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Old 18th February 2012, 05:41 PM   #2601
dvv is offline dvv  Serbia
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Quote:
Originally Posted by janneman View Post
I fully agree with you. Yet, there are many out there that still 'go out and really do something better'.
I try to capture that, twice per year, in my Linear Audio bookzines.

Sure, there's not enough to support a multi-10k-copies monthly, and Linear Audio doesn't make any money.
But the interest is there, and the very high level of designs and analysis is there as well, you just have to look for it.

jan

Disclosure: I am the editor & publisher of Linear Audio
News to me - but for a change, good news to me.

I think it's safe to say that really good audio and valid attemps to do something new and better today lives in small companies at the outskirts of the big name industry, on the fringe, so to speak.

Perhaps I am being unfair to the big names, but as far as I can see, the vast majority of them all concerned on how to make it smaller, more portable and MP3/WiFi/MPEG compatible.
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Old 18th February 2012, 05:43 PM   #2602
tvrgeek is offline tvrgeek  United States
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Quote:
Originally Posted by dvv View Post
How did you measure the color?

Was it a scientfic test, or just fooling around?

Which spectrometer did you use and why?

How big are the phase shifts of the three prime colors?

Is the wife frowning or clowning?

Is price a painful memory?

And I was wondering if "one in the pocket" was a universally understood safety practice! OSHA would never approve.
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Old 18th February 2012, 06:02 PM   #2603
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by bcarso View Post
The allegation that linear distortions accounted for all perceptible differences between two phono preamps (and by extension ALL components), expressed in a letter from Lipshitz, Vanderkooy, and Young (a letter they wanted to withdraw but it was too late) was followed by forum contributions and letters from Jung, Moncrieff, and Curl, and additional articles about subjective/objective stuff.
Yes.

Same Greek Tragedy about the Angel Thesis and the Dæmon Antithesis being acted out, with never a resolution, just like a stuck record.

Same Dramatis Persona as well. With a few additions, but few deletions.

Hence my regular appeal to leave all these antique arguments behind and move on.

Yet we all seem remain attached to the argument like a bunch of bulldogs to a T-Bone Steak. Even those who wish to get past this cannot, due to the Tar Baby principle.

And the warnings on the map "Yonder Way Be Monsters" is ignored too by "newbies"...

Ciao T

Last edited by ThorstenL; 18th February 2012 at 06:04 PM.
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Old 18th February 2012, 06:03 PM   #2604
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Dvv, you are correct in that the controversies debated here are virtually the same as the controversies we debated 30 years ago. However, let me give you just one example of how something has actually progressed (if people will allow it) that we virtually ignored (on both sides) back in 1979, for example.
This was high speed vs low speed diodes for 60Hz operation, and, or, the use of snubbers in typical audio products. In those days we selected a rectifier bridge, already potted, and thought it enough. Yet I have found that changing out the low speed diodes for fast-soft recovery diodes made both measured and listening differences. (If you know what and how to measure for the problem)
Slowly we move forward, as the inexperienced are finally being shown such a change and finally it becomes 'obvious'. I will save the 'history' of how this particular breakthrough came about for another time.
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Old 18th February 2012, 06:27 PM   #2605
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Hi,

Quote:
Originally Posted by DBMandrake View Post
Out of curiosity I've attached the schematic of an amplifier that I particularly like the sound of, which measures well with conventional measurements but I find sounds significantly better than many other similar spec amplifiers I've heard, and I'm quite interested in any comments from the likes of Wavebourn and ThorstenL on (a) whether they think the design is good or bad in their opinion and (b) whether its just a typical by the numbers "textbook" design or whether there is anything clever/unique/novel about it that might account for a subjectively pleasing result. (or is it all just in my head )

Extra points for recognising/guessing what brand/model it is
I also think it looks luxmannish, though they usually did a more interesting job.

Good points:

Tripple darlington output - this keeps non-linear VAS Loading down.

Hawksford Cascoded J-Fet input - rather wider range of linear input voltage than undegenerated bipolar, low noise, no non-linear input current (espeically if a volume control is before it) and very linear with high signal

Double Differential - moves the current mirror (to convert diff to se) problems to a higher level node where their relative impact is lowered.

Class A Driver Stage - at least only the output transistors switch.

Mixed Miller and lead/lag compensation - keeps the slewrate fairly high, but the heavy handed compensation of the tripple darlington put's a dent in that.

DC Blocking is implemented intelligently - allows high quality film cap's INSIDE the AC feedback loop, compared to a low quality cap OUTSIDE the feedback loop.

Not so good points:

No degeneration in the second stage - this means the VAS is not linearised, it helps slew rate (compromised by heavy handed capacitive loading) though, so may be the lesser evil. Then again, some degeneration may allow lower compensation cap's on the output and improved stage level linearity.

Primitive current mirror with minimal degeneration - underlying linearity is not good, probably, together with the un-degenerated VAS implemented also to limit drop-out voltage. A set of separate rails for the front-end a few volt higher than the output stage would introduce another degree of freedom, which may help.

