Benchmark DAC1 - which input to use?
Dec 8, 2013 at 11:50 AM Thread Starter Post #1 of 12

matti620

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I just got the DAC which I bought in a hurry and didn't notice has no usb input... now I don't know if there's a way to use it without jitter as it has no asynchronous usb input, only xlr, coaxial, and optical digital inputs.
Which is a better option and how can I connect to a computer with Linux OS?
 
Dec 8, 2013 at 12:50 PM Post #2 of 12
  I just got the DAC which I bought in a hurry and didn't notice has no usb input... now I don't know if there's a way to use it without jitter as it has no asynchronous usb input, only xlr, coaxial, and optical digital inputs.
Which is a better option and how can I connect to a computer with Linux OS?

 
The level of jitter from the Benchmark is at least an order of magnitude lower than the audible threshold for jitter http://www.stereophile.com/content/fifth-element-18-measurements seriously you have no need whatsoever to worry about jitter even a far less competent DAC will produce inaudible jitter 
 
 
http://downloads.bbc.co.uk/rd/pubs/reports/1974-11.pdf - A BBC paper from 1974
 
 
E. Benjamin and B. Gannon, ‘‘Theoretical and audible effects of jitter on digital audio quality,’’ Preprint of the 105th AES
Convention, #4826 (1998)

 
Detection threshold for distortions due to jitter on digital audio; Kaoru Ashihara, Shogo Kiryu, Nobuo Koizumi, Akira Nishimura, Juro Ohga, Masaki Sawaguchi, and Shokichiro Yoshikawa, Acoust. Sci. & Tech. 26, 1 (2005) https://www.jstage.jst.go.jp/article/ast/26/1/26_1_50/_pdf
 
Dec 8, 2013 at 3:33 PM Post #4 of 12
Dec 8, 2013 at 3:49 PM Post #5 of 12
   
I had one of the 2nd options, it worked fine for me but I do not know if it will work under Linux, the seller sells these on ebay - you could send him a line
http://www.ebay.com/itm/FANMUSIC-FM-6011-COAX-USB-SPDIF-COAX-Converter-NEW-/120644872218?pt=US_USB_Cables_Hubs_Adapters&hash=item1c16fea81a


OK thanks. It looks like the optimal option, but unfortunately only the former is available locally. Will it convert the digital signal to spdif in higher frequencies than 48Khz which is specified? It's unclear from the specifications. Otherwise I can't see any cheap way to convert the signal.
 
Dec 9, 2013 at 10:06 AM Post #6 of 12
UPDATE: I bought the external sound card with the SPDIF output and now there are small low volume ticks repeating in constant rhythm... 
confused_face.gif
What could be the reason?
 
Currently I'm running PC --USB-> external sound card (ENCORE ENMAB-8CM 7.1) --optical-> Benchmark DAC1 --unbalanced-> HD650
 
Dec 9, 2013 at 11:25 AM Post #7 of 12
I just got the DAC which I bought in a hurry

 
 
Why not send it back and get the USB version instead. It's only $200 more.
 
In fact you could send it back, pay a restocking fee, get a RME Babyface or MOTU Ultralite and still have change. Quite a lot of change too.
 
Dec 9, 2013 at 11:48 AM Post #9 of 12
You could still sell it on. Consider this.
 
The vanilla DAC1 only accepts S/PDIF of one kind or another. S/PDIF doesn't only contain the samples themselves (the 16 bit part) it also contains the timing data (the 44.1kHz part).
 
With USB the samples are sent, under some control from the receiving DAC, reclocked and converted as one single operation. So the question is. Why spend so much money for ultra pro grade S/PDIF to analogue conversion and still depend on the accuracy of the clock on your PC S/PDIF card?  That's not such an issue for the DAC! in it's natural environment (a studio) because they will have an ultra accurate master clock somewhere. Yours is a $10 part. If that.
 
Take the hit. There are dozens of really excellent quality USB audio interfaces available for as little as half what you must have paid. I mean. Why muddle through with a botched up front end or always be forced to buy units with S/PDIF out (which not many will have in future) when you can leave an interface on your desk and simply shove in a USB plug  from whatever you happen to want to use at that time?
 
Jan 8, 2014 at 5:24 PM Post #11 of 12
Other things to consider, since I'm in the same boat (2nd-hand base model DAC1 and computer audio):
 
First off, the DAC1 USB only does 24/96 via USB input. The DAC2 does 24/192 with asynchronous USB, but that's a hell of a lot more than just a $200 difference. I'm currently using an iBasso D7 as a transport, with a Blue Jeans Audio RCA to BNC cable, and this works relatively well. Upgrading the USB cable may or may not improve matters further, and I'm still wondering if an M2Tech HiFace 2 would improve things further or not. Upsampling audio in Windows avoids the annoying popping noises.
 
I believe that Toslink is also limited to 24/96, but sound quality with it is so noticeably inferior to electrical SPDIF that it's not worth the bother. As such, that Encore device is probably only good as a hold-over until you can get a better transport.
 
I've also discovered that it's VERY susceptible to vibration, and the stock feet make matters worse. Not an issue if you have the rack mount version and can actually mount it, but for the rest of us, vibration handling seems to be a must. Place your hand on top of the case while it's playing to hear the difference, or just pick it up and hold it. That alone takes care of a lot of the remaining high-frequency grain and bass bloat that remain after ditching the Toslink. If you can't hear the difference, your headphones are a bigger issue. With my markL-modded Denon AD-D2000, the difference is clear. I have some Herbie's Tenderfeet on the way to try with it. Hopefully it will help matters.
 
The Benchmark is a nice unit that seems a little misunderstood. It needs a little TLC, but otherwise it's pretty nice. I don't regret the purchase, especially not for what I paid (really good price from a friend). Do yourself and search for a better source, though, matti. It's worth it.
 
EDIT: Tenderfeet arrived last night, and stuck under the DAC1 today. TREMENDOUS improvement, particularly with something placed on top of the DAC1 as well (I have my iRiver in its iSkin sitting on top dead center, with the Toslink cable connected). The Tenderfeet are right at the edges of the case, next to the stock feet. The bass bloat and grainy, fatiguing highs that I'd been experiencing are gone, and the soundstage seems to have deepened and cleared up as a result. So very worth it! It's not exactly CHEAP at $15 per foot, but for a desktop-bound DAC1, I would consider it essential, particularly in light of the prices you can get for used DAC1's. http://herbiesaudiolab.net/compfeet.htm
 

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