PMA said:
Hi Pavel;
when I worked for KAMAZ (major Russian automotive corporation) we had once a meeting with representatives of some well known computer corporation. They wanted to sell their computers for our manufacturing plants. They were nice computers, and I would like to have some, but our VP asked, "Why do you use computers of your competitors for your own manufacturing, if yours are better?"
So, I use my PA stuff for home listening. If it would be bad, I would be punished by bad sound. High End PA does not forgive errors, because you hear all differences immediately: the same performers sounding directly and through PA. You can't choose "which distortions to prefer", you have to answer the question, "Why the sound differs", and "What is different", involving direct comparison, instead of a long term audio memory of sound on some recording studio you never heard.
I participated in listening tests. It was not my equipment then, but friends tried to prove that speaker cables sound. I heard the difference, and had a guess why. When I brought my cables especially made for the test they concluded that my cables sound well. The trick was, I suspected that plain stable linear frequency independent (in the band) resistance between their amp and speakers helps, and my cables proved my guess.
Later, I brought my class A+C amp and they found that cables sound the same, and the amp with completely switching off transistors sound better than their amp with carefully biased ones. It was one more proof of my design concept, that is in short, to put most of resources where the end results benefits the most instead of spending enormous resources on actually work-arounds.
Yes, I design PA systems. But my goal is to design High End PA systems that are affordable. That means, using of critical resources in really critical places to get more bang per buck.
Hi Anatoliy,
thanks for your explanation.
KAMA3
- poor competitor to our Tatra it was. I had worked on Tamara system for 6 years, if you know what I speak about.
http://en.wikipedia.org/wiki/Tamara_passive_sensor
thanks for your explanation.
KAMA3
- poor competitor to our Tatra it was. I had worked on Tamara system for 6 years, if you know what I speak about.http://en.wikipedia.org/wiki/Tamara_passive_sensor
PMA said:Hi Anatoliy,
thanks for your explanation.
KAMA3
http://en.wikipedia.org/wiki/Tamara_passive_sensor
Heh... 20,000 heavy duty trucks per month is a poor competition?
I worked almost with software development and support then (CAD/CAM, if you know SPRUT system, I participated, also ERP), later creating one of first in Russia Internet nodes, and first Intranet applications as soon as CERN and NCSA revealed source codes of Mosaic and httpd. All my hardware related work then consisted of participation in restoration of damaged quality control systems.
Tatra trucks were nice. Such curved-legged creatures.
PMA said:The only that had survived Siberian winters ...
Okay, I did not speak about quantity. And will not bother with my career history, it is also pretty long and wide
Yes, Tatra trucks were comfortable and reliable. I grew up in Siberia. Drivers liked them a lot. But KAMAZ won Paris - Dakar and Paris - Cape Town competitions, demonstrating the best qualities in a potential desert war. However, they were trucks carefully custom built in the "KAMAZ Scientific and Technical Center", like JC preamps. They were not ordinary trucks from the conveyor, so when some very rich man from Middle East brought a huge case with real paper Dollars to buy 20 of such trucks that won competitions he could not afford them...
syn08 said:
I can discount neither.
Many years ago, I became interested in the possibility of skin effect and the discussions surrounding how it was either bad (or good), and decided to determine the extent to which skinning could affect anything within the audio bandwidth.
As I set out to design and build an apparatus that was capable of discernment of the effect, I found that there were no parameters against which to judge, other than amplitude and phase, and these numbers were also gross entities based on monophonic criteria.
So I began to examine what it was we actually do with the stereophonic sound wavefronts. This led me down the path first of lateralization (a direction first spurred by an e-mail from Jon Risch {at the time I believe he considered me a bitter "enemy"}mentioning Nordmark), then of localization (many, many papers, articles, and authors to present day.)
I am amazed at the interchannel sensitivites exhibited by humans.(tested/peer reviewed, and duplicated by researchers). 1.5 uSec??? That is an inverted bandwidth of 600 Khz if I were purchasing an old tek scope probe. Obviously, we cannot hear at that frequency..
I am also amazed that even though localization is somewhat (yet poorly) understood, there are people who insist on dbt's using musical stimulus that does not contain the correct ITD/IID relationships required for accurate and unadulturated localization, in a test that is trying to determine image placement and accuracy..
