PMA said:
I may say whatever I please 😀 and btw. verifying has nothing to do with building.
I understand though, you are trying to build a business, that explains a lot. But otherwise, as long as the only thing to show is your own personal opinion, your word is as good as anybody's else. Do a controlled test and report back, that might show something interesting.
Be careful, PMA, Syn08 claims to be a friend of Willy!🙄
Personally, I am glad for your progress, and please remember the word OP AMP can have a broad meaning. I design OP AMPs with complementary differential input most of the time. Look at the example of the Parasound JC-1 for example, or even the Parasound JC-2.
Personally, I am glad for your progress, and please remember the word OP AMP can have a broad meaning. I design OP AMPs with complementary differential input most of the time. Look at the example of the Parasound JC-1 for example, or even the Parasound JC-2.
Yes, I agree, you may design hybrid opamp completely according to audio design rules.
I meant generallly used simplification as VFB, usually dominant-pole compensated device, with low roll-off corner and with very strong NFB. BTW, I have recently made interesting simulations of PIM, that is inherent to this structure, only a question of measure.
I meant generallly used simplification as VFB, usually dominant-pole compensated device, with low roll-off corner and with very strong NFB. BTW, I have recently made interesting simulations of PIM, that is inherent to this structure, only a question of measure.
PMA said:
You can compensate opamp circuits in a gazillion of ways as well, nobody is forcing you to use "dominant pole compensated device, with low roll-off corner". I just posted a couple of days ago an example of a composite amp that doesn't use dominant poles etc... It's just an almost textbook example of what kind of amazing things can be done using the modern opamps. Hardcore "Three legs good, eight legs bad" (to quote Scott) denotes a) lack of understanding and/or knowledge on modern opamps features, or b) trying to fool yourself and everybody else about audio as voodoo magic rather than just engineering.
One problem with b) is that this is 2008 - and there are no longer audio voodoo sorcerer job openings. You were born 40 years to late and in the wrong place for that.
Otherwise, good luck and no hard feelings please 😀
PMA, that is why I often make my best designs with transconductance amp topology. Raises the open loop bandwidth, all else being equal. CTC, Levinson JC-2 line stage, Vendetta 2'd stage and Dennesen JC-80, all design winners, use transconductance topology.
Hi John,
Not low-noise input stage, but MOS-FET outputs.
At the time you did the vandetta phonostage, Krell was using Supertex mosfets in the PAM-3, PAM-5 and KSA-50, KSA-100 and the KMA-100.
I believe you used Hitachi in the Vandetta. How do you rate the VN0206, VP0206 series?
mkc
Not low-noise input stage, but MOS-FET outputs.
At the time you did the vandetta phonostage, Krell was using Supertex mosfets in the PAM-3, PAM-5 and KSA-50, KSA-100 and the KMA-100.
I believe you used Hitachi in the Vandetta. How do you rate the VN0206, VP0206 series?
mkc
Hi John,
Thanks for the reply.
I bought some back then. I have 10-15 pieces left of each.
Also have some 2SK147, 2SJ72. But, not enough to build an Vandetta and certainly not enough to select them for noise.
But, there is always Erno Borbely🙂
Best regards,
Mogens
Thanks for the reply.
I bought some back then. I have 10-15 pieces left of each.
Also have some 2SK147, 2SJ72. But, not enough to build an Vandetta and certainly not enough to select them for noise.
But, there is always Erno Borbely🙂
Best regards,
Mogens
Transistors are old enough technology, now..that it should be possible (like buying old record plant cutters and stamping gear, etc) to have someone make their own 'hobby' line of transistors. I'm amazed that it has not been done. The big guys can't get into it, otherwise they'd end up charging more than the hobby guy, as the line (manufacturing position) could be used for a more large scale salable product. Like Black Gate capacitors being pushed out of production for that exact reason.
I'm using Supertex parts in a current design in production today. No real problems getting them. I have been a fan for a very long time. No real problems getting them. The part numbers have changed and the variety is smaller but they still have what I have needed.
John, I have reviewed dozens of my power amp spectral measurements. The 7th appears only if output stage leaves class A. Right you are, again.
PMA, the problem is KEEPING the power amp in class A. You just run out of heatsink, especially with very powerful designs. I work very hard to make the transition between class A and class B as smooth as possible. I 'baby' my best output stages with low impedance drive, matched betas, optimized R(E), and very linear complementary devices running with significant Iq in each device. I usually still i can measure 'some' 7th harmonic, but it will be -115dB or below.
I know. I run my poweramp at 35W/8 ohm class A and it seems to be maximum reasonable top limit.
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