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Gustard A18 Balanced Desktop DAC Review

amirm

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#1
This is a review and detailed measurements of the Gustard A18 Balanced Stereo DAC. It was kindly sent to me by shenzhenaudio. The A18 costs US $560.

The A18 is a bit distinctive in a very crowded market:

Gustard A18 DAC USB RCA Balanced Stereo Review.jpg


While I like the high-resolution display (nicer in person than in the above picture), I don't understand why the sample rate is highlighted in large letters rather than volume. On sample rate, I like to also see the bit depth. Maybe they can change the firmware in the future to fix these. Otherwise, the unit works and is easy to navigate.

I understand there is a newer version now with Toslink optical? If so, mine which was sent a couple of months ago doesn't have that:

Gustard A18 DAC USB RCA Balanced Back Panel Outputs XLR Bluetooth  Stereo Review.jpg


Bluetooth is included as it has become standard in this price category.

Gustard A18 Measurements
Let's start with our usual dashboard via XLR Output terminals and USB input:

Gustard A18 DAC USB XLR Balanced Audio Measurements.png


Distortion at -128 dB is well below threshold of audibility. Noise though is added enough to that to derate SINAD to below state of the art:

Best desktop USB Balanced XLR DAC Review.png


And zoomed:
Best desktop USB Balanced XLR DAC zoomed top 10 Review.png


So #12 in best of the best.

And here is RCA output performance:

Gustard A18 DAC USB RCA Audio Measurements.png


Naturally there is more ground leakage reducing performance some.

Since the output is capable of going above nominal 2/4 volts, let's sweep and see how the performance varies:

Gustard A18 DAC USB RCA and XLR THD+N vs Output Level  Audio Measurements.png


Looks like best case performance is above nominal voltage so take advantage of that if your amp has low enough gain to allow it.

Dynamic range is excellent but again, shy of best of the best:
Gustard A18 DAC USB XLR Balanced Dynamic Range Audio Measurements.png


IMD test shows similar performance:

Gustard A18 DAC USB XLR Balanced IMD Audio Measurements.png


Here is our multitone:
Gustard A18 DAC USB XLR Balanced Multitone Audio Measurements.png


And distortion vs frequency:

Gustard A18 DAC USB XLR Balanced THD+N vs Frequency Audio Measurements.png


Linearity is perfect though:

Gustard A18 DAC USB XLR Balanced Linearity Audio Measurements.png


Finally, a few filter types are provided:

Gustard A18 DAC USB XLR Balanced Filter Audio Measurements.png


Conclusions
Looks like the A18 aims at very high level of performance, stopping just shy of heroic efforts to squeeze down the last bit of noise and distortion. In return if my memory is serving me correctly, you save money compared to the ones that do go that extra inch. So you more choice of pricing and performance in the top bracket.

I am happy to recommend the Gustard A18 DAC.

-----------
As always, questions, comments, recommendations, etc. are welcome.

Enjoyed fantastic tasting apples and pears from our orchard with chocolate Fondue while watching a movie with my wife last night:

Apple Chocholate Fondu.jpg


Could use some kind donations as always: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

Helicopter

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#3
Thanks for the review. I am surprised something with this performance is not a slam dunk, but the field is becoming more crowded, especially at this price point. I certainly appreciate the sample rate information as an Amazon HD user; Amazon can make this information elusive and I am happy to see it over volume on my DAC.
 
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amirm

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Thread Starter #5
How difficult would it be for these DAC makers to include an analog crossover and a sub out? Earnest question.
Not difficult at all.
 

Tks

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#6
Anything that beats the DX3 Pro in IMD testing is a thumbs up in my book (usually followed by good performance everywhere else when that happens).

The lack of Optical is a bummer, but I'd say somewhat made up for with Bluetooth input at least.
 
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amirm

amirm

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Thread Starter #10
Alright, amir

Time to start doing reviews of food from your garden :)
Working on that just in case this gig does not work out.....
 

pavuol

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#11
Some "investigative" findings:
- seems like Gustard relies more on resellers and social media propagation as their website seems to be down (?).. /personally I don't care, I'd rather see solid products than poetry filled webpages :)
- link to user guide

As to A18 product page on shenzhenaudio, some friendly remarks:
- small typo there ("flsgship")
- as mentioned elsewhere #41, "humanized operation"..
- you list all the quality components there, in pictures it seems like Nichicon caps are used, as there has been some discussion about the topic lately, why not to explicitly mention them as well? ;)
 
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Ddd

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#13
@amirm
Hello, just curious, at minus how many dB to get the XLR output 4.8V?

And when setting the A18 into Fixed Pure DAC mode,
what's the output voltage of both RCA and XLR output?
And any difference in SINAD when in Fixed DAC mode? :)
 

JohnYang1997

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#16
How difficult would it be for these DAC makers to include an analog crossover and a sub out? Earnest question.
You should ask how difficult for those Sub makers to add an analogue crossover. Though majority of them do.
If you include crossover in the dac how do you implement it? Can you change crossover frequency? Continuous or a few selection of frequencies? And then do I also make a high pass for the rest of your speakers? Do I also design those two circuits with low noise in mind, meaning low resistance and high capacitance? Then I need something to drive the low resistance with current. Large capacitors with low distortion are bulky and expensive too.
This can quickly turn into a complete new product on its own. If you just put a simple relatively noisy 1st order 80hz roll off, many people will complain even more by simply including it.
 
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amirm

amirm

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Thread Starter #18
@amirm
Hello, just curious, at minus how many dB to get the XLR output 4.8V?
Just use a dB Voltage calculator.
 

JohnYang1997

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#19
@amirm
Hello, just curious, at minus how many dB to get the XLR output 4.8V?

And when setting the A18 into Fixed Pure DAC mode,
what's the output voltage of both RCA and XLR output?
And any difference in SINAD when in Fixed DAC mode? :)
The performance degradation is due to switching range on AP. Not the dac itself. Just use the max level that your amplifier can still handle.
 

Morla

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#20
so my amp has a input gain bypass (audiophonics purifi https://www.audiophonics.fr/en/powe...ass-d-stereo-purifi-2x400w-4-ohm-p-14393.html).

Settings explained herre: https://www.audiophonics.fr/en/blog...-bypass-on-purifi-amplifier-module-ampli.html
Quote:
  • Gain of + 7.2dB, for a total of 20dB (default) - Maximum power reached with a signal of ~ 4.2V RMS
  • Gain of + 12.5dB, for a total of 25.3dB - Maximum power reached with a signal of ~ 2.2V RMS
  • Bypass: in this case the signal passes directly from the inputs to the modules, allowing the lowest possible gain of 12.8dB. This mode can be interesting when using a powerful preamplifier, capable of driving a load of 2 to 4kOhm and reaching a voltage of ~ 10V RMS
Would it be a good idea to bypass it when using this dac (reading performance increases a little bit above nominal volts)?

(Speakers a 95dB)

Planning to control volume in the minidsp studio -> dac -> power amp

Or maybe I'm mixing up things again. Audio is not easy :-(
 
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