Upgrading AkitikA GT102

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What would you change/add to the Akitika GT102 in order for it to be improved overall? Personally, I am curious what could be done to raise the WPC over 100, flatten frequency response, and perhaps other sonic qualities that it is currently lacking (I read it was missing some bones approaching top end). Can this chassis be made to turn into a dual monoblock, for example?

Thank you, any sort of advice would be wonderful.
 
AkitikA GT-102 power amplifier Measurements | Stereophile.com :
"AkitikA specifies the GT-102 as clipping at "a bit more than 60W into 8 ohms at 1kHz." (Texas Instruments' datasheet for the LM3886 chip claims "68W of continuous average power [into] a 4 ohm load.") Defining clipping as when the THD+noise in the output reaches 1%, I measured a clipping power of 64W into 8 ohms (18.1dBW, fig.4), with one channel or both channels driven. However, when I tried to measure the clipping power into 4 ohms with both channels driven, the GT-102 turned off its outputs at 61W (14.8dBW). With one channel driven, the AkitikA clipped at close to 120W into 4 ohms (17.8dBW, fig.5). This lack of power with both channels driven might explain why HR preferred the low-frequency reproduction of the GT-102 when it was paired with the high-impedance Falcon speakers."

....dual monoblock sounds great!
 

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It is very well thought design to start with, not much to improve on.

What could be done is to parallel two channels, to improve its behavior into low impedance loads. This will not increase the power into 8r but, as asuslover explained it above, it will increase the effective power into nominal 4r speakers (which often dip even lower in impedance).

Since it's AC-coupled and there's no offset to worry about, it could be as easy as to add a pair of low value power resistor at each output (something like 0.15r-0.22r) and match as well as possible the gain setting resistors. Even that might not be necessary as the manual already specify 0.1% resistors for the feedback network.

I would contact the seller for more information as it is somehow that he himself suggests: Can I wire an amp in parallel? | Audiokarma Home Audio Stereo Discussion Forums
 
Unfortunately I am not of an electrical background. I am fascinated by the conversations here and would like to learn. The reason why I posted about the Akitika is because I received one from a friend who told me that it simply did not have enough power for him. So I wanted to know what I could do to make it a better version.

Are you saying that power will be capped to 60WPC no matter what I do with the amp internals? When you showed the difference between W for 4Ohms vs 8Ohms, I did not really understand.

Could you tell me what I should do to this amp to make it a better amp that puts out at least 120WPC, with great dynamics? What about those capacitors were you talking about? How do I make it a dual mono? If you could give me directions w/parts, I could at least attempt to rebuild it.

Thank you very much
 
did your friend give you the whole amp? can you post a picture?
It is a little strange that driving 2 channels low impedance speakers 60w will be the max out each amp, but using only one channel , the amp will deliver much more, so I believe that using a PS for each channel will be an improvement.
 
did your friend give you the whole amp?

Hi asus - yes, the entire amp. There are many pictures of stock amp online.

It is a little strange that driving 2 channels low impedance speakers 60w will be the max out each amp, but using only one channel , the amp will deliver much more
Sorry I don't know what that means when you said before:

"...I measured a clipping power of 64W into 8 ohms (18.1dBW, fig.4), with one channel or both channels driven." [/QUOTE]

Also this part, I have no idea what that means:
"This lack of power with both channels driven might explain why HR preferred the low-frequency reproduction of the GT-102..."

...so I believe that using a PS for each channel will be an improvement"
OK...could you explain what I would need to do? Is this cap changing that I have read about? What amount is necessary, 60,000? Is this all I would need to do in order for this amp to produce around 120wpc clean? What about how to dual monoblock?

All I request is that you tell me what parts I need. I appreciate any feedback.
 
Here's a tiny upgrade that I did to my GT-101

A snubber for my Akitika GT-101 (2 x LM3886)

Hi - does that relate to the new model? Is this GT102 model even worth upgrading? I can't seem to understand the previous threads regarding this model. It is as if people were implying that there are major design flaws that create a critical bottleneck that can't be fixed. I apologize if I am misunderstanding things.

One part that I really would like to understand is the part where 1 channel vs 2 channel does not seem to show improvement in WPC for 8 Ohms. My speakers are rated 8 Ohms but resides at 5 Ohms and dips into 3 Ohms.
 
