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Valab NOS DAC, anyone using it? - Page 3

post #31 of 54
Quote:
Originally Posted by nick_charles View Post
No, that would be serial. Parallel means the original signal is split into 8 and each chip takes one copy, then there is an averaging of the outputs, theoretically this lowers the error down to below 1/2 LSB.
I'm not really sure of the technical details but if the signal is sampled once by each DAC chip (i.e. 8 times in total), then how is this different from 8x oversampling?
post #32 of 54
No because;

Quote:
Upsampling vs. Oversampling
Oversampling in the context of the D-A process involves multiplying the sampling frequency by a whole number, typically between 4 and 32, or even higher. For example, in ‘8x oversampling’, CD’s base rate of 4.4.1kHz is raised to 352.8kHz by introducing seven new ‘empty’ samples between the original data samples.
These new samples, though, are often not just empty strings of noughts, but based on mathematical models to assist the DAC to work more linearly with the extracted data.

Oversampling, as well as easing the workload of the anti-aliasing filter, which can now operate more gently at a higher frequency, can also reduce distortion created when those analogue signals are first turned from continuous, analogue waveforms into stepped, digital, stair-like curves.

This quantization noise is now spread over a larger band after oversampling, and can even be somewhat shifted out of the audible envelope by the technique of noise-shaping. Sony/Philips’ Direct Stream Digital, as used in SACD, takes this idea to its limit, in order to dump high levels of digital noise up to higher frequencies than are not directly audible.

Upsampling is a solely digital domain process where the data stream is also stretched out by interpolation — guessing the points in between, again mathematically — and is typically used to refer to small, non-integer changes, such as from 44.1 kHz to 48kHz. When the change is larger than this, such as 44.1 kHz to 192kHz, ‘upsampling’ is a more popular term.

'There is apparently no extra information in the upsampled signal that was not present in the initial signal,’ says Mike Story of dCS. ‘With a 44.1 kS/s input, both the input data stream and the upsampled data stream will only contain a spectrum that must be between 0 and 22.05 kHz and is probably only between 0 and 20kHz.'
NOS DACs performs no filtering or oversampling.

This link has good info on the DIY NOS DAC its 5 pages long: http://www.tnt-audio.com/clinica/convertus1_e.html

Both the Valab and Gigalab Moon DACs (correct me if I'm wrong) are based on the same design improved upon.
post #33 of 54
Thread Starter 
So I guess the question is which one is the best? I researched the DAC chips used in these and I didn't hear to many complements on them but perhaps it is all in the implemenation.
post #34 of 54
Thread Starter 
This dac claims low jitter via the USB. How does this particular implementation of the USB to I2S reduce jitter? If this sounds good via USB with a mac or windows with the correct drivers then perhaps I'll just go ahead and pick one up for portable use.
post #35 of 54

Valab Nos Dac........ from my perspective!!

Are you SURE you wanna do ANY buisness with this Valab guy... read on,



First delivery was super slow....... his response,


"I get 14 dac orders last week, while I can only quality testing 3 dac a day.
So your dac delay so long time. While I promise you will get my best work.
Your dac will in perfect condition. "

Best work?? It lasted 10 sec. & then exploded!!Yeah,best work!

Wait,there is more.... read on

......His response,
Dear Sir:
"All dacs were tested before ship out. It is quite expensive if I ship failed one to buyer.
Because I will need to pay more to refund and pay ship-back shipping fee.
I will responsible to my product. Please ship it back to me.
My address is
'Kuo-Wei Tsai, 3f, no. 26, shalun rd, danshui town, 251, taiwan. TEL:886-936219288'
I will immedialtely sent refund to you when I get the ship back dac.
Please ship back that dac by USPS ecpnomical air post.
And tell me how many you need to pay for it."

Well, I did ship the DAC back to Taiwan(via US postal priority Air) & he
did receive the item...(I did checked with customs & US Postal)...take a look ...
Label/Receipt Number: CP77 6082 304U S
Status: Delivered Abroad

Your item was delivered in TAIWAN at 7:16 PM on January 10, 2009.( I am pretty sure he is going to say he never received the DAC.)

He never answered my e-mails, no response whatsoever........AND NO REFUND.
This was my first purchase on eBay. I normally buy my stuff on Audiogon.
So $180 went down the drain,but hey that's how they do it on good ol' E-bay..........And Kuo-Wei Tsai( aka Kevin ????) is NO-NO-NO guy to buy from...no wait, he is NO-NO-NO on the square guy to buy from!!!!!!!!!!
LOTS OF SHADY PEOPLE OUT THERE.......BE AWARE!


OR WAS IT JUST A BAD LUCK?
post #36 of 54
He's quite a responsive guy and was refunded or replaced with his products with no problem previously. Maybe you can take a look this http://www.head-fi.org/forums/f7/val...ssions-378459/, you can find some answers. Wait for his reply, you'll get feed back from him. I bought this DAC in the beginning of Jan, it works perfect than expected, just be patient, Kevin will always answer but maybe he still enjoying his Chinese New Year holidays.
post #37 of 54
Supposedly Chinese New Year can run 15 days. I understand your frustration but Valab has taken care of problems that I have heard about. I had a problem with my first dac and customer service was excellent, I got a replacement in short order. He'll answer your E-mails.
post #38 of 54
Kevin, will refund your money, im positive. I had to ship a defective dac back to him and he was going to refund my money no problem, but I told him i wanted another dac instead. I've been waiting quite awhile to recieve it and im getting a little frustrated myself. Though to his credit, he does respond to email's sometimes it takes him a few days though. he's also polite and does seem to want to take care of me, just wish it would happen a little faster.

hang in there..
post #39 of 54

Valab NOS DAC !!

