UcD400 Q & A

[FransDHT]

Hi,

So I just might be able to keep my enclosure! Yes!

Another question: The guys at Hypex suggested I should have a soft start module, because otherwise my home electricity fuses would blow the moment I turned on the amp.

I guess I should put the line-fuse after this module? Or not?

Frans

[ackcheng]

About the power supply for Ucd400, other than large vol caps, should one consider adding a choke as well to reduce the ripples further?

[peranders]

Jan-Peter, Bruno, the UcD400 has been out for some time now (also most likely review units), have got any response you want to share with us?

[tiki]

Hi Frans,

if you mount the modules nearly diagonal, I would put them upside down in a manner, that the output choke is passed by the "vertical" air flow nearly first. That would guarantee always fresh/cool air for the chokes. It's not as good for the rest of the parts, but they generate far less heat. And don't forget to let enough spacing between modules to enable the "Kamineffekt" (don't know the English description).
BTW, a very nice idea, to stratify the modules inclined.

Good luck,
Timo

[DSP_Geek]

Originally posted by Bruno Putzeys

a: yes. The improvement in stereo imaging is clearly noticeable, and therefore worthwhile
b: no, but. You can use lower voltage rectifiers, making the use of schottky diodes practical. If you're using non-schottky rectifiers, don't bother.

Separate supplies improves imaging? I understand the UcDs have decent PSRR, so how does this happen?


Francois.

[Gerald Jansen]

I think I will use this to put it all in:
http://www.etnshops.com/supermoduul/listings/264.html

I might need some help with this. I will let you know how things proceed.

Frans

Hi Frans,

Thank you for posting the link of your case supplier. That's about the kind of rack-mount chassis I had in mind to look for while I'm considering to build a 2 channel UCD amp myself. I think I won't have to proceed my search.

Last week I visited the new Hypex facility where I met Jan-Peter who was kind enough explain some more details on the minor differences between the 180 and 400 version.

I think I'll start off with the UCD180's to get a feel with the technology.

As I also live in Groningen, it would be nice to team up and learn from eachothers experiences. I hereby offer you my help, if needed with your construction. For example, don't forget the space needed for wiring and in-/output terminals.

In case ( you won't be able to fit all required parts for your 5 channel amp into your 2HE chassis, I'd be glad to buy it form you.

Gerald

[FransDHT]

Hi Gerald,

Nice to know there is someone nearby with the same interest, and speaks dutch!

As soon as the enclosure arrives I will let you know if I can use it!

I had thougt of the space for wiring, in- and output terminals and the soft start module. I do not know the size of this module however, so that could become a problem (but I don't think so).

Frans

[Bruno Putzeys]

Originally posted by FransDHT
I guess I should put the line-fuse after this module? Or not?

Security regulations require that the line fuse be the first thing after the plug.

[Bruno Putzeys]

Originally posted by ackcheng
About the power supply for Ucd400, other than large vol caps, should one consider adding a choke as well to reduce the ripples further?

Chokes can be used to good effect to smooth the ripple current going into the mains, but vacuum-tube-amp style choke input circuits are not a good idea, since they need a minimum load to operate correctly (loaded, the supply produces a dc voltage equal the average rectified voltage. unloaded, it produces the peak voltage). Apart from that, they are undamped rc circuits that will respond very strongly to load variations.
Pi-filters (CLC) are possible from the first point of view, but the second issue still needs to be taken into account, requiring all sorts of damping circuits.

[Bruno Putzeys]

Originally posted by DSP_Geek
Separate supplies improves imaging? I understand the UcDs have decent PSRR, so how does this happen?

65dB is certainly decent, and it will insure a channel separation of better than 100dB over most of the audio range. 100dB is not infinity though, so there is a small difference. Any difference, however small, is worth an investment from an audiophile's point of view.

That said, a pair of UcD's sharing one supply still have better stereo imaging than most linear amps, including mono blocks.