Benchmark DAC1 now available with USB - Page 15

I never quite understood this -- are there some advantages to Firewire that people don't want to give up for USB 2.0? Macs support USB 2.0 now, don't they? Is it just that there's a lot of stranded investment in Firewire equipment? I guess Firewire 800 is faster, and would acquit well on raw data transfer stuff. Why all the defensive wars for Firewire?

Firewire is designed more for real-time and streaming, which makes it proper for audio. But, of course, everyone fought over the fw standards for audio, and now you have consumer hardware that 'supports' but not fully like you can't run jvc with mitsu without issues. I've had nothing but trouble with the format mainly because of the connector shape and the fragility of a connection when bumped

800 has nice bandwidth, and usb2 has the same bandwidth as fw400. both good tech, and as an Apple user I couldn't be happier to have the choice of USB 1/2 and Fw400/800 out of the box.

It's not a religious thing to Mac users, since it's been a while since our platform was USB1 only. I think Apple was trying to keep the FW400 platform viable and that's why we fell behind there. I also think they learned their lesson there, and embrace change a lot more.

But this is a derail, and mods can move it out if they wish.

I'm listening to Béla Fleck and the Flecktones "Left Of Cool" album on my DAC1 right now and WOW. ^_^;

No burning desire to experiment with balanced XLR output direct to your Grados, or, more understandably, other cans, eh? The native sound is good enough not to care? Do you know if the headphone amp components of the DAC1 USB have been upgraded since Iron_Dreamer did his seminal review a year ago putting it at the bottom of the group of DACs?

No.. The XRL were not made for headphones but for loud speakers..But I hear all headphones benefit when balanced..especially higher OHM cans..I have yet to hear someone say they thought their cans single ended sounded better then when they were balanced..

See http://www.head-fi.org/forums/showthread.php?t=89411

In addition to Iron_Dreamer, who has put a great deal of thought into it, and made it work more successfully than the front panel headphone jacks, there appears to be a healthy community of 'amp-less' head-fiers who are going balanced directly out of their DACs into their HD-650s. The consensus seems to me to be that it doesn't take the place of a dedicated balanced headphone amp, but it's pretty darn good and the tradeoffs of tonal distortion are either inaudible or greatly outweighed by the increase in depth, soundstage, and especially articulation of bass.

All that and you don't even have to spring for a balanced amp?! That is too good to pass up trying. Another encouraging thing is, based on my readings of the threads, deriving the sonic benefits of balanced implementations is not terribly dependent upon the quality of cable used, unlike single-ended traditional stages. So I bought two pairs of replacement stock HD650 cable from Sennheiser for $12 apiece, and a couple of female XLR adapter for three bucks apiece which I will use to replace the TRS 1/4 plug on the cable, and hopefully by this time net week I'll be swimming in $3k waters for a mere $1250. :-)

I'd still be very curious to hear Elias' considered thoughts on this, given we now know how widespread and loved a practice it is. You've shattered "general knowledge' before, in this very thread, so it would be great to know if you think there is any method most likely to approach optimal results.

Thanks!

If I understand your question correctly, you are asking if there are additional features on the DAC1 USB that are not available on the DAC1 (non-USB)...correct?

There are several features on the DAC1 USB which are not available on the DAC1, and they are as follows:

- Selectable gain range for headphone amp
-- Lets you select the optimal range for your specific headphones so that the volume knob can be utilized more optimally

- Main output mutes upon headphone insertion (defeatable)
-- The analog outputs on the rear of the DAC1 USB will be muted when you insert the headphone plug if this feature is enabled.

- High-Current output drivers
-- The XLR and RCA outputs can now drive longer cables, low-impedance loads, high-capacitance loads, and/or high-inductance loads without any loss in THD+N performance

- Advanced USB Audio for true native 96/24 bit-transparent playback
-- No drivers or configuration necessary...plug it in and immediately get bit-transparency at rates up to and including 96/24

Unfortunately, the DAC1's are not able to be upgraded to include these features.

