analag

Discrete OPAMP
« on: March 25, 2020, 04:51:40 PM »
I am about to mock this one up and finetune it, Stay tuned, but in the meantime I welcome the wise men to step forward and advise me!
« Last Edit: March 25, 2020, 05:13:10 PM by analag »
Audio engineering suffers from misinformation, disinformation, and downright lying more than most fields of endeavour.


john12ax7

Re: Discrete OPAMP
« Reply #1 on: March 25, 2020, 07:30:17 PM »
Disregard
« Last Edit: March 25, 2020, 09:24:42 PM by john12ax7 »

analag

Re: Discrete OPAMP
« Reply #2 on: March 25, 2020, 08:12:50 PM »
It's a current feedback opamp which is saidto be much better sounding than the voltage feed back type, I have built the 990 style many times, so this is a welcomed change
« Last Edit: March 25, 2020, 08:47:27 PM by analag »
Audio engineering suffers from misinformation, disinformation, and downright lying more than most fields of endeavour.

JohnRoberts

Re: Discrete OPAMP
« Reply #3 on: March 25, 2020, 09:08:45 PM »
I think I've seen something similar to this inside an exotic IC, back when they used to publish schematics for the innards.

JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

john12ax7

Re: Discrete OPAMP
« Reply #4 on: March 25, 2020, 09:28:54 PM »
My bad,  been a while since I've used a current feedback opamp.  The feedback resistor usually needs to be optimized for these. What is the application? They wouldn't work for some audio applications,  but a good choice for high speed gain blocks.

analag

Re: Discrete OPAMP
« Reply #5 on: March 25, 2020, 11:59:30 PM »
I want to try it in a microphone preamp. R4 have a hugh control over the offset so optimization, some compensation will be needed.
Audio engineering suffers from misinformation, disinformation, and downright lying more than most fields of endeavour.

gyraf

Re: Discrete OPAMP
« Reply #6 on: March 26, 2020, 04:17:06 AM »
Why not just build it IRL and check out how it behaves, then take it from there?

It's probably much easier to help you tweak it if we know what it lacks in the chosen application: imo, sim-games can tell you go/nogo, but not anything about the subjective perceived qualities.

And if it's not the subjective perceived qualities you're after, I think it will be VERY hard to beat the run-of-the-mill integrated micpre chips from that and ssm.

/Jakob E.
..note to self: don't let Harman run your company..

analag

Re: Discrete OPAMP
« Reply #7 on: March 26, 2020, 10:08:08 AM »
I fully intend to build it. Just last week I completed an M1 type mic where I simulated and built an 990 type opamp that to my ears sounded better than a clone of the original design. 
Audio engineering suffers from misinformation, disinformation, and downright lying more than most fields of endeavour.

gyraf

Re: Discrete OPAMP
« Reply #8 on: March 26, 2020, 11:20:54 AM »
 :) Now we're talking..! Please report back on your findings!

/Jakob E.
..note to self: don't let Harman run your company..

boji

Re: Discrete OPAMP
« Reply #9 on: March 26, 2020, 12:31:25 PM »
Gents, might you recommend a book to learn more about audio opa design? 

Perhaps Self's Audio power amp designer's handbook?
https://www.amazon.com/Audio-Power-Amplifier-Design-Handbook/dp/0240521625

Thanks


abbey road d enfer

Re: Discrete OPAMP
« Reply #10 on: March 26, 2020, 12:42:30 PM »
It's a current feedback opamp which is saidto be much better sounding than the voltage feed back type
Indeed, with an open-loop BW of about 70kHz and open-loop THD of about 0.3%, you may expect very good performance at the indicated 20dB gain. certainly devoid of TIM.
Fine for line-level operation, e.g. as a line driver, but what about two of the most common uses for DOA's: mic pre and summing amp?
I'm not sure those BC550/560 running at 2mA are optimum for the task.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

analag

Re: Discrete OPAMP New
« Reply #11 on: March 29, 2020, 10:14:51 AM »

It works and it sounds every bit as good as it's said to,  but it needs to fine tuned .
« Last Edit: March 31, 2020, 02:20:37 AM by analag »
Audio engineering suffers from misinformation, disinformation, and downright lying more than most fields of endeavour.


 

Related Topics

  Subject / Started by Replies Last post
4 Replies
2889 Views
Last post March 02, 2006, 01:57:09 PM
by Samuel Groner
18 Replies
10376 Views
Last post April 11, 2008, 04:25:27 PM
by Samuel Groner
9 Replies
1202 Views
Last post October 11, 2018, 01:53:55 PM
by squarewave
40 Replies
2276 Views
Last post February 26, 2020, 04:41:59 PM
by Matador