Discrete Opamp Open Design - Page 164 - 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 13th October 2012, 02:46 AM   #1631
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Just noting the results and what I will use and why. To each his own. BUT and IF I can buy this thing from a vendor in taiwan with or without smd, I'll try it at least. Making it myself is not the great fun it is for most over here in the DIY category.

That reminds me -- how is the pcb coming along?
Got my Audio Precision brought over and doing some work (as thier ex -CEO) and play.... Got a lot of software to buy while still in S.E.Asia... -RNM

Last edited by RNMarsh; 13th October 2012 at 03:01 AM. Reason: status of pcb?
  Reply With Quote
Old 13th October 2012, 02:47 AM   #1632
fas42 is online now fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Quote:
Originally Posted by bear View Post
but, what, no error correction circuitry?

inquiring minds want to know?

_-_-bear
They call that feedback resistors, fiendishly cunning designers ...

But, the intrinsic design has remarkably good distortion figures, performs excellently even at very high gains ...

Frank
  Reply With Quote
Old 13th October 2012, 02:52 AM   #1633
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
Quote:
Originally Posted by Wavebourn View Post
Vishay today is the common name of the holding that bought many companies, together with their production and techsupport. Hence it's name does not mean high quality.
vishay precision group (VPG) I think you will find is still just the one company. there are simply not that many factories geared up to make this stuff. besides like I said, better to buy from Texas components unless you need very large production quantities

Last edited by qusp; 13th October 2012 at 02:55 AM.
  Reply With Quote
Old 13th October 2012, 03:02 AM   #1634
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Default SW-OPA FFT's -

Quote:
Originally Posted by fas42 View Post
They call that feedback resistors, fiendishly cunning designers ...

But, the intrinsic design has remarkably good distortion figures, performs excellently even at very high gains ...

Frank
Got FFT's on a working prototype ??
  Reply With Quote
Old 13th October 2012, 03:11 AM   #1635
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
Quote:
Originally Posted by RNMarsh View Post
To each his own.
agree totally!

Quote:
BUT and IF I can buy this thing from a vendor in taiwan with or without smd, I'll try it at least. Making it myself is not the great fun it is for most over here in the DIY category.
me too, but at least at this stage it seems not to be the BF862 version? myself I still love building though, mainly so I can make idiosyncratic parts choices =)

Last edited by qusp; 13th October 2012 at 03:25 AM.
  Reply With Quote
Old 13th October 2012, 03:21 AM   #1636
fas42 is online now fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Quote:
Originally Posted by RNMarsh View Post
Got FFT's on a working prototype ??
Nope, this is purely from sim fiddlings ... I'll be keeping entirely out of the building game, my interest in the exercise at this point is to see how closely sim behaviour can match up with real componentry working, and to investigate whether the sim mechanism can help to refine the design in any areas. Also, I enjoy understanding how circuits tick by looking at the waveforms at various points through the beast ...

One thing that is intriguing, is that the distortion figures hardly vary if different BJTs are used, but the PSRR figures change dramatically ...

Frank
  Reply With Quote
Old 13th October 2012, 03:38 AM   #1637
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Sure Frank. When Scott knows what to SIM and feels how to tweak, it can help to refine the design.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 13th October 2012, 03:46 AM   #1638
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Warning to No More Deadline Scott..... I am suppossed to be retired... but a company i was CEO for several years had its president die and now I am back here in Bangkok helping with product development. Seems there is only one way out.

My main interest was to have SW (by hook or by crook) to put his immense knowledge and talent for analog design out and up and running for the benefit of all -- before he retires (?) :-)

besides C of high C jFEts and its affect on PSRR - are there any other factors you found to make a big difference in PSRR. That is interesting to me as it gets little attention elsewhere.

BTW - I find the same thing re transistors make a minor difference in an audio designs' THD where the topology dominates and why symmetrical/balanced topologies are so important. Thx - RNM

Last edited by RNMarsh; 13th October 2012 at 03:56 AM.
  Reply With Quote
Old 13th October 2012, 04:19 AM   #1639
fas42 is online now fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Quote:
Originally Posted by Wavebourn View Post
Sure Frank. When Scott knows what to SIM and feels how to tweak, it can help to refine the design.
Tsk, tsk ... everyone has their own approach and ideas on things, I enjoy playing with other people's ideas, to see where that can lead, since I'm coming from a completely different perspective.

For example, I feel the +ve PSRR figure could go a bit better at high frequencies, trying a few things to see what makes a difference, but apart from extra cascodes haven't come with anything significant so far ...

Still a lot to explore; as I've mentioned before I have very little instinct for how such circuits work, so this is a journey of discovery for me ...

Frank
  Reply With Quote
Old 13th October 2012, 09:00 AM   #1640
PHEONIX is offline PHEONIX  Australia
diyAudio Member
 
Join Date: Jul 2004
Location: Australia
Default Fet Current source question

Hello

Thankyou Scott and Barsco for your approach to fet matching.

I have another fet question that you might be able to shed some light on, do you know what the closet fet is that is used to make up the J500 series of Current Regulating Diodes.

Regards
Arthur
  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 05:02 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 09:59 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