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
