UcD400 Q & A

[premmetje]

These guys have amazing stuff! Too bad you can't order online - I'm going to give them a call...

The DC protection is great (has its own power supply, I guess it keeps the relays open in case of problems)

I want the slow start as well.... You can use this to start the unit at audio signal (like a subwoofer)

And those 47.000uF Caps!

Are these good specs?



In the picture I see +/- 20% capacitance error...

I think they might have them custom made at BHC. In their standard range there is a very similar capacitor:

http://194.205.122.12/servlet/AdminBHC?purpose=spec&partNo=ALS31A473RD063

 

[subwo1]

It wouldn't be too difficult to add a second crowbar to accomplish simultaneous crowing . I left it out because I thought the bridge rectifiers would keep the reverse voltages out (apart from two diode voltage drops), but I guess that even the odd 1 or two volts might not be so good for some of the electronics.....

I was thinking a similar thing about the rectifier diodes. The question would be how much the surge current and voltage drop would be.

 

[Yves Smolders]

So it's BHC caps... hmm... I'll see if I can find them in Belgium

 

[matjans]

www.schuro.de

 

[Yves Smolders]

Does anyone have experience with the BHC T-network caps? Is it a large advantage to normal caps?

How about the BHC AL10 slitfoil vs the BC 154? I kinda like the last one for the screwmount

Thanks

 

[onixuser]

just a question about caps for the UcD400

i can get these caps from percyaudio:

Nichicon KG Series Gold

4700µF KG-Gold .......80V ..........$7.95...........35mm x 50mm
6800µF KG-Gold .......63V ..........$6.95...........35mm x 50mm

i'm not sure if i should get the 80V 4700uF or 63V 6800uF, if 63V is ok, i'll use a bank of 4 x 6800uF per rail, if i go with the 80V i'll use 6 x 4700uf per rail

i think the 63V rating of the caps can handle a surge voltage greater than the overvoltage protection of the UcD400 module (68V), is this correct?

the transformer that i'm going to use are two Avel 800VA dual 40V sec., this will be used in mono power supply setup.

thanks

 

[richie00boy]

40V secondaries is within the limit for 63V caps, so I'd use the 6800uF ones. They should survive a surge of 68V, as long as it's not a regular occurrance.

 

[BOB LEWIS]

Yves Smolders,
I use quite a lot of T-Network caps and find them better than other caps I`ve tried,excluding BGs.
All other things being equal a 4 pole cap will give better ripple rejection due to the outputted dc not being mixed with the incoming rectifier pulses.

Bob Lewis

 

[Yves Smolders]

Bob,

Does that mean you think BGs are better, or you never use BG's at all?

What's the story on the current limiting that is done on the T-caps inputs?

Thanks,
Yves

 

[BOB LEWIS]

Yves Smolders,
I use BGs for all applications barring primary supplies,for cost reasons!
The T-Networks are above average but like all electrolytics which use ion transfer they impart the usual grainy splashy colourations to the signal which the BGs do not. This is due to the much higher noise and distortion compared to BGs,which typically have a 60dB advantage.
Take a look at Martin Colloms`test report on BGs on the AUDIONOTE website where he and his listening panel were shocked at the improvements BGs gave over other well regarded capacitors.
At the very least you should replace all bypass electrolytics on circuit boards etc to hear the benefits of BGs,don`t just replace one or two and expect to hear big improvements;any conventional caps downstream will compromise the BGs performance advantages.
As for using resistor feeds with the T-Networks;OK for pre-amps etc but I would imagine not a good idea for poweramps where you don`t need any possible current limiting effects!

Bob Lewis

 

[Yves Smolders]

I just wonder if caps' effects are the same in AB and D class designs.

AB is a discrete signal that can have all kinds of interference before the amp.

D is a rapid on-off switch and has another kind of stress on the equipment before the amp.

My test sounded wonderful with nichicon (sp?) caps and a non-toroidal transformer, with a very basic rectifier from the old amp.

Sigh... decisions decisions...

 

[FransDHT]

Back in business

Well, as I wrote about 4 weeks ago, I ruined the modules for my stereo-amp (the three-channel works fine).

Finaly I got the new modules (the ruined ones were economically irrepairable) last week and finished the amp saturday. This time I did nothing wrong....

Well I am impressed, the amp sounds even better than the 3 channel (with 'old' UcD400's). I heard things I didn't hear before and the control is magnificent.

Frans

 

[Yves Smolders]

Frans,

Lovely! I hope you're happy.

I wanted to start building my amp this weekend but electronics stores in Belgium aren't that good, they need to order everything, and all they have is velleman.

Can't even find decent 2*40V power supply

Yves

 

[Duck-Twacy]

I think they might have them custom made at BHC. In their standard range there is a very similar capacitor:

http://194.205.122.12/servlet/AdminBHC?purpose=spec&partNo=ALS31A473RD063

No, those Thel caps are made by Krummer and resold by several brands (Thel, Mundorf, Fischer)

I dont know if this offer still holds:

http://www.diyaudio.com/forums/showthread.php?postid=575084#post575084

Those quotes prices are very low! 23 euro, a similar Mudorf costs 96 euro (only that one is 80V)!

 

[onixuser]

i found this nice looking chassis

An externally hosted image should be here but it was not working when we last tested it.

"High quality aluminum chassis 17.5"x13"x3.25" Front and back plates .1875" thick custom extruded aluminum polished and anodized. Top and bottom plates .125" thick aluminum mirror polished. Chassis comes with solid, machined aluminum feet with felt pads and red oak wood sides with a tung oil finish."

i'm building dual mono w/ 2 800VA avel transformer 40-0-40 Sec.

my question now is how can I provide ventilation for 2 UcD400 modules inside, is it ok if I drill holes under the chassis? or do they have to be on the sides or top?

onixuser

 

[Yves Smolders]

Are you willing to share where you find this with the rest of us?

It's a great looking chassis!

 

[MurrayP]

enclosures

Has anyone found a nice simple (black preferably) extruded style enclosure with end caps to suit a UCD400 plus power supply monobloc style? Sort of like a Rowland 201 but without the need for the flash front panel?

thanks

Murray

ps have built a pair on "chipboard" - seem to outperform a well respected local amp. Great! Now I need a box!

pps a different world to some tripath amps I built - both in audio quality and rfi!

 

[mac]

par-metals series 20 chassis

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[ewildgoose]

The par-metal chasis looks nice. I think its all alu as well including the sides? I prefer the alu sides of the ones from audiokit to be honest, but they use nasty steel tops and bottoms. (OK, nasty is a bit strong).

By the way, where did you get the feet from?

 

[mac]

The par-metal chasis looks nice. I think its all alu as well including the sides? I prefer the alu sides of the ones from audiokit to be honest, but they use nasty steel tops and bottoms. (OK, nasty is a bit strong).

By the way, where did you get the feet from?

The par-metal series 20 chassis is available in a variety of sizes and features all aluminum construction. The feet that I used are made by "EAR" (http://www.earsc.com). They are available from Partsconnexion and Percyaudio here in the states.