Benchmark DAC1 now available with USB - Page 3

So are you guys saying this DAC isn't worth consideration for USB use? As a "normal" DAC it was rated pretty high.

Hey Clark,

My thinking was that the price of the Transporter was less than my Arcam CD33, DAC1, and Squeezebox. So off they went, and now I can use the Transporter as a high-end source for my PC music AND as a DAC for cable box and PS3.

I'm sold on PC audio and have been using Squeezeboxes in secondary systems for a quite a while. But until the Transporter arrived I was not ready to give up shiny disks in my main rig. Frankly, I'm surprised there isn't more talk about the Transporter. Very nice component.

worthless to me as well. people buy DAC cost that much are expecting something designed to contribute to the sound quality.

Just wanted to add some premature impressions of the PS Audio Digital Link III DAC that my local audiophile friend just loaned me this afternoon....

So far so good... the DAC is indeed a solid upgrade from the sound I'm getting straight from the Squeezebox3, I'm very happy about the improvement! I'm going to listen more to this DAC tomorrow and get better impressions, but as of now, the impressions are very favorable.

I would say that this DAC at 1000$ is a good value especially since it has the USB inputs that many on this forum value. Plus this thing is hefty! Atleast 15 to 20lbs just for a DAC. Not too shabby.

I found an ad on Audiogon for preorders of the Dac1 w/usb for $975

http://cls.audiogon.com/cgi-bin/cls....7386&demo&3&4&

In the title of the ad, it says that the price for preorders of the usb benchmark is $1275.

I must be completely misreading this post.

Going by your sig:
You're using the Benchmark DAC in your food chain right now to that Maverick SACD player and it only handles CD and nothing else?

Under the asking price it says $975. May have to email for clarification.

DAC1 USB info

Hi there! My name is Elias Gwinn, I'm an engineer at Benchmark Media Systems. I'm glad to see such a lively discussion about the new product!!

I would like to answer some of the questions about the new DAC1 USB.

When we decided to add a USB interface to the DAC1, we purchased a 'boat-load' of USB audio interfaces to test and use. Our goal was to get familiar with the various technologies available and determine what we would want for our solution.

The testing consisted of the 'psuedo-random' bit-test that was mentioned in the press release. This is, quiet simply, testing "what-bits-go-in-and-what-bits-come-out". This is a standard test developed by Audio Precision, the leading audio electronics testing equipment manufacturer. When the Audio Precision (AP) sends a digital audio signal into a device, it checks to see if the exact same bits come out. So, for example, if the AP sends in 101100111000, a 'bit-transparent' data path will output the exact same bits: 101100111000. This was our testing proceedure.

An ideal transport will deliver to the DAC the original digital audio data bit-for-bit without a single bit changed. This is true for CD/DVD transports as much as computers.

Through our testing, we found that USB audio devices with custom drivers were rarely, if ever, bit-transparent. This includes ASIO devices.

Conversely, 'native' (without custom driver) devices were ALWAYS transparent. This was true with Windows and Mac. The problem with native solutions was the lack of 24-bit 96-kHz capablities.

At first we suspected this was a limitation with Windows USB audio. However, Microsoft audio software engineers assured us 24/96 was possible using the native USB driver (usbaudio.sys). Both Microsoft and Apple had a DAC1 USB prototype during the development period and our engineering team was in constant communication with their engineers.

After walking down the long, unpaved road towards a truely native 24/96 USB audio solution, it was finally achieved!!

-Elias Gwinn

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

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?

Elias,

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?

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.

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. It’s 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!!

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 .