Thanks,
Elias

I'm not going to mod my Grados because they're hard wired. But since Sennheiser HD650s have those clip-in wires, I'm willing to try the output from the DAC1 on them. I'm not going to spend upwards of $100 on a cable to do so, however. If someone in the Raleigh area has a set of cables we can try them out.

Since Iron_Dreamer's review of the previous version of the DAC1, the line stage has been improved, and the HPA-2 has been updated to handle 30-600 ohms instead of just 30-300 ohms. Of course the Senns were right on that border of the old amp design, which could have been a problem in the past.

Benchmark hired Centrance as an independent programming contractor for the USB firmware. This press release is intended to celebrate their companies new technology. However, this programming design effort was nearly an equal collaboration between both parties. From Benchmark, specifically John Siau, the director of engineering, contributed huge amounts of troubleshooting programming code relating to issues of the typical dreaded USB audio "hiccups". The troubleshooting process took months of correspondence between our companies. The result, however, is very satisfactory, if I may say so!!

Thanks,
Elias

As I mentioned before, we do not recommend using the XLR outputs to drive headphones. However, with that being said, I would be interested to try it !!

Thanks,
Elias

Hi there Elias,

it is great that there are employees like you who enjoy it to share detailed information that only 'insiders' know but which are of public interest.

I'm a user of the 'classical' DAC1. Actually, I'm pretty satisfied with it, although I have to admid that I can't really distinguish between it and a low priced Yamaha DVD-S540 (so far, tested with 44,1 kHz / 16-Bit material only).

However, I recognized terrifying differences when it comes to headphone usage. My Sennheiser HD-650 for example sounds very thin when directly connected to a notebook equipped with the Intel HDA Codec for example. The headphone output of my David Hafler preamp is much better but doesn't stand a chance compared to the HPA2 the DAC1 features.
I also noticed the L/R-balance which tends to the right channel below the 3rd step of the volume control in my case.
The gain reduction which is available on the DAC1 USB should of course attenuate this issue because the inaccuracy is spread over a wider range. But I wonder if this attenuation leads to an even more reduced THD or whatever. I mean, does it make any difference if the potentiometer or this jumper element reduces the volume except for the aspect of the loudness comfort and the improved L/R balance? At least when listening to HD 650 with their 300 Ohm. Since they were recommended by Benchmark in the first place (long before the USB version) I would suppose that the sonic results already reached the maximum. Am I correct? I hope so. :-) Except that, I've heard that electronical volume controls don't suffer from any gain asynchronism. Why does Benchmark then use potis instead of such a solution?

From what I read in the manual, the source selector on the front doesn't have fixed positions anymore and goes back to its centered position instead, "scrolling" the inputs up and down. Is this true?

When it comes to the much-lauded USB input which doesn't need 3rd party drivers, etc., I want to note here that one could still even beat this solution because it is limited to 96 kHz support. Assumed that there is any device from USB to S/PDIF which works up to 192 kHz (whether or not it used native drivers would be secondary for me as long as it is bitperfect). Not that I had heard about any such yet - just a thought. ;-)
At this point a further question arises for the first DAC1 editions (with the removable dustcap for the toslink receiver): In the US-manual they wrote that sample rates up to 192 kHz would be supported optically while the German translation claimes 96 kHz only. I asked the distributor who explained that the older versions had not always worked reliably above 96 kHz. It is open what means "not always". It still seems possible so far. Did Benchmark ever change something in regard to the S/PDIF receivers?

Some people claim that they hear differences between DAC1s which were manufactured some years ago and more recently. Again - where there ever any changes which could have any impact to the sound?

And a last question for now (although off-topic per se):

How about the handling of "intersample peaks" of the DAC1 in general?

Many thanks in advance!

Sounds like a plan!!

