Go Back   Home > Forums > Amplifiers > Chip Amps

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
Reply
 
Thread Tools Search this Thread
Old 29th March 2008, 03:58 AM   #11
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
I've got a couple of wild guesses for you, and that's exactly what they are. Here goes.

There's no dampening on the input. If a potentiometer isn't used, then a 22k or 50k resistor (between hot and ground of input--make a load at input) could be helpful. That would be one resistor per each channel, if a dual gang stereo potentiometer is absent. Load at input--try this first.

The rectifier board is darn far from the amplifier, and the cables for left and right are uneven lengths. Uneven lengths for stereo layout is a pet peeve of mine, but the too long part is a problem. I think the power supply can't overcome that cable length, and thus perhaps the large caps onboard the amplifier boards are performing smoothing rather than having any reserve, and thus leaving the amplifier without that resource makes. . . rectifier buzzzzz
Well, that's just a guess.

Do you have a ground loop breaker? If not, then your source device may be preferring your amplifier's ground to its own power ground (buzzzz).
So, do you have a buzz when using a battery powered source? If not, then consider a ground loop breaker.

Also useful against ground loops, perhaps 8R in series with the input signal ground? When I tried that, it didn't help much, but it made a lovely bass booster, for no reason I could think of.
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.
  Reply With Quote
Old 29th March 2008, 04:31 AM   #12
diyAudio Member
 
Join Date: Nov 2005
Location: Ohio
It still hums (no buzz here) even with battery sources. We just ordered some decent hookup wire tonight and some larger guage. I'm going to try and do a quad star ground. The wire thats in there now is some reprocessed stuff from radio shack because its what I had. So when I get that wire I'll rewire the amp with the star ground scheme. I don't really know how to get the rectifier board any closer. Peter Daniels sells these amps in this chassis and doesn't have any issues. So I don't think its the rectifier board being far away.
  Reply With Quote
Old 29th March 2008, 03:26 PM   #13
diyAudio Member
 
Speedskater's Avatar
 
Join Date: Sep 2002
Location: Lakewood, Ohio
Try unbolting the power transformer and temporally place it out side of the enclosure. Or at least as far as possible from the amp PC boards.
__________________
Kevin
  Reply With Quote
Old 29th March 2008, 03:44 PM   #14
diyAudio Member
 
Join Date: Nov 2005
Location: Ohio
I don't really think thats it honestly like I said before Peter Daniels uses this chassis for a lot of his amps and has no problems. I'll try it when I go to rewire it though just to try it. Should have the wire and stuff next week sometime.
  Reply With Quote
Old 30th March 2008, 11:37 PM   #15
diyAudio Member
 
Speedskater's Avatar
 
Join Date: Sep 2002
Location: Lakewood, Ohio
Your transformer looks to be larger than the receiver's. The receiver's AC wiring is much neater and farther away from the PC boards.
__________________
Kevin
  Reply With Quote
Old 30th March 2008, 11:39 PM   #16
diyAudio Member
 
Join Date: Nov 2005
Location: Ohio
You mean the transformer wiring? Not sure what your getting at here? The new wire I ordered is larger.
  Reply With Quote
Old 31st March 2008, 12:27 AM   #17
diyAudio Member
 
Speedskater's Avatar
 
Join Date: Sep 2002
Location: Lakewood, Ohio
All the AC power wiring.
Start at the power cord connector (by the way where is the chassis ground ?)
Twist and dress the power wires against the chassis side wall.
Pull all the excess into the front compartment.
Rotate the transformer so that the wires are as near the front as possible.
No power wires should be anywhere near the amp PC boards.
Dress the audio input wires against the rear chassis wall then stright forward to the PC board connectors.
Probably do the same for the speaker wires.

Did I say twist all the power wires and get them far from the PC boards?
__________________
Kevin
  Reply With Quote
Old 31st March 2008, 12:54 AM   #18
cuibono is offline cuibono  United States
diyAudio Member
 
cuibono's Avatar
 
Join Date: May 2006
Location: City of Angles
Quote:
Originally posted by Speedskater
(by the way where is the chassis ground ?)

ditto. What is your ground pin of your power cord connected to?

I have the exact same boards. I use two transformers, and no case at all - all the parts are mounted on a wood board. I have absolutely no noise at all, which is pretty amazing.

Make sure CHG is connected to the ground of your power cord.
  Reply With Quote
Old 31st March 2008, 12:58 AM   #19
cuibono is offline cuibono  United States
diyAudio Member
 
cuibono's Avatar
 
Join Date: May 2006
Location: City of Angles
What do you have connected to PG- and V- (which has a green wire? shouldn't be grounded...)?
  Reply With Quote
Old 31st March 2008, 01:00 AM   #20
diyAudio Member
 
Join Date: Nov 2005
Location: Ohio
The AC ground is connected to the chassis right above the transformer in that pic. It's hard to see. Also note thats an old picture the AC wires are shorter and are twisted up and stay pretty much against the wall. they really aren't close to the PCB's.
  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
Output Noise question ianc13 Tubes / Valves 2 20th August 2007 10:48 AM
static noise question kambrian Car Audio 2 15th July 2005 11:59 PM
LM4780 and noise (question) john_lenfr Chip Amps 12 7th July 2005 05:16 PM
Question about noise from kits. caxxxxxx Power Supplies 3 30th April 2005 12:47 PM
ZenV4 noise question Deafboy Pass Labs 5 18th August 2004 04:22 PM


New To Site? Need Help?

All times are GMT. The time now is 09:16 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