Gotta get the hand carved from solid BS .. I mean Unobtainium .. by Virgins label in somehow.
JC, who are these "music professionals"?
On my opinion, there is nothing wrong with class D alone. High open-loop bandwidth and gain, then high feedback.
The only problem, for the moment, is the switching speed of the fets not fast enough: So, we dissipate a lot of power in the parasitic capacitance of the switching device.
This set a relatively low limit to the switching frequency, therefore obligation to filter-it with high slope. And the passive filter introduce some (little) distortion.
One solution is the one used in Ncore: include the filter in the feedback loop. Need all the talent of Bruno to deal with the poles.
An other solution would be, on my idea, to serialize class D amps with a delay, in order to oversample.
Advantages would be less voltage in each (so faster devices), and the 'sample rate' would be multiplied. What do-you thing about ?
The only problem, for the moment, is the switching speed of the fets not fast enough: So, we dissipate a lot of power in the parasitic capacitance of the switching device.
This set a relatively low limit to the switching frequency, therefore obligation to filter-it with high slope. And the passive filter introduce some (little) distortion.
One solution is the one used in Ncore: include the filter in the feedback loop. Need all the talent of Bruno to deal with the poles.
An other solution would be, on my idea, to serialize class D amps with a delay, in order to oversample.
Advantages would be less voltage in each (so faster devices), and the 'sample rate' would be multiplied. What do-you thing about ?
I had an interesting question asked of me, yesterday, when my tech Tim (19 years old) who the week before helped me measure a Parasound A21, and weeks before, move maybe a 1000 pounds of old amps, asked me whether a chip power amp was as 'good' as a discrete power amp? And how could I test for the difference?
It is a difficult question, to PROVE your opinion.
It is a difficult question, to PROVE your opinion.
This question is as old as time, itself. For example, how do you know that you exist? These questions are often asked in philosophy classes everywhere.
You MIGHT think that you are sure of your existence, but the person next to you can't be sure that you exist, you might be part of his (her) dream. Who knows?
Now, as I have stated many times before, I have been working on amps-preamps for a long time, about 45 years professionally. I started with used Dyna tube equipment that was turned in when solid state started to be introduced. It was OLD FASHIONED in 1963, but it seemed to work OK. ONLY with time, could I detect a SIGNATURE of the original components in my system. Maybe the preamp was a little too 'smooth' and the power amp had a sort of slight 'metallic' quality. These things might reside in the distortion residual, or maybe not. It might be something more subtle.
By 1967, I was working on my OWN power amp design to drive my single K-horn. I already had a Dyna Mk3 with Genelex KT88's, but I wanted to try to make as good a solid state amplifier as I could, that would perhaps beat the Dyna tube design. I knew there were better sounding tube amps, as well, having heard a number of triode amps, like the Marantz 9 (in triode mode) and the Radiocraftsman triode amp.
After working on the project for about 6 months with state of the art solid state parts, I developed my first complementary differential input stage, then all direct coupled complementary pairs to the output. I only needed 10W or so, so I could use 0.5A of quiescent current, and relatively fast, and linear complementary output transistors. I still have this little amp in a drawer in my lab, and I have shown it around in the past to Nelson Pass and Scott Wurcer just to back up my history. In any case, I happened to meet Mark Levinson when he was a student of music in 1968. I helped him make a duplicate master tape as I had a professional analog recorder, as I worked at Ampex, at the time. He heard my little amp with my single K-horn, and apparently remembered it, because 5 years later, he hired me on the basis of remembering what it sounded like.
Now, was he imagining things, could a cheap IC have done as well? I doubt it. In any case, it has been my avocation to continually improve on solid state amps and preamps, and that is what I do for a living, as well as for a hobby. Yet I cannot PROVE to a cynic that I have done anything useful at all, for all the time and money spent. That is just the way it is.
You MIGHT think that you are sure of your existence, but the person next to you can't be sure that you exist, you might be part of his (her) dream. Who knows?
Now, as I have stated many times before, I have been working on amps-preamps for a long time, about 45 years professionally. I started with used Dyna tube equipment that was turned in when solid state started to be introduced. It was OLD FASHIONED in 1963, but it seemed to work OK. ONLY with time, could I detect a SIGNATURE of the original components in my system. Maybe the preamp was a little too 'smooth' and the power amp had a sort of slight 'metallic' quality. These things might reside in the distortion residual, or maybe not. It might be something more subtle.
By 1967, I was working on my OWN power amp design to drive my single K-horn. I already had a Dyna Mk3 with Genelex KT88's, but I wanted to try to make as good a solid state amplifier as I could, that would perhaps beat the Dyna tube design. I knew there were better sounding tube amps, as well, having heard a number of triode amps, like the Marantz 9 (in triode mode) and the Radiocraftsman triode amp.
