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SONCOZ SGA-1 Review (Headphone Amplifier)

amirm

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#1
This is a review and detailed measurements of the SONCOZ SGA-1. It was sent to me by one of their resellers, Aoshida Audio and costs US $650.

The SGA-1 matches the look of their DAC naturally:

Soncoz SGA1 Review Balanced Headphone Amplifier.jpg


What is better than my favorite orange colored LEDs? Having them show two decimal places for dB value! :D So happy about that. I am ambivalent about the interface though. To change anything you have to push the rotary button in and then rotate it to land on the appropriate option. The process seems to have a built-in delay in it which makes it hard to navigate. Even after you select an option such as Gain, it takes it 1 to 2 seconds before it registers a change. There is a useful feature here where sound is faded out and maybe it is waiting for that to happen before acting on the user input. Not sure. For testing purposes where I have to keep changing outputs and gain, this was tedious. On the positive front independent gain and volume are memorized for each output which is very nice.

A minor change I like to see is a time out. When you adjust the gain, I like it to time out and default to volume. Right now it says on Gain which doesn't make sense to me.

The back panel is as you expect:
Soncoz SGA1 Review back panel Balanced Headphone Amplifier.jpg


The power supply must be linear given the voltage switch. Mine came configured for 220 which I noticed and changed. Otherwise I suspect it won't power on.

Overall I am a fan of the look of the unit, but not so much operating it.

Soncoz SGA1 Measurements
My first dashboard measurement was confusing. Usually with 0 dB gain, you set the volume to max and get what comes in being what goes out. With SGA-1 this took reduction of volume to almost 6 dB: [text should say minus 5.7 dB]:
Soncoz SGA1 Measurements Balanced Headphone Amplifier.png


Seems that there is no compensation for using balanced input with its higher input voltage relative to unbalanced. The bigger confusion was the rather high distortion and SINAD that was some 13 dB worse than company specs. I reached out to the company and realized that to get their SINAD you need to use 0 dB volume. Doing so gives us that SINAD but then the output has shot up:

Soncoz SGA1 Measurements Full value Balanced Headphone Amplifier.png


There is a digitally controlled volume IC which must be raising distortion when you reduce volume. To see if I can get a 0 dB volume measurement, I switched to unbalanced out and that indeed, gave me the company measurements:

Soncoz SGA1 Measurements UnBalanced Headphone Amplifier.png


Not sure how to put these results in the rankings. Decided to user the unbalanced output because that is indeed a value use case:

best balanced headphone amp tested.png


Signal to noise ratio is very good but short of class leading products:
Soncoz SGA1 Measurements SNR Balanced Headphone Amplifier.png


most quiet headphone amplifier.png


Frequency response is nearly flat to 100 kHz and hence very good:

Soncoz SGA1 Measurements Frequency Response Balanced Headphone Amplifier.png


Measuring power versus distortion and noise produced eye popping amount of output:

Soncoz SGA1 Measurements Power into 300 ohm Balanced Headphone Amplifier.png


Wow, that is a ton of power at nearly 1 watt! Some penalty comes in the form of rising distortion and higher noise so you can may want to use the 0 dB gain which still produces excellent power at 200 milliwatts.

Strangely, power dropped way down and clipped with low impedance of 32 ohm:

Soncoz SGA1 Measurements Power into 32 ohm Balanced Headphone Amplifier.png


Current delivery seems to be the weak point as you see in this sweep of impedance:

Soncoz SGA1 Measurements Power vs impedance Balanced Headphone Amplifier.png


The benefit of digitally controlled volume comes in the form of exceptionally channel matching:

Soncoz SGA1 Measurements Channel Balance Headphone Amplifier.png


Volume control goes down to whopping -110 dB while maintaining matching. Compared this to analog controls that would be great if they achieved 40 dB.

Listening Tests
I started with my Sennheiser HD650 using unbalanced output with gain of 6. As I approached maximum volume, the sound was sublime with incredible fidelity and dynamics. There was no hint of distortion and there was more volume left to be had. If you switched to balanced output, you would have even more room to grow allowing you to enjoy 600 ohm impedance headphones just as well.

Switching to Drop Ether CX auralized the measurements quite well. At low to moderate level the sound was fine. Turn up the volume more though and distortion set it and by the time you pushed the volume to max, the sound was extremely distorted. And this was with balanced connection. Note that my standards of evaluation as far as volume is much higher than most people so you may be OK listening.

Conclusions
The SGA1 takes a different path than many high-end desktop amps by using a digitally controlled volume control. As we have seen in some other devices, this increases distortion but gives you the convenience of perfect channel matching, and volume memory. You have to decide on the value of one versus the other. There is another strong decision impacting performance: optimizing for high impedance headphones with tons of output at the expense of very low impedance.

I am going to recommend the Soncoz SGA1 on the strength of its its ability to drive high impedance headphones, nice looks, and perfect channel matching. If these match your criteria, you are good to go.

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

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
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amirm

amirm

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Thread Starter #3
It is the right graph but I highlighted the wrong bar. Came back from eye doctor and my eyes were dilated. Still can't see well. :)
 
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#7
It's a nice looking piece of gear with great features but too bad about the delayed response when taking commands and the low current output. Perhaps $650.00 is a bit optimistic.
When the knob is setting menu options, SGA1 will first mute(fade out) the output. After the adjustment is completed then output enable(fade in). This design is conducive to the protection and audio equipment and it also continues the features of SGD1.
 

Doodski

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#11
When the knob is setting menu options, SGA1 will first mute(fade out) the output. After the adjustment is completed then output enable(fade in). This design is conducive to the protection and audio equipment and it also continues the features of SGD1.
Thanks for clarifying that for us @EMMA
 

enricoclaudio

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#12
As always s, Great review, @amirm . Front panel looks very like my MA mini-i Pro 3 ;)
 
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amirm

amirm

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Thread Starter #14
Probably a badly formed sentence, unless the output impedance is actually high? What is it btw?
Thanks. I rewarded it to make it more clear. I don't measure output impedance these days as just about all of them have low impedance or else amount of power goes to hell.
 

gvl

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#15
I'm curious about these orange indicators that Soncoz is using on their SG models. Are they custom design?
 

GWolfman

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#19
Never heard of this company, and too $$$ for my wallet (especially as there are cheaper, more performant alternatives).
 

PeteL

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#20
I'm curious about these orange indicators that Soncoz is using on their SG models. Are they custom design?
I am not sure what this question mean, but no audio equipment manufacturer in its right mind would design a LED (or other technology) screen. It is strictly impossible with the kind of sales volume these products get. Did you mean electronic design of the screen? The content fed to it can be custom, or at least customized. The screen itself is obviously a third party component, there are no shortage of value options of all kinds. They are a commodity.
 

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