[nicke2323]

Question to Elias:

I just posted a link to several ABX tests comparing low-end to high-end CD players:
http://www.head-fi.org/forums/showthread.php?t=246048

I have been considering an upgrade to the Benchmark DAC1, but as I mention in the above thread, ABX tests like these are starting to make me reconsider. Since your recent 20-generation D/A-A/D loop test shows that you at Benchmark are no strangers to ABX testing, perhaps you can shed some light on the sonic advantages of a high-end DAC like the DAC1?

More specifically, do you think the DAC1 can be distinguished from modern entry-level CD-players in an ABX test? Have you done such tests at Benchmark?

I have no doubt that the DAC1 measures very close to perfection, as all reviews seem to indicate. But I am not certain this translates to an audible difference. Does it?

 

[Crowbar]

ROFL, the Audio Note DAC3 is a 12 year old NOS DAC, of course others would be preferred.

None of these tests were performed to ITU standards (see Recommendation Recommendation BS.1116-1), thus you can safely ignore them. Various of Peter Aczel and related (Douglas Self, Rod Elliott) 'debunking' claims have been themselves debunked in forums such as diyaudio and so on. Self's 'blameless' class B comes to mind (not so blameless after all heh). The Audio Engineering Society wouldn't be accepting papers on distortion any more if this was a solved issue as you're incorrectly implying. I have very rarely seen properly conducted blind tests as it is a huge undertaking. You can't just put people in a room for a few hours and perform a quality test; even the ITU recommendations are lacking if one is aiming for perfect guarantee. I've mentioned above the Pass comment so it's worth finding it in the thread.

Also refer to the sticky thread in the DIY section here entitled "Subjective vs measurements in the perception of sound quality"; most of the points here have been touched upon there already.

 

[audioengr]

ABX tests are only as good as the system used and the listeners ears and training. The system is usually the culprit. If stereo salons cannot put together a decent sounding system, how can you expect reference systems to be used in these tests? It tends to be "professionals" that do these tests.

Steve N.

 

[mofonyx]

Regarding the non-USB Benchmark DAC1, I have heard that the BNC digital coax input is not truly 75 ohm and this would cause some issues when connecting via coax from true RCA 75 ohm digital outs.

Is this true and can anyone verify this?

 

[dip16amp]

Quote:

Originally Posted by mofonyx /img/forum/go_quote.gif Regarding the non-USB Benchmark DAC1, I have heard that the BNC digital coax input is not truly 75 ohm and this would cause some issues when connecting via coax from true RCA 75 ohm digital outs. Is this true and can anyone verify this?

This was asked in this thread on page 21 post 419 and answered on page 22 post 424.

 

[EliasGwinn]

Quote:

Originally Posted by nicke2323 /img/forum/go_quote.gif Question to Elias: I just posted a link to several ABX tests comparing low-end to high-end CD players: http://www.head-fi.org/forums/showthread.php?t=246048 I have been considering an upgrade to the Benchmark DAC1, but as I mention in the above thread, ABX tests like these are starting to make me reconsider. Since your recent 20-generation D/A-A/D loop test shows that you at Benchmark are no strangers to ABX testing, perhaps you can shed some light on the sonic advantages of a high-end DAC like the DAC1? More specifically, do you think the DAC1 can be distinguished from modern entry-level CD-players in an ABX test? Have you done such tests at Benchmark? I have no doubt that the DAC1 measures very close to perfection, as all reviews seem to indicate. But I am not certain this translates to an audible difference. Does it?

Nicke,

I've read the thread you posted, but I choose to steer clear of such debates for a number of reasons (particularly because people get very angry in these types of debates

)

In response to your question "What are the sonic advantages of the DAC1"...: To answer this, I'd like to address the debate of objectivity vs. subjectivity. If you can permit a metaphor for the sake of explanation, audio is like a picture. Some people prefer classic black and white pictures, some people like Sepia, some like classic film, some like crisp digital, etc. All of these preferences are absolutely valid...they should not be discredited as user inexperience / ignorance / etc. Subjectivity is as real and valid as objectivity....but very different.

Subjectivity has the uncanny ability to change over a period of time. If you looked at the world through Sepia lenses 24/7, you would be in awe if you caught a glimpse of full, natural color, even if it is a blurry, out-of-focus image. You see my point?

Our goal with the DAC1 is to offer 20/20 vision for D-to-A conversion. This is why measurements are very important. It is important to know exactly what is happening to the audio from a completely objective standpoint. Objectivity does not change over time. That is not to say that listening (subjectivity) is less important...its apples and oranges.