After working on the project for about 6 months with state of the art solid state parts, I developed my first complementary differential input stage, then all direct coupled complementary pairs to the output. I only needed 10W or so, so I could use 0.5A of quiescent current, and relatively fast, and linear complementary output transistors. I still have this little amp in a drawer in my lab, and I have shown it around in the past to Nelson Pass and Scott Wurcer just to back up my history. In any case, I happened to meet Mark Levinson when he was a student of music in 1968. I helped him make a duplicate master tape as I had a professional analog recorder, as I worked at Ampex, at the time. He heard my little amp with my single K-horn, and apparently remembered it, because 5 years later, he hired me on the basis of remembering what it sounded like.
Now, was he imagining things, could a cheap IC have done as well? I doubt it. In any case, it has been my avocation to continually improve on solid state amps and preamps, and that is what I do for a living, as well as for a hobby. Yet I cannot PROVE to a cynic that I have done anything useful at all, for all the time and money spent. That is just the way it is.
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You could spend a little more time & effort on properly conducted Listening Tests.
You could test some of your designs instead of claiming your 45 yrs experience absolves you from such inconvenient trivialities.
When you do test your stuff, you could release the results ... instead of claiming us unwashed masses can't possibly interpret them properly.
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In my opinion, as it was 33 years ago, ABX double blind tests do not work for me. If they work for anyone and everyone else, you have my blessing. IF you do not think that I do anything more than a typical commercial package, please refrain from considering purchasing, copying, or even talking to me about the products I design, please, if you will.
Err.rrh! Most 'commercial operations' :
- at least attempt Listening Tests
- do other tests on their products
- publish the results of these tests
Kgrlee - John doesn't have to prove himself to you or jump when you say jump, the market place has voted for 45 years and he's done alright there. I realize the beach isn't likely a gold mine of test equipment and the coconuts don't share your taste in music, but you could be little less abrasive in your quest for proof.
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John and Tick,
This whole questioning of John's amplifiers reminds me of a common question that I use to here at the CES shows. People would come and listen to the speakers I was showing and ask who's speakers we had model our sound after. It was as if I had to copy the sound of some other brands speakers for mine to sound good... It is a ridiculous premise. It is like saying why would you build a Corvette unless it is a copy of a Ferrari or has the same exact engine package of some other car. While you may like one verses the other that does not mean one way of doing something is the only way or the correct way to do it. If all you want to do is copy something else why do it in the first place? I doubt highly that John is just using a common circuit design that he copies from some other manufacturer, what would be the point. If you like a product does it have to be compared to another to be good or great? If I like a Seiko watch do I go and compare it to a Bulova before I can decide that I like it and it does what I want? If John said he never tested any of his circuits and just designed them in a sim then I would worry, but that must be far from the reality here. I agree let's leave the comparisons to those who only buy products based on someone else opinion and not their own.
This whole questioning of John's amplifiers reminds me of a common question that I use to here at the CES shows. People would come and listen to the speakers I was showing and ask who's speakers we had model our sound after. It was as if I had to copy the sound of some other brands speakers for mine to sound good... It is a ridiculous premise. It is like saying why would you build a Corvette unless it is a copy of a Ferrari or has the same exact engine package of some other car. While you may like one verses the other that does not mean one way of doing something is the only way or the correct way to do it. If all you want to do is copy something else why do it in the first place? I doubt highly that John is just using a common circuit design that he copies from some other manufacturer, what would be the point. If you like a product does it have to be compared to another to be good or great? If I like a Seiko watch do I go and compare it to a Bulova before I can decide that I like it and it does what I want? If John said he never tested any of his circuits and just designed them in a sim then I would worry, but that must be far from the reality here. I agree let's leave the comparisons to those who only buy products based on someone else opinion and not their own.
The analogy isn't quite right.
I'm quite sure many of JC's designs will produce a NULL result against evil 4558 in a properly conducted Double Blind ABC test as has been discussed in this thread. The exception is Blowtorch.
Here we have a Ferrari (with price tag) that has NOT been tested (or if tested, the results are secret) that is not only slower but will probably be worse to drive than a 1980's Lada (the evil 4558).
For him to attempt to sell a second hand example of this product on this forum for $10,000 is IMHO cynical dishonesty of the highest order.
__________________
Perhaps JC should keep to discussing pseudo tech and Unobtainium hand carved by Virgins. I have little expertise in such matters and won't say anything as long as a product isn't made worse than a cheapo 4558 product,
But he can spare us the "45 yrs, zillion awards, bla bla" and particularly "there is no proof but my stuff is still the best".
His self congratulatory adverts are fair game in the light of his refusal to test and release the results of tests on Blowtorch.
