Challenge was over, where it was used as the prototype for the M1.0t amplifier that was released in 1986. Stereophile reviewed this model in April 1987 (review not yet posted in our archives) and found that it neither measured nor sounded like the C-J tube amp of which it was supposed to be a clone. The null I measured between the production M1.0t and the tube amp using the same methodology as Bob Carver was just 36dB and then only in the midrange.

John Atkinson
Editor, Stereophile
OK, fair enough, I can't remember all these things these days...but, there is no argument, he made an inexpensive solid state amp sound indistinguishable from a "high end" tube amp. And they acknowledged it. That is the fact I put forth. They preferred the sound of that tube amp and, at the time, Bob duplicated it. They had better ears then than now, lord knows what kind of authority they are on the sound of anything these days... [That was written by Tomelx not JA I beleive]
The situation with the Carver Stereophile Challenges is complicated. The original challenge in 1985 (before I joined the magazine) involved blind testing the prototype Carver amplifier against a pair of Conrad-Johnson monoblocks on just the treble and midrange panels of Infinity RS1B loudspeakers. (The Infinity speakers used powered woofers.) The report on this Challenge can be found at http://www.stereophile.com/content/carver-challenge . And yes, it did appear that the final version of the Carver amplifier sounded like the C-Js - but only in the midrange and above.For the rematch at the beginning of 1987, I insisted that the amplifiers be compared full-range, using Celestion SL600 speakers. I measured the null as mentioned above with the amplifiers driving these speakers, and the maximum null was indeed just 36dB and then only in the midrange. Bob Carver subsequently said in an interview - see http://www.stereophile.com/content/b...himself-page-3 - that 36dB was certainly not enough to guarantee that the amplifiers would be indistinguishable. We did a series of blind tests at that time and Bob Carver agreed that J. Gordon Holt _could_ distinguish the amplifiers by ear, contrary to what you say. I did take part in these tests, but when it came time to score my tests, Bob Carver couldn't remember what amplifier I had been listening to in each trial. This was all reported in the April 1987 issue of Stereophile - that article will be posted in our on-line archives next year, 25 years after the event.

One thing that came out of the 1987 Challenge was that halfway through the tests, Bob hooked a long length of narrow-gauge wire in series with the Carver amplifier's output to increase its source impedance to better match that of the Conrad-Johnson. This was something he subsequently incorporated in production, to the best of my knowledge.

John Atkinson
Editor, Stereophile
[Emphasis supplied by gregadd]
http://www.whatsbestforum.com/showthread.php?4133-Tube-vs-Solid-State-Is-the-War&p=68587#post68587 Post #118

 

[Phelonious Ponk]

So Carver modified the amp to sound like the CJs, knowing they were going to be played back on the mids and tweeters of the Infinitys. The golden ears couldn't hear the difference. Later, they re-tested the same amps on full-range speakers and Holt could ID the difference. No surprise there. I'm sure, given the chance, Carver could have made his amp as soft and uncontrolled in the bass as the CJs.

Tim

 

[KeithR]

Hmmm... I need to find the paper. SS distortion is not neccesarily "digital", and "digital" circuits generate "digital" distortion tube or SS. Not enough info. Either way, 0.005% (-86 dB) is well below any threshold of audibility I recall, and would be swamped by the nonlinearity of any speaker I have ever heard/seen/read about/measured.

It's under the "why vac doesn't use single ended circuits" white paper---Dolby related study from 1987.

 

[KeithR]

So Carver modified the amp to sound like the CJs, knowing they were going to be played back on the mids and tweeters of the Infinitys. The golden ears couldn't hear the difference. Later, they re-tested the same amps on full-range speakers and Holt could ID the difference. No surprise there. I'm sure, given the chance, Carver could have made his amp as soft and uncontrolled in the bass as the CJs.

Tim

Tim- do you know of a study that compares odd and even orders of harmonic distortion? I would like to read one if so and am curious on the subject.

 

[Gregadd]

So Carver modified the amp to sound like the CJs, knowing they were going to be played back on the mids and tweeters of the Infinitys. The golden ears couldn't hear the difference. Later, they re-tested the same amps on full-range speakers and Holt could ID the difference. No surprise there. I'm sure, given the chance, Carver could have made his amp as soft and uncontrolled in the bass as the CJs.

Tim

Tim I think you missed the point. I said bass was not included. My credibility was challenged. The test went exactly as I said it did.
The key is an amplifier is defined full range. Holt id 'ed the amp when it was run full range. Even more importantly his t-mod amps failed to When Holt identified the amp it was Carver who waffled. As for what you are sure of, well that's just speculation.
One thing is sure. Bob Carver deserves all the accolades he has received and possibly more. tas named has Phase Linear one of the ten most significant.

 

[Gregadd]

With all the talk about typos I went looking for a document that described the dangers of blind spell checking. I could not find it. Here is a different one.
Ode to My Spell Checker.”

Eye halve a spelling checker
It came with my pea sea.
It plainly marks four my revue miss steaks eye kin knot sea.
Eye strike a quay and type a word and weight for it to say
Weather eye yam wrong oar write.
It shows me strait a weigh as soon as a mist ache is maid.
It nose bee fore two long and eye can put the error rite.
Its rare lea ever wrong.
Eye have run this poem threw it,
I am shore your pleased to no.
Its letter perfect awl the way.
My checker told me sew.