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Old 22nd May 2012, 04:48 PM   #5721
dvv is offline dvv  Serbia
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Originally Posted by Wavebourn View Post
Suboptimal means criteria of optimization are wrong. As the result, vital parameters are sacrificed in favor of parameters that are less significant.
Right, but there's always the degree of compromising in any product. AFAIK, nobody has made a compromiseless circuit so far.

Accepting that as my premise, I'd say some op amps are very, very good. And I'd add that a discrete circuit which would better them would be far more expensive and bulky.

That too is a compromise.
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Old 22nd May 2012, 04:56 PM   #5722
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Originally Posted by dvv View Post
Right, but there's always the degree of compromising in any product. AFAIK, nobody has made a compromiseless circuit so far.

Accepting that as my premise, I'd say some op amps are very, very good. And I'd add that a discrete circuit which would better them would be far more expensive and bulky.

That too is a compromise.
Optimization itself means choice of better compromises to satisfy requirements. When I design audio amp I do not need for example CMRR and similar parameters vital for analog computers, so I can use couple of vacuum pentodes and couple of MOSFETs and get results you can never obtain with opamps. If you want to speak of prices and ICs, I am hundred percent sure that an IC that contains 5-6 transistors inside can be comparable with an IC with hundred of them if to manufacture it in certain quantity. And it can be no less universal for audio than opamp that was well advertised in textbooks for engineers and in magazine articles, thanks to requirement for analog computers that does not exist anymore.
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Old 22nd May 2012, 05:34 PM   #5723
dvv is offline dvv  Serbia
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Originally Posted by Wavebourn View Post
Optimization itself means choice of better compromises to satisfy requirements. When I design audio amp I do not need for example CMRR and similar parameters vital for analog computers, so I can use couple of vacuum pentodes and couple of MOSFETs and get results you can never obtain with opamps. If you want to speak of prices and ICs, I am hundred percent sure that an IC that contains 5-6 transistors inside can be comparable with an IC with hundred of them if to manufacture it in certain quantity. And it can be no less universal for audio than opamp that was well advertised in textbooks for engineers and in magazine articles, thanks to requirement for analog computers that does not exist anymore.
This is not leading anywhere, as too many ifs are at play.

It's a simple fact that audio is no longer in the vogue it was say 30 years ago. Therefore, most manufacturers of op amps see no particular reason to develop extremely high quality audio orientated op amps. Since the arrival of digital audio and video, even less so.

I agree that they could, if they wanted to, develop outstanding strictly audio circuits inside that small plastic, ceramic or metal package, but it's a simple fact that its price would be a problem to most manufacturers, even when buying in bulk.

ALL of us here, I think, need to understand we are are the diehards, the old guys, still salivating over a great amp or whatever. It's a fact of life that modenr kids care incomparably more about the next generation of i-Pods, cell phones and tablets than about audio. In other words, audio as we know it is rapidly dying. It will never disappear completely, of course, and who knows, it may once again become fashonable in the "in" crowd once every Joe and his dog have the latest i-Pod type device, but even so, it will more of a swan song than anything.

I know I have lived since 1966 with audio playing a very important role in my life, and I will not let that change. After 46 years with it making my life better, why the hell should I?

But op amp manufacturers have a completely different logic. To them, it's a business first and foremost, and if they don't see a profit down the road, they won't do it.

Let me ask you this - how many NEW tubes (meaning new designs, not new versions of the same old same old) have appeared over the last 20 years? THAT'S the point. Measure it however you like.

Look at how many truly NEW transistors have been introduced in what we would think of as interesting for us - now compare that with the number of very good transistors you used to have that are no longer with us, and what do you get?

Just when you think - aha, here's a new BC type transistor, you are disappointed, because it turns out that it is in fact VERY sightly reworked old type, with a new name and almost insignificatly improved parameter or two. And if they won't introduce REALLY NEW transistor types, the chances of really new high audio quality op amps appearing are way smaller. Not because of technology, but because of the money involved.