As an example, a simple pan pot used for moving an image from one side to the other causes a widening of an image by frequency. I believe David Griesinger detailed this in his paper "Stereo and Surround Panning in Practice", AES 112 convention, 2002. Figure 6 on page 5 details the breakdown of the sin law by frequency (note that the figure is mis-named figure 5).
And yet, we insist on using false material to judge accuracy of image placement?
And to top it off, humans ADAPT to the variation in localization stimulus..yet nowhere has anybody measured the adaptation time constant..it's not zero, it's not infinite.
But when we measure something, we require the instrument be stable with time...and care not if the ears adjust?? A dvm which arbitrarily changes range or gain without notification is sent to the cal lab, or thrown out.
As I said, for me the jury is still out. Neither side has proven the other incorrect to the level I would like to see.
Cheers, John
PMA said:
Both did, as you know ......
Yep!
http://www.metacafe.com/watch/426319/kamaz_in_dakar_rally/
SY said:
Hey guy, what up??
Gettin close to that time again, eh?? Another year...where do they go?
Did a lot of run-throughs for biwiring analysis on the ol laptop, used microcap 9, ran it in transient mode. Whatta pain. the first few cycles were a real problem, the math package did not like me atoll atoll..
Cheers, John
syn08 said:
No no, I can. The SMPS equipped device sounds much worse than player with linear PSU. Isolation trafo makes difference.
Regarding cables, I measure different HF EMI background on any 2 different cables. The difference vs. SMPS supplied player is that with SMPS the EMI is at least 20x or more higher (you seen the image here).
No 2 cables sound same and no 2 cables have same EMI pickup. Quite perfect, is not it?
Re: trucks amuk
It is built like a car for competitions, especially tuned. Working for KAMAZ I was trained by a competition spirit, from top to the bottom of the huge corporation, where technology matters. The best results per the Ruble won. However, when we needed to show the best military monster-truck in very different conditions, we used special approach to create one for special conditions of competitions. Anyway it was an optimization, and always criteria of optimization were different, but we were winners because we could optimize for certain criteria. Like it is impossible to build the best truck for all conditions (Pavel's Tatra won reliability game in Siberia during winters mostly because of the cooling system), it is impossible to build the best audio device for all conditions regardless of criteria.
Optimization, optimization, and again optimization, my friends, and you will be happy...
wayness_tamm said:
It is built like a car for competitions, especially tuned. Working for KAMAZ I was trained by a competition spirit, from top to the bottom of the huge corporation, where technology matters. The best results per the Ruble won. However, when we needed to show the best military monster-truck in very different conditions, we used special approach to create one for special conditions of competitions. Anyway it was an optimization, and always criteria of optimization were different, but we were winners because we could optimize for certain criteria. Like it is impossible to build the best truck for all conditions (Pavel's Tatra won reliability game in Siberia during winters mostly because of the cooling system), it is impossible to build the best audio device for all conditions regardless of criteria.
Optimization, optimization, and again optimization, my friends, and you will be happy...
Re: well anyway
Wouldn't know. Never built high distortion equip (on purpose anyway)
What I used to do was build SWTPC tigers, and drop the bias to zero..that way, they NEVER entered runaway.
(just don't listen to em at normal levels, nor without a coupla drinks..great for nightclub, sucks for listening..
btw, the tigers survive reversing supply polarity...go figure..
Cheers, John
albin said:
Wouldn't know. Never built high distortion equip (on purpose anyway)
What I used to do was build SWTPC tigers, and drop the bias to zero..that way, they NEVER entered runaway.
(just don't listen to em at normal levels, nor without a coupla drinks..great for nightclub, sucks for listening..
btw, the tigers survive reversing supply polarity...go figure..
Cheers, John
I built many amps. When I was young I was under the fashionable influence of "More symmetrical, less THD" approach, but anyway I was smart enough to understand which kind of distortions are needed to be take care of the first. Taking care of the average temperature of patients through the clinic, you loose patients one by one.
So, my tigers consisted of nice class A amps and class C tooth breakers working in parallel; as the result of approximation using multiple feedbacks.
So, my tigers consisted of nice class A amps and class C tooth breakers working in parallel; as the result of approximation using multiple feedbacks.
Southwest technical independently invented the complementary differential input stage a few years after Jon Iverson and I had separately invented it. They were the first to openly publish the circuit in 'The Audio Amateur' and allegedly showed the circuit to Jim B. who then took it to SAE. Circuit topology is advanced, but followthrough is weak, and the amps were not very reliable.
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