Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

Discrete Opamp Open Design
Discrete Opamp Open Design
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 13th September 2012, 09:47 PM   #921
scott wurcer is offline scott wurcer  United States
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: dorchester ma
Quote:
Originally Posted by RNMarsh View Post
The non-IC discrete here should do that and more, if possible -- Key to design for: be very simple -- use the fewest transistors. Low cost, easy to find parts. Drive low Z. No dc servo. wide OL bandwidth. THD and noise < -100db ref 1v. Gain at a range of 4-10X etal. Others can decide what more can be done by their design. -Thx RNM

You said it not me , " it must be able to also do lower Z at low thd than IC opamp/IC buffer combo. Or what's the point -- just use an IC. -RNM " I just pointed out that there are single IC's that do all of the above (and they even look like op-amps).

Yes, an ADSL driver won't make a good phono pre-amp.

I choose not to particpate in your challenge, do you mind?
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."

Last edited by scott wurcer; 13th September 2012 at 09:54 PM.
  Reply With Quote
Old 13th September 2012, 09:56 PM   #922
Kindhornman is offline Kindhornman  United States
diyAudio Member
 
Kindhornman's Avatar
 
Join Date: Aug 2012
Location: Los Angeles, California
Discrete Opamp Open Design
John,
I think that I have some of your earlier amplifier designs from Parasound that are about that vintage. One has been sitting for quite some time with all the output devices fried. My fault with an unstable crossover that went into oscillation and the amp was running in bridged mode, couldn't turn it off fast enough. Still want to fix that though. Needs all new NPN and PNP devices though.
  Reply With Quote
Old 13th September 2012, 09:57 PM   #923
john curl is offline john curl  United States
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
What is the model #?
__________________
"Condemnation without Examination is Prejudice"
  Reply With Quote
Old 13th September 2012, 09:58 PM   #924
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Discrete Opamp Open Design
Quote:
Originally Posted by scott wurcer View Post
You said it not me , " it must be able to also do lower Z at low thd than IC opamp/IC buffer combo. Or what's the point -- just use an IC. -RNM " I just pointed out that there are single IC's that do all of the above (and they even look like op-amps).

Yes, an ADSL driver won't make a good phono pre-amp.
Ok - you get one point for that.

It was thought up to do a best effort in a discrete form.
My question or challenge was -can the limitations/conditions I gave be all met and still do as well or better than an IC opamp? Maybe.

No. Of course, I dont mind, Scott. Just keep doing what it is you are doing is fine. -Dick

Last edited by RNMarsh; 13th September 2012 at 10:08 PM.
  Reply With Quote
Old 13th September 2012, 10:11 PM   #925
Kindhornman is offline Kindhornman  United States
diyAudio Member
 
Kindhornman's Avatar
 
Join Date: Aug 2012
Location: Los Angeles, California
Discrete Opamp Open Design
John,
I have to find it. I also have the smaller amp from the same time that is the HCA 800 ll but that was a smaller 100 watt amp. The one I am thinking of had 200 watts per channel. I have two of those around here somewhere. One still working and one dead.
  Reply With Quote
Old 13th September 2012, 10:14 PM   #926
john curl is offline john curl  United States
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
The 800 is not a product that I am directly identified with, but I might be able to help, if I have more info as to your problem.
__________________
"Condemnation without Examination is Prejudice"
  Reply With Quote
Old 13th September 2012, 10:42 PM   #927
coluke is offline coluke  Italy
diyAudio Member
 
Join Date: Mar 2009
Breadboarded a slightly modified version of the circuit in #271 - more or less a JC2 with a diamond out: *** unselected *** J113/J175 in the front-end, BC550/560 in the gain/driver stages, MJE243/253 in the output stage. Even with randomly choosen devices, it rocks - THD < 0.001% @ 1kHz, 0dBV into 30 ohm, only low order.

More to follow.

Ciao,

L.
Attached Images
File Type: png JC2-HP 1kHz.png (29.8 KB, 372 views)
  Reply With Quote
Old 13th September 2012, 11:58 PM   #928
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Discrete Opamp Open Design
Quote:
Originally Posted by coluke View Post
Breadboarded a slightly modified version of the circuit in #271 - more or less a JC2 with a diamond out: *** unselected *** J113/J175 in the front-end, BC550/560 in the gain/driver stages, MJE243/253 in the output stage. Even with randomly choosen devices, it rocks - THD < 0.001% @ 1kHz, 0dBV into 30 ohm, only low order.

More to follow.

Ciao,

L.
Very nice -- esp. unselected and not a sim of ideal perfectly matched parts. :-)
  Reply With Quote
Old 14th September 2012, 12:36 AM   #929
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Discrete Opamp Open Design
Coluke -- what is the schematic, pls?

I am tinkering with boot-strapping a whole circuit and see if it stays together. Just adds two more transistors. Thx - RNM
  Reply With Quote
Old 14th September 2012, 12:53 AM   #930
bear is offline bear
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Discrete Opamp Open Design
Rumbling around back here in the pantry... minimum parts count is certainly something that minimalists will like... and of course anything that has low parts count may also be elegant which is always good.

But equaling the JE990? Is that a valid goal today? I would think exceeding it? No?

Wonder if things like rise time, settling time, overshoot show up in the distortion figures? (I really do not know if there is a direct relationship that can be drawn) If there is not a direct correlation, should these factors be considered as well?

Are all these designs Class B output stages?
Should Class A output stages be under consideration?
At a thermal and power cost, will they yield a better spec (and sounding) op amp?

And, is the claim being made that from a listener's point of view that any device with sufficiently low distortion is audibly not different than the next? Personally, I have yet to find that to be the case. In some instances I have been rather surprised by this.



I'd say the winner is the one that sounds the best, measures the best and not only looks the best on sims and specs... and do we *need a single "winner"?* (rhetorical question)



_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- every once in a while I say something that makes sense... ]
  Reply With Quote

Reply


Discrete Opamp Open DesignHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Discrete OPAMP audio-gd Vendor's Bazaar 28 12th May 2015 07:32 PM
discrete opamp help blackpowderaudio Parts 0 16th December 2009 04:46 PM
THAT transistor headphone amp (250ma discrete opamp) design sanity check. Russ White Headphone Systems 19 13th December 2007 01:52 PM


New To Site? Need Help?

All times are GMT. The time now is 02:17 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki