Review and Measurements of Benchmark DAC3

[garbulky]

As you see, I almost always run additional tests to address points people raise. It is not like a print magazine where reviews are published once and that is that.

Yes, I have noticed you put effort in to this and providing additional measurements.

 

[RayDunzl]

Wouldn't it make more sense to test at 2V?

I run my DAC2 HGC in the HT Bypass Mode without jumpered attenuation (+23dBu maximum per the manual) with no ill effects here at home.

Volume control is handled at the preamp (old Krell KCT), mostly because I managed to get the TV Cable Box remote to recognize it, and it is convenient to use.

When I do use the volume control on the DAC2, my ear notices no quality differences at any chosen level. So, it's another thing to not worry about.

 

[John_Siau]

The maximum output on the DAC2 HGC was 23 dBu. We decided to increase the calibrated output level on the DAC3 HGC to +24 dBu. We also added the ability to boost the gain by an additional 3.5 dB of boost allowing a maximum output level of +27.5 dBu at 0 dBFS. The upper 3.5 dB of boost will impinge on the 3.5 dB of headroom over 0 dBFS because the analog clip point of the converter is set at +27.5 dBu.

At the calibrated 'HT' bypass setting the headroom is 3.5 dB. Above this operating point, the headroom in the ESS is reduced. But, the DSP ahead of the ESS still has 3.5 dB of headroom above 0 dBFS.

 

[svart-hvitt]

@John_Siau , I have no need for a new DAC, or a new amplifier, or a new preamp/headphone stage, but I wish I did - so I could order one of your products.

I have one question to you which may seem «audiophile» related. It’s about clocks...

Some audiophiles spend thousands on external clocks, though measurements never back up the hypothesis that these clocks improve the audio system’s specifications. So I was surprised to see that an improved clock in RME’s DAC, which used (!?) to be @amirm ’s benchmark, also improved the DAC specifications.

(https://www.rme-audio.de/download/adi2dac_e.pdf)

So my question is: What’s your view on the clock’s importance in a DAC or ADC? And would a newer clock - like the one in RME’s design - also improve the specifications of the DAC3?

 

[jaytrinitron]

My guess is that this is noise modulation or crosstalk. Normally the linearity curve should stay flat and then bend upward when the test tone disappears into the noise floor of the measurement. But, when you see the output level dip lower than expected, before subsequently curving upward, this is an indication that there is noise modulation or crosstalk.

To test for crosstalk: Try turning the second channel on and off, and try inverting the polarity of the second channel. If the shape of the curve changes, crosstalk is influencing the measurement. This is not a linearity issue. It may just be a very low-level crosstalk issue.

If narrowing the band pass filter preserves the dip in the curve, but moves it lower in amplitude (moves it to the left), the cause is noise modulation (usually inside the DAC IC) . Many converter chips generate slightly less noise when producing very low output levels. This change in output noise may only happen at very low output levels (near 1 LSB). It is caused by fewer 1-bit switching transitions when levels are very low. The slight change in noise raises havoc with linearity measurements. This is not a linearity issue. It is noise contaminating the measurement.

The lesson from all of this:

Once noise begins to bend the linearity curve, anything below this point is highly suspect.

First off, I apologize for my lack of knowledge and none of this is meant to be accusatory.

If it is noise modulation or crosstalk as you say, shouldn't a DAC have the capability to reject these things? You say it is noise contaminating the measurement but the noise will still affect the single-ended output in typical use, right? In fact, wouldn't it be much higher since the analyzer is probably designed not to color the measurements too much?

And could this issue be solved by buying a pair of XLR to RCA cables?

 

[DonH56]

Can a car's tire fix the potholes in the road?

OK, less snotty, some things are just beyond what the DAC itself can do, but better ones do everything they can. And all the data presented indicate the Benchmark is exemplary in that regard.

