Swapping Op-Amps... you have checked to see it's stable haven't you ? - Page 3 - 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 4th September 2011, 10:53 PM   #21
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by Andersonix View Post
I don't like being brow-beaten (esp. by a moderator!) into spending $150-200 minimum on a tool that might get used once a year. Seriously. Is that unreasonable?
I got mine off ebay for 60.
Has worked fine for numerous years now.

You can always sell it on after you have finsihed with it for a similar price.
__________________
PCBCAD50 software. http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 4th September 2011, 10:55 PM   #22
diyAudio Member
 
Andersonix's Avatar
 
Join Date: Jan 2004
Location: Silicon Valley
So now we're arguing about exactly how much money we may or may not have?
  Reply With Quote
Old 4th September 2011, 11:44 PM   #23
diyAudio Member
 
Join Date: Mar 2007
Location: Canandaigua, NY USA
My first reaction is, "get a scope or get a different hobby!"

That said, you can do a lot with a little if you're very clever. Most radio hobbyists in the past didn't have scopes, either because they couldn't afford them, or because the scopes of the day didn't cover the frequencies needed. It was common to make an RF probe for a common voltmeter using a germanium diode and small capacitor. One could make basically the same thing to look for oscillation- any reading is cause for concern. I've also looked for high frequency oscillations and diode switching noise with an old transistor radio tuned between stations. The problem with these ideas is that if you know enough to use them, you probably know enough not to have made the original opamp mistakes to begin with.

BTW, excellent post!
__________________
I may be barking up the wrong tree, but at least I'm barking!
  Reply With Quote
Old 5th September 2011, 12:19 AM   #24
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
Quote:
Originally Posted by Andersonix View Post
I don't like being brow-beaten (esp. by a moderator!) into spending $150-200 minimum on a tool that might get used once a year. Seriously. Is that unreasonable?

(One of NP's early articles, A40, even has a suggestion on how to check DC at the outputs for the DIYer who HAS NO volt meter....!)
I suppose it depends on what you do, but my scope is probably the most useful piece of kit I've got. If the only thing you're going to get up to is little more then opamp rolling, then I'm sure you'll think that a scope is a waste of money - Mooly's thread would naturally disagree and I know this will perhaps irritate some of the opamp rollers, but if you haven't got the ability to measure if a new substitution is stable, then don't even bother doing it. There are of course lots of substitutions one can make without causing oscillations, the trouble here is that the more stable opamps don't tend to be a part of the crowd that's supposed to sound 'better'.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 5th September 2011, 01:02 AM   #25
tade is offline tade  United States
diyAudio Member
 
Join Date: Feb 2005
Location: Ralieigh nc
Send a message via AIM to tade
Quote:
Originally Posted by Andersonix View Post
I don't like being brow-beaten (esp. by a moderator!) into spending $150-200 minimum on a tool that might get used once a year. Seriously. Is that unreasonable?

(One of NP's early articles, A40, even has a suggestion on how to check DC at the outputs for the DIYer who HAS NO volt meter....!)

Yeah, that tone was unnecessary. Don't mistake confidence with rudeness.
  Reply With Quote
Old 5th September 2011, 06:39 AM   #26
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by RCruz View Post
Thank you for pointing me this thread Mooly.

Suddenly I started to understand and correlate all the points I have read about (separatedly).

I also want to thank all involved for the clear and consise sharing
Thanks
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 19th October 2011, 02:34 PM   #27
diyAudio Member
 
Join Date: Apr 2011
Mooly, nice thread!

I've seen many threads on internet where DIY hobbyists replace op-amps on their tastes. At first I thought there would be possibility of stability issues but as nobody talked about it, eventually I accepted the idea it wasn't a deal. Now I discovered swapping op-amps it's not that simple.

I was about to replace the stock op-amps of my MiniMax DAC, but because of your warning I will rethink it as I don't have a scope.

Thank you very much indeed!

Last edited by Audio Maniac; 19th October 2011 at 02:38 PM.
  Reply With Quote
Old 19th October 2011, 05:05 PM   #28
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by Audio Maniac View Post
Mooly, nice thread!

I've seen many threads .................
Your welcome.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 19th October 2011, 05:17 PM   #29
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Great thread but that first post is just plain scary!!

Disclaimer. I own an O'scope. Bought used on eBay.
  Reply With Quote
Old 19th October 2011, 06:48 PM   #30
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by Pano View Post
Great thread but that first post is just plain scary!!

Disclaimer. I own an O'scope. Bought used on eBay.
Thanks Pano... and Mooly with a scope is indeed a scary site
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  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
Why do solid state guitar amps need so many op amps? razorrick1293 Solid State 2 8th June 2011 10:06 AM
Op amp swapping liquias Digital Source 37 29th October 2010 07:45 AM
Burr Brown op amps,in amps,power op amps for sale magneticnorth Vendor's Bazaar 1 23rd September 2010 10:50 PM
swapping op-amps in a vestax pmc-55 sr126 Chip Amps 4 26th June 2008 04:23 PM
FS PA02 Power op-amps +/- 18v, 5 amps modifry Swap Meet 0 11th August 2004 07:45 PM


New To Site? Need Help?

All times are GMT. The time now is 01:46 AM.


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