[mb]

Hi.

Has anyone tried any of the following, and if so, what are your recommendations for / against these variations from the standard AKSA supply (55W in particular):

1) higher than 160VA transformer
2) schottky diodes instead of the soft recoveries supplied by Hugh
3) snubber caps at rectifier bridge
4) higher power cap size (6800uF or 8600uF)

From day 1, my AKSA55 has had 230VA x'formers (sale price, 230VA cheaper than the 160VA...), and shottkys. That obviously makes it difficult for me to make a before/after comparison.

Just today, I've added snubber caps (0.1uF) accross each diode, and increased the capacity by adding 2200uF Panasonic FC caps parallel to the existing 4700uF Chemicons. It's too early to make a call on the results, but *certain* music is sounding very much better (classical, esp. violins, which used to be edgy). It will take some time for things to settle. If there isn't great change from the present, it's very likely I will not reverse these trial mods (3) and (4).

[AKSA]

Hi Mervin,

Hmmm.  Try removing the extra capacitance, just listen to the snubbers.  You might pick a difference here!

It's VERY difficult to do one thing at a time, bukan?

Cheers,

Hugh

[mb]

Hi Mervin,

Hmmm.  Try removing the extra capacitance, just listen to the snubbers.  You might pick a difference here!

It's VERY difficult to do one thing at a time, bukan?

Cheers,

Hugh

Yah, pak!

I just hate removing 12 screws for one tweak at a time.  I'm aware of your comments regarding a slowing down due to too much capacitance, but almost none is perceived.  There is a slightly more relaxed presentation -- akin to my Krell, which seems to play with more ease. Also slightly towards the sound of the Ampzilla.

My guess is that you agree with the idea of snubbers for each rectifying diode? Cleaner treble? Even less grain?

[AKSA]

My guess is that you agree with the idea of snubbers for each rectifying diode? Cleaner treble? Even less grain?

Betul Pak, I was hoping you might give me your opinion.    

Cheers,

Hugh

[mb]

Snubbers: like bleeder resistors, a "can't hurt" item. I would include them in any future power supplies I build. I use 0.1uF/100V film caps. As a matter of fact, I think they help a lot. The treble on my system has improved a small notch since the last two supply tweaks.

Increasing total capacitance: by commercial standards, 4700uF is moderate for a (genuine) 55W, but seems just a little on the low side. I know the Chemicons have been selected for price / performance, so rather than ditch them, I supplemented with 2200uF/50V FCs. I've used them quite extensively, and they're a good, balanced choice -- no major vices.

Overall after 1-1/2 days listening, the top end is more refined, midbass has gone richer, and the AKSA sounds like it's been given a light pressure turbo. I thought that the amp might sound 'slower', as cautioned by Hugh,but after a few hours, the amp actually seems to have gained a little speed (burn in?).

I've A/B'd my AKSA v. a pair(!) of Ampzilla monoblocks, and recently brought my Krell KSA-100S back in service. My AKSA fares very well against both -- fast, clean, great soundstaging, detailed -- but doesn't have  control & fluidity of the Ampzilla or Krell . Neither ever sound flustered, and it's not a matter of ultimate power, as the listening is well under clipping level. This tweak *may* be the answer for me.

[SamL]

added snubber caps (0.1uF) accross each diode

Hi MB,

Well, your finding interest me as I am currently building my AKSA100n power supply.
Hope you don't mind my dummy question. How do you wire the snubber caps to the diode? A diagram will be very helpful.


Thanks,
Sam

[mb]

Hi Sam,

I don't mind any reasonable question! In my case, one 0.1uF is installed across each diode, ie. in parallel. Do make sure that your snubbers have the correct rating -- at least 2x the rail voltage, plus some headroom.

Perhaps you'd consider installing them later, after your 100N has burned in, and you're familiar with its sound. That way we can get more consensus on the effect, if any, of the snubbers.

Cheers,
mb