UCD400 input question...

[ptwining]

Does anybody here feed their 400's with a PC based DAC?

I use an Onkyo SE-90PCI (Japanese Wavio) 24/196 and both my UCD180's and the 400's (when fed by this card) seem too quiet. The fidelity is amazing but the SPL levels are low.

Could this be the DAC? All the specs seem to be in Japanese so I can't find (or read!) the output of the DAC itself.

Do most folks run a preamp after a PC based DAC?

Do I need to do that to make the 400 take off?

The 400's are supplied by a DIYCable 1kVA toroid and a Hypex HG power supply - wired as indicated in the Hypex app note.

I'm taking the DAC output on gold AR RCAs directly to the modules (the computer, DAC, and 400's are in the same chassis).

Regards,
Tom

[mazurek]

The gain is 26 dB.

You can measure the input and output signal with a voltmeter.

[lucpes]

Check out your sound card volume settings first, I had to actually decrease the gain on the amp for usage without a preamplifier with my soundcard or any external DAC connected to it.

[KeithC]

If you feed a power amp direct from a DAC, problem is usually output level is too high (0db > 2V).

If the level is very low, check that the DAC-> UcD cables are wired correctly.

When I ran direct from PCI DAC to amp I used 10db attenuators.

[ptwining]

Thanks all for replies...

KeithC : DAC --> UCD Cables are correct with signal ground
paired with in- at the DAC and headed up on the modules thru UCD input cables.

lucpes : No sound card present, just the Onkyo DAC in a PCI slot straight out to the modules.

mazurek : thanks, I'll break out the meter... (where in the world did you find specs?)

What else might bring my level down?

Don't get me wrong, the UCD 400 volume isn't shockingly low, just less than I'd expect - in this implementation the 400's aren't really a whole stronger than my 180's - certainly not 2x (even at 8ohms).

Regards,
Tom

[mazurek]

The gain is the same on both modules.

http://www.hypex.nl/docs/UcD400_manual.pdf

http://www.hypex.nl/docs/UcD180_manual.pdf

You can feed a higher signal into the UCD400.

Check out the following

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

[ptwining]

I was concerned (and still am a bit) that my implementation was lacking. This is the third UCD I've built and I'm pretty sure it's okay. I'm going to go thru the amp stem to stern tonight and verify that I am okay (sure I am tho...)

Then I'll have a look at the gain issue to see what happens.

Has anyone done this mod?

Great find mazurek! Thanks...

Regards,
Tom

[lucpes]

Originally posted by ptwining
Thanks all for replies...
lucpes : No sound card present, just the Onkyo DAC in a PCI slot straight out to the modules.

The Onkyo SE-90 is a soundcard. It must have some form of volume control. If you use windows type sndvol32 at the run prompt and see what the sliders look like there.

[ptwining]

Thank you, you're right. The Onkyo is a sound card.

I suppose I meant that the Onkyo isn't the same deal as an Audigy - it is, of course, a sound card- but it doesn't have the bells-n-whistles others have - just an SPDIF and two RCA's.

I refer to it as a DAC because that's the component (with the right specs) I was interested in.

The Onkyo 90-sePCI is based on the Envy drivers and there is a control panel for it, as well as the Windows volume control. Both are maxed out when I test.

Regards,
Tom