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Review and Measurements of Benchmark DAC3

pozz

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There can be the problem that many are just like they were on the subjective sites they came from. They just refuse to learn and insist that they hear it and that's the end of the discussion. "Beleive in your ears only" is their bible. ;)
We're pretty good at arguing the point. A few verbose positions and the Robert Harley book vs. all the research assembled here doesn't amount to much.
 
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So I'm after some advice: a friend of mine is selling his DAC3 HGC for 900 AUD. Do I get that or a brand new Topping DX7 pro?
That's a bargain price for a DAC3.
Don't know about the DX7 but I own the DAC3 and Topping D70 - I'd take the DAC3 in a heartbeat.
 
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I haven't been able to scan all the 27 pages, i'm sorry if this has been discussed before.

But does the high output of the DAC provide any real advantage ? Is that a desirable quality in a DAC ?

Thank you in advance for helping out.
 

RayDunzl

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But does the high output of the DAC provide any real advantage ? Is that a desirable quality in a DAC ?
If your associated gear will accept it, use the higher levels.

If not, engage the output pads (XLR only).

The RCA outputs are the usual 2V.

I have a DAC2, the preamp I use after it will accept the 12V/24dBu XLR.

Were I to plug the XLR from the DAC directly into my power amp. I'd need to pad it, as the input sensitivity of the amp is 2.45V
 
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If your associated gear will accept it, use the higher levels.
Thanks for helping out Ray. Iam trying to decide if i need to get the Benchmark DAC to go with the abh2 - the combo is expensive and i would prefer to use the SMSL 500 or maybe the RME as my DAC unless of-course the Benchmark's higher output gives it a distinct advantage.

So yes the abh2 will accept the higher output but does the higher output DAC (20 v vs 7v) give any advantage for amplification levels?

Will using a higher output DAC result in a higher output in amplification or a higher SINAD ?
 

Sal1950

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The ABH2 has switchable input sensitivity for optimum performance with any realistic input level.
 

RichB

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The ABH2 has switchable input sensitivity for optimum performance with any realistic input level.
I have no trouble driving the AHB2 directly from the Oppo UDP-205 in the high and mid gain settings. It sounds great too.

- Rich
 
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Thats good to know. Thank you all. Wonder why then Benchmark went to the trouble of adding such high output to the DAC. I'm guessing it was costlier than not doing it. Maybe @John_Siau might know. Its a pity the RCA is not so great as per Amirs measurements, it would have made a perfect choice too for folks who need that.
 

RayDunzl

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Will using a higher output DAC result in a higher output in amplification or a higher SINAD ?
I would expect the maximum output to remain the same.

SINAD for this unit as tested - 113db.

Shoutometer says just under 326 miles.

I'd think you could lose a few dB and never notice it unless you were measuring.

I won't win any records for SINAD here, at least not on the more popular end of the scale.

Do I have a noise problem? Maybe measurably, not listenably.

Idle amplifier measurement:
Using a scale that would (Ithink) be equivalent to the XLR output levels at the DAC

1573326649657.png


SINAD (not more than 72dB) is bound by AC Power noise, wherever it is coming from. Cables? Amp output? Not a sterile environment here.
The amplifier spec says it will push 49Vrms (though it is differential, so 138Vpk-pk across the speaker terminals).

Using 49V as the 0dB might press the relative measurement down another 12dB. Unsure how to properly configure things here.


Wonder why then Benchmark went to the trouble of adding such high output to the DAC.
It's designed to be able to be used places other than at home.

Like the RME ADI-2 Pro FS:

Output level switchable +24 dBu, +19 dBu, +13 dBu, +4 dBu @ 0 dBFS

1573326209318.png

http://www.sengpielaudio.com/calculator-db-volt.htm
 
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RayDunzl

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Idling today, at the amplifier output, using what may be a more appropriate scaling factor. The interface says the maximum input (0dBfs =26dBu=15.45Vrms) with the minimum gain (input volume knob).

That lowers my idle SINAD to about -85, putting me mid-pack in the amp contest.

1573428623949.png




Making a tone at a reported 4.72Vrms (5W into 4 Ohms) I get this:

The AC noise didn't change, and only a hint of 3rd harmonic poke up out of the noisy flooring.

1573429403043.png


I'm not convinced that's 5W though, if only 83dB is emitted, with both speakers.