Ok, let's try to make this as simple as possible.

Inside a GT102, you have three main components: one power supply and two amplifiers (based on the LM3886 IC). Each of these components define the power you can get from the amp.

Let's start with the power supply. It provides 72Vdc. This sets a first limit. The maximum power you can get from 72V with a 8R load and the lm3886 is 60W. There is no way around that. With a 4R load, you get in theory a bit less than twice that, about 120W. But that's only if the power supply can also provide a lot more current. With both channels working and a low frequency signal that might not be the case currently (as asuslover said). So, either you might get more power by beefing up the power supply (that means a bigger transformer and a modification of the regulated power supply board or even a second one), or you turn the amp into a monoblock, using only one amplifier section (which now gets all the current from the power supply).

But that's all theory because then we run into the limitations of the lm3886. Let's look at its datasheet. It says that with a 4R load and a 70V supply, you only get 95W or so. And that's a best case scenario. The lm3886 is equipped with multiple protections to prevent it destructing itself, protections which are likely to activate and limit the power further (by limiting the current it can delivers). The lm3886 really isn't made to operate at such high voltage into 4R loads to be true.

So here are our hard limits: 2x60W into 8R due to the power supply, 2x95W (likely less) into 4R due to the lm3886. And that's even if you extensively modify the power supply.

What I was saying earlier is that you can turn it into a mono amplifier by paralleling both channels, but that will only get you a single 60W into 8R, 120W into 4R.

If you want to dig deeper, this is a good read : Taming the LM3886 Chip Amplifier – Neurochrome
 
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I was impressed seeing the small signal performance of this amplifier. Noise is low. So is distortion.
This is a unique chip amp design. Regulated single rail power supply and capacitor output coupling.
I built a Pass design like a this and it played music fine. Not sure how well it measured, the GT102 measures well.
Like has been said, this amp is power supply limited. But really, 60 watts is plenty for most applications. Parallel connecting two channels would be beneficial if driving speakers that have an impedance under 4 ohms.
 
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So here are our hard limits: 2x60W into 8R due to the power supply, 2x95W (likely less) into 4R due to the lm3886. And that's even if you extensively modify the power supply.

What I was saying earlier is that you can turn it into a mono amplifier by paralleling both channels, but that will only get you a single 60W into 8R, 120W into 4R.

As I have declared previously, I have no hard science background like the rest here. I have read a lot of the threads, not just about GT102, but regarding Purifi and Modulus, all those 100+ pages threads, just trying to understand and take away some meaningful piece of information - which has been difficult. This is the first time someone has written a post that was helpful for layman like myself, so thank you very much for this. Really appreciated!

I will take your advice and keep the amp the way it is. I think this amp will be great for my beloved Energy Connoisseur C5s.
 
What would you change/add to the Akitika GT102 in order for it to be improved overall? Personally, I am curious what could be done to raise the WPC over 100, flatten frequency response, and perhaps other sonic qualities that it is currently lacking (I read it was missing some bones approaching top end). Can this chassis be made to turn into a dual monoblock, for example?

Thank you, any sort of advice would be wonderful.

buy & build the Neurochrome lm3886 amp.. If you demand better ;)
 
Already posted this in another thread, but this one seems more appropriate...I am 10 hours into break in, and the GT-102 is definitely a fantastic bang for the buck. Excellent instructions, and Dan is awesome!

However, actually bought this to drive the bass woofer on some bi-amped 3 way bookshelves I’m building. Maybe bass will kick in, as it ‘burns I ‘, but right now- the bass is less in quantity and clarity compared to my VTA70 (which is almost half the wattage...3x the price). I bought this for tighter and more authoritative bass than my tube amp, but it’s not happening thus far. Anyone have any thoughts on this getting better over time, or know of mods? Thanks in advance!
 
Have you compared damping factor? Many people use nc400 to drive passive (sub)woofers.

Good thoughts. The NC400 is nice, and I was hoping to spend less...but that doesn’t always work out.

The damping factor on the Akitika is >80, vs the 16 on my VTA-70. I would think that with almost 2x power and 5x damping bass would be stronger and/or cleaner (I understand that a stronger/faster/more controlled amp can sound leaner)...but it’s not either at the moment
 
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