Kgrlee - you continue with your excessive personal attacks now accusing John of " cynical dishonesty" because he won't do what you want. John isn't pushing to sell a Blowtorch, it's the cost of admission if you want to spend some time listeng to or testing one. Through the course of this thread John has gone through the cost and selection criteria for the cases, boards, switches, volume controls, wire, device selection/matching of the very high IDSS dual jfets, and hand assembly by very skilled individuals to show that at twice the $10,000 price in the low volumes it could be built in it wasn't viable as a commercial product.
They were built to show what the Blowtorch's electrical and mechanical designers could do without commercial consideration, for their personal use, and put a few out there until one of the designer/builders Bob Crump passed away and John doesn't see any worthwhile return to continue to go through all work to aquire the parts and build them. It's been a great insight to most of us to learn what he and other knowlegeable desgners contribute and discuss here. The thread gets side tracked and there is difference of opinion of what matters, but we learn from most of them.
The Parasound JC2 is a commercial version of an alternative design that benefits from the Blowtorch's development that could be reproduced at reasonable cost.
John's here to share, not to satisfy you. There's enough information in the first 200 pages to build a reasonablly close one if your interested -assuming power amp, speakers, and source of comparable build quality are accessible to you in your Robison Crusoe paradise. Please report back after you have tested and listened. John's better off working on future Parasound and Constellation Audio products that actually pay his bills than wasting his time making you happy for nothing. Are you likely to buy a Blowtorch if it performs better or sell your Blowtorch if it doesn't? Me I've built a reasonable clone of it and compared it to both tube and solid state design's - it is very good and compete's with the best out there, but like scotch, wine, women, food , art, and cars your and other's preference or value judgements may differ...If you think or know the Blowtorch performs no better than the 4558 preamp think of the money you'll have saved for coconut rum....
They were built to show what the Blowtorch's electrical and mechanical designers could do without commercial consideration, for their personal use, and put a few out there until one of the designer/builders Bob Crump passed away and John doesn't see any worthwhile return to continue to go through all work to aquire the parts and build them. It's been a great insight to most of us to learn what he and other knowlegeable desgners contribute and discuss here. The thread gets side tracked and there is difference of opinion of what matters, but we learn from most of them.
The Parasound JC2 is a commercial version of an alternative design that benefits from the Blowtorch's development that could be reproduced at reasonable cost.
John's here to share, not to satisfy you. There's enough information in the first 200 pages to build a reasonablly close one if your interested -assuming power amp, speakers, and source of comparable build quality are accessible to you in your Robison Crusoe paradise. Please report back after you have tested and listened. John's better off working on future Parasound and Constellation Audio products that actually pay his bills than wasting his time making you happy for nothing. Are you likely to buy a Blowtorch if it performs better or sell your Blowtorch if it doesn't? Me I've built a reasonable clone of it and compared it to both tube and solid state design's - it is very good and compete's with the best out there, but like scotch, wine, women, food , art, and cars your and other's preference or value judgements may differ...If you think or know the Blowtorch performs no better than the 4558 preamp think of the money you'll have saved for coconut rum....
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"This pops up with the tiresome regularity of an unbeloved season"
All null result proves nothing, it´s really tiresome how people that have no idea how proper tests are designed keep putting up this "burden of proof has shifted due to a null result" thing.
There have been ABX tests with compression codecs vs. original where the listeners could not _tell_ a difference yet there was a significant higher stress level and brain activity measured (!) (EEG) in the case of the compressed codec.
If you can measure (!) an impact on your listener but he can´t tell, then
the method of just asking the listener is flawed.
The "null result" is more an indication that the test setup is unsuitable for
the purpose at hand.
"All amplifiers sound the same" has been "proven" by null results, yet there are
some with which you want to listen all night long and others that stress and
give an upleasant feeling after half an hour.
...there were also ABX tests (and other DBT formats- that confusion of terms seems to be rampant) where listeners could.
All it takes is one good, solid, replicable piece of data to establish audibility of whatever is under test. "Audible" does not mean "audible to everybody." Another example- I can't hear a 20kHz tone. I'm sure John can't, either. But I'm also sure that some other people can, and it's been demonstrated, and it's not difficult to set up a DBT to show that some people can.
Here is an example, but in german unfortunately. But there are more to find, I´m leaving for the holidays now so I can´t "google that for you".
Gehirnjogging mit MP3 - Komprimierte Dateien steigern neuronale | Forschung Aktuell | Deutschlandfunk
BTW, listening to music activates a lot of regions in the brain which are different from
those when asking a question...
And my post was not about "advertising a product", where did you get that from ?
Gehirnjogging mit MP3 - Komprimierte Dateien steigern neuronale | Forschung Aktuell | Deutschlandfunk
BTW, listening to music activates a lot of regions in the brain which are different from
those when asking a question...
And my post was not about "advertising a product", where did you get that from ?
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