Is this a bad idea? - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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 10th January 2013, 04:50 PM   #1
diyAudio Member
Join Date: Dec 2003
Location: Massachusetts
Default Is this a bad idea?

Hi Folks,

I'm currently making a Pass DIY B1 preamp/buffer and was going to use a recycled power supply I got which is basically brand new. Its a 24v 3.2amp switcher made by Cosel:

(pic attached)

Its the LCA75S-24. It has a switching frequency of 190kHz. I'm having second thoughts about using this PSU now, the frequency is well outside the audible range and the B1 board incorporates at least 15,000uF of PSU filtering capacitance. Plus I'm loading the PSU at such a low level it should minimize ripple.
Should I not be worried about this? Should I add a big series inductor and some chokes on the DC side to try and knock down any high frequency ripple?
I do have access to a nice PC based oscilloscope which I could use to measure the rails and probably the B1 output to look for any ripple etc.

Any advice is appreciated.

Attached Images
File Type: jpg photo (7).JPG (454.2 KB, 103 views)
  Reply With Quote
Old 11th January 2013, 08:38 PM   #2
diyAudio Member
Join Date: Dec 2003
Location: Massachusetts
Default update

I decided to add a linear regulator stage after my switcher, I figured it would help smooth the output of the PSU down. I put a clip on choke on the DC supply from the regulator to the B1 board.

I got the pre-amp finished and tried it out and there is no noise on the output that is audible, I'll check with an oscilloscope to confirm its all good now:
Attached Images
File Type: jpg photo 2.JPG (514.7 KB, 66 views)
  Reply With Quote
Old 11th January 2013, 09:50 PM   #3
diyAudio Member
Join Date: Sep 2010
Location: Melbourne
Cute , is that a baking tin? I never thought of using one as an enclosure
Good to see the signal wires twisted. While linear regulator might be helpful, Using an SMPS with a proper enclosure would probably have given more benefit. You could still put a full height metal strip attached to the case at both ends to separate the power and signal if desired. The ferrite on the supply lead to the amplifier is a step in the right direction though these provide little attenuation until well above 1MHz, a common mode choke of say 1mH would have been my choice, these attenuate well into the the audio spectrum and are normally used close to the SMPS input or output, your mains filter will probably contain one. The things I mentioned are not critical and if the output is clean just enjoy it
  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
Why Google-Cam is a bad idea jackinnj The Lounge 3 11th September 2011 07:00 PM
Series woofers Bad idea or okay domtweaker Multi-Way 5 6th July 2011 04:49 AM
Painting Heatsinks..I Know..Bad Idea valveitude Parts 30 9th March 2007 02:38 AM
Is this a bad idea? Jimmy154 Multi-Way 3 24th November 2002 12:18 AM
is this a bad idea? ChesterFuzzin' Multi-Way 2 28th June 2002 05:15 PM

New To Site? Need Help?

All times are GMT. The time now is 01:05 AM.

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