[Hegemony]

Hi all,

I am a long time lurker,  thought I would contribute my experience with a new amplifier from Hugh at Aspen Amps.

I have previously had a LifeForce 55 with mods, I run this through a squeezebox via a modded Zhaolu 2.5 dac.  I have benn quite happy with this setup for many years and when I first had the LF55 it was a big jump over my previous amp...it has happened again.

Brought the Naksa home this afternoon after a pleasant listen at Hugh's place.

This amplifier is in a different universe than the one it replaces.  I am not a frequent upgrader and it takes something special to prompt me to move! 

On first listen with less than 4 hours on the amp it is detailed beyond anything else I have heard, but amazingly not at the expense of musicality and smoothness.  There is stomping bass, magnitudes above what the Lifeforce is capable of; deep and musical.  Vocal highs are unstressed and presented so separate and forward it is uncanny.  The thing is, from some prior listening comparisons of this amp, I was expecting to sacrifice some detail given the smooth analogue slightly tube sounding presentation, but it is not the case, the presentation is revealing and detailed while remaining eminently listenable and relaxing.

I have read many reviews of many audio products and I get a bit tired of the cliches.  But every now and then you come across something that makes your jaw drop. (well mine anyway).  This is one of them.

I am just blown away.  I am just excited about listening to music and this amp has added a level of listening enjoyment I have not felt before, a musicality and palpable toe tappin goodness that just makes you want to listen to more!

Thanks for the build Hugh!  Much appreciated.
Russ.

[Hegemony]

Should have added if anyone is interested in an audition feel free to pm me...

Russ

[Jens]

OK, Hugh - cat's out of the bag. Now lift the veil for the story about this amp and let us all know when we can have one (or two) 

Thanks for sharing your impressions, Russ, much appreciated! 

[AKSA]

Ahem, thanks Russ!!     I gotta get the NEWS out on the website, and might even do another page entitled 'Philosophy, Approach and Products at Aspen'.  It really needs a fuller explanation because in the last five years my thinking has changed radically about audio and the products coming onstream now reflect this, of course.   

A few words on the NAKSA.

When I ran out of AKSA55 boards about two years ago I thought little of it.  I had the LF55 and it was a clear improvement.  Sure, I'd shifted to modules, but that was to avoid the 20-30 emails daily that had grown to dominate my life and I was fed up with it.

The LF55 sold very well, particularly with the early trades for existing AKSA customers.  But over time it became clear that the modules, which I personally built and which took a lot of time, lay in a higher price bracket which restricted sales.

In the interim I'd become even more besotted with sound quality and launched the Soraya, and moved on, and now am working on the Maya with Colin in Canada.  However, these are flagship models, with commensurate complexity, high R&D commitment, and slow gestation to market.  Fewer would ultimately be sold, even though they would become the benchmark by which all other Aspen products would be regarded.  But the biggest selling BMWs have four cylinders, so I really needed an inexpensive, fully built product that the DIYer could easily connect to a transformer, source and speaker - a half hour job.  And this set me thinking.   

About this time, a repairman friend from my country town (I am the Oz equiv of a US mid-west farmer's son) rang to say he had an NAD with an unusual output stage in for repair.  He sought my advice on parts purchases.  Once going, I asked his opinion of the sound.  He said it was amazing, magical even.  He then went on to build a few variants, and determined me to do the same.

I felt this could be it.

I began design immediately, but modified the output stage to something different again.  I give no details here, but suffice to say that there are just three devices in the output stage;  it's wildly asymmetrical.  I cobbled up a few test bench blocks, tested them all individually, things looked good.  I spent weeks on the simulator, deriving the distortion profile of the design.  Then, prematurely as is my perennial fault, I moved to the pcb design which had to incorporate both channels AND the power supply onto one board for direct attachment to the heatsink.  Difficult piece of layout, to be sure.

When the protos came back - four of them - I and a good friend in Melbourne built two immediately.  One unstuffed pcb was sent to Canada for Colin.  At audition, there were some minor changes.  At first audition the amp gave promising but unspectacular results.  I then tried a trick I use in the AKSA - it solved a difficult offset problem and boosted the sonics hugely, stunningly in fact.  The mod had been a hunch, and others followed, adding refinement.  All the engineering parameters improved;  the simulation showed that the seventh harmonic dropped to below -125dB.  What was so important was the very, very low distortion beyond H4, all of it even order, and the astonishingly, supernaturally quiet noise floor.

There were some issues.  I was concerned with rail efficiency - the ability of the amp to clip to the rails.  This is not so important in domestic power amps, but critical in PA and sound reinforcement amps.  Russ (aka Hegemony) heard the amp and absolutely loved it for its musicality.  I decided to boost the power rails to achieve more power and thereby lift the appeal to DIYers.

