Frankly, if I'm resorting to USB, I'll just use my MicroDAC. My Mac has optical out and the DAC1 handles that just fine.
I'm disappointed that this was their big news. I thought we'd be hearing about a discrete headphone amp in the DAC1.
My thoughts as well. Anyone come up with a compelling enough reason to need to go over USB in the instance you have a computer equipped with an optical output?
My thoughts as well. Anyone come up with a compelling enough reason to need to go over USB in the instance you have a computer equipped with an optical output?
hm... still depends on what you do downstream. I'm willing to bet that a nice (tubed?) USB DAC like one from wavelength is going to trounce whatever a cheaper (three-figure) DAC can do with your optical in. and all things being equal (i.e. let's set a hypothetical cost/quality inflection point for both DACs) I am further convinced that jitter is something that we ought to take seriously, even and especially in computer audio. USB has a firmer lock than many SPDIF solutions (especially if it means longer signal paths). for that reason, I own three amps that take USB input, and don't own a separate DAC anymore.
__________________
head: Ety ER-4P, Grado SR60, UE Superfi Pro5, AKG K280
Yes, jitter is a very serious matter with computer audio. In fact, one interesting piece of information we found (though we did not confirm) is that computer manufacturers will ADD JITTER to their clocks for the purpose of spreading the energy across a wider bandwidth to pass emissions testing. Apparently the spike at the fundamental clock frequency was causing interference of some sort.
This is detrimental to audio, as most digital audio connoisseurs will attest to. In the simplest terms, jitter causes the digital audio converter to misfire. Its like a bad timing system on a car's engine causing the spark plugs to fire when the pistons are not quite ready for it.
The Benchmark DAC1 and DAC1 USB are designed with a special clock recovery system that makes jitter irrelevant. The way it works, in simple terms, is - the DAC1 clock is not discretely attached to the signal clock, but instead monitors it and replicates it with an isolated clock which is extremely stable. This is described in more detail including performance curves in the manual (http://www.benchmarkmedia.com/dac1/DAC1-Manual.pdf).
With this clocking system, the DAC1 will perform exactly the same no matter how much jitter is on the clock...quite literally. There aren't too many converters that can make that claim, but we encourage you to compare. It is for this reason that we tell our customers that it is not necessary to buy extremely expensive (<$100) digital cables. We've tested the DAC1 with cables of varying quality, and it made no difference whatsoever.
What does this all have to do with USB, you may be asking (please excuse my rambling...can you tell I'm not in marketing)? We haven't yet tested the jitter on USB interfaces, but from everything we know about computer hardware architecture, all signs point to it being a very serious problem.
USB protocol was not designed to stream data fluently and consistent; it was designed to transfer 'bursts' of data. This is the reason why audio drop out and 'ticks' are common complaints from users of USB audio devices. The DAC1 USB interface software and buffers were designed with this in mind; it 'monitors' the data flow to maintain a consistent and fluid audio stream.
The reason we announced this as our 'big news', is because this type of USB audio solution is the first of its kind with regard to the scope of the solution. It addresses more concerns then any interface of its kind. Even engineers at Microsoft and Apple were impressed!!
Thanks for taking the time to post in this thread. Welcome to Head-Fi and, er, sorry for what you do to our wallets.
Interesting point about working with the MS and Apple folks. How seriously do their engineers take their audio at the respective companies?
Monkey (if that is, in fact, your real name...),
MS and Apple folks take their audio very seriously. However, the beast that is called 'product developement' sometimes prevents a designer from optimizing every aspect of every function of their product. This can be for many reasons: cost, development time (time to market), stability, and intra-compatibility.
The latter (intra-compatibility) refers to something very common in computer hardware and software. That is, when a product performs such a wide array of functions as a computer does, the designers are often limited by other functions within the product. A quick and dirty example is: traffic build-up on a road may not be limited to how many lanes make up the road, but actually by an intersection with another road. Another example: the USB port is built to feed printers and audio devices!!
