[bhobba]

Welcome, Mike....... Folks, we have a speaker developer in our midst, possibly one of the best in Oz (except Laurie, of course!!) I hope you find something here you like, Mike Lenehan......

Did Mike do a post that somehow got removed?  I know from speaking to him he was quite interested in the NAKSA and wanted to hear mine when I get it.

Thanks
Bill

[AKSA]

No, Bill,

He merely visited, but I happened to see his calling card......

I'm starting your amp enclosure Monday, after a long queue, metal work slows me right down, module is done!

Hugh

[bhobba]

He merely visited, but I happened to see his calling card......I'm starting your amp enclosure Monday, after a long queue, metal work slows me right down, module is done!

Great to hear Hugh.  I know Mike is keen on hearing it as well.

Thanks
Bill

[audiopip]

Hi Everybody,

As Hugh alluded to earlier in this thread I was responsible for building the very first NAKSA, and also some of the fine tuning thereof. Without giving too much away I was highly skeptical of this design, particularly the configuration of the output stage.

However, from day one the design exhibited a sonic signature which marked it out as something special, and further work by Hugh, myself and others has now turned this into an exceptional product.

I've listened to countless amplifiers in my career and I consider this latest creation of Hughs unique both in performance and packaging/ease of assembly. Talk to Hugh, have a listen!

Great job Hugh

[ginger]

Its Alive,
My NAKSA experience did not start well - I did all the "metal bashing" Thursday night ready to wire it all together on Friday (my day off). Friday I rushed the wiring, did NOT read the instructions carefully and managed a monumental "step upon my wozza". The power tranny I bought, Altronics M5530, has 2 secondary wires exiting close to each other and a second pair similarly arranged. I ASS - UMED they were the secondary pairs (without checking) and wired it up that way - WRONG, I got one wire from each secondary winding paired on the connections to the board. Then again without a final check I hit the power switch - flash, bang and a brown smell - "poo" sez I.
Take it all apart and look to see what I've damaged. Visually it was clear that the centre dual diode pack (off 3) on the negative supply was in many pieces. A CAREFULL check showed that the diode in the outside 2 diode packs on the positive supply were short circuit. As luck would have it I had a stash of these diode packs from a couple of AKSA55N+ that I upgraded to Schottky diode packs so I fitted replacements. I then pulled the amp fuses and powered up again. This time I got good power supply rails. Power OFF, fit the fuses and with much trepidation about what the military types call "Collateral Damage" powered it back ON. No flashes, bangs or smoke. Checked the offset voltages both channels - all good, checked the bias levels - all good. Huge sigh of relief and hooked it up to the speakers and preamp - MUSIC!!
SO KUDOS HUGH - Your Amp is Bullet Proof, It didn't mind me blowing up its power supply at all. (ASIDE: Now that I've done it there is no need for anyone else to repeat the experiment, CHECK those transformer secondary connections carefully).
Took the amp to the lounge room and connected the VAF Research DCX speakers (95dB/W/m, nominally 6 ohms).
Tried Mark Knopfler and Emmylou Harris "All the Roads Running" - At low listening levels I did'nt think it quite matched the Baby Huey tube amp BUT as soon as I turned it up a little it left the BH for dead. So where did the NAKSA lose out to the Baby Huey at the lower listening levels? In the highs, which mostly showed up in the stereo image, not surprising really, as the BH is a zero global feedback design.
Since the NAKSA left the BH far behind as soon as I turned it up a bit I decided to give it the "head Banger" torture test with some Spiderbait, Rogue Traders, Bodyrockers and the like, the NAKSA has a truely "humungous pair".
I decided to try some "difficult" music, in this case Sergio Mendes "Brasileiro". This is a very crisp recording with lots of drums, bad amps tend to really screw it up. The NAKSA delivered it beautifully, so I turned it up, the NAKSA just kept on pumping with no adverse affects at all, so naturally I turned it up again - no strain, no pain.
I was out Saturday so no tests.
Sunday morning Les B. dropped in to pick up his AKSA 55N+ which I had repaired for him after a speaker wire short incident.  We had a listen to the NAKSA playing his favourite music which happens to be Miles Davis. This was the best he or I had ever heard Miles. A quick shootout with the AKSA 55N+ to confirm that the NAKSA was a better amp - It is.
It was one of those mid winter days in Adelaide where the sun came out and the temp reached 15 degrees C so after Les left I had an afternoon of sitting on my front door step in the sun with a good book and a glass (or two) of wine and just let the NAKSA "flow" the music from the lounge, down the hallway to my spot in the sun. I listened to Vivaldi "Four Seasons" and Bach's "Brandenburg Concertos" - lovely.
From a disasterous start Friday night to a delightful Sunday afternoon. I'm impressed
Cheers,
Ian

[jkeny]

Fantastic Ian,
Thanks for doing the "Survival Experiment" It does prove it to be a robust design.

