advertisement


AKSA 55 amp

T

TDI

pfm Member
I'm about to start on an active loudspeaker project, and need to decide on which power amps to use.

Has anyone here had any experience of the original AKSA 55 amps compared to Naim clones for sound quality ? Hugh Dean of Aspen has made the AKSA 55 circuit available to the DIY audio community, now that this model is no longer sold.
 
TDI said:
Has anyone here had any experience of the original AKSA 55 amps compared to Naim clones for sound quality ? Hugh Dean of Aspen has made the AKSA 55 circuit available to the DIY audio community, now that this model is no longer sold.
Click to expand...

Doing a shootout of an AKSA 55 against one of my Naim 250s, 10-12 years ago, was the reason I ended up with AKSA amps. :D The AKSA 55 simply blew it away, in terms of musicality - so I bought kits for 2 x AKSA 55s and 1 x AKSA 100 (active tri-amped speakers) and then sold all my Naim kit when I finished building the new amps.

Actually, Hugh had come up with the "Nirvana" upgrades by the time I ordered my kits (which made the amps sound better) so that meant I started off 2 steps ahead of my Naims. :D

He then came out with a new design, the Lifeforce (55 & 100) - which I put in about 5 years ago - and recently the NAKSA 80, which I am about to replace my Lifeforce modules with.

You won't go wrong with a 55 ... unless your speakers need a hundred watts to make them sound alive.


Good luck,

Andy
 
Doesn't the import duty and VAT put you off? I got a bill of £20 for duty, VAT and admin for a less than £20 T-shirt. Didn't impress me much. Having said that, stuff from Asia never seems to get duty & VAT added.
 
I've been down almost exactly the same road as Andy, starting with the AKSA 55 Nirvanas and upgrading to Lifeforce 55s. I agree completely with his assessment, having owned a Bolt-down Naim 250 before the AKSAs.

One small caveat - Hugh spends an awful lot of time on parts selection and operating points for his amps, so don't stray too far from the original parts list if you want to hear them as intended.

If you need more info there's an archived Aspen manufacturer's forum over at audiocircle with loads of AKSA 55 info.

BTW my AKSAs were driving Isobarik DMS speakers with no problem at all.

Ron.
 
TDI said:
Hugh Dean of Aspen has made the AKSA 55 circuit available to the DIY audio community, now that this model is no longer sold.
Click to expand...

Does he also supply the PCB ... or have you got to breadboard it?

Regards,

Andy
 
My impression is that for active operation it's less critical. I know a lot of people who have gone active and made them work with 3 x T amps or similar. I get the impression that if you are wrestling with a crossover then the amp is working reasonably hard and you do pick up on its sound, probably distortions as it's doing its thing. Go active and your amp is running a pair of mids and no XO, whoop-de-doo, no distortion, very little work to do so pretty well anything works.
 
stevec67 said:
Go active and your amp is running a pair of mids and no XO, whoop-de-doo, no distortion, very little work to do so pretty well anything works.
Click to expand...

It's your prerogative to believe that (that an amp makes no difference) ... but how do you explain that I got a significant upgrade in SQ when I moved to Hugh's Lifeforce amps from his original AKSAs? :confused:

My experience is that better-sounding amps are still important in an active setup.


regards,

Andy
 
TDI said:
Not as far as I know, but I'm happy to design my own PCB.
Click to expand...


I find using 1/8" (3mm) teflon sheet is useful, rather than knocking up a PCB. The teflon sheet holds the components in "real-space", matching the circuit diagram which is "virtual-space" and then you do PTP wiring on the underside. :)

Regards,

Andy
 
TDI said:
Has anyone here had any experience of the original AKSA 55 amps compared to Naim clones for sound quality ? Hugh Dean of Aspen has made the AKSA 55 circuit available to the DIY audio community, now that this model is no longer sold.
Click to expand...

Can you provide a link? I have not been able to find the 'Official' circuit diagram anywhere.
 
Greg Erskine said:
hi TD1,

I still use my AKSA55N+.

Have you seen my thread BAKSA thread at DIYAudio? You will see my PCBs in post #3, it might save you some work.

http://www.diyaudio.com/forums/solid-state/168554-based-hugh-deans-aksa-55-a.html

regards
Click to expand...

Hi Greg,

Yes I saw your thread, and indeed I got the schematic from your site.

I actually posted on DIYAudio (user ID cs) concerning using different output devices in the AKSA. I have found it extremely difficult to get hold of mounting kits for the TO-264 transistors in the UK, so I would like to use alternatives from Sanken. They do several complementary pairs with very similar specs to the Toshiba parts, but come in TO-247 packages which are easy to get mounting kits for. Any experience of using different output transistors in the AKSA ?

My current plan is to do a single PCB comprising two PAs, the active crossover, and maybe the PSU components.

Regards,
Chris.
 
andyr said:
It's your prerogative to believe that (that an amp makes no difference) ...
Click to expand...
I said "It's my impression that amps are LESS CRITICAL..." Nothing about "all amps sound the same".

but how do you explain that I got a significant upgrade in SQ when I moved to Hugh's Lifeforce amps from his original AKSAs? :confused:
Click to expand...
I don't have to explain anything that you may have observed.

My experience is that better-sounding amps are still important in an active setup.
regards,
Andy
Click to expand...
Good.
 
BTW, the AKSA is exceptionally sensitive to the front end decoupling values and types of components. It uses a simple resistor as the "tail" of the LTP and the bootstrap cap is also connected to the shared decoupling cap. Hardly surprising then that the AKSA has (quite) a bit of character.
 
S-Man said:
BTW, the AKSA is exceptionally sensitive to the front end decoupling values and types of components. It uses a simple resistor as the "tail" of the LTP and the bootstrap cap is also connected to the shared decoupling cap. Hardly surprising then that the AKSA has (quite) a bit of character.
Click to expand...

Would you mind, S-Man, explaining in simple Engrish for us simpler characters, WTF you are talking about? ("Character"? :confused: )

Regards,

Andy
 
Colouration.
I was trying to be nice by calling it character.

BTW, I did some testing for Hugh - mostly related to front end decoupling - as well as my own experiments.

Oh, and no need to GTF upset. It's only an opinion.
 
S-Man said:
BTW, the AKSA is exceptionally sensitive to the front end decoupling values and types of components. It uses a simple resistor as the "tail" of the LTP and the bootstrap cap is also connected to the shared decoupling cap. Hardly surprising then that the AKSA has (quite) a bit of character.
Click to expand...

Hi S-Man,

By "front end decoupling values" are you talking about the input filter?

What is a "simple" resistor? the LTP resistor on mine looks like all the others. :D

I think your comments are valid for any amp that does not use CCS and current mirrors, not specifically the AKSA.

I am starting to think it is the implementation of an amp is important not the topology. If there was a perfect solution we would be seeing a convergence of opinions by now.

regards
 
You must log in or register to reply here.


advertisement


Back
Top