Gamma-2 (γ2) DAC Thread

[Draguljce]

Hi,

Ps. If anyone does have extra SRC4192IDB or AD1896AYRS, please sell it to me, both are out of stock from Farnell and I do not want to order from Mouser since P&P would be too much.

I ordered from here, RS has it in stock but price is

2x SRC4192 24-bit 192 kHz Sample Rate Converter New USA - eBay (item 110480409506 end time Feb-10-10 21:05:15 PST)

 

[Draguljce]

Hi,

Just quick question about C19 and C25... Parts list says 1µF metallized polyester capacitors "or metallized polypropylene (MKP) in a lower capacitance". Does it actually matter what I throw in or is it "up your personal preference"?

From parts list notes:

"C19 and C25 are "bypass" capacitors for the C20 and C26 audio-grade electrolytic output coupling capacitors. Depending on your preference, you may omit C19/C25 and run C20/C26 unbypassed, or you may omit C20/C26 and run C19/C25 alone (but increase their capacitance of C19/C25 to 3.3µF or higher to avoid low-frequency rolloff and phase shift within the audio band). If you choose the latter option, the Wima MKS 3.3µF 50V or 4.7µF 16V capacitors are the only known ones that would fit. "

I presume that idea was to make a small trade-off because default part list uses panasonic for output coupling capacitors which are presumably less good sounding that some "fancy" capacitors and those bypass caps should compensate for this (especially for higher frequencies AFAIK). As you can read in many places some people prefer bypassing electrolytic and others don't.

 

[jarpatus]

Quote:

Originally Posted by jarpatus /img/forum/go_quote.gif Hi, 2x SRC4192 24-bit 192 kHz Sample Rate Converter New USA - eBay (item 110480409506 end time Feb-10-10 21:05:15 PST)

Thanks for the link, just ordered those! Why didin't I think eBay, perhaps was afraid of forged IC's but then again, seller have good reputation and price is low so I do not have much to loose.

 

[jarpatus]

Quote:

Originally Posted by Draguljce /img/forum/go_quote.gif I presume that idea was to make a small trade-off because default part list uses panasonic for output coupling capacitors which are presumably less good sounding that some "fancy" capacitors and those bypass caps should compensate for this (especially for higher frequencies AFAIK). As you can read in many places some people prefer bypassing electrolytic and others don't.

I take that as "it's up to you decide"

I just don't trust my ears enough to tell the real difference without proper blind test so I try to rely on specifications which can be measuer or calculatred.

But just as hobby, perhaps I actually do some kind of blind test. There is room for socket on the backside of gamma2 PCB, perhaps I'll try different caps with my friends and try if I can tell any difference when blindfolded.

 

[K3cT]

Quote:

Originally Posted by MisterX /img/forum/go_quote.gif How did you ever get past the third step in the "initial check" without knowing that? The γ1 Modular Miniature DAC Can you please follow the instructions? (if U2U was a problem you would have never made it past the third step because the instructions also tell you "If, at any point you do not pass the check, do not proceed to the next step until the problem is first corrected") That way we have some idea if you have a problem with the Gamma 1 USB section, the Gamma 1 S/PDIF section or the Gamma 2 board. Follow?

Sorry if I didn't express myself properly. I did that test and the results were within specification. It seems that this drop only occurs when I mate the 2 boards together AND only when I use USB to power both boards. These are what I get:

With Sigma25
- 5V: 5.13V
- DAC 4.75V: 4.754V
- DAC 3.3V: 3.32V
- USB 3.3V: 3.31V

With USB
- VBUS: 4.2V
- 5V: 4.16V
- DAC 4.75V: 4.01V
- DAC 3.3V: 3.32V
- USB 3.3V: 3.31V

The y2 itself is working properly though with both power sources. It's detected normally and plays music fine. I tried switching computers and I got roughly the same reading, I'll see if I can borrow another mini-B USB cable to do further testing.

 

[amb]

K3cT, your γ1+γ2 is fine. The problem is your computer's USB voltage being out of spec at only 4.2V. While the DAC still "works" at this voltage, the 4.75V voltage regulator has dropped out of regulation because its input voltage is lower than what it's supposed to output, that's why you're only seeing only 4.01V at the test point. The result is that the analog output sections' supply rails aren't regulated (read - noise would get through), and you may experience clipping when the output peaks approach 0dBFS.