Finally,(... after how long ?? ) I got my refund from Kevin.

Thanks, but I am done with E-bay!

There are some nice Benchmark DACs on Audiogon.....
post #40 of 54
Sorry to hear of your experience. So far, it has been an aberation and not a norm. I hope you won't be discouraged from a first mishap.

Kevin is a respectable person and businessman. I bought a Valab DAC and tube buffer from him w/o a hitch and am getting more stuff. Sound quality on this piece is just top notch. He's been extremely busy lately due to the popularity of this piece and thus, the delay with answering emails and such.
My buddy went from Benchmark to PS Audio Link III to Bel Canto DAC3. I just did a comparo with the Valab NOS DAC and it killed his DAC3. I don't think the Benchmark will stand a chance if you're into musicality instead of specs.

Good luck,

Luc


Quote:
Originally Posted by spock63 View Post
Finally,(... after how long ?? ) I got my refund from Kevin.

Thanks, but I am done with E-bay!

There are some nice Benchmark DACs on Audiogon.....
post #41 of 54
Quote:
Originally Posted by Kenobi View Post
Sorry to hear of your experience. So far, it has been an aberation and not a norm. I hope you won't be discourage from a first mishap.

Kevin is a respectable person and business man. I bought a Valab DAC and tube buffer from him w/o a hitch and am getting more stuff. Sound quality on this piece is just top notch. He's been extremely busy lately due to the popularity of this piece and thus, the delay with answering emails and such.
My buddy went from Benchmark to PS Audio Link III to Bel Canto DAC3. I just did a comparo with the Valab NOS DAC and it killed his DAC3. I don't think the Benchmark will stand a chance if you're into musicality instead of specs.

Good luck,

Luc
Luc, I was thinking to grab the DAC3 a while ago but seems fortunately not. I have my Valab 2009 version from 21 Jan till now with some mod and non stop burn-in with 2 CDP alternatively, sounds amazing and am impressed. I have a NOS JOB DA96, the Valab kills the Job in the very first minute. More mod will come later when Bill, Pat, Phill or anyother have more idea in making it better
post #42 of 54
Hi Dannie,

The comparison I did with the DAC3 was with the Dec. 08 version of the Valab NOS DAC. So, I think there's more to be expected from the 2009 version due to all the latest and greatest update.

Regarding parts swap and such, I would check with Kevin first if he approves of whatever upgrades being proposed as he should know best what can be improved upon with this piece. Can't wait to get the new version to further enjoy my music.

Best regards,

Luc

Quote:
Originally Posted by dannie01 View Post
Luc, I was thinking to grab the DAC3 a while ago but seems fortunately not. I have my Valab 2009 version from 21 Jan till now with some mod and non stop burn-in with 2 CDP alternatively, sounds amazing and am impressed. I have a NOS JOB DA96, the Valab kills the Job in the very first minute. More mod will come later when Bill, Pat, Phill or anyother have more idea in making it better
post #43 of 54
Quote:
Originally Posted by Kenobi View Post
Hi Dannie,

The comparison I did with the DAC3 was with the Dec. 08 version of the Valab NOS DAC. So, I think there's more to be expected from the 2009 version due to all the latest and greatest update.

Regarding parts swap and such, I would check with Kevin first if he approves of whatever upgrades being proposed as he should know best what can be improved upon with this piece. Can't wait to get the new version to further enjoy my music.

Best regards,

Luc
Hi Luc,

If you love the sound from the 2008 version, you will then love more the 2009 version for sure. Swapping better caps and resistors aren't that difficult if you are just replacing with better brands parts in same value and with a little skill of solder. Of course you are taking your own risk to void the warranty from Kevin. I'd love it's sound in the beginning and was improved than I can expect when after some modding and burn-in.

Hope you'll enjoy your 2009 version like me lately.

Best regards,
Danny
post #44 of 54
Hi Danny,

Thanks for your feedback. Good to know that the 2009 version is even better. Noticed how quickly the new DACs were snatched up? I think it started out with 15 or so pieces in the morning and by the evening, they were completely gone. Good for you Kevin!

Regarding my previous notes w/ mod/parts swap, I was referring to some folks who mentioned replacement items not of the same value and types. I am sure you know what you're talking about and I may have to go to you later for advice since you're 'been there and done that'.

Thanks again,

Luc
post #45 of 54
Hi Luc,

It's good to share experience by trial and error. Yes, your friend is right, sometimes when we swapping parts will use different value and types such as non polar for output caps which rare uses by manufacturers due to matter of COST. I would appreciate to share what I've done in my DAC and in the forum I can find lot of experts in electronics and experienced in modding. I always keep my eyes open in http://www.head-fi.org/forums/f7/val...ssions-378459/ to see what will be happened in new modding.

Cheers and hope you enjoy your 2009 version and modding to make it to a higher level for music listening.

Danny
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