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Old 25th December 2011, 11:36 PM   #131
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Originally Posted by tvrgeek View Post
(they may actually have, just on a price range I can't play in)...(
I'm mystified as to what the price range has to do with it. I would expect the difference between good and bad to be in terms of design, not the cost of the hardware for a given output power, for example. I have read some threads where a design is improved (measurably) by removing an end of a capacitor from one point, and re-connecting it somewhere else, or changing the values of a couple of resistors. Even introducing extra components must add only a few cents or a few dollars at most to the price, surely.
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Old 26th December 2011, 12:12 AM   #132
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Originally Posted by wahab View Post
This , is unrealisticaly exagerated and at odd with all known
measurements/comparisons of best tube amps vs common SS amps,
let alone these latters best ones , unless you re talking about the
early transistorized amps , of course...
This is what I would have thought myself, yet would tubes make for a better VAS, stage with mosfets on the current side .. An tube amp with no transformer ...


Anyway the measurements of tube amplifiers , especially on simulated speaker load throws a monkey wrench in whats sounds good vs specs.....
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Old 26th December 2011, 12:13 AM   #133
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TVR-Geek, Please don't buy an HCA-800 and hope to come back to me with what you hear or measure. It is listed below my acceptance level, and may not even have any circuit topology that I am generally familiar with. I would recommend an HCA-1000, 1200, 1500, or 2200, if you want to buy a used Parasound Amp. At least you will have something then that we can talk about, as I am associated with those designs. The others may be OK, but they are completely outside my control, so don't complain if you are disappointed, and they are generally designed for the absolute minimum in heatsinks, parts and materials that they can get away with.
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Old 26th December 2011, 12:16 AM   #134
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Originally Posted by tvrgeek View Post
I wonder, with the basic tendency of a tube to act like a compressor more than a transistor does, maybe one raises the average level a little and the perception is more detail?
The same can be done with transistors, but you will need much more sophisticated topology than couple of tubes. And of course, due to many devices involved result will be worse.


What I do in tube power amps, I sense screen grid current of output tubes and control by this result an opto - attenuator. It works exactly like an optical compressor that engages as soon as the amp approaches clipping.
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Old 26th December 2011, 12:29 AM   #135
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Quote:
Originally Posted by wahab View Post
This , is unrealisticaly exagerated and at odd with all known
measurements/comparisons of best tube amps vs common SS amps,
let alone these latters best ones , unless you re talking about the
early transistorized amps , of course...
You may ask SY, we measured my Pyramid on his laboratory setup.

I have no intentions to exaggerate, when I work to satisfy my own curiosity. And I always find that common beliefs, fashions, and legends are plainly wrong. I was one of victims of them before, when design of electronics equipment was my profession.


Quote:
Originally Posted by a.wayne View Post
This is what I would have thought myself, yet would tubes make for a better VAS, stage with mosfets on the current side .. An tube amp with no transformer ...
Such divisions on VAS, current stages, etc... is not the best approach to build the best audio device. However, amps with vacuum tube preamp and mosfet outputs sound very nice. The same with measurements.
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Old 26th December 2011, 01:19 AM   #136
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by john curl View Post
TVR-Geek, Please don't buy an HCA-800 and hope to come back to me with what you hear or measure. It is listed below my acceptance level, and may not even have any circuit topology that I am generally familiar with. I would recommend an HCA-1000, 1200, 1500, or 2200, if you want to buy a used Parasound Amp. At least you will have something then that we can talk about, as I am associated with those designs. The others may be OK, but they are completely outside my control, so don't complain if you are disappointed, and they are generally designed for the absolute minimum in heatsinks, parts and materials that they can get away with.
Tried one of the big stereo halo last year, good sounding amp but the protection would interrupt us after about 10 min of playing....
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Old 26th December 2011, 01:22 AM   #137
a.wayne is offline a.wayne  United States
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Originally Posted by Wavebourn View Post
You may ask SY, we measured my Pyramid on his laboratory setup.

I have no intentions to exaggerate, when I work to satisfy my own curiosity. And I always find that common beliefs, fashions, and legends are plainly wrong. I was one of victims of them before, when design of electronics equipment was my profession.


Such divisions on VAS, current stages, etc... is not the best approach to build the best audio device. However, amps with vacuum tube preamp and mosfet outputs sound very nice. The same with measurements.
interesting to hear in what way do tubes measure superior to SS and what in those measurements make you know its a good sounding amp..?
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Old 26th December 2011, 01:29 AM   #138
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I have read endless articles (in WW) and books by D.Self where he quite clearly stated that the 553X series was "as good as it gets" and there was no benefits to any supposed exotic Op-Amp's...

It may be that he has in recent times changed his view (though his slight modification as you stated it does not really change the meaning dramatically).

I am not one of his followers who reads each and every thing he writes (his writings have become increasingly dull, old-fashioned and outdated).
Hmmm, I am confused. Apparently, you read "endless articles" by Self but not all of them? Are they not different? Or has hyperbole crept in for the sake of embellishment of your argument?

Nearly twice as many posts and it still holds true;
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The only purpose it serves that I can see is is to give a few people the opportunity to invite themselves into the elite class of the 'golden eared'. Paradoxically it seems that the older you all get and the worse your hearing the less capacity you have to resist the temptation to see yourselves as the true arbiters of quality.
Frank
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Old 26th December 2011, 01:32 AM   #139
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Quote:
Originally Posted by a.wayne View Post
interesting to hear in what way do tubes measure superior to SS and what in those measurements make you know its a good sounding amp..?
Dynamics. Dependence of distortions on frequency, on power output, phase - related distortions. Tubes don't have Kirk and Early effects, don't change base width, don't have such thermal distortions. They don't care what frequency in audio band how to distort. And what is most significant, it is easier to design tube amps such a way that distortions depend on power such a way they are less audible. SY saw how my Pyramid behaved, on 40W of output power 2'nd harmonic was visible at -80 dB, the rest was below noise floor. The less was power, the less was that 2'nd harmonic. However, approaching full 80W the amp started showing growing up grass of harmonics, but such behavior is not audible as distortions, due to psycho-acoustical properties of perceptions. Also, dumping factor was high (though, I did not bother to measure it) due to nested feedback, part of which was directly across output tubes.

Such experiments show that despite of very low level of measurable distortions tube amps still sound as tube amps: clean and transparent. That means that myth about "people like tube distortions" have absolutely no foundation under it.

However, I took care of clipping adding compressor-limiter, because clipping in any amp with deep negative feedback, be it on diamonds or steam engines, sounds as clipping, and is unacceptable to my taste.
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Last edited by Wavebourn; 26th December 2011 at 01:37 AM.
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Old 26th December 2011, 01:57 AM   #140
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By the way, what is inside of Denon AVR-591 receiver? I bought it an year ago to take it's Audissey digital processor and use with tube amps, but still never opened the case. It is the first stock budget solid state amp I like as is. It sounds almost like a tube amp.
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