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Akitika GT-108 Stereo Amplifier Kit Review

Rate this amplifier kit:

  • 1. Poor (headless panther)

    Votes: 104 46.2%
  • 2. Not terrible (postman panther)

    Votes: 100 44.4%
  • 3. Fine (happy panther)

    Votes: 8 3.6%
  • 4. Great (golfing panther)

    Votes: 13 5.8%

  • Total voters
    225

amirm

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This is a review and detailed measurements of the Akitika stereo amplifier kit. It was purchased preassembled by a member and kindly sent to me.
Akitika GT-108 stereo amplifier kit review.jpg

As you see, the case is rather simple but for a kit, it is not bad. That large power switch is reassuring, giving you the feeling that it could switch a lot of "gigawatts." :D
Akitika GT-108 stereo amplifier kit back panel review.jpg

We can excuse the lack of serial number. :)

The unit is rather heavy which I imagine is due to power transformer. Company notes says the kit originally was based on a TI IC but that was hard to get so they switched to a discrete design. Manual is very comprehensive. There are a ton of parts in there so you better have lots of patience to assemble it!

Akitika GT-108 Amplifier Measurements
As usual we start with our dashboard:
Akitika GT-108 stereo amplifier kit measurement.png

I worked to reduce the mains noise and that is the best I got. SINAD though is dominated by that second harmonic distortion spike. It lands the GT-108 below our average for all amplifiers tested:
Best streo amplifier kit review.png

Best streo amplifier kit zoomed review.png


Noise performance was better than I expected:
Akitika GT-108 stereo amplifier kit SNR measurement.png


Being traditional class AB (MOSFET output stage), frequency response is load independent and broad:
Akitika GT-108 stereo amplifier frequency response kit measurement.png


The high amount of distortion predictably produces less than rosy results in multitone and 19+20 kHz tests:
Akitika GT-108 stereo amplifier kit Multitone measurement.png

Akitika GT-108 stereo amplifier kit 19 20 kHz intermodulation distortion measurement.png


Crosstalk is about average for amplifiers tested:
Akitika GT-108 stereo amplifier kit Crosstalk measurement.png


Company only specifies power into 8 ohm load. Let's see what we get in both 4 and 8 ohms:
Akitika GT-108 stereo amplifier kit power 4 ohm measurement.png

Akitika GT-108 stereo amplifier kit power 8 ohm measurement.png

Akitika GT-108 stereo amplifier kit max and peak power 4 ohm measurement.png

Strange that "continuous" power at 4 ohm is less than 8. So seems long term current limited as peak power is substantial at 108 watts.

Even more strange is flat distortion profile with power and super sharp clipping. Best to make sure you don't need more power as this amplifier will go from good to nasty in an instant.

EDIT: forgot to add power sweep vs frequency:

Akitika GT-108 stereo amplifier kit Power vs Frequency vs Distortion measurement.png


The amplifier is essentially stable on power up:
Akitika GT-108 stereo amplifier kit warm up measurement.png


There is substantial power up noise in one channel:
Akitika GT-108 stereo amplifier power on noise measurement.png


Conclusions
Objective performance ranges from very good when it comes to noise and frequency response to less than ideal for distortion. Power output is modest for how much this amplifier costs. All of this would normally force me to give a poor rating to the GT-108. But something about a kit that is so well documented (including a set of measurements), makes me be more lenient. :)

I would not personally buy the Akitika GT-108 amplifier as a finished product. If I had a need for a kit, then it may make a good target. It would be a much more substantial experience than building an amp with modules.

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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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A User Testimonial​

"Completed the GT-108 and all went according to your excellent Assembly Manual, which is reminiscent of the old Dynaco and Heath kit manuals. Very well done indeed. Particularly enjoyed the Theory of Operation section.

More importantly is how excellent the GT-108 sounds. It is dead-quiet through my Cornwall III's. The improvement to the clarity and richness of the sound, compared to my Yamaha R-S500 receiver's PA section, was impressive, like getting brand new eyeglasses. You might be interested to know that my preamp and source include a Schiit SAGA S preamp and MANI phono preamp, Pro-Jext Debut EVO turntable with a Nagaoka MP-200 cartridge. The system sounds just fantastic now, thanks to your GT-108.

Best Regards

Fort Worth Audiophile"


from https://www.akitika.com/GT108.html
 
As someone who reminisces, disappointedly, for never having built a Hafler amp back in the day, for $425, I’d spend my funds elsewhere and use my saved assembly time to listen to some relaxing music on a Hypex, Purifi or TI based Class D amp.
 
Even more strange is flat distortion profile with power and super sharp clipping. Best to make sure you don't need more power as this amplifier will go from good to nasty in an instant.
This is interesting. I suppose the power supply/output impedance(Z) is at fault here. Any thoughts about this anybody.<?>
 
Is this a old style quasi complimentary layout? It has those capacitors with inductors around them on the amp PCB. What is that about?
 
It's a regulated supply, single rail amp with capacitor coupled outputs (looks like in the feedback loop) and some clearly quite aggressive current limiting.
Other than a old Marantz amp quasi complimentary design similarity I have never seen such a design before. Why would they make such a thing? It has very obvious drawbacks.
 
Dont want to retest but, were there power versus distortion measurements done?
Thanks for the review.

note : grammer corrected.
 
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Other than a old Marantz amp quasi complimentary design similarity I have never seen such a design before. Why would they make such a thing?

It's not quasi. They are just using I would say, the supply they had for the previous model, which likely was a BTL IC based single rail amp. The transformer is a single secondary tap by the looks, so they had to use up inventory.

edit: it looks like its a twin tapped secondary that they series connect.

It works, kinda, but the whole thing is strange. For someone who really wants to build someone elses kit and it still look like a kit when all said and done, it could be a good thing to waste a few cold nights over the soldering iron.

In another thread there's a discussion about the matching preamp taking out an amp or two. Looks like it may have had some dubious design issues too.

But, gotta agree with @amirm, the instruction manual is the highlight. It's a seriously well done manual. 56 pages full of photos and details. Nothing like the B&W kit manual on 20th generation photocopied & folded-up rat-paper like I had growing up.

Hopefully they supply a country specific Made In USA sticker for people who build it in another country... ;)
 
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Dont want to retest but, were there be power versus distortion measurements done?
Thanks for the review.
Oops. Added just now.
 
Thanks @amirm

Adding current price:

GT-108 Stereo Power Amplifier Assembled and Tested (GT-108A) - $599 plus $26.00 shipping (48 states)

Failure and a rip off? No, I wouldn't even look at this with a binocular.
 
Not the sort of thing I'd want to use or look at but it would be fun to build.
 
i think the whole thing does not seem to fit any niche in the market place

for $599 a 19" wide unit that i assume weighs over 10kg and it's a 50w 8 ohm amp admittedly double to 100w at 4 ohms... but as typical none of the test results shows any kind of even above average performance...

so why does it exist? why would someone buy it?

you could probably get a slimline integrated at 50w or so for about this money assuming you dont want class d?

and then why do you want a very middling power amp then? if it rocked out at over 100w then that's another thing

this company does sell a matching preamp but then you have a $1k+ two box stack that has really middling performance...
 
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