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Old 17th May 2003, 08:20 PM   #1
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Default New AKSA 55

Finally found the time and patience to finish and debug. Had some problems terminating the primaries due to the varnished leads.

Sounds good so far. Still have some packaging issues to overcome.
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Old 17th May 2003, 11:15 PM   #2
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Default Re: New AKSA 55

Quote:
Originally posted by ultrachrome
Finally found the time and patience to finish and debug. Had some problems terminating the primaries due to the varnished leads.

Sounds good so far. Still have some packaging issues to overcome.
I love the vestigial look. I really do need to find time to do mine up -- will be AKSA 25s thou.

dave
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Old 18th May 2003, 04:11 AM   #3
AKSA is offline AKSA  Australia
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Hey Ultra,

Love the 'Metropolis' look! Very swish, and nicely made, good touch with the Allen studs.

How's it sound?

Cheers,

Hugh
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Old 18th May 2003, 05:13 AM   #4
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Thanks. I call it the cat killer. Luckily I have no pets or children. I need to come up with something different for the back plate that I mounted the heatsink on. But there's no reason why I can't enjoy it while I'm tweaking the chassis design.

It sounds really good so far. My first impression (after not listening to my stereo in about a week) was that the soundstage was quite a bit wider than my Adcom GFA-545II although placement of sounds is a bit more diffuse. The couple of CDs I've listened to (Beck, Pearl Jam, Sting) easily extended beyond the speakers. We'll see what happens over the next 10-20 hours.
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Old 18th May 2003, 05:59 AM   #5
AKSA is offline AKSA  Australia
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Ultra,

The resolution and sound stage placement takes about 20 hours to mature. There will be some high end harshness, which will dissipate over this period. This is just a very low voltage cap bedding in, and you need to be patient.

My congratulations for a very tidy build. Something to be proud of!

Cheers,

Hugh
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Old 18th May 2003, 02:02 PM   #6
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Default dual transformers

I always wonder how grounds of both channels, should be connected in amps with two transformers - in dual mono design. Aksa is one of the design where is one star ground (at psu board) where are coming all ground wires.
In most of cases I saw grounds run separately, like in mono block designs.
Is one of these solutions better?
I guess, in case with just one star ground, may be problem with ground loops.
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Old 9th June 2003, 09:44 AM   #7
AKSA is offline AKSA  Australia
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Hi Jarek,

I believe you are right that separate star earths are a very good idea.

However, there are issues here. One, very obvious, is that most CD/DVD players, the signal source, use conjoined grounds for both outputs. But the other is more significant.

If we are to use two star earths, one for each channel, then the chassis cannot be connected to star earth and star earth must float. Then safety comes back to good quality transformers. In medical equipment this is normal policy, but often they also specify tighter insulation standards on the transformers.

Thanks for your input,

Cheers,

Hugh
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Old 10th June 2003, 10:33 PM   #8
mlloyd1 is offline mlloyd1  United States
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Default Re: New AKSA 55

ultrachrome:

VERY nice! Congratulations. and my sympathies to the cats.

Hey for you other AKSA builders and owners (and Hugh):
any of you ever dialed up the AKSA to low power (10-20 watt) Class A? (only after adding appropriate heat sinking and power supply enhancement, of course). If so, what did you think? I'm curious (again...)

mlloyd1


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Originally posted by ultrachrome
Finally found the time and patience to finish and debug...
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Old 10th June 2003, 10:39 PM   #9
AKSA is offline AKSA  Australia
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Mlloyd1,

I have dialled up Class A on the AKSA during my R&D.

Up to 350mA of bias the bass control tightens, eventually ending up very powerful but dry. From about 125mA forward, the sound stage begins to close in, and some dynamics are lost.

I really do not recommend an AKSA in Class A. It was specifically designed for optimal Class AB, and functions best at these levels. To be honest, I've never heard a Class A with outstanding dynamics (even those of my own design! ) and really do prefer to stick with Class AB for its huge efficiency advantages as well.

Cheers,

Hugh
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Old 10th June 2003, 11:08 PM   #10
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Quote:
Originally posted by AKSA

If we are to use two star earths, one for each channel, then the chassis cannot be connected to star earth and star earth must float. Then safety comes back to good quality transformers. In medical equipment this is normal policy, but often they also specify tighter insulation standards on the transformers.

I'm using two separate star earths in my GainClone amp (one for ea. channel). Initially I used one of the - speaker post in one of the channels to connect one of the star grounds to chassis (only one channel only). But in some setups, the was a noise generated in the other channel, which star ground was not connected to the chassis (for instance when somebody was close to the amp with a cordless phone). So I figured I had to connect both channels star grounds to chassiss and I did it with 2 pieces of wire from ea. star ground to a central point on the chassiss. The noise was gone and it works fine. Are we talking about same thing?
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