pre amp buffer suggestions. - Page 5 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

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
Thread Tools Search this Thread
Old 30th July 2011, 01:39 AM   #41
diyAudio Member
Join Date: Jan 2006
Location: Sydney
Additional Note, i had been using 3.9ohm load across the terminals during test, and replaced them with some speakers, now the temps have dropped to ~33C with that easier load.
  Reply With Quote
Old 30th July 2011, 01:51 AM   #42
diyAudio Member
Michael Bean's Avatar
Join Date: Sep 2004
Location: Minneapolis, Minnesota, USA
Good deal, sounds like it's under control. With two chips running in parallel you'll be able to drive loads as low as 2 ohms in theory, and of course it depends on how efficient the heat sink is. Have fun!

  Reply With Quote
Old 30th July 2011, 01:57 AM   #43
diyAudio Member
Join Date: Jan 2006
Location: Sydney
cheers mate. I've just tested the DC offset of a couple other retail amps i've bought, and they are measuring +15mV on each channel, i too have adjusted those down to ~0 fairly easily enough. Thanks everyone for the direction and advise, i'm sure i'll be here soon asking a few more questions.

  Reply With Quote
Old 30th July 2011, 05:53 PM   #44
bcmbob is offline bcmbob  United States
diyAudio Member
Join Date: Dec 2009
Location: Bay City, Michigan
Richard, I have two of these - one working at 17VDC on all three chips. The other one is producing some oscillation that makes the DC readings fluctuate wildly. I couldn't tell from your posts if you actually installed the 100K pots and/or added a second surface mount resistor.

I bought the boards only from Jim's Audio on eBay and he sent a diagram.
Click the image to open in full size.

I'm going to do the two chip mod and hope I get as good results as you.
Bob M.
"Arrange Whatever Pieces Come Your Way."

Last edited by bcmbob; 30th July 2011 at 06:16 PM.
  Reply With Quote
Old 30th July 2011, 11:18 PM   #45
diyAudio Member
Join Date: Jan 2006
Location: Sydney
Hi bob,
thats the very same amp circuit i have, one thing i can see that is different is the C1 capacitor. On that schematic it's rated at 10uF, i have a 4.7uF used on my board. I had removed the centre chip from each board to make lowering the DC offset abit easier and stable to adjust and maintain between the chips. There was too much varience between three chips that was unable to be controlled.
One thing i have observed during warm up, warm down is, what ever change in DC offset one chip has, it is countered on the other. So now i would recommend replacing those 50K pots to 100K, i havn't done it yet, but my guess is that a higher range pot, you may get more stable and tighter DC offset.
And whats this oscillation problem your seeing? i'm assuming your talking about the phase between the two?


Last edited by richard.C.; 30th July 2011 at 11:38 PM.
  Reply With Quote


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
Buffer pre-amp panson_hk Analog Line Level 23 13th February 2013 07:31 PM
OP+Buffer pre-amp/headphone monkey29 Chip Amps 0 25th October 2010 09:34 AM
My pre-amp / buffer SimontY Solid State 12 15th November 2008 05:48 PM
Pre-Amp / Buffer on Ebay poynton Solid State 1 22nd June 2008 12:40 PM
Pre amp or Buffer for Inverted GC? 5150ed Chip Amps 9 11th July 2006 06:27 PM

New To Site? Need Help?

All times are GMT. The time now is 02:22 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2