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

Chip Amps Amplifiers based on integrated circuits

Computer PSU for LM1875
Computer PSU for LM1875
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 20th May 2009, 01:49 PM   #1
lespoils is offline lespoils  Canada
diyAudio Member
Join Date: Feb 2007
Location: montreal
Default Computer PSU for LM1875


I just got 2 LM1875 chip and am looking for a way to power them.

Since i do not have acces to a transformer and am not sure i want to make the whole PSU, i thought about using a spare computer PSU that i have lying around.

i really just want to have you guys opinion. Is this a bad idea from the start ? what other option do i have ?

Also, i was wondering, if i have a wall transformer (those black box things) that gives 24V DC, is there an easy way to get -24V DC to power the chips ? (go from positive to negative tension)

Thanks in advance
  Reply With Quote
Old 20th May 2009, 02:21 PM   #2
Geoff H is offline Geoff H  Australia
diyAudio Member
Join Date: Oct 2006
It is unlikely that the -12v rail of a PC PSU will supply sufficient current.

A simple way of getting the power required is from an old amplifier of about 15 to 20 watts. The Pioneer SA-5500 II is an ideal candidate. A pair of LM1875s will run circles around the original monolithic power IC in terms of noise and distortion.

The main requirement is a spilt supply not exceeding +/- 30 volts unloaded. It is pointless going above about 2x18 volts on the transformer as the overload protection prevents any gain in output power.
  Reply With Quote
Old 20th May 2009, 03:23 PM   #3
anti is offline anti  Slovakia
diyAudio Member
Join Date: Jun 2008
Ha, that makes two of us.

I was also thinking on using an ATX psu for powering a chip-amp. Afaik, the "-12V" rail must be somehow upgraded, because these psu's usually have only 0,3-0,8A current capability on the -12V rail.

One alternative I know is to use two of them, sort-of connected like batteries; in series, so you use only the powerful +12V rails.

Modding an atx psu so that a single one could be used would be neat.

Patiently waiting for the gurus...
  Reply With Quote
Old 20th May 2009, 07:39 PM   #4
star882 is offline star882  United States
diyAudio Member
star882's Avatar
Join Date: Mar 2007
There's also the option of running two chips in BTL.
"Fully on MOSFET = closed switch, Fully off MOSFET = open switch, Half on MOSFET = poor imitation of Tiffany Yep." - also applies to IGBTs!
  Reply With Quote
Old 20th May 2009, 08:02 PM   #5
tomchr is online now tomchr  Canada
diyAudio Member
tomchr's Avatar
Join Date: Feb 2009
Location: Calgary
PC power supplies are incredibly noisy and often requires rather large loads (1 A or more) on either the +3.3 or +5V supply in order to provide good regulation. Typically, the +/-12 V supplies are not regulated. They rely on the tight regulation of the logic supply to work.

Building a linear power supply isn't that hard. I think I was in fifth grade when I designed my own for the first time... But if you really don't want to build your own, I'd suggest looking at one of the many supplies available from Digikey, Jameco, and others. I'd aim for a linear supply that can deliver the voltages at the currents you need. I would imagine that the medical switchers would be fairly decent as well. They are typically switchmode supplies followed by a linear regulator.

  Reply With Quote


Computer PSU for LM1875Hide 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
LM1875 PCB, Which To Use Paswa Chip Amps 281 7th February 2018 08:06 AM
LM1875...how low can you go? Gcollier Chip Amps 7 6th May 2010 03:43 AM
lm1875 siemensc65 Chip Amps 4 23rd May 2006 03:28 AM
Lm1875 soundNERD Chip Amps 14 12th October 2003 02:26 AM

New To Site? Need Help?

All times are GMT. The time now is 02:54 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio