[AKSA]

Hi Ray,

Thanks for coming along to our party......!

Nah, no preamp plans at this stage, though there is a design there I do not enjoy building them at all.

For the 100W NAKSA (when it comes) the trafo will be a 40-0-40Vac with a 500VA rating.

Board size is 5 1/2" x 2 3/4" for each module of the 100W NAKSA, about the same size as the Soraya module.

Not quite sure on the price of the 100W version (which will actually be closer to 120W//8R) but around the $USD1080-1200 mark for a stereo pair with power supply, with amps as modules and attached heatsinks, fully assembled, biased, tested and warrantied.

Yes, I've looked at the digital amps, have built a power amp using the Hypex UCD180 modules and carefully done the listening tests.  Broadly speaking they are very good, particularly bass and imaging, but still pipped at the post for engagement and musicality by a good Class AB linear amp.

Cheers,

Hugh

[guest1632]

Hi Ray,

Thanks for coming along to our party......!

Nah, no preamp plans at this stage, though there is a design there I do not enjoy building them at all.

For the 100W NAKSA (when it comes) the trafo will be a 40-0-40Vac with a 500VA rating.

Board size is 5 1/2" x 2 3/4" for each module of the 100W NAKSA, about the same size as the Soraya module.

Not quite sure on the price of the 100W version (which will actually be closer to 120W//8R) but around the $USD1080-1200 mark for a stereo pair with power supply, with amps as modules and attached heatsinks, fully assembled, biased, tested and warrantied.

Yes, I've looked at the digital amps, have built a power amp using the Hypex UCD180 modules and carefully done the listening tests.  Broadly speaking they are very good, particularly bass and imaging, but still pipped at the post for engagement and musicality by a good Class AB linear amp.

Cheers,

Hugh

Hi Hugh,

Well, on the digital front, there's better stuff out there now versus the Hypex. They are old news.

Ok, so your Naksa 100 won't be in a kit form like the Naksa 70? Now if I understand, the "module" is both channels or one channel per module?I was under the impression you were getting out of the kit building stuff, and would be just concentrating on a retail market.

Ray

[AKSA]

Ray,

Both the NAKSA70 and NAKSA100 will be sold as completed modules, with separate power supply pcb for the 100W version, but essentially all built and ready to roll, just add case, trafo, binding posts and mains switch.  You are surely correct about wanting to get away from the kit market;  each sale needs a few emails, and for ten years I did not have a life, day and night belting out emails.  This modular approach should be different.

I'm quite prepared to admit that the digital amps have moved on.  But I'm not prepared to say that they are truly musical, just yet.  This is an opinion, of course, we all have them!

Cheers,

Hugh

[guest1632]

Ray,

Both the NAKSA70 and NAKSA100 will be sold as completed modules, with separate power supply pcb for the 100W version, but essentially all built and ready to roll, just add case, trafo, binding posts and mains switch.  You are surely correct about wanting to get away from the kit market;  each sale needs a few emails, and for ten years I did not have a life, day and night belting out emails.  This modular approach should be different.

I'm quite prepared to admit that the digital amps have moved on.  But I'm not prepared to say that they are truly musical, just yet.  This is an opinion, of course, we all have them!

Cheers,

Hugh

Hi Hugh,

Well, haven't heard a digital amp lately. Go check out the "Cheap and cheerful hifi" circle, and see what all the fuss is about. that is if you have the time.

anyway, maybe I missed this, but each module is one channel or both on one module?

Ray

[jmc207]

anyway, maybe I missed this, but each module is one channel or both on one module?

At least with the Naksa 70, both channels are on one module. Very sweet and simple.
http://www.audiocircle.com/index.php?topic=81041.msg788729#msg788729

[AKSA]

Ray,

My apologies;  difficult for you to interpret an image!  Yes, for the NAKSA70 on one 12" (300mm) heatsink there is a large board which incorporates the left channel, the power supply for both channels, and the right channel, in that order.  It's neat, symmetrical, and compact, and with the heatsink turned right way up for best cooling the pcb is in fact vertical, since it's attached to the pcb with four long M3 screws which also attach the four output devices.

Hope this makes it clear, and thanks to jmc207,

Hugh

[AKSA]

I have been sending the audition NAKSA about amongst friends and audiophiles in Victoria and NSW.
Reports are coming back, and I'm well pleased.  It seems this is a worthy successor to the AKSA, and it has the magic.......

Two were despatched to Jens in Copenhagen yesterday, the very first EuroNAKSAs, and from here on in I will be filling orders with some pace.  I have tried to get a review, so far unsuccessful (failed to answer my email) so I will approach Stereomojo, see what happens.

