Akitika GT-108 Stereo Amplifier Kit Review

[restorer-john]

What performance Chart? Any measurements?

Follow the link. Click the links. You have a computer, right? It's the left click button on that weird mouse thing...It's not hard...

 

[ZolaIII]

Kit is bit special , the idea is that someone is able to solder it together and roll their own amp for the fun off it.

Industrialized automatic mass production beats artisan work all the time for actual quality for your money.

Maybe someone that knows should open a recommended kits tread it sure must be better ones than this

Even if you want to play that way you buy either already soldered PCB's or do it yourself with LJ one's which are mostly actually Yamaha clones and for a fraction of the price.

 

[daniboun]

What performance Chart? Any measurements?

Check measrements into the shared link by clicking here :

LM3886 Done Right

The LM3886 Done Right wrings every bit of performance out of the LM3886 chipamp. Thanks to a high-end PCB layout, the LM3886DR gainclone provides better performance than indicated in the LM3886 data sheet.

neurochrome.com

You can also check the Modulus 286 review by Amir :

Review and Measurements of Neurochrome Modulus-286 Amp

This is a review and detailed measurements of the Neurochrome Modulus-286 Power (speaker) amplifier Kit. It is on kind loan from company designer and member, @tomchr. It is to ship by end of this month and costs $1,299. See: https://www.neurochrome.com/product/modulus-286-kit-2/ As you may...

www.audiosciencereview.com

 

[Scrivs]

Daniboun, I applaud you for your ongoing/unrelenting enthusiasm, and unbridled passion you bring to the forums. You remind me of Maty’s more well-behaved big brother.

That is all.

*Apologies for the unsolicited, random O.T. Need to give credit where it’s due

 

[AaronJ]

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

Because Randy the Cheapaudioman likes Akitika.

 

[solderdude]

Me thinks the excessive hum is due to the wiring scheme.
The distortion profile is not even that bad. Mostly even order and gradual sloping.

If grounding was done properly it probably would have measured better.
Ground lifter may even make things worse here.

The output cap is also not in the feedback loop, a 100uF polar cap is in the feedback loop.

 

[Hart]

This amp has everything, low power without the stigma of low distortion.

 

[Gorgonzola]

I've looked at Akitika GT-108 kit from time to time as a DIY project but I'm dissuaded by this objective review. Also, I'm non-technical but I've been skeptical about the need for 4 vs. 8 ohm models; seems to me that a competent amp ought to be able to handle both with not problems.

I rated the GT-108 'Poor' because it seems to me to be markedly poor value for money, especially the constructed version of course. There is no contest against, say, Hypex NC122MP amps.

 

[Multicore]

I never ever vote in these polls but I made an exception here: IT'S GREAT.

Read the manual and you see it's hard to do better if you want an all-analog electronic builder project. The amp and supply circuits are as simple as possible under the constraint of fair performance and home PCB soldering. The audio performance of the amp seems just right for this job, delivering satisfying results that could be improved with a more complex design. You (and your child?) could research those designs while planning your next project. Or maybe you'll instead decide to build an radio controlled car next.

If you want to buy an audio amp, that's easy. If you want to build a stereo hi-fi amp for fun and learning then this is great. Go change your vote now!

If you want to build a mono tube amp, these look like fun family projects too https://www.stewmac.com/kits-and-projects/electronic-kits/amplifier-kits/

 

[daniboun]

Me thinks the excessive hum is due to the wiring scheme.
The distortion profile is not even that bad. Mostly even order and gradual sloping.

If grounding was done properly it probably would have measured better.
Ground lifter may even make things worse here.

The output cap is also not in the feedback loop, a 100uF polar cap is in the feedback loop.

GT102 and GT108 are pretty close

Check GT102 measurements here

AkitikA GT-102 power amplifier Measurements

Sidebar 3: Measurements

www.stereophile.com

 

[IamJF]

Here are those big fat 10K micro Farad 63 V capacitors on the amp PCBs.
View attachment 357448

It has 10u AFTER feedback? Why didn't they do a symmetric power supply to avoid that?
This is clearly a circuit to achieve some "sound".

 

[lc6]

Here are those big fat 10K micro Farad 63 V capacitors on the amp PCBs.
View attachment 357448

This amp appears to have a unipolar PS, hence the need for the large C13 coupling to the speaker to remove the DC offset of about half VCC. To avoid a loud "thump" and speaker overload upon power up, K1 is likely in the O position so that C13 can charge through R35 and R38 to about half VCC. Then K1 is switched to the S position, at which point the internal resistive load (to keep C13 charged) changes to R40. But it seems that the speaker is connected to the OUT terminal, not the L1A point. If so, the 10 Ohm / 1 Watt R35 is kept in series with the speaker, which does not seem a good thing even if negative feedback is connected to L1B. Am I reading the schematic incorrectly?

 

[Koeitje]

Thanks @amirm

Adding current price:

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

Wow, that's expensive.

 

[Cbdb2]

This is interesting. I suppose the power supply/output impedance(Z) is at fault here. Any thoughts about this anybody.<?>

Overly aggressive current limiting?

 

[Gorgonzola]

Wow, that's expensive.

It's ludicrous compared with a Topping LA90 for the same price.

 

[Doodski]

Overly aggressive current limiting?

I'm not sure. I look at that circuitry and my eyes roll back into my noggin! gg* I'm leaning to Z and power supply too.

 

[The Capstan]

It's a regulated supply, single rail amp with capacitor coupled outputs (looks like maybe in the feedback loop) and some clearly quite aggressive current limiting.

I remember this design with decoupling series capacitor back in early '70 the 20th century, in fact my first power amp I built had similar design (well, with glorious 2N3055 as finalstage) so a bit too much old school for my taste, and results shows the consequence.

 

[Hipster Doofus]

I have a soft spot for DYNACO and have burnt up a few 410's. i was once thinking about this one in my cult days.

Fun to see the review and also glad it's in the rear-view mirror now... I was only half ripped off because I bought a Pass Amp Kit instead and that ended up having half the gain as a normal amp .... maybe that's why it cost half as much as this one...

But now I know better I spend all my money on supplements ...vegetables in a powder anyone?

 

[restorer-john]

This amp appears to have a unipolar PS, hence the need for the large C13 coupling to the speaker to remove the DC offset of about half VCC. To avoid a loud "thump" and speaker overload upon power up, K1 is likely in the O position so that C13 can charge through R35 and R38 to about half VCC. Then K1 is switched to the S position, at which point the internal resistive load (to keep C13 charged) changes to R40. But it seems that the speaker is connected to the OUT terminal, not the L1A point. If so, the 10 Ohm / 1 Watt R35 is kept in series with the speaker, which does not seem a good thing even if negative feedback is connected to L1B. Am I reading the schematic incorrectly?

You missed the inductor (L1) (wound around the cap can) that sits in parallel with the resistor...

 

[Doodski]

You missed the inductor (L1) (wound around the cap can) that sits in parallel with the resistor...

Is that capacitor inductor for feedback?