UcD400 Q & A

Jump to Latest
B

Bgt

Member
Joined 2005
grotel.nl
Another thing I see here are the big toroids people use for the UCD's. I think a waist of money and weight. If you think about it, the class D amps. never use their full spec continiously. They use what they need +10%. So the PSU's are never fully loaded. F.i. I use a 300VA toroid with left/right rectifiers and caps and they can play so loud that's not nice anymore. The toroids have a very low impedance and if you use good caps. like the 0154 series you don't need a 1KVA toroid for a UCD 400 amp. It also makes the amps. like giant blocks cq monsters. Just read that the 0154 series is no more, replaced by the Vishay 102PED and 106PED series. The 106 has better specs.
 
B

Bgt

Member
Joined 2005
grotel.nl
Try the bridge mode with 2 UCD 400, than the single UCD mode. If you here a difference in tight, dry bass(also mid tones) your PSU is to blame. It should not be different at the same level. A high Z PSU makes a sonic difference. Bad ESR caps. can be compensated(to a certain extend) with a very high VA rating toroid.
 
G

ghemink

Member
Joined 2004
Bgt said:
Try the bridge mode with 2 UCD 400, than the single UCD mode. If you here a difference in tight, dry bass(also mid tones) your PSU is to blame. It should not be different at the same level. A high Z PSU makes a sonic difference. Bad ESR caps. can be compensated(to a certain extend) with a very high VA rating toroid.
Click to expand...


In case the supply is no good, the bridged mode should sound better, is that what you mean? In bridged mode, the supply peak currents would be less so would be less demanding on the supply (at least with the same output power).

Gertjan
 
richie00boy

richie00boy

Member
Joined 2003
readresearch.co.uk
ghemink said:
In case the supply is no good, the bridged mode should sound better, is that what you mean? In bridged mode, the supply peak currents would be less so would be less demanding on the supply (at least with the same output power).

Gertjan
Click to expand...

Surely the currents must be identical? The difference is in whether the full current is drawn through one winding or two?
 
C

classd4sure

Disabled Account
Joined 2004
diyaudio.com
If the supply can push it, current output will double.

Usually output current doesn't double, because of current limiting circuitry, some part due to inefficiencies, but if the transformer is the weak link.. it's not going to supply it cleanly ..transformer will overheat.. etc. The point was with a five channel system made up of UCD400's all running off of one 500VA transformer, the transformer is the weak link. It's got nothing to do with gain.
 
X

xman737

Member
Joined 2004
My UcD400 is singing

Hi,
My UcD 400 based strero power amp is singing finially. As a beginner, it is a hard work to me. Especially when my softstart and fuses was burned couple weeks ago. I rebuilt the softstart and found one of my transformers is short to ground after troubleshot by mt friend Mr. Lin. Now I use one 600VA transformer and 2 X 22,000 UF cap to power two UcD 400s. It will be changed to dual mono PSU when I receive the warranty replacement.
Compare with my AV receiver DENON A1D, A1D as a preamp, the bass is more deep and the separation between different instruments is more claer. But not a quantum jump as I expected. It just runs about 2 hours, therefore, it is too early to descripte the sound. I would say I see the potential.
I would like to say thanks to Mr. Gertjan, Mr. Chrisb03, my friend Mr. Lin and all of you in this forum. I will not complete this project without your help! ;)
 
G

ghemink

Member
Joined 2004
Re: My UcD400 is singing

xman737 said:
Hi,
My UcD 400 based strero power amp is singing finially. As a beginner, it is a hard work to me. Especially when my softstart and fuses was burned couple weeks ago. I rebuilt the softstart and found one of my transformers is short to ground after troubleshot by mt friend Mr. Lin. Now I use one 600VA transformer and 2 X 22,000 UF cap to power two UcD 400s. It will be changed to dual mono PSU when I receive the warranty replacement.
Compare with my AV receiver DENON A1D, A1D as a preamp, the bass is more deep and the separation between different instruments is more claer. But not a quantum jump as I expected. It just runs about 2 hours, therefore, it is too early to descripte the sound. I would say I see the potential.
I would like to say thanks to Mr. Gertjan, Mr. Chrisb03, my friend Mr. Lin and all of you in this forum. I will not complete this project without your help! ;)
Click to expand...


You're welcome, I don't think I was of much help but anyway thanks. Maybe the Denon uses class D amps?? All class D amps I heard so far, although they can sound different, have some sound characteristics in common.

Best regards and happy listening

Gertjan
 
jam

jam

Member
Joined 2001
Jan-Peter,

You should make Bruno's head move around when you move the mouse pointer over his picture, like the modules.................;)

I am sure he will be a great addition to your company.

Regards,
Jam............................waiting for UCD1000's.:cool:
 
You must log in or register to reply here.
Top Bottom