Noise modulation is a function of the underlying DAC architecture; that is, the design of the actual data converter IC, and out of Benchmark's control (other than the choice of chip). Crosstalk can happen inside the chip, on the board, etc. It's worth noting (again) that most of these things appear in rigorous testing and are present at levels far beneath what we can hear.

If the noise is external common-mode noise, or a ground loop, or other noise source that acts differently on single-ended vs. balanced signals, then using XLRs might help. Using RCAs converts back to single-ended and obviates all the differential "goodness" you had with XLRs so is usually a step backwards.

IMO - Don

 

[jaytrinitron]

Can a car's tire fix the potholes in the road?

OK, less snotty, some things are just beyond what the DAC itself can do, but better ones do everything they can. And all the data presented indicate the Benchmark is exemplary in that regard.

Noise modulation is a function of the underlying DAC architecture; that is, the design of the actual data converter IC, and out of Benchmark's control (other than the choice of chip). Crosstalk can happen inside the chip, on the board, etc. It's worth noting (again) that most of these things appear in rigorous testing and are present at levels far beneath what we can hear.

If the noise is external common-mode noise, or a ground loop, or other noise source that acts differently on single-ended vs. balanced signals, then using XLRs might help. Using RCAs converts back to single-ended and obviates all the differential "goodness" you had with XLRs so is usually a step backwards.

IMO - Don

Fair enough, I appreciate the analogy. Though this means there are much cheaper equal/better measuring DACs for single-ended use.

 

[DonH56]

I thought Amir remeasured the new unit and SE and balanced were comparable? Have not been keeping track... But of course there are many cheaper DACs that probably have audibly similar performance (I can't say what someone else might hear).

 

[amirm]

I thought Amir remeasured the new unit and SE and balanced were comparable?

No, that is one thing that didn't get resolved with the new sample:

 

[Dro]

Any chance of a comparison of the ADI-2 Pro and Benchmark DAC3 headphone outptus?

 

[amirm]

Any chance of a comparison of the ADI-2 Pro and Benchmark DAC3 headphone outptus?

Sure. Give me one output impedance to test as otherwise, it is fair bit of work.

 

[amirm]

BTW, I did run a test with a real headphone with the original review sample: https://www.audiosciencereview.com/...easurements-of-benchmark-dac3.3545/post-85580

 

[DonH56]

No, that is one thing that didn't get resolved with the new sample:

Ah, missed that, thanks Amir.

Do you ever sleep?

 

[Fitzcaraldo215]

Ah, missed that, thanks Amir.

Do you ever sleep?

He won't sleep until he has measured EVERYTHING!,

 

[DonH56]

He won't sleep until he has measured EVERYTHING!,

Good, I've been waiting for him to measure how high is up and all that Schitt...

I think he picked Sir Thomas as moderator simply to have someone on the other side of the pond to prod him awake all night long.

 

[svart-hvitt]

Good, I've been waiting for him to measure how high is up and all that Schitt...

I think he picked Sir Thomas as moderator simply to have someone on the other side of the pond to prod him awake all night long.

No, Sir Thomas and Amir are the same guy. Amir just thought it would look too funny if people noticed him being active 24/7 365.25.

So he invented Thomas.

 

[Dro]

Sure. Give me one output impedance to test as otherwise, it is fair bit of work.

You mean load impedance? 33 and 300 or 600 ohm. One high, one low impedance.

 

[amirm]

No, Sir Thomas and Amir are the same guy. Amir just thought it would look too funny if people noticed him being active 24/7 365.25.

So he invented Thomas.

Turns out, one of my worst inventions ever!!! Next to these sandals:

 

[Thomas savage]

Turns out, one of my worst inventions ever!!! Next to these sandals:
View attachment 14450

Well who knew, not everybody wanted feet like yours...

 

[Thomas savage]

No, Sir Thomas and Amir are the same guy. Amir just thought it would look too funny if people noticed him being active 24/7 365.25.

So he invented Thomas.

I think we are a pair of one offs , humanity breaths a sigh of relief...