I was looking forward to this comparison with the Baby Huey & thought, as Hugh did also, that it would hopefully match it for sound quality or just be a matter of taste. Can you say which version of the BH you were using - as you know mine is the original ECL86 version (but it is de-commissioned at the moment).

That the Naksa comes close to the BH at low vol is great. That it beats the BH when turned up is a great result. How high a volume are we talking about? Can you say in what areas? I presume authority & grip on the music?

Thanks for this comparison against your own designed tube amp!

[AKSA]

Ian,

Fantastic result, thanks for the comparison!

Good to see that you, a seasoned, crusty professional, make the odd little mistake.  Nothing big, mind you, just blowing up the diodes is a tiny mistake, I've done precisely that myself, though not on the NAKSA.

That the amps survive a power supply miswire handily is terrific news, thanks for the destuctive test, something from which potential buyers can take heart!

BTW, the BH is a seminal design, the fruit of Yves in Ardeche, France, further refined by Ian in South Australia.  Here's the link:

http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-89.html

This thread has been going for 89 pages and more than four years now......  so it must be a damn good circuit.  I had hoped to match it, that the NAKSA bests it at high output is wonderful to hear.

As you all know, I'm only interested in subjective sound quality, by whatever means.  So this has been a terrific result for me, and I'm really happy, thanks again Ian, very nice story!

Cheers,

Hugh

[audiopip]

Hi Ian,

Guess that saves you burning in the power supply caps!

If I had a dollar for the number of times I have made mistakes like that I would be much better off! 

[ginger]

Hugh and John (and other AKSAphiles),
The Baby Huey I was testing against is pretty much the original circuit I posted on page 1 of the BH thread with EL84 Output Tubes. It has 2 tricks added since then. The first is a mod to reduce 3rd (and other odd) harmonic distortion products BUT also reduces intermodulation distortion a lot  by introducing some common mode feedback. The second, is a roll off of the local shunt feedback at high frequencies and it may well be this which is giving it the stunning stereo imaging performance. It maybe that the BH is therfore artificially enhancing the image allthough it doesn't sound that way. I say this because the NAKSA has no lack of top end, either in level or detail, cymbols, snare drums, bells etc. all come through crystal clear. This was what I was listening for when I played the Sergio Mendes. For a low power tube amp the BH has good bass authority but nowhere near the NAKSA in this regard. The low level I referred to is low to normal listening levels for a small (8 to 10W per channel) tube amp. Lower than what I would normally call normal listening levels for a grunty Solid State amp. I hope that helps clarify the comparison.
Otherwise, the NAKSA has a lot of the "tube amp" character which we so enjoyed from the AKSA55N+, just does it better than the 55N+ which as any 55N+ owner can tell you means the NAKSA is a "damn good" amp. So am I giving up on tube amps - no way, I just have to scale up a bit and spend about 4 times the NAKSA cost on parts for the next one. Actually I've already done that, A$2000 worth of Plitron Transformers (Power and Output) and A$1000 worth of Electroharmonix 300B tubes are sitting on the shelf ready to go.
The NAKSA gives me a VERY SERIOUS reference amp to try to beat and something else worth listening to in the mean time.
Cheers,
Ian   

[jkeny]

Thanks Ian,
That puts it in perspective for me. Enjoy the amp - I found it just kept getting better as I put some hours on it, you might find the same - report back if you do?

John

[Seano]

NO disrespect to Ian.....but the fact that a man of his skills can turn an amp PS into a temporary welder in such an elementary fashion is sooooooo......comforting. 

[AKSA]

Seano,

Me too, I found it hilarious and immensely comforting too.  I know Ian reasonably well and visit each time I go to Adelaide, and few people I have met in the electronics field impress me more.  His knowledge and ability are stunning, there is nothing he cannot do.  But I make these mistakes several times every month, and it just proves that the human pays a high price for creativity.  We are so fallible......  witness our institutions.  You should follow the Myki fiasco on our public transport system, it's an urban legend.  It still doesn't work, over $AUD1.5 billion spent!

