Whistling Coldamp - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

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 31st July 2007, 04:03 PM   #1
diyAudio Member
 
Join Date: Oct 2005
Default Whistling Coldamp

Hi
I connected up a pair of ColdAmp's BP4078 modules with a single SPS80 switch mode power supply last night and found that I was getting some whistling at the speaker outputs. When I cut the power and the modules were running on the PSU's capacitors for a few seconds it disappeared suggesting the PSU was the source.

I've emailed technical support but if anyone has any tips I'd be grateful? The power supply wires are twisted but I haven't used the supplied chokes yet - I will try this tonight.

Thanks
Simon
  Reply With Quote
Old 31st July 2007, 04:19 PM   #2
BWRX is offline BWRX  United States
diyAudio Moderator Emeritus
 
Join Date: Jan 2005
Location: Pennsylvania
Can you post a picture of the physical layout of your amp? If not, how close is the supply module to the amp modules? Does the whistling still occur if only one channel connected to the supply?

It would be best if you could get rid of the whistling without using the chokes, but do try them and see if they help.
__________________
Brian
  Reply With Quote
Old 31st July 2007, 04:43 PM   #3
diyAudio Member
 
Join Date: Oct 2005
They're about 8 or 9 inches from the PSU - nothing is in an enclosure yet, just flat out on the floor. The whistling occurs with one or both of the modules connected.

I've tried moving things around and it does have some effect on the whistling but it always remains audible.

Thanks
Simon
  Reply With Quote
Old 31st July 2007, 06:34 PM   #4
luka is offline luka  Slovenia
diyAudio Member
 
luka's Avatar
 
Join Date: Sep 2005
Location: in Slovenia :)
Send a message via Skype™ to luka
Hi

Put chokes in. This will help a lot, probaby problem will go away
__________________
home page @ http://www.classdaudio.tk/ @ 24/7 all year long
I FEEL SLOVENIA
  Reply With Quote
Old 31st July 2007, 08:03 PM   #5
ssanmor is offline ssanmor  Spain
diyAudio Member
 
Join Date: Jan 2002
Location: Madrid
Hello, Simon.

Usually, no whistles are produced, but depending on the layout, the fact that you don't have any earth that may act as shield, etc, may increase chances. It is usually solved at first attempt with the chokes, though.
You may want to connect everything as you plan in your case, etc, and, if you still experience the issue, cut the wires and insert the chokes.

We provide 4 chokes per supply, you have to connect them in series with VCC and with VSS, one per rail, and the same for the other module. Have a look at page 12 of this document: (except for the aux supplies):

http://www.coldamp.com/opencms/openc...ppnotes_en.pdf


BTW: We haven't received any technical support question from you about this, Simon. Please check that you sent it to info@coldamp.com or to sales@coldamp.com

Best regards
Sergio
www.coldamp.com
  Reply With Quote
Old 31st July 2007, 08:22 PM   #6
diyAudio Member
 
Join Date: Oct 2005
Thanks for the replies everyone, no joy I'm afraid even with the chokes I'm still getting the whistling. I've got 1 module connected with chokes at the module end.

Should I try earthing the ground in case there's noise on that?

Sergio, I mailed technical.support@coldamp.com as per your DIY web page: http://www.coldamp.com/opencms/openc...elf/index.html

Thanks
Simon
  Reply With Quote
Old 31st July 2007, 08:30 PM   #7
ssanmor is offline ssanmor  Spain
diyAudio Member
 
Join Date: Jan 2002
Location: Madrid
Please post your question with all the info you can, and if possible a photo, to info@coldamp.com , the other account seems to be down.
  Reply With Quote
Old 1st August 2007, 10:12 AM   #8
diyAudio Member
 
Join Date: Oct 2005
Got to the bottom of the problem last night, something to do with PSU earthing as tightening the screws that secure the SPS80 PCB to its Aluminium base plate got rid of the whistling even with no chokes on the PSU lines.

I'll be trying it against my TAG 5x100R tonight to see how it compares. From last night's listening the bass seems very good giving a full sound with plenty of scale.

Simon
  Reply With Quote
Old 1st August 2007, 10:31 AM   #9
ssanmor is offline ssanmor  Spain
diyAudio Member
 
Join Date: Jan 2002
Location: Madrid
Thanks.
Here is the explanation: there are some capacitors that AC-couple switching nodes to earth chassis in order to minimize HF emissions. The connection is made by means of the PCB screws at the corners. If one of the screws was not tight due to transport or whatever, that could cause the problem.

Nice to hear that everything is ok now.
  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
Whistling noise from an Arcam delta 250 (cdm9 pro) DRC Digital Source 3 26th October 2006 12:57 PM
Pioneer PD-75 Cd Player whistling allanlew25 Digital Source 5 7th May 2006 01:22 PM
CDM-12 Problem - Whistling / Oscillation poynton Digital Source 4 8th December 2005 08:50 PM
Whistling Sound after modding Philips Player diyman Digital Source 4 18th November 2005 02:46 PM
ML TQWT: is it whistling ? teodorom Multi-Way 0 12th June 2004 11:45 PM


New To Site? Need Help?

All times are GMT. The time now is 12:25 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