Am I right, or not?
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Old 22nd May 2012, 05:42 PM   #5724
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I think you have slightly overstated it, Dvv. It is in our interest to REMIND IC designers that their product is not 'perfect', and really not even good enough for the serious listener, in many cases. IF we do not remind them, they will be satisfied with what they make, and ultimately, we will all lose. It is a bit like 'fast food'. It is OK, at times, but it is not 'haute cuisine' and a visit to a quality restaurant can 'awaken' our taste buds, just like listening to a really high quality sound system can remind us of what we are missing with our portable hi fi's.
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Old 22nd May 2012, 06:09 PM   #5725
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the demands of precision op amps for instrumentation used to be largely limited to DC, to a few kHz

today, last decade or so, medical ultrasound, xDSL have driven op amp design to new levels in processes and topology

raw speed increases alone make high loop gain feedback work much better at audio frequencies

SiGe devices give a slightly better i_noise in bjt

Analog Devices linearized diff pair gives a huge reduction in high frequency distortion in feedback op amps into the MHz - that is loop feedback working into the MHz

National made some effort with the LME series – claimed to have setup subjective audio testing room in addition to getting the AP # down into the noise floor

TI/BB keeps releasing new “Sound Plus” branded op amps

Several manufacturers have released parts in the past decade aimed at the OPA627, a still prime performance device, if pricey


and of course there is my personal hobby horse - composite op amp circuits using great input op amps, buffering, adding loop gain themal/load isolation with CFA ouput op amps - smt cuts the PCB real estate required

I really don't understand complaining about single op amp performance limitations when 2 modern $2 op amps in a multiloop removes virtually all active device performance limitations at audio (other than input noise)

Last edited by jcx; 22nd May 2012 at 06:22 PM.
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Old 22nd May 2012, 07:06 PM   #5726
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Let me ask you this - how many NEW tubes (meaning new designs, not new versions of the same old same old) have appeared over the last 20 years? THAT'S the point. Measure it however you like.
All my designs are new.

Well, some of them are more than 20 years' old (because I am almost 3 times older than this number), but some are very new. And I don't use opamps that cost 1 dollar instead of tubes that cost 1-5 dollar each, because for $3,000 product difference in few dollars (and even tens of dollars) does not matter at all.
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Old 22nd May 2012, 07:29 PM   #5727
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Well said, Wavebourn.
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Old 22nd May 2012, 09:34 PM   #5728
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Originally Posted by dvv View Post
Just when you think - aha, here's a new BC type transistor, you are disappointed, because it turns out that it is in fact VERY sightly reworked old type, with a new name and almost insignificatly improved parameter or two. And if they won't introduce REALLY NEW transistor types, the chances of really new high audio quality op amps appearing are way smaller. Not because of technology, but because of the money involved.

Am I right, or not?
No.

Relatively recently Zetex introduced transistors that would cause me drooling 20 years ago. And SemiSouth recently introduced devices that could not be imagined then. If to think about design of something new you will find new components, technologies available. But if to think about reproduction of old good designs however components disappear, even when they would be great for new designs.

The life always brings new problems and new resources to solve them. It is dynamic. The same as music itself. That's why we designers are still needed: to match new solutions to new problems. To create new fashions that create new problems that require new resources.
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Old 22nd May 2012, 10:42 PM   #5729
gpapag is online now gpapag  Greece
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Originally Posted by john curl View Post
I don't understand you input, George. Can you clarify?
Mr. Curl
I responded to your comment in here:

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Originally Posted by john curl View Post
I hope I have not been too 'strong' on this topic, but 'reason' must prevail, even though I am often attacked as 'unreasonable' on this website.
George
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Old 22nd May 2012, 10:53 PM   #5730
a.wayne is offline a.wayne  United States
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Originally Posted by nigel pearson View Post
I will have to pick this up in the morning . Big Bang I didn't realize was a Joke made by Fred Hoyle . Then someone did a bit of maths and said it is correct . The truest words often spoken in jest . I think I believe big bang .

Good night .

I get peoples names wrong so correct any mistakes .
I do believe in the big bang theory, well at least that's what I told her .....
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