HiFimeDIY UD20

NullDev

I recently received a HiFimeDIY UD20 USB "True Digital Power Amplifier" (based on the SA9023 & STA335BW) and it worked without issue with Rune and a BeagleBone Black. I have the asynchronous version of the amp, so I can't vouch for the adaptive mode, but I can't see how that would cause any issues.

ACX

I have heard about it but I still hadn't the opportunity to try it. How does it sound? Have you the possibility to compare it with a classic T-Amp (TA2024) solution? It would be interesting.

Our teammate Carmelo owns this DAC:
http://hifimediy.com/index.php?route=product/product&path=62&product_id=123
and it's quite good considering its price.

tux

I am really curious about this amp too!

I am also an owner of a HifiMeDiy Dac too, and although I am not experienced with DACS, i am very satisfied with it and i would spend my money again for a hifimediy product in the future:

http://hifimediy.com/index.php?route=product/product&path=62&product_id=87
http://hifimediy.com/index.php?route=product/product&path=61&product_id=108

NullDev

My father had a T-Amp from several years ago. I'll need to see if he still has it and if I can borrow it for a comparison. I truly hate to compare things as I don't have the equipment to do it properly. Ears have a tendency to play tricks where proper equipment doesn't lie.

That being said, there are a few things I plan to mod on the UD20:

1. For instance, the 4 DC input filter caps are 25V devices and I swapped them for 35V devices. That gives me a little more piece of mind that I won't melt the caps if we get a slight power surge or if the supply regulation drifts. Do NOT use an unregulated 24V supply with this amp.

2. The 3.3V linear regulator on the board idles at over 110C with the cover off the case. This is much hotter than the amp chip itself, and has very little in the way of heat sinking. I plan to swap this out for a compact 3.3V switcher which is a drop in replacement plus a couple filter caps. The temps should drop drastically and increase the efficiency.

I would be happy to provide part numbers if anyone is interested.

ACX

NullDev wroteI would be happy to provide part numbers if anyone is interested.

Of course we are: we set up an entire forum section for things like that

What kind of speakers are you driving with that low-power amp?

NullDev

I'm currently driving a pair of NHT SuperZeros circa 1994.

The caps that I used as replacements for the input power filter are Panasonic EEU-FM1V681 (680uF 35V 18 mOhm). The originals looked to be Panasonic EEU-FC1E561S (560uF 25V 65 mOhm).

The 3.3V linear regulator mod is still a work in progress, but I plan to use a CUI V7803-1000 (3.3V 1A). Some additional ceramic caps will need to be used to help filter out any remaining switching noise. That will require experimentation, but I plan to post more details once I work it out.

ACX

NullDev wroteI'm currently driving a pair of NHT SuperZeros circa 1994.

Specifications show a 86dB/W/m sensitivity (with 15W minimum) for these bookshelves, so they should not be so easy to drive, even more difficult for a 2x20W digital amplifier. How do they sound together?

NullDev

They actually sound quite nice together. Keep in mind they are used in a kitchen above the cabinets, so I wasn't expecting concert hall acoustics. I also was concerned with how the pair would match up, but I have been pleasantly surprised thus far.

As I've mentioned before, I wish I had more equipment to objectively measure performance. I do know that the match up nicely fills the room with sound and the Kill A Watt meter that I have hooked up shows only 8 watts total system power draw (including the BBB). I will re-measure this after I make the 3.3V regulator mod.