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Review and Measurements of Gustard A20H DAC & AMP

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#41
Hi Team

Geez I am finding it hard to decide on a all in one unit to purchase. I've been looking for over 12 months. The Topping Dx7s looks the goods but has high impedance. I was hoping this would measure up and solve my problems but I don't think so. It would be great to see the Aune A6 measured but its the size of a house for a desk top unit.

So maybe I buy separates? The SMSL SU-8 Dac looks good, but how does the matching amp measure I wounder? And of course I'd need it to match, the Massdrop THX amp would be the amp to get but wonder if they will release a DAC that matches it's performance and looks? Also doesn't the use of cables create the opportunity for degradation?

Being in Australia doesn't help, have to make the purchase correct first time.

Sure am loving this forum, very informative, a big thanks.
 

amirm

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#43
Also doesn't the use of cables create the opportunity for degradation?
No, and at any rate, I test them with those extra cables so there is no impact at all.
 

folzag

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#44
If you mean for output, it doesn't need it since it has so much power already.
Right, OK. I thought you were mis-remembering Atom as having balanced outputs, not just that it had plenty of power.

BTW, I listen on low gain w/ 80 ohm, DT-1350's. At max volume it's loud enough for all but if I really, really want to "rock out," which, to be honest, I haven't yet.
 

derp1n

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#45
In my experience, you need tons of power for good bass performance. Our hearing sensitivity is poor in that region so you need the power to "feel" the sensation of bass. And yes, you do feel it in the cups and impact of the bass.

As for what is enough, the math people use never computes for me. I generally find that you need more power than the computation of sensitivity would tell you.
These things are easily measurable, but instead here we have a bunch of uncontrolled subjective feelings.
 

amirm

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#48
@amirm
While the results are not ideal for an expensive device like this, for completeness could you check the dynamic range and add the result to the chart as well? thanks.
Here you go:
1544753513089.png
 

graz_lag

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#50
I find this Gustard brand name with some funny content each time I cross it on my eBay browsing, with some kind of cartoon relationship, like :
Gustard, Garfield's dog best friend ... :)
 

Graph Feppar

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#51
I always think about custard. :D Also Topping... why do chi-fi brands have food related names? If you google "topping" its all cakes and sweet foods.You got your custard,put on some chocolate topping and nom nom it all alone without sharing.
 

graz_lag

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#52
I always think about custard. :D Also Topping... why do chi-fi brands have food related names? If you google "topping" its all cakes and sweet foods.You got your custard,put on some chocolate topping and nom nom it all alone without sharing.
It gets nastier if we look at the names Korean manufacturers give to the cars ... :facepalm:
 

Veri

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#53
It's really weird by the way, they used high quality Accusillicon clocks on this device.



Not sure how much of this jitter "performance" is implementation, or those clocks being actually worse than other common "femto" clocks (Crystek/NDK/...)
 

graz_lag

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#54
It's really weird by the way, they used high quality Accusillicon clocks on this device.

Not sure how much of this jitter "performance" is implementation, or those clocks being actually worse than other common "femto" clocks (Crystek/NDK/...)
Totaldac's owner (French manufacturers of highly regarded R2R ladder DACs ...) says :

“Many of the less expensive units do not use a fixed oscillator and instead use a frequency synthesizer and therefore have worse jitter than a dedicated fixed oscillator. Many companies don’t even know how to power fixed oscillators. If you go to say Crystek and ask for a really good oscillator and then power it with a 3 terminal regulator the results will be less than staggering. For high end you need a discrete regulator with ultra low noise to establish a really good low jitter Master Clock.”
 

amirm

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#55
Not sure how much of this jitter "performance" is implementation, or those clocks being actually worse than other common "femto" clocks (Crystek/NDK/...)
Jitter predominantly is caused by circuit design, not the quality of the clocks themselves. Anything that bleeds into clock circuits (and reference voltage) will degrade its performance. And these factors are much more significant than differences between clocks.
 
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#57
Would you say that badly implementing a high-end DAC chip is the equivalent of playing Lionel Messi in the Argentinian National Football team vs FC Barcelona? (in one of the cases, he sticks out)
 

graz_lag

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#58
Would you say that badly implementing a high-end DAC chip is the equivalent of playing Lionel Messi in the Argentinian National Football team vs FC Barcelona? (in one of the cases, he sticks out)
Exactly !!! :cool:
 

trl

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#59
Measured performance has nothing to do with the AK4497 but with the fact that this device has discrete output stages instead of OP amps.
Perfect match of output transistors in a mass-market device, to get the lowest harmonics, is almost impossible. However, keeping harmonics @ -100dB means are not audible.

Also, transistors noise is usually higher than latest audio laser-trimmed opamps (e.g.: OPA1612, AD797 etc.), especially that around transistors there are several passive components too and few more inches of PCB traces (so...EMI, RFI & thermal noise).

Despite of all the above, I'll always like more a company that invests in R&D and makes it's own design and implementation, so replacing opamps with transistors is very challenging, especially if measurements-figures/price ratio needs to be good enough.
 

Krunok

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#60
Perfect match of output transistors in a mass-market device, to get the lowest harmonics, is almost impossible. However, keeping harmonics @ -100dB means are not audible.

Also, transistors noise is usually higher than latest audio laser-trimmed opamps (e.g.: OPA1612, AD797 etc.), especially that around transistors there are several passive components too and few more inches of PCB traces (so...EMI, RFI & thermal noise).

Despite of all the above, I'll always like more a company that invests in R&D and makes it's own design and implementation, so replacing opamps with transistors is very challenging, especially if measurements-figures/price ratio needs to be good enough.
Problem with such designs is they usually cost more and there is little they can offer to justify that, unless you can find pleasure in owning such "exotic" peace of technology.
 
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