Ciao T
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Old 18th February 2012, 06:29 PM   #2606
bcarso is offline bcarso  United States
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Quote:
Originally Posted by john curl View Post
Bcarso, good for you in looking at the articles and controversy in TAA in the late 70's. Please remember that in those days, home computers were crude, and we hand typed our LTE's and submitted them by mail. One important person who you might unfortunately overlook, is Dr. Rod Rees and his articles of listening tests. Please check him out.
Yes, it was in fact a piece by Rees and Shaffer that started this, as the issue that had floated to the top of the take-home stack had a Reg Williamson amp on the cover, and within an article that ruminated on the letters exchange and forum I mentioned. It was titled The Saga of Golden Ear and Meter Reader (TAA 4/1979). Reading that led me back to the earlier issues.


And yes, I know that word processors (other than carbon-based lifeform ones) were nonexistent in those days, and someone had to set type. It still seems like something nearly invariant though. We now have auto-correct functions (that usually don't catch wrong words, just misspelled ones) and other utilities, but I still see gross errors everywhere. It is easy to do.

But I once read a PhD dissertation by the now-professor David Meyer, and he told me I would find no typos. He was correct! I think that's the only time it's ever happened to me.

Brad
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Old 18th February 2012, 06:58 PM   #2607
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A short story: Dr. Rees tried to work with both sides of the controversy. However, when he found that he was being 'blind-sided' by some of the meter readers, he withdrew his support for getting the two sides together.
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Old 18th February 2012, 07:00 PM   #2608
bcarso is offline bcarso  United States
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Quote:
Originally Posted by DBMandrake;2912257 [snip
Out of curiosity I've attached the schematic of an amplifier that I particularly like the sound of, which measures well with conventional measurements but I find sounds significantly better than many other similar spec amplifiers I've heard, and I'm quite interested in any comments from the likes of Wavebourn and ThorstenL on (a) whether they think the design is good or bad in their opinion and (b) whether its just a typical by the numbers "textbook" design or whether there is anything clever/unique/novel about it that might account for a subjectively pleasing result. (or is it all just in my head )

Extra points for recognising/guessing what brand/model it is
Of course it is all in your head, but no less real

Thorsten has done all the heavy lifting here in his analysis, IMO, but I would add just a bit more about the bootstrapped-drains input stage*, namely that the JFETs have nearly constant power dissipation with signal swing, provided that there is plenty of gain following (and there is). The parts are monolithic duals (now unavailable although some substitutes exist) which helps thermal tracking too --- but it's nice to have the dissipation constant with signal as well.

Brad


*popularized by Hawksford but predated by a bunch.
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Old 18th February 2012, 07:05 PM   #2609
bcarso is offline bcarso  United States
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Quote:
Originally Posted by john curl View Post
A short story: Dr. Rees tried to work with both sides of the controversy. However, when he found that he was being 'blind-sided' by some of the meter readers, he withdrew his support for getting the two sides together.
A lot of dirty work in this field. Sad. I sometimes wonder how I can remain in the relative good graces of some of my friends, particularly the meter readers and double-blinders, but as well those who have an attitude that can only be described as theological, as I too try to preserve an open mind, while trying to decode what is "really" going on.
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Old 18th February 2012, 07:08 PM   #2610
dvv is offline dvv  Serbia
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Quote:
Originally Posted by john curl View Post
Dvv, you are correct in that the controversies debated here are virtually the same as the controversies we debated 30 years ago. However, let me give you just one example of how something has actually progressed (if people will allow it) that we virtually ignored (on both sides) back in 1979, for example.
This was high speed vs low speed diodes for 60Hz operation, and, or, the use of snubbers in typical audio products. In those days we selected a rectifier bridge, already potted, and thought it enough. Yet I have found that changing out the low speed diodes for fast-soft recovery diodes made both measured and listening differences. (If you know what and how to measure for the problem)
Slowly we move forward, as the inexperienced are finally being shown such a change and finally it becomes 'obvious'. I will save the 'history' of how this particular breakthrough came about for another time.
Agreed, but we also both know how few such diodes were at that time. The choice wasn't, shall we say, plentyful, was it?

Fortunately for us, the times have changed, and such diodes today are many, certainly enough to make one's choice quite reasonable in type, number and price.

Personally, having read what I read here, I am willing to give them a serious try, which I have not done so far. But I looked at the catalog of my local suppliers and I note an abundance of them - thus, I expect no problems.

You see, this is not the USA, locally I do not have available 20% of what you have over there, and when I do have it, I have at abonmibale prices. You can order Analog Devices op amps form Analog itself, and I can't because they won't ship over here. Same thing with Motorola/ON Semi samples batches, and this severely limits my choice in just about everything.

If I do find a part I'd like to have, instead of paying $3.80 you'd pay buying from AD, I am asked to pay the equivalent of $28 for it. And people wonder why are US made devices shrinking in sales volume - as opposed to them, I can buy a Toshiba 2SC5200/2SA1943 pair for almost the same as you'd pay for them in the US, maybe sa 5% more expensive.

My point is, these variances in purchase prices also influence how much work is going on around the world. If my test bed initially costs twice what yours costs, but my salary is like 1/8 of yours, how likely am I to experiment much? I believe this dichotomy is a part of the answer why there is so much less reserach and development going on - the prices have escalated to unbearable levels.
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