41Hz amp6 problem - 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 7th February 2007, 09:01 AM   #1
diyAudio Member
 
Join Date: Oct 2005
Default 41Hz amp6 problem

I have finished my first 41Hz kit (an amp6 basic) and everything works brilliantly - a very good sounding small amp.

The problem is that whenever I switch off my TV (sitting on the same Isotek mains distribution unit as the amp) I get a big thump through my speakers and the drive units 'suck in' and rest at maximum excursion 'inwards'. This remains the situation until I disconnect the power supply to the amp, at which point the cones return to the normal resting position.

I am aware that it requires DC to keep a cone sitting at maximum excursion, so I am worried about this damaging my speakers.

When I initially noticed this problem I was using an SMPS to power the amp, and thought that this might be due to a lack of grounding in my AV system (TV and DVD are double insulated, dac and amp6 powered by single rail SMPS). I switched to a linear power supply with a big cap between the PSU and the amp, and ran an additional ground wire from the - side of the cap to the Isoteks grounding post. This initially prevented the problem occurring, but the problem came back this morning.

Does anyone have any suggestions for solving this?

Thanks in advance :-)
  Reply With Quote
Old 7th February 2007, 11:22 AM   #2
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Kona, Hawaii
Blog Entries: 4
Hmmmm... That is certainly a strange one. Will have to think about that.

The DC offset normally comes from a problem at the inputs. Is there room for you to get to the input caps to measure the DC there when this happens? Also measure the DC out, for reference.

Another question. Does this happen if you disconnect the inputs to the AMP6?
__________________
Big Altec Moving Sale!
  Reply With Quote
Old 7th February 2007, 11:37 AM   #3
diyAudio Member
 
Join Date: Oct 2005
Thanks Pano,

I will measure the DC at the input caps later on and see if anything strange is happening.

I will also try running the dac from the same linear PSU as the amp6 is now using, to tie these grounds together at PSU level. The dac is still using a SMPS (am I correct in thinking that the 0V rail is floating and separate from ground in switch mode PSUs?) so removing this SMPS may prevent 'ground plane offsets' from occuring.

I will also try disconnecting the inputs, and report back.

My previous two gainclones and two modified t-amps didn't suffer from this! (one gainclone now in use in my bedroom, the other in my flatmate's bedroom, both 'pimped' t-amps sold to grateful friends!)

Thanks again for the useful pointers :-)
  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
41Hz Amp6 BASIC minireview kristleifur Class D 20 26th July 2009 03:37 PM
DC bias (AMP6,41hz) pikkujöpö Class D 2 6th December 2007 06:27 PM
Power transformer for 41hz amp6 ecl86 Class D 7 27th June 2007 11:06 PM
Help a noob troubleshoot his 41hz Amp6 migrane Class D 4 24th February 2006 04:56 PM
41Hz Amp6 cadbike Class D 9 8th January 2006 05:30 PM


New To Site? Need Help?

All times are GMT. The time now is 12:32 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