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Valab Dac-First Impressions - Page 56

post #826 of 1578
I just wanted to chime in and offer my impressions on this nice little DAC. First, a thank-you to tubes for starting this thread, and to everyone else who dared give this DAC a try.

I bought the new 2009 version right before Chinese New Year. Kevin shipped it out quickly and luckly for me, it didn't get stuck in customs.

Before buying this DAC, I would either run my PC (with a Creative X-Fi sound card) to my receiver, just use the plain-ol' headphone jack on my laptop, or occasionally let my Xbox 360 play a cd directly to my receiver via optical. My receiver is an older JVC unit, fairly low end, but still works. I also owned a Sony SCD-CD595 for a bit, after reading about how "great" it sounds. Since receiving the DAC, I've burned it in for about 120 hours.

The headphones I've been using are a pair of Sony MDR-V6's that I've had for a few years and know very well, Grado RS-2's, some Denon AH-D1001's, and a friend's Sennheiser HD-600s. I've had the Valab hooked up via USB from my laptop for all comparisons.

So now that you know my basis for comparison, here's what I like about the Valab DAC.

The first thing I noticed was an increase and tightening of bass. In particular,tracks like "Folsom Prison Blues" by Johnny Cash become a lot more energetic and fun. Even early Metallica songs benefit here, as it brings depth to what I feel are pretty bass-light recordings. I haven't found any bass to get boomy yet, just clear and, well, more.

The next thing I perceived was better timing to the music. Sounds seem to stop and start on a dime where they are supposed to, such as the rapping of a snare drum or fast plucks on a guitar. It took me a while to figure out what I was hearing; at first the only way I could describe the music was "more toe-tapping." I suppose it doesn't need to be described to be enjoyed, but for me, this is the most impressive and unexpected musical quality from this DAC.

Lastly, I can hear much better instrument separation and soundstaging from this DAC compared to my other sources. I never knew what these terms meant until I let the Valab burn in for about 80 hours or so. If you've never experienced it, I take instrument separation to mean being able to easily distinguish all the notes of, say, the two guitars behind the rising synthesizer noise in Coldplay's Life in Technicolor track. On my PC, or even the Sony SCD-CE595, the quieter, higher pitched guitar can get swallowed up and swept away by the powerful synthesizer and drums.

What don't I like about the Valab DAC? Well, it does get a little warm, and the blue light on the front is really bright, so I can't leave it on all night for burn-in. Also, Windows didn't want to initially recognize the DAC unless it was turned off before being connected via USB.

That's all for now. I may update my impressions after a few more weeks of use, but for now, I'm really enjoying it. Well worth the $180 I paid, and I think it's still worth it at $200.
post #827 of 1578
well, i got my Dac in today, burning in now, it sounds pretty good out of the box, but the power LED does not work. hopefully that's the only thing wrong with it. It looks like kevin does not even plug these things in when he gets em, just puts em in a box and off they go.
post #828 of 1578
Hi, I am new here. I just wonder if anyone know what is its output impedance ? Can we measure it?

Thanks for all info on this dac.

Vincent
post #829 of 1578
Thread Starter 
As far as I know there are no published specs.. Maybe Kevin can answer that one for you.
post #830 of 1578
I took it apart and looked at the connection to the LED and it appears to be fine, at least from the top of the board, I don't know how to fully dismantle it to look at the bottom, wonder if it's a bad LED. When i shine a flashlight though the LED's the USB is yellow and the LOCK is green, and the POWER led is White, you'd think it would be blue...

Actually, when I move my head to eye level with the power LED I can see it flickering, kind of like a shorted light bulb, like a bad connection.
post #831 of 1578

blue

It's blue alright.

Just take all the screws off back and front. With the 2009 there are probably screws which lock the DACs to the bottom of the chassis. Once you get the top off there might be something they screw down into.

You can easily see the solder joints on the bottom of the board where the LED is. Look for a weird bulb of solder, or solder that does not wrap all the way around the lead. You can simply lay more solder right on top. It's not as if it is carrying audio signal. If that doesn't work you can easily source an LED.

To see if the connection is poor you might try pressing on it with you fingernail and see if it gets brighter. You might be able to force it to make a connection. If so then a bit of solder should fix it.
post #832 of 1578
Pat,

you are a star well done. This is the most clear explanation I have seen on how to mod the VALAB DAC.

Just one tip, I would not change any value of the components, but just replace them with better ones. After all I still trust the designer of the VALAB DAC
(Kevin?) and changing values I think it will de-balance the circuit.It might sounds better in certain areas but then it will take something back in others affecting the frequency spectrum.

Then, of course we can always fine tune it as we wish, to match our ears

JJ
post #833 of 1578
A few hours ago there were 7 Dac`s availiable on the ebay site. Then there were two left. So I took the chance and bought one of them, so now there is only one left. you really have to be fast to aquire these Valab Dac`s!
post #834 of 1578
Quote:
Originally Posted by PatOMalley View Post
Kooka,

560pF. I read that 500pF should filter over 30kHz.
Should I go back?
I don't notice any flattening.
Now I'm paranoid.

EDIT: took 'em out. I was getting used to caps burning in ... Seems faster, more open with them out. How stupid. Under the steps I go with my water dish.

Oh, well, now the question is: better with the 560 silver micas, or better withou anything?
post #835 of 1578
And now there are no Valab Dac`s left on their ebay-site! All sold out in a minimum of time.
post #836 of 1578

ch-ch-changes

Quote:
Originally Posted by jjlucas76 View Post
Just one tip, I would not change any value of the components, but just replace them with better ones. After all I still trust the designer of the VALAB DAC
(Kevin?) and changing values I think it will de-balance the circuit.It might sounds better in certain areas but then it will take something back in others affecting the frequency spectrum.
JJ
Yeah, I got bit by that.

Quote:
Originally Posted by Kooka View Post
Oh, well, now the question is: better with the 560 silver micas, or better withou anything?
Better without. It's doesn't look like there is any consensus/standard on what value that output filter cap should be. Like JJ says, staying with the designer chose is the best practice. Taking them out made an improvement for me but that was a dogleg route, so, ...
post #837 of 1578
i looked at the connections on the bottom of the pcb, and they appear to be fine as well. I may have a bad LED, wonder how hard it would be to source a new one and install it. anyone know where to buy these small LED's at ? and how do you know which lead go's to where, does it matter? One thing I noticed when I took the front face off is one of the 8 dac chips does not appear to be fully seated against the bottom of the chasis.
post #838 of 1578
Quote:
Originally Posted by PatOMalley View Post
Yeah, I got bit by that.



Better without. It's doesn't look like there is any consensus/standard on what value that output filter cap should be. Like JJ says, staying with the designer chose is the best practice. Taking them out made an improvement for me but that was a dogleg route, so, ...
After a test I found that the 5600pf caps give a little more "black background" in my system.
I guess this could be something really not definitive but conncted to the system we're using.

What I found definitely worth a try is bypassing the 3 Rubycon caps (actually I have 3 Rubycons and 2 smaller Panasonics, there) on the psu with some Reederstein MKT 0.1uF caps. Definitely better.
post #839 of 1578

will try

kooka,

I have a few .1uF BG non polars laying around.
This is a worthy cause.
post #840 of 1578
Quote:
Originally Posted by PatOMalley View Post
kooka,

I have a few .1uF BG non polars laying around.
This is a worthy cause.
Pat,
give them a try...
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