Commercial available discrete OP-AMPs - Overview wanted

tiefbassuebertr · 2014-10-16 5:00 pm

tiefbassuebertr · 2014-10-27 11:02 am

no advices?

tiefbassuebertr · 2015-01-12 4:59 pm

Are there discrete devices available for the no longer produced AD846? Check out this thread:
http://www.diyaudio.com/forums/digital-line-level/118303-ad-846-replacement-3.html

tiefbassuebertr · 2015-01-24 3:43 pm

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?

tiefbassuebertr · 2015-01-24 6:23 pm

also of interest:
http://www.diyaudio.com/forums/analog-line-level/218373-discrete-opamp-open-design.html
http://www.diyaudio.com/forums/digital-source/185945-discrete-opamp-class.html

Monte McGuire · 2015-01-25 1:01 am

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.

Mark Johnson · 2015-01-25 2:10 am

Monte McGuire said:
... why a discrete op amp? There are some pretty amazing monolithic op amps available now ...

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.

dchisholm · 2015-01-25 2:58 am

Mark Johnson said:
I can't speak for others but for me, I like the ability to choose the compensation network myself. . . .

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.

tiefbassuebertr · 2015-01-26 6:18 pm

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.

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.

RJM1 · 2015-01-26 6:40 pm

Another advantage of using a discrete op amp is that that you can chose the the devices such that you are not limited to +-18 or +-22V.

Shinja · 2015-01-27 8:15 am

There are still some commercial discrete OPA provider in japan ,though I don't know whether they ship oversea or not.
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scafas · 2015-01-27 8:55 am

jensen 918 clone

i have to sell this pcb to clone jensen 918 with bc550-560 transistor.
Pcb circuito stampato opamp jensen 918 | eBay

tiefbassuebertr · 2020-08-23 10:50 am

What new releases are there now ?

tiefbassuebertr · 2021-07-13 1:03 pm

any news ?
Do discrete versions still outperform modern versions of integrated OP-Amps like OPA1611 ? - go to
https://www.ti.com/lit/ds/sbos450c/...604100&ref_url=https%3A%2F%2Fwww.google.de%2F

I ask this, because I want to replace the potted modules (four different versions) from Jeff Rowland's C1 (JRDG Coherence ONE).

check out also post #26831-26839 from page 2684 under
John Curl's Blowtorch preamplifier part II

Mark Johnson · 2021-07-13 4:53 pm

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.

_

stinius · 2021-07-13 6:20 pm

The title of the thread is:

Commercial available discrete OP-AMPs - Overview wanted

Do you think that the SG composit thing fits in?

Mark Tillotson · 2021-07-13 6:38 pm

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).

tiefbassuebertr · 2021-07-13 7:58 pm

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.

_

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?

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).

tiefbassuebertr · 2022-09-30 10:30 am

are there interesting news concerning commercial offered discrete OP-Amps ?

Andersonix · 2022-10-01 5:30 am

Academy Audio describes the BA2018 line stage as a discrete op amp:

Commercial available discrete OP-AMPs - Overview wanted

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