Hotrodding the UCD modules - 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 10th June 2005, 03:24 PM   #1
diyAudio Member
 
sx881663's Avatar
 
Join Date: Nov 2003
Location: so. ca.
Default Hotrodding the UCD modules

A new thread for general discussion of upgrades made to the UCD modules.
Safety issues must be dealt with like proper fuse protection, covers for exposed mains voltages, storage caps drained before service done, etc.
Any replacement parts should first be given the "Lars" magnet test.
Quality solder should be used as well as a fine tip low wattage iron.

Please add to required proceedures list.
Letís try to keep all the mods in this thread so they can be found!!
Roger
  Reply With Quote
Old 11th June 2005, 01:37 AM   #2
matjans is offline matjans  Netherlands
diyAudio Member
 
matjans's Avatar
 
Join Date: Aug 2003
Location: Utrecht, NL
Send a message via MSN to matjans
ok then, what are the "hotrodding" options for the ucd modules?
I think I'll constrain myself to only replacing parts on the upper side of the pcb; my smd soldering skills aren;t really that good (and my hands tend to shake ;( )

What is there to modify?
- input filter caps
- output filter cap
- on-board psu caps
- more?

Hintd? Tips? Tricks?

I've only removed the input caps, which has lead to a change, definitely for the better, in the sound of the modules. They sound clearer, like a curtain has been removed from the sound. Less warm in the mid-bass region but with more definition in the low-low regions. At first, I've bypassed them with a solid pieces of copper wire of ~5mm length, and after having tested my pre and some other sources I;ve removed the caps completely. I couldn;t hear the difference between removing and merely bypassing the caps so if you want to keep the modules in a sort-of-original state, there's (afaik) no reason to remove them completely.
__________________
Si fractum non sit, noli id reficere!
  Reply With Quote
Old 11th June 2005, 02:16 AM   #3
diyAudio Member
 
sx881663's Avatar
 
Join Date: Nov 2003
Location: so. ca.
Default cap question

I think all the 400 modules have the caps right at the input connector. So if you remove the originals and connect new ones from the input jacks to the amp connector the circuit remains the same. Kind of ironic, using caps that are larger than most of the modules parts put together. This is what it takes for good sound.
Later I will be experimenting with new circuits for the opamp regulators as there is room for improvement there
Roger
  Reply With Quote
Old 11th June 2005, 02:18 AM   #4
diyAudio Member
 
sx881663's Avatar
 
Join Date: Nov 2003
Location: so. ca.
Default Cap question

Sorry, meant remove and jumper out the originals.
  Reply With Quote
Old 11th June 2005, 10:11 AM   #5
Pasi P is offline Pasi P  Finland
diyAudio Member
 
Join Date: Jan 2004
Location: Finland
Dont know if this is correct thread for power supply caps but..

Hypex is using BHC Slit Foils capacitors in their HG power supply.
Bruno has said that BlagGates are very good but maybe too expensive to many of us.

I am currently using 4x 10000uF Rifa PEH200 (4 channel dual mono UCD180). Some has said that Rifa dont sound too good but i cannot yet say because i have not tried anything else. Anyway, i feel that sound of UCD is good even with this PS.

Maybe i will try BHC Aerovox T-Power 4 pole caps. Anybody have experience from these with UCD?

Some other good PS caps?
  Reply With Quote
Old 11th June 2005, 02:16 PM   #6
rha61 is offline rha61  France
diyAudio Member
 
Join Date: Jun 2004
Location: paris
Hi

One day i will try the very famous Jensen 4-pole caps :



http://www.jensencapacitors.com/audi...rs/default.asp

http://www.referenceaudiomods.com/Me...ory_Code=JE4PA


alain
  Reply With Quote
Old 12th June 2005, 08:03 AM   #7
diyAudio Member
 
sx881663's Avatar
 
Join Date: Nov 2003
Location: so. ca.
Default 4 pole caps

Quote:
Originally posted by rha61
Hi

One day i will try the very famous Jensen 4-pole caps :



http://www.jensencapacitors.com/audi...rs/default.asp

http://www.referenceaudiomods.com/Me...ory_Code=JE4PA


alain

rha61,
These caps are new to me. I looked through all their tech stuff and am very impressed. I really like the idea of separate input and output terminals to isolate charging current induced ripple and noise. In the equivalent circuit shown for conventional caps, the nasty high freq. trash is hardly attenuated at all. In the Jensen the equivalent series impedance works in your favor to reduce HF noise transfer.
A couple of things that bother me;
In their description they talk of several ohms of resistance between the input and output terminals. Seems using these terminals separately would severely limit ripple current capability. This resistance will also effect regulation and cause some rail voltage drop. They talk of using a series inductor between input and output to correct this so you still get the good HF isolation. However this destroys the low freq ripple isolation and makes it the same as a conventional cap with bypass as below. They donít recommend this hookup for audio. Of course if you are using a SMPS, using inductors to couple the input to output would still give you the really nice HF attenuation with very little low freq ripple to worry about.
Doing a poor mans version would be to bypass conventional storage caps with large value film caps first then doing 1/10 value and 1/10 value again. (10uf, 1uf, .1uf etc) This will meet or exceed the specs of the Jensen but wonít give you the ripple current isolation.
I would like to try them, too bad they are so expensive. Cost nearly as much as the amp modules! Sure would like someone to try them and report it here.
Roger
  Reply With Quote
Old 12th June 2005, 09:42 AM   #8
diyAudio Member
 
Join Date: Feb 2005
Location: Antwerp
OK in my quest for the best:

A few questions:

* The input caps, that's C23 and C24 I suppose? I'm a total newbie with soldering iron... if these caps are bled dry, is it possible to just drop a little blob of solder on both poles?

* Using new caps, how to put them on the signal path? Same way like the caps in the power supply? anything more that should be added?

* I'm interested in the HQ power supply by Hypex. Is there a PDF or something, I want to see what all the connections are for. Anyone here that is already running this power supply? I just want to see if it is possible to use 2 smaller toroids connected to one PS, and want to know how the DC protection works.

* Right now i'm running quite large 22.000uf BC 154 cans - will the slitfoils be better?

* At what VA rating is a soft start absolutely needed? (230V mains) I'm considering LC Audio

Thanks
  Reply With Quote
Old 12th June 2005, 12:21 PM   #9
Pasi P is offline Pasi P  Finland
diyAudio Member
 
Join Date: Jan 2004
Location: Finland
How about this Polyphenylene Sulphide to output cap:
http://uk.farnell.com/jsp/endecaSear...=3891057&N=401
Maybe better than polyesters?
  Reply With Quote
Old 12th June 2005, 03:57 PM   #10
diyAudio Member
 
sx881663's Avatar
 
Join Date: Nov 2003
Location: so. ca.
Quote:
Originally posted by Pasi P
How about this Polyphenylene Sulphide to output cap:
http://uk.farnell.com/jsp/endecaSear...=3891057&N=401
Maybe better than polyesters?

Moot point as their voltage rating isnít high enough. Even 63 volts is too close to the rail voltage for me.
Roger
  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



New To Site? Need Help?

All times are GMT. The time now is 05:11 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