Discrete Opamp Open Design - Page 20 - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 24th August 2012, 05:45 PM   #191
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
Quote:
Originally Posted by bear View Post
Brad, sorry I should have said "that I had not seen elsewhere...". Doesn't mean that this stuff was not out there, just that sitting in relative isolation, I had not found it via various pseudo random efforts to locate this sort of information - this was before the internet as we know it today... that meant trips to various university libraries and bookstores - many of the texts were even back then in the >$100 range, which was daunting. I persuaded someone to make me a photocopy of Grebene, because I couldn't swing the bux for even a used copy... whaaaaa!

_-_-bear
I know the feeling. Some out-of-print texts and monographs are holding their value extremely well. That Grebene you mentioned is available as shown in the reissue Classics series, but isn't cheap --- and it's softcover!

Just checked bookfinder.com for Ed Cherry's Amplifying Devices and Low-pass Amplifier Design, a generally reliable book and one with a unified treatment of hollow-state and sand-state, from 1968. A somewhat beaten-up ex-library copy is offered for nearly $200, while a Canadian seller helpfully offers one for a mere ~3500. Of course it can hardly cover everything, and much of it is very dated, but fundamentals are pretty much timeless. They will pry my copy from my cold dead hands
  Reply With Quote
Old 24th August 2012, 05:51 PM   #192
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by jneutron View Post

Is the PMI SSM2210 still being made?

jn
Yes, and THAT makes matched NPN's and PNP's too.
__________________
Silence is so accurate.
  Reply With Quote
Old 24th August 2012, 05:52 PM   #193
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Default Tricks of the trade?

Quote:
Originally Posted by scott wurcer View Post
The crossover is an "S" shaped voltage discontinuity across the output stage. Inside the loop the current needed in the compensation capacitance is the derivative of this voltage or a "hump" at zero crossing which gets larger as the dV/dT increases (higher input frequency). The more bias (also degeneration tricks) will reduce the size of the discontinuity in the first place.
Thank you. Are there any degeneration tricks that you would be allowed to show/teach?
  Reply With Quote
Old 24th August 2012, 05:56 PM   #194
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Look everyone, I KNOW how to design audio gain modules, already. I am only trying to help out with some 'new' (typically 40 years old) ideas. Have fun, but in my opinion, you won't get farther at this rate, than what is already out there.
  Reply With Quote
Old 24th August 2012, 05:58 PM   #195
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by RNMarsh View Post
Thank you. Are there any degeneration tricks that you would be allowed to show/teach?
As I proposed before, close local feedback before the buffer. If you want to keep high DC gain for better output zero control at the buffer's output when global feedback is closed, use series R-C for this local feedback path.
__________________
"Our youth [...] have bad manners, contempt for authority; they show disrespect for their elders, contradict their parents, [...] and tyrannize their teachers. -- Plato, 447-367 BCE
  Reply With Quote
Old 24th August 2012, 06:00 PM   #196
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by RNMarsh View Post
Thank you. Are there any degeneration tricks that you would be allowed to show/teach?
The one I was thinking of is well known (Bernie Oliver?), just the right drop on the emitter degeneration resistors (output devices) will do some first order distortion cancellation. I don't remember the exact numbers.
__________________
Silence is so accurate.
  Reply With Quote
Old 24th August 2012, 06:04 PM   #197
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
Quote:
Originally Posted by jneutron View Post
Do they still make the LM 194/294/394?

Is the PMI SSM2210 still being made?

jn
I think there is still some NOS on 194 but the word on the street is that you can do as well with existing monolithic duals for about every parameter (the MAT series?).

Don't know about the 2210.

Also not to be forgotten is THAT's arrays, (EDIT: just noticed SW's post crossed in cyberspace) which have emphasized log conformance. I wish they could do something with higher beta though. I spoke to them about this and was told that they had played around with attempts in that direction, to find that breakdown voltages were all over the map.

I wish I could afford to fund some duals based around the BF862.

The obsolete parts problem reminds me of the story about the Arnoux Associates design for Infinity (the Harman company) of a switchmode power amp for automotive aftermarket. The product was announced about three years running at Winter CES, and then never shipped until after that. The late Mack Turner was the designer, and he swore that the only comparator that worked for the pulse-width modulator was a part that had been discontinued by TI. Steve Dove and I joked about this a bit, perhaps somewhat naively, but Infinity took the admonition seriously, and with the financial resources available then, commissioned a run of devices. I think the tab was over 100k

The saddest part of the story was that when the amp was finally shipping, it was somewhat expensive for the output power, and the market, consisting mostly of "kids" pimping out their vehicles, was almost nonexistent: the thing didn't look like it could do serious power, no big heatsinks etc. I heard that there was a final attempt to sell it by simply putting it in a larger chassis! Still no dice.

As I've said before, You can't make this stuff up --- no one will believe you.

Last edited by bcarso; 24th August 2012 at 06:08 PM.
  Reply With Quote
Old 24th August 2012, 06:04 PM   #198
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
John is my hero.

Love this one :

Discrete Opamp Open Design

and this one :

Discrete Opamp Open Design

But stupid question, where to put the -Vin on the second one ?


Patrick
__________________
xen-audio.com
  Reply With Quote
Old 24th August 2012, 06:11 PM   #199
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by bcarso View Post
The saddest part of the story was that when the amp was finally shipping, it was somewhat expensive for the output power, and the market, consisting mostly of "kids" pimping out their vehicles, was almost nonexistent: the thing didn't look like it could do serious power, no big heatsinks etc. I heard that there was a final attempt to sell it by simply putting it in a larger chassis! Still no dice.
I am going to try today in the field Behringer 2x300W per channel amp, class D with SMPS. I paid $185 for it including shipment. No heatsinks (almost), just a fan.
__________________
"Our youth [...] have bad manners, contempt for authority; they show disrespect for their elders, contradict their parents, [...] and tyrannize their teachers. -- Plato, 447-367 BCE
  Reply With Quote
Old 24th August 2012, 06:16 PM   #200
diyAudio Member
 
dirkwright's Avatar
 
Join Date: May 2011
Location: Virginia
Quote:
Originally Posted by bcarso View Post
I think there is still some NOS on 194 but the word on the street is that you can do as well with existing monolithic duals for about every parameter (the MAT series?).

Don't know about the 2210.

Also not to be forgotten is THAT's arrays, (EDIT: just noticed SW's post crossed in cyberspace) which have emphasized log conformance. I wish they could do something with higher beta though. I spoke to them about this and was told that they had played around with attempts in that direction, to find that breakdown voltages were all over the map.

I wish I could afford to fund some duals based around the BF862.
Linear Systems makes duals:
Linear Integrated Systems - Products
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Discrete OPAMP audio-gd Vendor's Bazaar 27 20th September 2012 04:02 PM
discrete opamp help blackpowderaudio Parts 0 16th December 2009 03:46 PM
THAT transistor headphone amp (250ma discrete opamp) design sanity check. Russ White Headphone Systems 19 13th December 2007 12:52 PM


New To Site? Need Help?

All times are GMT. The time now is 08:37 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2