Using the million sample FFT:

Is that cheating? I expected the "noise floor" to drop but not the AC noise (maybe it is more variable than constant)
Test tone and 3rd harmonic are still reported at the same level, though.

1573429833386.png



Right or wrong, overlaid with Nord One (Hypex) -rated 96dB SINAD:

1573430687125.png


Ok ,good enough. a little inaudible power noise, cleaner harmonics (but unsure of the exact power level)

I'll go be terrified about whatever worry I come up with next.
 

RayDunzl

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Thats a lot isnt it....is this not desirable ?
That would be the amplifier output as 0dB - 49Vrms, 98V across the speaker terminals, since it is differential and there seems to be some confusion on measuring things, or 138Vpk across the speaker...

The higher "0dB" is the lower (relatively) some unchanging smaller value becomes.

This is all academic, I don't have any pruchase plans.
 
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SINAD (not more than 72dB) is bound by AC Power noise, wherever it is coming from. Cables? Amp output?
Does it help to use power conditioners, sine wave ups etc to rectify power noise ? Or ia it a fools errand in a home env ?

ps : what equipment do you use to perform these measurements ?
 

RayDunzl

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Does it help to use power conditioners, sine wave ups etc to rectify power noise ? Or ia it a fools errand in a home env ?
I don't think I'm looking at external power noise - these harmonics could well, I suspect, be present even with a perfect power company sine wave.


ps : what equipment do you use to perform these measurements ?
REW software and a Focusrite Clarett 4Pre.

1573438897065.png


Not the best choice, nor the worst. Serviceable within its range.

But I'm not understanding the voltage levels and calibration issues, especially when measuring balanced vs unbalanced with the Focusrite and REW,, so need to whip out the 'scope to see what's really going on there.
 
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I have a DAC2 HGC (w/firmware update). Which set-up is preferable?

1) Using the DAC2 to send the +8.2 dBu/ 2 Vrms "Bypass" level signal into the AUX-input of a pre-amp with a 200mV sensitivity @47k Ω. This arrangement would only put the pre's volume control (no additional gain) in the signal path

- or -

2) Using the DAC2 as a pre-amp (with it's own volume control) into an amp-in section which is rated at 1V @47k Ω.

Both examples using unbalanced RCA. Which would be a better match?
 
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John_Siau

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I have a DAC2 HGC (w/firmware update). Which set-up is preferable?

1) Using the DAC2 to send the +8.2 dBu/ 2 Vrms "Bypass" level signal into the AUX-input of a pre-amp with a 200mV sensitivity @47k Ω. This arrangement would only put the pre's volume control (no additional gain) in the signal path

- or -

2) Using the DAC2 as a pre-amp (with it's own volume control) into an amp-in section which is rated at 1V @47k Ω.

Both examples using unbalanced RCA. Which would be a better match?
Either connection will work but the direct connection from the DAC2 to the power amplifier will provide the best SNR and lowest THD.
 
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Either connection will work but the direct connection from the DAC2 to the power amplifier will provide the best SNR and lowest THD.
Hi John- thanks for the reply, makes sense. I've tried both methods and they do work but I was surprised that at reasonable listening levels the volume knob positions were very close in either setting. In other words, regardless of the path (or volume control) at about 11 o'clock I was getting the same pink noise SPL in both configurations. I get that this could be coincidental and that the scale of the volume controls may be different but it got me thinking about the gain matching differences between the two options.

Actually, the more I think about this the more I think that the 200mV rating of my AUX-input is accounting for the additional 14dB of gain in the pre-amp section which I normally bypass, so that would further reduces the sensitivity. I think that by just keeping the volume control in the signal path (and bypassing the pre-amp gain) my AUX-IN sensitivity is closer to 1V which might explain the similar volume knob levels. Hmm, I will have to investigate this further.

Also, second question - if using the balanced connections from the DAC into a 1V amp, what would be the best jumper setting on the DACs balanced output?
 

John_Siau

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The 20 dB pad on the Benchmark DAC1, DAC2, or DAC3, will give you 1.23 Vrms (+4 dBu) on the XLR outputs at 0 dBFS when the DAC volume control is bypassed. You will reach the full 1 Vrms requirement of your amplifier at just 2 dB below the bypass (or calibrated) volume setting, so the gain staging will be almost perfect between the DAC and the amplifier. This assumes that the amplifier sensitivity is also 1 V on the balanced input (check the amplifier specifications to verify this).
 
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