diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   Class D (http://www.diyaudio.com/forums/class-d/)
-   -   need help ! ucd 400 turn off and on (http://www.diyaudio.com/forums/class-d/62881-need-help-ucd-400-turn-off.html)

jj2 21st August 2005 07:40 AM

need help ! ucd 400 turn off and on
 
just finished building a stereo ucd 400 amp, every works but it will for no reason turn off and come right back on while playing music and this has happen a few times today.
Thanks for any help. :mad:

IVX 21st August 2005 08:01 AM

Try to check the rails voltage.

jj2 21st August 2005 04:53 PM

all votage check ok, 56.6 VDC
 
voltage rail 56.6 VDC

stef1777 21st August 2005 05:57 PM

Both UcD400 turn off? or only one !

jj2 22nd August 2005 02:09 AM

it was the tube pre amp.
 
it was the Aes1 tube pre amp, after switch to a 10K passive pre amp it went away.
how can i make the tube amp to work with ucd400 ?????
thanks for all the help .:D

sx881663 22nd August 2005 02:38 AM

preamp problem
 
What is happening is all the low frequency noise from the pre is triggering the protection circuits. You probably noticed woofer cone pumping as well. There are several ways to attack the problem but the more practical ones are to limit the input bandwidth severely in comparison to what it now is. That would be replacing the amp input caps with .047-.1UF. This might be enough to do it. The other thing would be to reduce the time constant of the preamp's power supply to so low to noise canít pass. This would require 5-10 times more DC filter capacitance being added. This is a better fix as it corrects the real problem, a preamp with low frequency stability issues.
Roger

jj2 23rd August 2005 11:12 AM

Roger how???
 
The other thing would be to reduce the time constant of the preamp's power supply to so low to noise canít pass. This would require 5-10 times more DC filter capacitance being added. This is a better fix as it corrects the real problem, a preamp with low frequency stability issues.

would like to do that but how? by putting bigger cap ?
Thanks.

sx881663 23rd August 2005 04:56 PM

Way off topic
 
Please send me a circuit drawing for this unit and I will send you back what to do. Use the forums email for this.
Roger

ac2005 24th August 2005 02:06 PM

just out of curiosity. How does your UCD sound?

sx881663 24th August 2005 06:13 PM

UcD sonic impressions
 
Quote:

Originally posted by ac2005
just out of curiosity. How does your UCD sound?
I assume this was addressed to me? The stereo UcD400AD amp I put together replaced an amp of my own design. This original was an all out A/B design that had been compared favorably to the best there are! It kicked over a lot of sacred cows for sure.
The UcD based amp was implemented in exactly the same way with the same power and chassis as well as all the support stuff so a direct comparison could be made to the A/B design. This means it is a non optimum layout for the UcD as it only will deliver 110W. This appears to be no real disadvantage as it immediately became our new reference. It has all the advantages everyone talks about but the bottom line is that it is just way more enjoyable to listen to. In fact you soon forget the system and concentrate on the music. Listening sessions can now last way too long as you donít want to stop.
It is just more right and I canít give it any higher praise than that.
Roger


All times are GMT. The time now is 09:38 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