The AKSA and LF amps used 36V rails and gave 55W before clip.  The NAKSA uses 42V rails (a standard 30-0-30Vac transformer of 300VA - just ONE only, another saving!) and delivers 70W of power per channel before clip onset.  THD at 13 watts output into 8R (+20dBU) simulates at 0.026% - quite high, in fact, but fantastically over 85% of this figure is second harmonic only!!  All the odd order distortions are vanishingly low;  the highest is third harmonic, which sounds pretty good because it's musical, and it's at -106dB, with all successive odd orders much lower than this!!  These are stunning technical results, even if we ignore the subjective sound quality, which is surreal.   

What is also astonishing about this design is the very low component count.  It uses just 5 semiconductors per module.  The AKSA used 8, the LF 11.  The Maya in its latest incarnation uses 16!  A low component count reduces cost, but more importantly, makes the amp easier to build and much more reliable.  Even so, the NAKSA is NOT simple;  it takes even an expert in audio amps some time to figure out what the heck is going on.  It's off the wall philosophy, the stuff of heretics no question, but very solid engineering nonetheless, with heavy influence in the design from human perception of sound.

Russ is the first adopter.  He showed great faith and confidence, and I thank him formally here for that.  It is always difficult to have anything but suspicion for a new approach.  I do not claim originality in anything, but I do claim to seeing the problem in a totally different light.  The good news?  This module, completely built, tested, warrantied and ready to connect to a single trafo, a source and a pair of speakers, will set you back just $AUD850, around $US755.

I am about to order the production pcbs from my supplier.  I am presently arranging components purchasers and manpower to assist me with assembly - my throughput is limited by ordinary health at present and failing eyesight.  I will have it built in a local electronics assembly company so that supply can be assured.  And best of all, there should never be any call for more than two or three emails with each sale!!

A stunning amp, low cost, with absolutely high end performance - and seventy very LOUD watts!!  I'm hoping this will be a good seller, it certainly is up there with the very best amps I've heard!

The NAKSA is a wonderful amp, intensely musical.  But it remains pipped at the post in some significant ways by both the Soraya and the upcoming Maya.  It is important to make this point;  there has been even more R&D go into both these products.

Folks, thank you for the interest, always appreciated.  Aspen has not been idle.....  and a lot of my friends have supported me in some very significant ways, thank you profusely....  the Maya, of course, is yet another story!

Cheers,

Hugh

[AKSA]

Folks, this to be the new sticky for any and all comments on the new NAKSA power amp module.

Hugh

[Seano]

Hugh.....just to seek a little bit of clarity here....you would consider the NAKSA as an upgrade to the ye olde AKSA55 and its variants, LF55 and (perhaps) the 100w versions of the same?

If yes.....in what way - apart of course from dollars?

I ask because (as I think I've said before) both the Soraya and Maya amps are beyond my price point....both realisticaly and philisophicaly

[bhobba]

Hi Hugh and All

Really enjoyed the post - thanks for posting it Hugh.

THD at 13 watts output into 8R (+20dBU) simulates at 0.026% - quite high, in fact, but fantastically over 85% of this figure is second harmonic only!!  All the odd order distortions are vanishingly low;  the highest is third harmonic, which sounds pretty good because it's musical, and it's at -106dB, with all successive odd orders much lower than this!!  These are stunning technical results, even if we ignore the subjective sound quality, which is surreal.

Interestingly Linkwitz reckons 'THD should be below 0.1%, as a starting point, for amplifiers not to sound different from each other'.  Now I don't agree with that for various reasons.  However yours is a lot lower than that and you still think its high.  Who said you are not into hard nosed engineering.

Looking forward to you release of the Maya.  Might be able to get it a bit earlier than November - maybe about August or even earlier.

Thanks
Bill

[Hegemony]

Seano,

Hi Russ here, I will comment as I have just had a LF55 (modded with upgraded input caps etc) and I can tell you the Naksa is a significant and obvious step up.  It has a clarity, warmth, musicality, transparency, bass extension and clear top end especially with vocals and strings that the LF55 could not approach.  The Naksa has no trouble driving the vsonics to unlistenable volumes.  Having also heard the Soraya in a few iterations, to my ears the Naksa is a bit more "analog" (smooth) and musical amp than the Soraya however maybe lacking the outright power of the soraya, but further comparisons would be needed.  I am compiling a few more comprehensive notes on the Naksa but I struggle to hear any downside at the moment compared to the LF, I will admit to being more interested in music than audio equipment but will see how I go. 