In response to your question "Do you think the DAC1 can be identified vs. a cheap CD player"...: This depends on the listener and the test setup. But, regardless of whether or not one can discern between the two in an ABX test, the inaccuracies of the CD player will be apparent more when you listen for long periods of time.

If we may use the picture analogy again: if someone put a film picture next to a digital picture, some people could tell the difference, and some would not be able to. However, if you looked at a film picture everyday for a few days/weeks/months, then saw the same image but captured digitally, the difference would jump right at you. Thats not to say one is better then the other, but the differences are accumulative and, therefore, more pronounced over time.

This accumulative difference is why we conducted the 20-generation test. If there were severe artifacts in the D-to-A conversion process, they would be exposed in early generations. If the conversion is well done, the accumulative affect should be minimal.

I apologize for all the metaphors...sometimes I feel its easier to make a point that way. I can elaborate on any point(s) if this isn't clear enough.

Thanks,
Elias

ps. If the root of your question is, "Should I buy a DAC1 even if I don't hear a difference", that is something only you can answer. If you're happy with your CD player as-is, then don't buy a DAC1. Even if it is better, happiness is a state of mind, not a signal-to-noise ratio. However, if you want to hear every detail of the music without missing something thats hiding behind jitter-induced artifacts, then the DAC1 can and will achieve that.

 

[EliasGwinn]

Quote:

Originally Posted by mofonyx /img/forum/go_quote.gif Regarding the non-USB Benchmark DAC1, I have heard that the BNC digital coax input is not truly 75 ohm and this would cause some issues when connecting via coax from true RCA 75 ohm digital outs. Is this true and can anyone verify this?

Mofonyx,

I will quote John Siau, the engineer who designed the DAC1:

"The connector is 50-Ohms. 50-Ohm connectors are far more durable than 75-Ohm connectors due to the extra dielectric material surrounding the center pin of the BNC. For this reason, it is common practice to use 50-Ohm BNC connectors in 75-Ohm systems when the signal bandwidth allows it.

"The short interruption of the 75-Ohm transmission line is only significant for frequencies that are much higher than any contained in a digital audio signal. The 50-Ohm connector would be a factor for signals having a wavelength of 2 inches or less in coax (about 3 GHz). A 192 kHz digital audio signal transmits data using a clock that is 64 times the sampling frequency (192 kHz * 64 = 12.288 MHz). 3 GHz is the 244th harmonic of 12.288 MHz and does not exist in a 192 kHz digital audio signal. If it did, the box probably would not pass FCC and CE emissions tests.

"Changing the connector would reduce the durability of the product and would have absolutely no effect even at 192 kHz." -John Siau

Thanks,
Elias

 

[nicke2323]

Thank you Elias for taking the time to reply to my questions! A few comments:

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif I've read the thread you posted, but I choose to steer clear of such debates for a number of reasons (particularly because people get very angry in these types of debates )

I'm pretty sure nobody here would take offense if you stated you had performed an ABX test and experienced listeners could easily tell the Benchmark from an entry-level CD player.

That's all I want to know. Frankly, the fact that not even an engineering-oriented company like Benchmark will make a clear statement like this seems to imply that the difference may be too small to hear.

Like I said before, I have no doubt that the DAC1 measures very close to perfect, and 20 generations of D/A-A/D looping introduce no audible artefacts. But would the result of the 20 generation ABX test be different if you used the DAC of a cheap CD player?

Unfortunately I have no possibility of auditioning the DAC1 without ordering one for 1100 euros - quite a price to pay for something that may turn out to have no perceivable sonic improvement for me. (Incidentally, I would appreciate if you guys could tell the European distributors to stop selling the silver version of the DAC1 at a 100 euro markup, when the price is the same as the black rack version in the US. This is in addition to the large markup they have on the original version. US price $975 = 730€, cheapest Euro price 1100€. Taxes and import duties explain less than half of the difference.)

In any case, it does inspire confidence that you are here, in active discussion with your potential customers. If I buy anything it will be a Benchmark.

 

[The Monkey]

Quote:

Originally Posted by nicke2323 /img/forum/go_quote.gif I'm pretty sure nobody here would take offense if you stated you had performed an ABX test and experienced listeners could easily tell the Benchmark from an entry-level CD player.

Let's leave ABX tests out of an otherwise excellent thread.

 

[little-endian]

Quote:

Originally Posted by nicke2323 /img/forum/go_quote.gif That's all I want to know. Frankly, the fact that not even an engineering-oriented company like Benchmark will make a clear statement like this seems to imply that the difference may be too small to hear.

Well, if you have a look into the manual of the DAC1, you can see that Benchmark is a little more brave with their promises here. There they state that they think, the reduced jitter will result in a clearly audible improvement. After listening to the DAC1 via Sennheiser HD-650 for the first time, I felt that I was able to follow that claim. It sounded somehow 'strange', like the midrange was reduced - exactly what is written in the manual. Interestingly, I made this experience *before* I read the text.

However when I tried the DAC1 on my regular loudspeakers (a pair of Nubert nuWave 8, connected to a David Hafler 110 preamp and Kenwood M1D amplifier), I couldn't distinguish it from a Yamaha DVD-S540 (for about 80 EUR in Germany) which I felt pretty frustrating to be honest. I have to admit that the equipment is not really highend but nevertheless, I expected at least any difference (no matter if better or worse).

I still think that the output of the Sennheiser headphones is 'reference' through a DAC1, probably due to its superb preamp function and match for the impedance, etc. I haven't compared 24-bit material yet though. Just plain 44.1 kHz/16-Bit.

I'm not sure but I feel that somehow the conversion process from digital to analog seems to be quite exhausted.

At the end, the DAC1 - as an external device - is more some kind of prove of concept for me. One can use the cheapest stuff as source as long as the data will be correct, the sound will be fine. Thanks to its great mute function, there are no crackling noises or pops if something goes wrong on its transfer.

 

[EliasGwinn]

Quote:

Originally Posted by nicke2323 /img/forum/go_quote.gif T I'm pretty sure nobody here would take offense if you stated you had performed an ABX test and experienced listeners could easily tell the Benchmark from an entry-level CD player. That's all I want to know. Frankly, the fact that not even an engineering-oriented company like Benchmark will make a clear statement like this seems to imply that the difference may be too small to hear.

Nicke,

I apologize for missing this question. We have not performed any such ABX tests with an inexpensive transports analog out vs. the DAC1.

Thanks,
Elias

 

[nicke2323]

Quote:

Originally Posted by The Monkey /img/forum/go_quote.gif Let's leave ABX tests out of an otherwise excellent thread.

OK, I'm starting to see what you mean. I apologize for polluting. To anyone else who may be tempted to respond with ABX-related comments, please do so here instead:

http://www.head-fi.org/forums/showthread.php?t=246048

And thanks again Elias for the reply.

 

[mofonyx]

Thank you for replying to an old question Elias and thanks dip16amp for referring properly to the post on the thread. I had some really informative reading.

I would like to add a question to my post because I can't seem to find these in the thread currently:

How are the balanced XLR volume outputs controlled when the volume control is set to "Variable"?
Is the headphone amp on the DAC1 ultilised as a "preamp" to control the volume output on the XLR outputs on the rear?

Thank you.

 

[puntloos]

Even with the level of candor Elias has been consistently showing, I doubt a he would ever say 'yeaaah well we tested until our ears started to bleed but the DAC that came with this bag of cornflakes was indistinguishable from our DAC1.'. Maybe his findings are in fact that their DAC1 is much better sounding, but even if it truely is so, his claim can't avoid sounding hollow either way, so it's best to stay away.

And yeah, please no ABXing in here, people have spent thousands of dollars on gamma radiation filters and will get very cranky if ever confronted with any solid facts proving it was wasted money.

What ive been trying to find out myself is the impact of the choice of resampling frequencies. Benchmark (through Elias) claims that their choice of 100-ish kHz (so they downsample a 192K source) is the 'best choice' given the state of the art in DAC and sampler chips on the market. I would be interested in ABX comparisons of sources:

192khz, nonresampled
192khz, resampled to 100k
96khz, nonresampled
96khz, resampled to 100k

Elias, a specific question if you will: The DAC1 resamples everything to 105 (or thereabouts) kHz. I get that there are arguments for downsampling from 192K to 105, and I get that there are good reasons for upsampling 44K to 105, but Ive always been taught that upsampling to neighboring frequencies (44->48 specifically, but I imagine it applies to 96->105 too) is a bad idea. Why do benchmark do this anyway? If the source is 96, why not pass it through 1:1? Why did you not provide a button to turn off resampling, especially in this case, but also in general?

 

[EliasGwinn]

Quote:

Originally Posted by mofonyx /img/forum/go_quote.gif How are the balanced XLR volume outputs controlled when the volume control is set to "Variable"? Is the headphone amp on the DAC1 ultilised as a "preamp" to control the volume output on the XLR outputs on the rear?

When the DAC1 is in variable mode, the balanced XLR outputs are controlled with the potentiometer on the front panel.

The headphone amp is isolated from the XLR outputs. Both the headphone amp and the XLR output drivers (when in variable mode) are 'down-stream' from the potentiometer.

I can clarify further if you wish.

Thanks,
Elias