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 12th May 2005, 06:41 AM   #1
pne is offline pne  Canada
diyAudio Member
 
Join Date: Mar 2005
Location: Canada
Default heavy distortion in sonic t-amp after input mods

i've just finished modifying the input stage according to the diagram on mardis's site. Blackgates are still on order so I used some plain electrolytic caps rated 2.2uf 50v with 22k 1/4watt resistors. The amp plays fine for a few minutes, then it outputs heavy sputtering/distortion. Could this be due to the caps I used?

The diagram
Click the image to open in full size.
shows the negative lead of the cap going to the resistor right? Are the blackgate c series nonpolar? Am I using the wrong type of cap?

thanks.
  Reply With Quote
Old 12th May 2005, 07:15 AM   #2
diyAudio Member
 
Join Date: May 2002
Location: Switzerland
AFAIK is the input potential of the Tripath chip around half the supply voltage so the cap should be soldered the other way around i.e. plus to the resistor - minus to the pot.

Regards

Charles
  Reply With Quote
Old 12th May 2005, 09:43 PM   #3
pne is offline pne  Canada
diyAudio Member
 
Join Date: Mar 2005
Location: Canada
blast! In the process of unsoldering the caps I accidently lifted one of the pads the resistor lead goes into. Is there another place I can solder the lead to or is this amp done?
  Reply With Quote
Old 13th May 2005, 12:42 AM   #4
diyAudio Member
 
Join Date: Feb 2005
Location: Huntsville, AL
It's been my experience that just about every foul up can be fixed. You just need to look at the input schematic and poke around a bit with an ohm meter to find "other" end of the trace...then bypass the trace with some blue wire.

I have to give mad props to those who've been able to solder thru hole leads onto those smd pads and get it to work. I would'nt even attempt it. For me it was much easier to remove all the parts in the signal path and then bridge these with blue wire. Basically making a direct signal path from the pot's connector to the signal inputs on the chip. I then ran the leads from my input caps thru the holes left behind by the removed connector.
  Reply With Quote
Old 13th May 2005, 03:27 AM   #5
diyAudio Member
 
Join Date: Feb 2005
Location: Huntsville, AL
Need to make a correction here... I do leave the 20k resistors in the signal path, but everything that comes before is removed.
  Reply With Quote
Old 22nd May 2005, 06:08 AM   #6
kujina is offline kujina  United Kingdom
diyAudio Member
 
Join Date: Mar 2005
Location: UK
Hi I'm a bit of a newb, how does this input mod benefit the amp/sound?
And can anyone give links to any other mods for this amp.

...Thanks...
  Reply With Quote
Old 23rd May 2005, 12:43 PM   #7
kec is offline kec  United States
diyAudio Member
 
kec's Avatar
 
Join Date: Mar 2001
Location: California
Do the input caps need to be electrolytic? Can you use Solen caps?

-Ken
  Reply With Quote
Old 23rd May 2005, 06:06 PM   #8
wim is offline wim  Netherlands
diyAudio Member
 
Join Date: Sep 2003
Location: Nootdorp, Netherlands
I have the same question as KEC, because i read over and over that people use electrolyts as inputcap; in all me amps the inputcap is a good quality cap with no polarity (most off the time i use chateauroux polypropylene (MKP)).

i always thought a electrolyt is no good inputcap, but please tell me if i am wrong, and why i am wrong.
__________________
Als er "X" artikelen benodigd zijn, blijken er "X" - 1 in voorraad te zijn.
  Reply With Quote
Old 24th May 2005, 01:20 AM   #9
Wayne1 is offline Wayne1  United States
diyAudio Member
 
Join Date: Nov 2004
Location: Colorado
I think people use NP electrolytics, such as Black Gate N or NX series, because they are physically small.

A film or film and foil cap of 2.2 or 3.3 uF is a very large cap.

If you have space in whatever chassis you are using, a film cap will work fine. If you have a LOT of space and money, try using a paper in oil cap, like the Jensen.

I personally use Sonicaps in all of my Tripath amp builds.
  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
Sonic Impact Gen 2 mods (for a newb) chuyler1 Class D 18 7th July 2013 08:55 AM
Sonic Impact Tio mods? irishpatrick33 Class D 0 12th March 2009 03:54 AM
Heavy Metal distortion. Stormrider Instruments and Amps 7 7th February 2008 09:52 AM
Sonic Mods update & UK users Pano Class D 1 16th October 2005 12:58 PM
mcintosh mc275 heavy mods!! richt Pass Labs 3 26th December 2001 11:08 PM


New To Site? Need Help?

All times are GMT. The time now is 07:46 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