Commercial available discrete OP-AMPs - Overview wanted

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tiefbassuebertr

tiefbassuebertr

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Joined 2005
tiefbassuebertragung.de
#1
There are many threads concerning discrete operational amplifier - here some examples:
http://www.diyaudio.com/forums/pass-labs/120445-pass-discrete-opamp-dip-8-package.html (BF862)
http://www.diyaudio.com/forums/soli...screte-clone-comparison-seven-variations.html
http://www.diyaudio.com/forums/solid-state/154131-anyone-have-made-those-diy-discretes-op-amps.html
http://www.diyaudio.com/forums/vendors-bazaar/127371-discrete-opamp.html
http://www.diyaudio.com/forums/parts/156870-discrete-opamp-help.html
http://www.diyaudio.com/forums/solid-state/51604-my-discrete-opamp.html
http://www.diyaudio.com/forums/analog-line-level/205332-discrete-op-amp.html
http://www.diyaudio.com/forums/solid-state/156474-yet-another-discrete-op-amp.html
http://www.diyaudio.com/forums/solid-state/123538-discrete-cfp-op-amp.html
http://www.diyaudio.com/forums/solid-state/93356-discrete-op-amp.html
http://www.diyaudio.com/forums/solid-state/61888-improved-discrete-op-amp.html
http://www.diyaudio.com/forums/solid-state/83517-discrete-lm3875.html
http://www.diyaudio.com/forums/chip-amps/17873-discretes-better-than-chip-amps.html
http://www.diyaudio.com/forums/solid-state/108731-ics-vs-discretes.html
http://www.diyaudio.com/forums/analog-line-level/221406-discrete-opamp-vs-regular-op-amps.html
http://www.diyaudio.com/forums/solid-state/154131-anyone-have-made-those-diy-discretes-op-amps.html
http://www.diyaudio.com/forums/solid-state/163905-tl071-hand-made-simulation-using-discretes.html
http://www.diyaudio.com/forums/solid-state/156674-my-take-buildable-discrete-op-amp.html
http://www.diyaudio.com/forums/solid-state/165961-simple-60db-discrete-low-noise-amplifier-lna.html
http://www.diyaudio.com/forums/pass-labs/86681-need-help-discrete-op-amps.html

But I want to know commercial manufacturers of discrete op-amps with highest sonic quality - maybe like Burson
Logitech Transporter - what a stunner! - pink fish media
http://www.seventhcircleaudio.com/OpAmps/sc99_about.htm
http://sparkoslabs.com/discrete-op-amps/
http://newclassd.com/index.php?page=55
http://www.johnhardyco.com/990OpAmpDetails.html
http://www.sg-acoustics.ch/analogue_audio/discrete_opamps/
http://www.purpleaudio.com/discrete-opamps/
http://fivefishstudios.com/diy-kits/doa-17-discrete-opamp
http://www.hairballaudio.com/shop/p...products_id=140&osCsid=vYniZF3d6TbK1ZGULz5T52
http://mnats.net/JE-990.html
http://www.hellotrade.com/sound-skulptor/sk99b-discrete-op-amp.html
http://www.tonelux.com/opampinfo.html

Thank you for your advices.
 
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#4
diyaudio member "Wavebourn" describes an interesting topology particularly for unity gain line preamplifier, where are long connection lines go to mono power amps. Only a push-pull darlington arrangement is in use together with some diodes. Go therefore to post #332+336 from follow URL:
http://www.diyaudio.com/forums/soli...john-curls-concerns-low-noise-designs-34.html
and the NUCLON thread about
http://www.diyaudio.com/forums/tubes-valves/88197-nuclon-my-first-hybrid-guitar-amp.html
The mentioned RF diodes KD213 (KD213A, КД213А) are only available as NOS parts. What currently available diode can replace this old ones?
 
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#7
Monte McGuire said:
... why a discrete op amp? There are some pretty amazing monolithic op amps available now ...
Click to expand...

I can't speak for others but for me, I like the ability to choose the compensation network myself. This is not possible with monolithic op amps. In particular, I like to set the phase margin at unity gain crossover, according to MY criteria. Monolithic 350 MHz GBW opamps seem to be engaged in a marketing war where GBW is maximized and phase margin is minimized, simply in order to claim a higher GBW on the datasheet, than The Other Guy.

It was a joy to listen to Scott Wurcer's presentation on discrete opamps at Burning Amp 2013 in San Francisco. He showed us that the industry has been building and shipping GBW= 1 GHz discrete opamps for 30 years (!). If grandpa could do it then, I can do it now. My own personal preference is to overcompensate and "squander" a factor of 8 in GBW, taking me down to "only" 125 MHz of GBW. But the phase margin! Oh the phase margin! How delightful.

You, of course, may feel differently.
 
#8
Mark Johnson said:
I can't speak for others but for me, I like the ability to choose the compensation network myself. . . .
Click to expand...
I've heard others mention a similarly-motivated desire to adjust output-stage bias (and/or protection network) for driving particular loads, and optimizing the input stage operating points for particular signal sources.

Dale

p.s. - There does seem to be some datasheet specsmanship in various corners of the industry. Be sure to look carefully at the measurement conditions for whatever parameters you are comparing from one manufacturer to another - and sometimes you need to "read between the lines" of datasheets to infer these conditions. You may find that the published values reflect operation under the most favorable conditions, or even conditions that are unreasonable in practice.
 
#9
Monte McGuire said:
No disrespect intended, but why a discrete op amp? There are some pretty amazing monolithic op amps available now that greatly exceed the performance of any discrete op amp I've seen, if cleanliness is your goal.
Click to expand...
Because nobody is able to determine the idle currents (quiescent current) at each internal transistor, if there is an integrated op-amp in use. Additional there is no possibility to optimize the compensation dependent of the wanted gain factor and the open loop gain factor.
Another great issue (at least for me) is to find out the appropriate type (e. g. at Analog devices or TI resp. NS), because the special features are often not mentioned or mentioned incomplete. This means, anybody must study all details in the datasheet for finding out only a single difference.
 
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#14
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#15
The lowest distortion opamp in the world, at the moment, is the Groner Composite; refereed Journal paper abstract below. Jan Didden made PCBs and sold off his spares at cost, right here on diyAudio, a couple years ago.

It costs about USD 175 to join the AES and get unlimited access to their library of publications.


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#17
My take on this I've never seen anything approaching a complete datasheet for a discrete opamp, so its not really possible to judge and it's a territory smeared in snake oil as a result.


Here's a challenge - find a commercial discrete opamp with the noise performance fully characterized...
(voltage, current and 1/f).
 
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#18
Mark Johnson said:
The lowest distortion opamp in the world, at the moment, is the Groner Composite; refereed Journal paper abstract below. Jan Didden made PCBs and sold off his spares at cost, right here on diyAudio, a couple years ago.

It costs about USD 175 to join the AES and get unlimited access to their library of publications.


_
Click to expand...
Thank you very much for this advice. here is the URL for the associated thread
Samuel Groner's super opamp
stinius said:
The title of the thread is:

Commercial available discrete OP-AMPs - Overview wanted

Do you think that the SG composit thing fits in?
Click to expand...
maybe one of companies for discrete OP-amps have realized Groner's approach under
https://convexoptimization.com/TOOLS/groner.pdf
AES E-Library >> Low-Distortion, Low-Noise Composite Operational Amplifier
but with the advantage of more available output current (mainly because of that they sound better than integrated ones).
 
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