If you are in Melbourne feel free to pm me for a listen.
Russ

[poseidonsvoice]

Seano,

Hi Russ here, I will comment as I have just had a LF55 (modded with upgraded input caps etc) and I can tell you the Naksa is a significant and obvious step up.  It has a clarity, warmth, musicality, transparency, bass extension and clear top end especially with vocals and strings that the LF55 could not approach.  The Naksa has no trouble driving the vsonics to unlistenable volumes.  Having also heard the Soraya in a few iterations, to my ears the Naksa is a much more "analog" (smooth), detailed and musical amp than the Soraya. I am compiling a few more comprehensive notes on the Naksa but I struggle to hear any downside at the moment compared to the LF, I will admit to being more interested in music than audio equipment but will see how I go. 

If you are in Melbourne feel free to pm me for a listen.
Russ

Okay, now I'm interested 

Anand.

[AKSA]

Hugh.....just to seek a little bit of clarity here....you would consider the NAKSA as an upgrade to the ye olde AKSA55 and its variants, LF55 and (perhaps) the 100w versions of the same?

If yes.....in what way - apart of course from dollars?

Hi Seano,

Thanks for the query.

Essentially, the NAKSA is a completely different amp, a different product altogether, with virtually nothing in common electrically with the AKSA or Lifeforce.  It has more clarity, bass punch, image precision, a larger sound field and a sweeter midrange and top end than either of the 55W amps.  It is my latest quantum quality leap along the way to a perfect amp......  an aspiration, perhaps, but a worthy goal.

If you mean how is it done electrically, I'm reluctant to discuss the details in a public forum, of course, but if you mean how is it better sonically, then mebbe Russ is giving you the answers already.  As my much loved, eccentric mate in NYC would say, more better 'n gooder.

The principle improvements come from a realisation of just what most amp designs do to the music, and how they modify the harmonic spectrum of the music they process.  I take the approach that distortion is inevitable in amps, and rather than strive valiantly to remove all traces, an exceedingly difficult task, we should work instead to modify the profile so that it is not inimical to human musical perception.  This means removing as many of the higher, odd order harmonics as we can, or at least reduce them to vanishingly low readings.  But to do this may require increasing even order distortion, which goes completely against the grain of most designers, bringing out the wooden cross and silver bullet.  With a knowledge of the structure of music (I studied piano and pipe organ for many years), it's possible to predict what is musical and what is not - there is a relatively defined boundary - and work within these constraints towards a better sounding amp.  The explanation for all this lies within the harmonic profiles and subjective listening experience of comparing SS with tube amps - it is a piece of musical and electrical detective work, nothing more.

The result has been the NAKSA and, at the higher level still, the Maya.

Bill,

Thank you for your positive comments!  As for hard nosed engineering, no, I could never be accused of that, I'm a touchy feely type and am always concerned most with 'musical engagement', whatever that is.

My most ernest and objective measure of amps would be to aim an interferometer on the feet, and time the period to foot tapping contentment, measuring also the periodicity and diversity of beats of the foot for best accuracy.  This would bear more fruit for 'real high fi sound' than any THD measurement, I feel.

Truth is my notions are sufficiently heretic for me to be darkly regarded as a quack.  I have been roundly accused of 'technical incompetence' on DIYaudio several times by the maths gifted experts of yore.  Tragically, none of these guys have heard my amps, ain't life grand?  But as Groucho said, 'I would never be a member of a club that would have me as a member.' 

Cheers,

Hugh

[Seano]

Hugh

As usual...more detail than I would ever need at a slant that was different to my original expectations.

As you well know, my knowledge of the electrickery inside amps is limited to guessing which is active and which one isn't.  Therefore, you could talk all sorts of bullshit about what's in the box.....and I'll nod unknowingly.  So there's not much point letting on....I simply wouldn't be interested.

What I would be interested in is whether the NAKSA would contribute to an improved experience of (for example) Craig Armstrong's "Weatherstorm" or the Alan Parson/Sphongle/David Gilmour collaboration "Return to Tunguska" compared to anyone of your 100 watters...

So to the nub of it.....for those of us with ye olde AKSA100 (like me) and LF100 amps......why should we (apart from the very reasonable price) consider the NAKSA as the next must have alternative?

Or should we not?

....here's your opportunity, Hugh! And now to Market!

Oh and Russ.......love to have a listen but I'm not often in Melbourne and when I am it is strictly a get-in-get-out proposition.  Might have to talk Hugh into a future demo via Australia Post.....thanks for the generosity though

[AKSA]

Hi Seano,

Knowing that you belong proudly to the solar plexus school of audio, I don't believe a 70 watter would cut it for you up against a 100 watter, particularly on Acerdacca and Australian Crawl at a hot Saturday arvo barby out amongst the vines!   