Thanks, Elias, for all your superlative information!! Really, you've done more to enhance the customer experience by participating in this one online thread than almost any other company does even directly with their customers. And in my case (as, I'm sure, for others), you've heavily influenced my purchase decision.

Even better performance with balanced headphones now?

Since the balanced XLR outputs have been substantially improved in the DAC1 USB, and "can now drive... low-impedance loads... without any loss in THD+D performance," this raises the question: will balanced headphones, HD 650s in particular, now play even better directly out of the balanced outputs? At 300 ohms they certainly qualify as low-impedance loads. Will the relatively minor distortion reported by current users playing their HD 650s out of the DAC1 balanced outputs be reduced? Any other benefits we can anticipate?

For 200 bucks you can get an EMU 0404 USB soundcard that has balanced outputs.

http://www.emu.com/products/product....&product=15185

There's also the Stello DA 220 MK2 and PS Audio Digital Link3 IIi.

Little-endian:

I will try to answer all your questions...let me know if I miss any or misunderstand any.

1. L/R issues below the 3rd step of the volume pot

Any potentiometer (in real life, at least) will be inaccurate at this end of their range. The reason is because of real life mechanical limitations. Specifically, the potentiometer wiper approaches the end of the resistive element and approaches a drop off. This drop off causes inaccuracies. Unfortunately, there isn't a dual-pot (stereo pot) in existence that defeats this limitation.

It is for this reason that we add the output pads (the DAC1 USB has selectable pads for the headphone output). These pads are intended to provide a listening level range so that the user's comfortable listening level is above the inaccurate portion of the volume pot. These pads do not change the THD+N performance, they simply attenuate to optimize the volume level range.

2. Why doesn't the DAC1 use electronic volume control?

We have not found, neither in our competitors products nor as available technology, any electronic volume controls that perform to our standard. All currently available electronic volume controls add significant amounts of distortion, so we have elected to maintain signal integrity rather then use these. It is unfortunate, however, as an electronic volume control would enable us to use a remote control, which has been requested by an innumerable amount of customers. However, we feel it is in the best interest of the goal of the product to maintain the signal integrity.

3. Is the DAC1 USB input selector a scrolling selector?

Yes. The switch is a momentary 3-position switch. You can scroll upwards through the inputs, or downwards through the inputs. Also, it is round-robin format - that is, the selections will go 3 -> 2 -> 1 -> 4 -> 3 -> 2 ....

4. Why doesn't the USB input do 192 kHz?

96kHz, 24-bit audio is the maximum bandwidth for the USB 1.1 protocol. 192 kHz is possible with USB 2.0. However, we elected to use the 1.1 protocol because there are A LOT (really, a whole bunch) of customers who do not have USB 2.0 ports. Conversely, we have a very small number of customers who are looking to stream 192 kHz audio via a computer. Hence, the decision was made to use the 96 kHz/ 24-bit, USB 1.1 interface.

5. Do old DAC1's optical ports handle 192 kHz?

DAC1's manufactured after 3/04 have optical ports that can handle 192 kHz.

6. Are there sonic differences in old DAC1's vs. new DAC1's (non-USB)?

There are no measurable differences between the older DAC1's and newer DAC1's. The main difference between the two is the RCA outputs are 30-ohms on DAC1's manufactured after 3/04. This will create a sonic difference DEPENDING ON THE EQUIPMENT DIRECTLY DOWNSTREAM OF THE DAC1. In other words, if you are driving a difficult load (an amplifier with a high capacitive input or low-impedance input, for example), the newer DAC1 will drive those better then the older. On properly designed loads, the older and newer DAC1's should perform identically.

7. How does the DAC1 handle intersample peaks?

Intersample peaks are true overs (greater then maximum possible value), thus will distort when played back. This is a very good question, however, as it is a topic the AES has recently been trying to tackle. Refer to AES R7-2006 for the latest discussion and details on standardizing measurement/metering practices for this.

Thanks,
Elias