-Elias
ps. Monkey, I'm sorry about your wallet, but my 176,000 mile, 12-year old car can attest that it goes into the product, not our wallets .
part of my weariness of direct usb connectsion has been frequent complaints about digital noise and interference. for example, there are plenty of accounts of this occuring on Stello and wavelength products. what does the dac-1 do to keep this from happening?
have you done testing between usb>spdif converters v. your native USB dac?
thankyou
Sorry for posting a million times in a row, but I just saw Granodemostasa's question.
Here's from a post I left about 10 min ago. It answers your question about typical USB audio problems...
Quote:
Originally Posted by EliasGwinn
USB protocol was not designed to stream data fluently and consistent; it was designed to transfer 'bursts' of data. This is the reason why audio drop out and 'ticks' are common complaints from users of USB audio devices. The DAC1 USB interface software and buffers were designed with this in mind; it 'monitors' the data flow to maintain a consistent and fluid audio stream.
The reason we announced this as our 'big news', is because this type of USB audio solution is the first of its kind with regard to the scope of the solution. It addresses more concerns then any interface of its kind. Even engineers at Microsoft and Apple were impressed!!
Very interesting thread. I recently sold my trusty Arcam CD player and now listen to PC audio exclusively. I've also had good experiences with the DAC1, but recently sold it because of its lack of USB input. For reasons I can't explain, I never really trusted the M-Audio Transit with an optical cable to the DAC1.
Two questions for Benchmark:
* Is it not true that Microsoft's Kmixer alters the bits as audio is output through it? If so, how does the DAC1 handle this without a driver?
* How does USB audio on the DAC1 compare to other high-end PC audio products such as the Slimdevices Transporter or the Empirical Audio USB converters? Is jitter as low as on these other products?
The short answer to the first question is: Kmixer will not affect the audio at all unless multiple audio streams are being played simultaneously.
Here is a summary of what kmixer does to audio:
CONDITION 1: One audio stream is sent through audio through kmixer at a time
RESULT: kmixer streams the audio bit-transparently - that is, bit-for-bit, what goes in, also comes out. We have tested and proven this using a test function called 'Bittest' by Audio Precision.
CONDITION 2: Two audio streams of same sample rate are sent through kmixer
RESULT: kmixer streams both without problems, ASSUMING THE SUM OF THE AUDIO STREAMS DOES NOT ECLIPSE 0 dBFS!! Just like any digital mixer, if the sum of the audio eclipses 0 dBFS, digital clipping will occur, which is not popular among audio enthusiasts. However, if it does not eclipse 0 dBFS, there should be no problems. This was confirmed by playing a 'Bittest' stream with one app and a silence (all 0's) stream with another. The result was bit-transparency. NOTE: When multiple audio streams are summed in kmixer (even 16-bit audio streams), the result will be a 24-bit audio stream. THIS IS WHAT WE WANT, assuming we have a 24-bit device to recieve it.
CONDITION 3: Two audio streams with different sample rates are sent through kmixer
RESULT: kmixer will up-sample the lower sample rate to the higher one. The higher one remains unaffected. This conversion is not very good though, and should be avoided. It is easily avoidable, however, as long as only one audio stream is playing at a time, or they are of equal sample-rates. But, who listens to more then one CD at a time anymore these days? (ok, Flaming Lips fans aside!!)
To answer your 2nd question, Gregeas, we don't have either of the products you mentioned to test in our facility. I would have to see Jitter measurement curves to check. We have our measurement curves posted in the manual of the DAC1 (http://www.benchmarkmedia.com/dac1/DAC1-Manual.pdf).
Lurkers like me also appreciate Elias's time in threads like these. It always helpful and appreciated when insiders and other folks like that participate with us 'round these parts.
.
It always helpful and appreciated when insiders and other folks like that participate with us 'round these parts. 
Linear Mode