So, stick with your AKSA for the mo, but for those with more genteel sensibility who contain themselves within urban dwellings of modest dimension, the NAKSA will elegantly lift the roof, perhaps not by feet, but certainly by Euro centimetres..... all with the speed of Paganini, the elegance of Mozart, and the majesty of Bach.   

But Sean, don't let me paint you too Australian;  show us yer gennul side, cobba!!   

Cheers,

Hugh

[bhobba]

Truth is my notions are sufficiently heretic for me to be darkly regarded as a quack.  I have been roundly accused of 'technical incompetence' on DIYaudio several times by the maths gifted experts of yore.  Tragically, none of these guys have heard my amps, ain't life grand?  But as Groucho said, 'I would never be a member of a club that would have me as a member.'

As usual Hugh you are being modest.  I did a degree in applied math and would be regarded as one of those 'maths gifted experts of yore'.  However I have noticed in your designs you do your tweaking by ear but your first cut designs use well respected engineering principles such as the simulation you mentioned.  Although the distortion figures you quoted are not the last word in what can be achieved they are quite respectable.  I seen to recall an amp I built in my misspent youth had distortion figures more than that.  However I don't believe chasing those ultra low distortion figures is of any value at all if it sucks the life out of the music - which some very well specked amps do. The thing that sets you apart is you wont leave it there - you will improve it by ear until you get what you want - which IMHO is exactly how you should proceed.  Well thats my view of it anyway.

Thanks
Bill

[AKSA]

Bill,

I do tend to tilt at windmills, product of a thin skin I guess, so I tend to forget that not all are adversaries, so my apologies to you and any other benign Mathematicians I have foolishly scorned.  A late friend (very sad, dead of multiple myeloma at 60) once said 'Hugh is much more the engineer than he would have you believe'.  The odd thing is that my great love is for the laws of Georg Simon Ohm and Gustav Robert Kirchhoff and these underpin all I know of electronics.  The rest, pretty much, is based on intuition....  and a helluva lot of dead semis, with the smoke long since dissipated......  'You learn nothing of electronics until you traipse daily through the silicon crematorium, and can recite all the tombstones by rote' - Hugh, 1997.

[Seano]

Knowing that you belong proudly to the solar plexus school of audio...

Cheeky!  But guilty as charged.... although these days it's not as loud as often as it used to be. A mild case of tinnitus and a new small household occupant have seen to that..

However, you've answered my query in your own sideways fashion. Detail over grunt, subtlety over sledgehammer.....the sort of thing my own father would prefer (he likes my old NAD 3020) but I'd still like to hear it.

[Opus Flatus]

I'm intrigued by the NAKSA. I like that fact that it is a plug in module; i've struggled with kits before. This would make for less frustration and "cussing" for sure. I'll be following the thread. Keep up the good work.

[bhobba]

I do tend to tilt at windmills, product of a thin skin I guess, so I tend to forget that not all are adversaries, so my apologies to you and any other benign Mathematicians I have foolishly scorned.  A late friend (very sad, dead of multiple myeloma at 60) once said 'Hugh is much more the engineer than he would have you believe'.  The odd thing is that my great love is for the laws of Georg Simon Ohm and Gustav Robert Kirchhoff and these underpin all I know of electronics.  The rest, pretty much, is based on intuition....  and a helluva lot of dead semis, with the smoke long since dissipated......  'You learn nothing of electronics until you traipse daily through the silicon crematorium, and can recite all the tombstones by rote' - Hugh, 1997.

I am 100% sure no offence was intended and certainly none taken.  Your late friend is correct - 'Hugh is much more the engineer than he would have you believe'.  Being an engineer is not about facility at math - it is about creatively designing stiff - math is just an aid to that.  Plenty of guys are good at math.  Although I am good at it there are also plenty of guys better than me - a lot better.  That is not what it takes to be an engineer - what you do is what it takes.

Thanks
Bill

[AKSA]

Bill,

Thank you.....  you are a gennulman and a scollop.....

Folks,

NAKSA announced here:  http://www.aksaonline.com/news.html

Cheers,

Hugh

[poseidonsvoice]

Kudos!

One proofreading comment. In the paragraph where you mentioned the timeline of completion for each of your amplifiers, i.e. Maya, Soraya, Naksa, I think your fingers slipped and the date came out as "September 20101."

Otherwise, I enjoyed the description on the current economic turmoil occurring in parts of the EU(!!)...

Anand.

[AKSA]

Thank you Anand,

Errors corrected - my old web editor has huge latency, takes seconds to throw up what you have just written!

Hugh