PJR, my old friend from the mid-seventies with whom I served in the Army, has just built ten, which will be here in Melbourne at the end of the week.  I have a large heatsink order in process, and final assembly will be short and sweet.  Every one built so far has functioned perfectly from first assembly, a production dream!

The bass on the NAKSA is really quite extraordinary, with a wonderful, luscious midrange.  Those with orders in can expect an email quite soon!

Cheers,

Hugh

[gaetan8888]

I have been sending the audition NAKSA about amongst friends and audiophiles in Victoria and NSW.
Reports are coming back, and I'm well pleased.  It seems this is a worthy successor to the AKSA, and it has the magic.......

I have tried to get a review, so far unsuccessful (failed to answer my email) so I will approach Stereomojo, see what happens.

Cheers,

Hugh

Hello Hugh

All excellents news.

Keep us in touch wen Stereomojo will reply to you.

Thank

Bye

Gaetan

[tg3]

Two were despatched to Jens in Copenhagen yesterday, the very first EuroNAKSAs, and from here on in I will be filling orders with some pace.

Hugh,

Are you taking orders? I've been waiting for an announcement. Feel free to send a PM.

[AKSA]

Hi TG3,

Thanks for your post!

I have taken orders, and will take yours right now, thank you - but I'm waiting on 30 heatsinks which have beeen specially machined and tapped for the mounting, and these are set to take about one week more.  Damn nuisance - dies take time to fabricate - but there it is.  The mounting of the assembled boards is a relatively quick process, about half an hour each.

Gaetan,

It was you who suggested Stereomojo - thank you again, I liked what I saw of their coverage of the 2009 RMAF, we will see what these guys say.....

Cheers,

Hugh

[gaetan8888]

Hi TG3,

Thanks for your post!

I have taken orders, and will take yours right now, thank you - but I'm waiting on 30 heatsinks which have beeen specially machined and tapped for the mounting, and these are set to take about one week more.  Damn nuisance - dies take time to fabricate - but there it is.  The mounting of the assembled boards is a relatively quick process, about half an hour each.

Gaetan,

It was you who suggested Stereomojo - thank you again, I liked what I saw of their coverage of the 2009 RMAF, we will see what these guys say.....

Cheers,

Hugh

Hello Hugh

Yes I know I've suggest it, I've post about it because I was thinking that maby some of the guy's here would like to know if Stereomojo will accept to do a listening test.

I'm sure that we will all be happy if they accept and we gone read the test.

Did you talk to them about all of your amps or only about the Naksa ?

Bye

Gaetan

[AKSA]

NAKSA PROGRESS

Folks,

Tomorrow I take delivery of tapped and drilled heatsinks for the new NAKSAs, and will commence delivery in the next week!

Sorry for delays, logistics have been tricky   

Cheers,

Hugh

[Jens]

Hi Hugh,

I guess that soon there will be a lot of impressions floating into this thread 

My NAKSAs are still being held up in Customs here - no word from them since I sent in the paperwork they asked for ...

Fingers crossed

[AKSA]

Jens,

Mine too.........  hope they turn up very soon,

Hugh

[jkeny]

I'm a new customer of Hugh's although I've spoken to him on & off for a good number of years & always enjoyed his communications both private & on the forums.

I've ordered a Naska amplifier also as I was impressed by both the preliminary reviews posted here & Hugh's outline, on another forum, of some of his technical principles behind a successful sounding amplifier - I hope he doesn't mind me repeating them here?

#1 We should strive for monotonic decreasing distortion spectrum, if possible with odd orders at least 20dB lower than the preceding even order artefacts, and H2 no higher than -70dB to start out. I'm also very interested in transfer at 20KHz.
#2 Increasing evidence points to the phase of the artefacts having influence on sound quality. LTSpice lists these phase relationships; they are fascinating. Phase shift varies for the distortion artefacts for reasons not entirely clear.
#3 Phase shift at 100KHz should be less than 10 degrees. 3 degrees is an excellent figure to strive for. This influences imaging focus and spatial integrity.
#4 Any coupling caps should always have an appreciable DC biasing voltage across them. This puts the dielectric into its more linear strain region and the result is a much better sounding transfer.

The first & last ideas I had seen before but 2 & 3 I had never seen referenced before. Well not quite - I had seen Susan Parker mention how she was so sensitive to phase distortion & her Zeus amplifier had very little of this. I'm hoping that the Naksa amplifier incorporates some or all of these principles as I believe Hugh has a unique blend of technical know-how, scientific adventure all tempered by his subjective listening. This excites my curiosity as new thinking of this sort is rare.

Maybe Hugh can say something about these aspects & how they are incorporated into his amps if it's appropriate here?

