Markw4, well I was rather curious...
I can say this much, it was a multi-thousand dollar system, with large and modern full range "planar ribbon" speakers. But that will tell you next to nothing about the sound or anything else.
It would (as it would for anyone, actually) be better if I could manage to play it back on my system.
But imho, "tambourine" would not be my preference as a sound to use for this sort of sonic discernment. Actually, the thing is a bit brutal. (yikes!)
I can say this much, it was a multi-thousand dollar system, with large and modern full range "planar ribbon" speakers. But that will tell you next to nothing about the sound or anything else.
It would (as it would for anyone, actually) be better if I could manage to play it back on my system.
But imho, "tambourine" would not be my preference as a sound to use for this sort of sonic discernment. Actually, the thing is a bit brutal. (yikes!)
Recording something else would not be out of the question. We have acoustic and electric guitars, electric bass, and various hand percussion. I think I would be willing to try something different and more to your liking, but probably not before you are sure you can play it back.
And I can record clean or with a bit of color, but clean may be better for this.
The tambourine was just because a lot of grainyness is at HF, and I don't have any cymbals on hand.
wrong interview?
there is NO mention of Otala, PIM or relatives in the Curl interview linked below
and any wanting to see the (ir)relevance of the latter 2 papers need only look in the output stage bias chapters of Cordell, Self PA design books of this last decade - nowhere will you find deliberate output stage under bias that the papers used to make their strawman case
there is NO mention of Otala, PIM or relatives in the Curl interview linked below
and any wanting to see the (ir)relevance of the latter 2 papers need only look in the output stage bias chapters of Cordell, Self PA design books of this last decade - nowhere will you find deliberate output stage under bias that the papers used to make their strawman case
op, wrong link.
Thanks for spotting the wrong link. Here is correct.
http://jockohomo.net/data/johncurl-v.0.1.pdf
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Presumably, he would take exception to your claim. I haven't been around here long enough to have read all the arguments pro and con myself.
ok Jan ,I'm not up on the history of his ideas other than the published interviews - papers but so called debunking even by ones friends is irrelevant to the question here.. Maybe his friends will catch up one day?
My concepts/proposals (and field trials) were 'debunked' by committees due to narrow herd mentality. Interesting that in the end my hunches always proved correct.
Does it (op-amps) sound good? and why? why not?
Possibly the IC only need a tweak in packaging or who knows at this point.
How can it be replicated,measured and modeled?
Are we missing something in the big picture?
I do not know John Curl and have never corresponded with him.
-bruce
MC1530 pops up in Dave Casasent's book called Electronic Circuits 1973. He also shows RCA CA3002 which is more like the valve op amps. MC1530 as configured can out run a 741 which like it or not is the origine of most op amps we now use ( and 78 series regularors ). Some say the MC1530 is interesting in being all NPN and might be a way of building a better power amplifier. I don't know. All I know is for a device that might pre date 741 it has a very wide bandwidth for it's day and about that of NE5534 if I am right. To build one I might use BC337. 10 transistors and 4 diodes. It looks to be a small stripboard project ( 2 x 1 inch ).
Looking for the first time in my life at CA3002 it is almost a good device. Perhaps the LM324 and LM339 strated life with it's input circuit. I have never thought an op amp this primitive had any value. It's not a complete no no. Hope this link works for anyone who is interesed.
One has to learn some history if wanting to have a true picture of how we got to where we are. In the case of Alan Blumleins familly they knew nothing years after he died as it was classified. It should be Sir Alan Blumlein at the very least. It is said if he saw an engineer in trouble he would ask " do you mind if I help as I have nothing to do tonight and I am a bit bored ".
https://books.google.co.uk/books?id...Q7C0kQ6AEIJjAC#v=onepage&q=rca ca3002&f=false
One has to learn some history if wanting to have a true picture of how we got to where we are. In the case of Alan Blumleins familly they knew nothing years after he died as it was classified. It should be Sir Alan Blumlein at the very least. It is said if he saw an engineer in trouble he would ask " do you mind if I help as I have nothing to do tonight and I am a bit bored ".
https://books.google.co.uk/books?id...Q7C0kQ6AEIJjAC#v=onepage&q=rca ca3002&f=false
I mean debunked as in proven technical measurements and tests showing it to be untrue. One guy, Bob Cordell, went as far as constructing his own special purpose test equipment to figure it out once and for all.
Even the guy who started it all in the 70-ies, Matti Otala, later backpedalled on his statements on TIM etc.
Then there was JC's buddy Ron Q who recently did an AES paper that also showed it not to be an issue at all (although JC had the nerve to call upon that paper as if it supported his views).
So there's a lot of documented well reviewed studies out there (and no I will not search out the links for you) as opposed to the useual 'but I know it is a problem' type of unfounded statements.
BTW Those 'interview papers' are nothing more than a collection of posts from diyaudio with the replies edited out; one could question whether it is a fair and honest way to present views in this one-sided way.
Jan
I'll re-read, but I think the point had nothing to do with class B bias points, or class AB bias points. Looked to me that it was related to 1/2 switching OFF at any point when driven out of class A (no matter how large or small the class A bias).
The author specifically mentions several sources, including Kendall Castor-Perry's "Class i" amplifier (now 5+ years back!!) as an example of output stages that do NOT switch off.
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PIM is NOT A MYTH! It does get generated in op amps that have a low open loop bandwidth. Now, is it below the threshold of audibility? I don't know, but to my ears, it seems to be significant.
We continue to discuss the PIM measurement and audibility behind the scenes, and the problem is far from resolved. Trying to put me away, so that I cannot express my opinions on op amp problems will not make better op amp designs, and I resent being slandered in this fashion.
We continue to discuss the PIM measurement and audibility behind the scenes, and the problem is far from resolved. Trying to put me away, so that I cannot express my opinions on op amp problems will not make better op amp designs, and I resent being slandered in this fashion.
"conventional 2 tone IMD measurement" includes PIM
PIM IS IMD, it just has quadrature shifted sidebands compared to "AM" IMD
so any measure of IMD includes PIM as a vector component
PIM cannot be higher than the total IMD
what is likely true is no one buying into Otala's mistake ever repeated or borrowed Cordell's phase resolving IMD measurement hardware that he built for his 1982 article
until we get to Ron Quan's work - where he had to test slower op amps than the TL07x to get measurements above his custom 3 tone hardware noise floor
Hirata DIM test signals may be intended to capture PIM, TIM like distortions but don't separately resolve phase effects in time/phase units from even order static/"AM" distortion components
so John's claim that that he designed for reduced PIM wasn't supported by actual measurements of PIM
working circuit's operating principles aren't much affected by designer's intent
PIM IS IMD, it just has quadrature shifted sidebands compared to "AM" IMD
so any measure of IMD includes PIM as a vector component
PIM cannot be higher than the total IMD
what is likely true is no one buying into Otala's mistake ever repeated or borrowed Cordell's phase resolving IMD measurement hardware that he built for his 1982 article
until we get to Ron Quan's work - where he had to test slower op amps than the TL07x to get measurements above his custom 3 tone hardware noise floor
Hirata DIM test signals may be intended to capture PIM, TIM like distortions but don't separately resolve phase effects in time/phase units from even order static/"AM" distortion components
so John's claim that that he designed for reduced PIM wasn't supported by actual measurements of PIM
working circuit's operating principles aren't much affected by designer's intent
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It is generated even in amplifiers with no feedback. Low OLBW has nothing to do with it.
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