Cheers,

Hugh

[ginger]

A bit off topic,

If someone tells you they never make a mistake you can assume one of 2 things:
a) They are selective with the truth
OR
b) They never do anything

I've been an Apprentice, Technician, Technical Officer, Engineer, Senior Design Engineer over the last 37 years. I ran out of fingers and toes to count the screw ups many years back, but along the way I've solved problems that other Engineers had long abandoned as too hard, by diving in and having a go. These days I really ONLY get annoyed with myself when I repeat a mistake. Why? Because mistakes should be "learning experiences" and from that perspective then the more mistakes you make the better you get.

If someone else can learn from my mistake, then it is my "duty" to point it out. Hopefully no one else will suffer "bangs, flashes and brown smells" from this basic mistake in wiring their NAKSA. If I have reduced that likelyhood then I am content.

As for turning stuff into a temporary welder - you should have seen what I did when I redesigned and rewired an aircraft ground power unit which was designed to deliver 2000 Amps at 28 Volts for starting the Rolls Royce Dart Jet Engines on an old Fokker F27. Now there was a welder.

Cheers,
Ian

[Jens]

I'm happy to say that I got one of my NAKSAs up and running late last night - without igniting anyting or turning any parts of the board into a temporary welder 

I live in an apartment, and since it was very late (around 3 in the morning) I couldn't really crank up the volume and give it a good listen. However, I was able to hear good clarity and airyness 

I will give it a good listen over the next few days and post my impressions here later 

I got two NAKSAs that eventually will go on the rear of my speakers, each driving a tweeter and a midrange directly via electronic x-overs, thus doing away with speaker cables ...

[jkeny]

Neils Bohrs definition of an expert "An expert is a person who has made all the mistakes that can be made in a very narrow field."  

[AKSA]

Good going, Jens!!

I think the bottom line is this:  We humans learn more from our mistakes than from our triumphs.  Someone who is genuinely competent therefore has made a lot of mistakes, and each of them has served to remind him of how little he knows.  Once we are aware of what we do not know, we have some probability of advancing.

The sole advantage of ignorance, I have found (and like anyone I have large areas of ignorance) is that you do not know that something cannot be done.  So you foolishly proceed, and once in a while, you surprise others by succeeding.

I'd much rather be underconfident than overconfident.  Too much confidence always seems to end in tears.......


Hugh

[SuperMart]

Hi all,

Hugh arrived at my place today with a Naksa slung under his arm, as you do.

Oh no I thought - I've only recently got used to my 2008 Soraya sound again!

This demo. Naksa had a small component change made to it shortly after I first heard it some time ago now.

I've been pleased to read that new owners of the Naksa have been making the same observations as I made.

Well, it's still all there. When we switched back to the Soraya I found myself immediately missing the hallmarks of the Naksa - engagement, the supple and deep bass, tonal accuracy and a very low noise floor all of which combine to produce simply a very musical presentation.

This thing likes to be whipped, too. Give it heaps of gain and the top end stays smooth and in control.

Ploughing through the usual test tracks from the likes of Jennifer Warnes produces big smiles all round.

 And the bass notes from "Yello" managed to excite the whole room, turning the V Sonics into bass monsters - look, no subwoofer!

I hope these few observations are of some help - I know that it takes a leap of faith to purchase something over the net without hearing it first - witness my collection of headphones.

Cheers,

. 

[AKSA]

Thanks Marty!!

I've built another NAKSA today, and it sounds exactly like the others I've built, very rich, textured, tubey, like gorgonzola cheese!!

It is not visible here, but there's a large rectangular 'window' beneath the heatsink to allow air to rise up past it for good cooling.  Top panel, sides, and front panel not fitted yet, of course.

This is a pro audio 2U racking case, locally available, all fits in very nicely.





Cheers,

Hugh

[AKSA]

Folks,

I'm guilty of overloading this thread, but here's a couple of piccies which visually and tonally define the NAKSA:









Ciao,

Hugh

[lonewolfny42]

Gorgonzola.....

It can be buttery or firm, crumbly and quite salty, with a 'bite' from its blue veining.

Sort of like the new Naksa amplifier....

Good luck with the new amp Hugh !!