preamp for aksa 55

[Bigun]

Originally Posted by rabbitz

My B1 (symmetrical supply / no cap version) didn't match my AKSA 55N+ but worked extremely well with the NXV200 and a LM4780. I've found the AKSA tends to thrive with a pre with a low output impedance (<75R) and my B1 is a bit highish at 330R.

Personal experience only so cannot generalise.

I am a newbie with regards pre-amps.

AKSA doesn't have a particularly difficult input stage to drive from the perspective of the source. Even at 330R output impedance from a B1, that's well within the comfort zone from a technical point of view ?????

[keantoken]

Originally Posted by Professor smith

Is that a mistake? $1K?

Not quite.

http://www.aksaonline.com/buying/buying_price.html

- keantoken

[Professor smith]

I would like to say that I am not very satisfied with the various problems I am having with this particular amp (AKSA). First of all there is the issue of hum and buzzing. It is more prone to the problem than my previous amp. It hums with some but not all things connected to it. Now when I approached Hugh about this, he said there was nothing wrong with the amp. My response is that the amplifier does not play music on its own. It has to be connected to something else therefore its all very well blaming the source, but that does not resolve the problem. Furthermore, I dont think its true to say that theres nothing wrong with the amp. It is partly to blame for the humming.

I have tried 2 commercial preamps now. Both brand new products both of which buzzed terribly and had to be returned at my expense. I just want to sort this out once for all.

[gaetan8888]

Hello Kenji

Please, don't blame the Aksa amp, I know this amp and never it would do any hum and buzzing.

You just have a ground problem, maby cause by your wires connection, have you check all wires and the 10 ohm ground lift resistor ?

Be sure that your Aksa amp input wires ground are connect at one end only to the amp ground, if you connect both end of the input wire ground you will have a ground loop.

Those ground problems will bring hum and buzzing wen you connect your amp to most brand of preamps.

Bye

Gaetan

[gaetan8888]

Hello Kenji

There was a little error in the drawing.

Here is a corrected version.

Bye

Gaetan

[mb]

Originally Posted by rabbitz

My B1 (symmetrical supply / no cap version) didn't match my AKSA 55N+ but worked extremely well with the NXV200 and a LM4780. I've found the AKSA tends to thrive with a pre with a low output impedance (<75R) and my B1 is a bit highish at 330R.

Personal experience only so cannot generalise.

That's an interesting observation. I recall a number of preamps being tested on AKSAs at local DIY gatherings, and the pre that has done consistently well is a buffered attenuator, with output impedance around 3R.

[sandyK]

I have heard both a Krell preamp (output impedance unknown) and a friend's home brew Solid State Class A preamp with an output impedance of <75 ohms driving an AKSA55, and there were absolutely no problems,
and only a small difference in performance, with the Krell preamp sounding slightly warmer.
Any problems are almost certainly due to the existing setup. Perhaps guidance should be sought from an experienced constructor who lives in the same area ?
SandyK

[AKSA]

Hi Kenji,

Gaetan obligingly supplied a nice diagram which you might check out in a search for earth loops.

Please follow this through carefully.

I remember well when we originally chatted via email. I quickly formed the conclusion that you would not be happy with any amp supplied, and told you as nicely as I could. Your expectations were too high, and I was not confident you had the skills to assemble a project of intermediate complexity.

But you insisted, and I sold you a traded AKSA55 at lower cost which I'd rebuilt to a high standard.

Then the trouble began. You had a lot of trouble getting it going, and caused a lot of angst, not just for me, but for many others. All this had marked effect on the reputation of my product. Eventually, you found that it performed well, and you even complimented the sound quality at one point. Until then, you cast aspersions on the design, on my help, and demurred again and again on the good advice given you by others.

Now it is happening again.

I exhort you to find someone skillful in hifi, and ask them to have a good look at your system, and the documentation. Have a third party go over it, check everything you have done with your system, and make sure that there are no ground loops or poor placements. This will go a long way to fixing all your problems.

The AKSA is a pretty good amp, and inexpensive for the sound quality it offers. There is definitely a magic to it, which has been exceptionally difficult in my later designs to improve upon. Try to listen to people here, instead of finding fault and agonising in public about it. Nothing worth doing is that straightforward, hum and compatibility issues can take some perserverance.

Have a good look at Gaetan's diagram. It's very good, and identifies the critical factors in earthing.

Cheers,

Hugh

[Professor smith]

Alright AKSA, thankyou for your reply. I have a few further questions to you and Gaetan.

The AKSA is a pretty good amp, and inexpensive for the sound quality it offers.

What sort of price range are you comparing to?

There is definitely a magic to it, which has been exceptionally difficult in my later designs to improve upon

What is this magic you refer to that I can hope to eventually gain? Can you try to explain a bit more?

To Gaetan:

Can you tell me what the dfference is between the way the inputs are hooked up to the amps in your diagram and just taking a pair of wires from each input to each amp?
I'd like to know how such a minor difference and a short distance could make any difference.
In any case, that is not what the instructions say and that confuses me more.

cheers

[gaetan8888]

Hi Kenji,

Can you take a big and clean close photo of the inside of your Aksa amp and show it here, so we could see all the inside of your amp and maby find the problems.

Bye

Gaetan