Anyway, I'm looking forward to hearing this amp & finally buying one of Hugh's products that I have read so many people praise in the past. I will post my impressions here when ready.   

[AKSA]

Hi John,

I'd forgotten about that post;  I'd hoped it would draw comment, but not even my critics said anything, a pity.
The monotonic distortion comment is not original, it came from Jean Hiraga, a Franco-Japanese designer raised in Paris but living in Japan since the seventies, and the designer of 'Le Monstre', a famous amp originally described in 'La Revue du Son' back in the eighties.  There is a thread on this amp in DIYaudio;  this guy is at least as significant to the history of audio as John Linsley Hood or Nelson Pass.

The thinking behind the comment seems connected to the psychoacoustic masking effects of human hearing.  A well documented effect holds that more lower order distortions, particularly H2, H3 and H4, will substantially mask the higher, more objectionable artefacts, leading to a more harmonious subjective listening experience.  I have found this to be generally true;  if we accept that amplifiers all produce distortion, it makes good sense to work with rather than against this phenomenon, in the manner perhaps of a pretty girl who works with makeup to mask skin imperfections and thus create the most pleasing appearance.

Phase shift is interesting.  Phase relationships from distributed sound (such as an orchestra) are picked up differentially by varying path lengths to the two ears, and this, along with relative amplitude, is used to discern direction.  We are talking very small phase differences here since path lengths may only be a few inches in thirty or forty feet, so any amp which introduces no phase shifts with increasing frequency should image more accurately.  At the high end of audio the image depth, accuracy and integrity are sought-after qualities, but not easy to measure, certainly not found in specifications.  Thus these issues are important, particularly where they relate to large distributed  sources like orchestras.  Classical music buffs like to be able to position the various instruments;  it's important, and adds to the credibility of the listening experience.  Drum sounds, for example, are so much more plausible if delivered from a point subjectively assessed to be right at the rear of the orchestra, just where they should be!! Image depth is notoriously difficult to achieve with solid state electronics, and is very well handled by most tube amplifiers.  I strive for a credible image depth in my amplifiers, and the Lifeforce, Maya, Soraya and NAKSA all exhibit very believable image depth.  It is definitely something one has to design in, and it is related to phase distortion.

Lastly, capacitor distortion is real and insidious.  Caps store electrical energy as mechanical energy - the powerful attraction between the plates squeezes the dielectric tightly, straining it like a taut spring.  When discharged, the attraction is dissipated, the dielectric 'relaxes', and the stored energy is transferred electrically to the load.  The initial compression of most plastic materials is very non-linear;  low pressures create quite a bit of strain, which soon linearises with increasing force.  Logically the low voltage charging of a cap corresponds to this non-linear region, so that energy transfer is less than ideal.  If the cap is 'primed' with a bias voltage at least exceeding the peak AC voltage moving through it, then the zero volt bias condition is thus avoided, and the transfer is much more linear.  In some ways this is akin to the crossover region of a Class AB amp, as the signal traverses the zero point during the switching of the output devices as they pass current to the load.  As a general rule for audio amps, this means around 2V DC should bias the input blocking cap, permitting it to transfer the audio signal with considerably less distortion than if the dielectric passes to and fro across the zero bias condition, as it does in most amplifiers, which generally place less than 0.1 volt across the input blocking cap.

When you do the comparison between biased and unbiased caps, you find that the 'quality' of the cap is not too important with a strong DC bias, and that boutique 'audiophile' caps can be eschewed as with DC biasing it is very difficult to hear any sonic difference.  I have verified this with cheap, good quality industrial caps versus high value teflon foil caps.

I use this principle now in the Soraya, the Maya and the NAKSA, and the result is more 'n better music.

Hope this answers your points, John, thank you for posting,

Cheers,

Hugh

[jkeny]

Brilliant, Hugh, thank you so much for such a comprehensive answer that even a dodo like me can understand the issues. It makes me even salivate more about the arrival of my Naksa. Apart form the first point I don't think many amp designers address all of these issues as you have done especially phase shift at 100K.

I wondered why it didn't garner much comment on the other forum as I believe these may be crucial concepts in amplifiers design. I guess it just shows where people's heads are at if they can ignore these seminal ideas!

Thank you for pushing the envelope - we are the grateful beneficiaries 

[AKSA]

My pleasure, John.

And here is your NAKSA 70, about to be despatched!

Cheers,

Hugh

[jkeny]

And what a gorgeous looking creature it is - I can't wait to get my hands on it & have a listen. Will be reporting back here when ready.
Thanks Hugh.

[painkiller]

Wow! I seriously have to get a couple of those. Too bad I just spent £1100 (around $AUD2000?) on a pair of 24" drivers. 

Did you say the NAKSA 70 goes for $AUD850 + shipping?