Hybrid Hypex UCD

[andyjevans]

Hello Pieter,

Indeed, I'll have to end up with a low impedence balanced signal. It could be done with some Mosfets - I have some Exicon ECX08N16-Z which I haven't used yet - not too familiar with solid state. This would require a different interstage maybe, though I have Londahl LL1671/PP which may work. Otherwise maybe 2a3 with a small stepdown. Or 4P1L with a larger stepdown like 4.1:1. That would give 5v out for 2v in and an output impedence of around 100 ohms. I could use a pair with a LL1660/18mA and have SE in and PP out.

What would you suggest? I am indeed thinking two stages like 26 into a driver stage.

andy

[andyjevans]

I've put together a power supply with a 300VA 35+35v toroid which I hope will supply either a UcD180 or a UcD400. About +-50v output - don't need much watts in a small room.

But I have the first version of the UcD400 - Ver1.0. This has a layout similar to the current UcD400ST shown below. The OEM version layout koifarm is using to remove the two caps is a different one - is this the UcD180 OEM? On mine removing the caps would be a nightmare, since there are lots of surface mount small parts underneath. So I'll have to leave it intact.

So a question about the hybrid version - which of these commercial modules can be used easily? On the HG versions there are a couple of red caps by the input - are these the ones to remove or what? Help please! I'm thinking UcD180 if I have to buy another couple of modules, but which version?

First picture is my original UcD400 Ver1.0, then current models

[Koifarm]

Andy, the first picture on page 1, 1 reply, you see the UCD180st. This board has the easiest access to the coppling capacitors.



Ronny

[Koifarm]

If you like to use a tubebuffer and not a inputtransformer, see below.



See here for more details, 6N16 12x preamp srpp/cathode follower with printed circuit board design.

Regarding the inputimpedance of the unbufferred UCD180st the "+" input has 10k impedance to ground and the "-" input has 1k8 impedance to ground. This makes to use a unbufferred UCD more difficult to use with symmetrical input. I use unbufferred UCD only with asymmetrical input.

Ronny

[andyjevans]

Thanks for that - looks like the UcD18o is the way to go. I was told, however, that right now the UcD400OEM is a generation ahead (some of the nCore technology) of the UcD180OEM, which will come out in a later updated version. There's also the UcD250LPOEM which you might have considered.

http://www.hypex.nl/docs/UcD250LPOEM_datasheet.pdf

Andy

[KBK]

Originally Posted by Koifarm

yes, i have compared the two smps with the UCD400oem modules. They sounded the same so price is an important issue.

Another issue is the opamp input stage of the hypex oem and st modules, if you use the inputstage with its supply from the smps then the background is not so quit and the highs are not so steady as with a conventional powersupply.



If you use your own inputstage with its own conventional powersupply with is easy with the OEM modules and the smps for the powerstage then the sound can be as the Hg modules with hxr. I tested this with several opamp and tube inputstages.

Ronny

question:

Where did you get the R-core transformer from?

[Koifarm]

The R Core transformer came with the housing with i used. This was a defect amplifier. But R Core transformers are sold on Ebay.

transformer r core | eBay

And here:

Audio Catalog

[dude2010]

Can someone post pics on how EXACTLY to route, going from unbalanced DAC into the naked balanced UcD 180st with the bufferstage bypassed.
Thanks.

[Koifarm]

Just connect sheilding of the dacout to the white and copperwire on the ucdboard as in the picture above. And connect signal from dacout to the redwire on the ucdboard.

[dude2010]

Just a regular unbal. to bal. - Are you completely sure? It dosn't need a capasitor??