As mentioned by others before, I hope you're not using a USB hub. They are notorious for low USB voltages. If your DAC is plugged in directly into the computer, and you still experience the low voltage, then I recommend using the σ25 at all times (even when using USB as your source), or use a different computer.

 

[amb]

K3cT, your γ1+γ2 is fine. The problem is your USB voltage being out of spec at only 4.2V. While the DAC still "works" at this voltage, the 4.75V voltage regulator has dropped out of regulation because its input voltage is lower than what it's supposed to output, that's why you're only seeing only 4.01V at the test point. The result is that the analog output sections' supply rails aren't regulated, and you may experience clipping when the output peaks approach 0dBFS.

As mentioned by others before, I hope you're not using a USB hub. They are notorious for low USB voltages. If your DAC is plugged in directly into the computer, and you still experience the low voltage, then I recommend using the σ25 at all times (even when using USB as your source), or use a different computer.

 

[Draguljce]

I take that as "it's up to you decide"

I just don't trust my ears enough to tell the real difference without proper blind test so I try to rely on specifications which can be measuer or calculatred.

Exactly ! I tend to be perfectionist when it comes to such details, so using the best possible solution (from technical point of view) is a must. Since all capacitors have specific influence on sound (more or less), using the most neutral solution available is only option for me. Some people have specific preferences considering sound signature and accordingly use parts that enhance those, but i prefer "clean" approach.

 

[K3cT]

Quote:

Originally Posted by amb /img/forum/go_quote.gif K3cT, your γ1+γ2 is fine. The problem is your USB voltage being out of spec at only 4.2V. While the DAC still "works" at this voltage, the 4.75V voltage regulator has dropped out of regulation because its input voltage is lower than what it's supposed to output, that's why you're only seeing only 4.01V at the test point. The result is that the analog output sections' supply rails aren't regulated, and you may experience clipping when the output peaks approach 0dBFS. As mentioned by others before, I hope you're not using a USB hub. They are notorious for low USB voltages. If your DAC is plugged in directly into the computer, and you still experience the low voltage, then I recommend using the σ25 at all times (even when using USB as your source), or use a different computer.

Thanks for the re-assurance, Ti! At least I can rest easy knowing that the γ1+γ2 are fine.

I'm not using a hub though and I mentioned that I tried using different PCs to test this. Perhaps it's the cable.

 

[Superfrag]

I just wanted to ask.. what do you guys think, should using a musiland monitor 01 USD as a USB to SPDIF converter do a better job with the y2 DAC which in turn feeds the WA6? I have the above setup, I havent tried USB to y2 directly till now.. need to get the respective cable..

 

[Beefy]

It would depend entirely on whether you have any material at higher than 16/48. If you don't, I wouldn't bother with the Musiland.

 

[knorthover]

Finished mine last night, after a delay caused by soldering X1 in rotated 90 degrees counter clockwise from the correct orientation. I know I need glasses but I could have sworn I checked the dot orientation

. I can vouch for Chip-Quik.

However everything survived both power on and desoldering. Worked straight away when I resoldered the X1 SMD in the right place.

It is a full y1++ configuration. Sounds sweet, will do some listening and comparisons over the weekend.
Thanks to amb, Mister X, and everyone on this forum for all the insights.
Kevin

 

[Superfrag]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif It would depend entirely on whether you have any material at higher than 16/48. If you don't, I wouldn't bother with the Musiland.

Ah thanks. I guess I'll stay with the Musiland.. got a lot of 24/96 files..

 

[jarpatus]

And another one lives, after having some problems with γ1 full++ and finally solving them all I had to solder missing op-amp and caps to γ2 and plug it in. And it works!

This one is AD8656 with Panasonic ECA0JAM471X 470uF output caps, no bypass caps currently (plan to do some experimenting later this weekend) and no upsampling as U4 is currently traveling somewhere over Atlantic ocean.

First impressions? With CK2III:

Would have to do some blind listening to say more, but IMO this sounds at least, if not better, than my M-Audio Audiophile 2496 and to be honest, it's probably way above performance of my ears anyways!

 

[punkerdood]

Apparently I'm the only dummy who's done this:

On U4 - pin 26 "MODE0" I buggered it and the pad it sits on trying to get rid of some excess solder. The only thing it seems to connect to is pin 27. Am I correct? can I just drop a dollop of solder on those two pins and call it good?