[Occam]

da Funk -

I've had the US touring AKSA 100 Nirvana+ for almost 2 weeks now, breaking in. Subjectively, the breakin is as torturous as Hugh has described. Its not the gradual change in certain characteristics that I've experienced with other components, but is rather best described as an extended scizophrenic episode.  But, IMO, well worth the patience and wait. That is the last vaugely positive subjective comment I'll make on the N+, and will let the tour participants form their own opinions. To be truthful, I can't be an 'honest broker' in this as I'm presently negotiating a business transaction with Hugh. [Hugh, I beg you to reconsider.... your daughters and my sons are perfectly matched. And my expected dowry payment of 7 100N+, 6 55N+, 4 GK-1, 8 AskaSonics, and 3 AksaDacs, even at the current exchange rates, really doesn't translate into all that many cows, goats and chickens. Just think of the grandchilldren! They'll have your looks and my people skills...]

da Noise -

I will make an objective comment.  My system with the N+ in place shows the slightest whine, which you can only hear by putting your ear against the speakers. Its not a hum, hiss, whatever... its a whine. But its not coming from the Aksa, it is coming from my Dac. I modded DI/O, with tweeks on both the dac and adc functions. As I really don't use the analog to digital functionality, I ultimately just pulled the vacuum tube from the DI/O to lessen the impact of the powersupply draw from its filament and plate.  The whine doesn't originate from the Aksa as when I turn the pre source selector to an open input, it goes away. Its not the pre, for when I turn off the dac, the whine goes away. Its the voltage muliiplier on the plate supply for the tube, drawing insignificant rectifying currents, which because its a voltage multiplier, its ripple is a whine. Its alway been there. But its alway been submerged in the inevitable hiss of my poweramps, even the straight Nirvana. With my better amps, its always been that ear against the speaker hiss, but there nonetheless. But with the N+, at the same volume setting, no hiss, at all. Spooky. This is (if aural memory can be trusted) the quietest, lowest noise floor amp I've ever had in my system. Admittedly, Hugh built the amp. If I'd built it , it might not be so quiet.

As to how that noise floor translates into subjective perceptions, I'll leave to the tour participants.

[Lost81]

Wait, so Hugh built these amps?

I was under the impression that it was done by one of his customers.

Oh, my!
Now I definitely MUST have a look and listen!



Cheers,
-Lost81

[Carlman]

I have a mostly-Hugh built AKSA burning in as well.  He built my Nirvana+ and I added the basics, torroids and binding posts... I asked him to do the N+ as a favor (at a price, of course) and he did it... and included a case, LED's, and whatnot..  This time I upgraded the RCA's, binding posts, etc., to the best I could afford... (or actually couldn't afford but did it anyway. )

I'm going through the same burn-in gyrations I think as Occam.  It's changed quite a bit since I first plugged it in.  I won't dilute the objectivity of the tour by saying what the changes have been and what I think now but, I plan to provide a full report when the timing is right.

I'm still amazed at the seemingly bottomless supply of energy this amp provides.  I will be getting a db meter just to see what crazy amounts of sound I'm getting.  It's louder than live and still distortionless.  This aspect seems to be an improvement over the Nirvana version.

I have a slight 60-cycle hum sound at idle but I believe it to be the tube preamp.  It goes away when I turn up the volume and it changes to a slight hiss.

How many hours would you say the break-in took?

[Lost81]

I will be getting a db meter just to see what crazy amounts of sound I'm getting.

Be careful with the dB meter. I loaned mine to a fellow audiophile and he nearly suffered a psychotic breakdown
 trying to modify / treat his room to yield a perfectly flat / linear response from 20Hz to 20KHz  



-Lost81

[AKSA]

Paul,

Thank you for your great post!

I nearly fell off my twig when I read your proposition about my daughters and your sons!!  I'm reminded of Bernard Shaw's quip to the beautiful society lady who had suggested that a union would create offspring with her beauty and his brains, 'But Madam, what if they had your brains and my looks?'       We talk intensely of the break-in of the Nirvana Plus, Mein Gott, what about the break-in of my adolescent daughters?  Have you considered this, Sir?  And your sons, are they ready?  I have one who can cut off a man's head bloodlessly at 100m with her tongue, and another who is charmingly determined to invent herself as a beguiling mix of Isadora Duncan and Donatella Versace, with the social cachet of Elizabeth Hurley.

Nonetheless, I will consider your dowry offer.  In the circumstances, it seems entirely reasonable, but I will need to examine the chicken entrails later in the day with Sri at the conjunction of Mars and Venus.......

I am considering all sorts of ways to break in the BGs before use in the AKSA.  It's something BG should be doing as a matter of course anyway.

Ahem, the audition amp is not built for swank good looks.  It is built like a bomb shelter to withstand constant transit around the States, and looks more like a HumVee than a Ferrari.  I mention this to avoid disappointing those expecting a Halcro-esque extruded masterpiece!!

Carl, from lessons I've recently learned, you can expect a faint steely glaze at the top end until it beds in fully.  This is entirely normal;  nothing to worry about, but will take two or three weeks of regular playing to dissipate fully.  I apologize to all for this aspect, it requires patience, but to achieve this sort of performance some of the componentry is uncompromising and there's just no way around it.....    

Benny, a session with a dB meter is very instructive.  There are peaks and troughs all over the spectrum;  it makes you cry.  This is the reason speaker placement makes such a difference.  And the differences are night and day, and remind one of the quest for fuel economy in autos;  the single biggest determinant is driving style - and so it is with audio, speaker placement is everything.

Cheers,

Hugh

[Carlman]

.... from lessons I've recently learned, you can expect a faint steely glaze at the top end until it beds in fully. This is entirely normal; nothing to worry about...

What gets me is that it didn't have that metallic sound when totally cold...  then it started... and the mid-bass had a nice bloom to it... then the highs got better again, then the midrange went sort of weird and thin..... and then fat again... It's f'ing moody!  However, things seemed to have stabilized to that faint bit of a metallic edge in the highs and the bass is almost as good as before.  So, I'm thinking things are shaping up and only time will tell.  I've only been using it a week (maybe 5 days actually) and mostly at low volume.

Keep in mind these are minor variations... it's not like the entire character of the amp changes but, what I've described are minute changes I've noted as it has been 'bedding in'... but has not 'fully' done so....

[ginger]

Your comments above are spot on - my experience exactly with the "bed in" process. Rest assured that that metalic edge does go away once fully bedded in. I tried a nunber of things to try to get the BGs to bed it in faster. I left the amp powered up and connected to speaker etc, but not playing anything for 48 hrs straight, I put it on the test bench and drove a 4R7 50W resistor on each channel with a 1kHz sine wave for a couple of days. I don't know if either of these things helped.

I was left with an impression, however, that the speed of bedding in was related to the number of times I turned the amp on and off. That is, each time I turned it on for a session I thought it was better than last time.

You might try running it for 30 mins switch off for 30 mins and repeat.
This might have been a purely subjective thing and I could be fooling myself (would'nt be the first time and won't be the last time either). If anyone else has had similar experience and can confirm or refute this, lets hear from you.  

CAUTION: Don't go cycling the power switch at twice per second. If there is any merit in the arguement it probably has to do with a relaxation (off) period hence the 30 mins on, 30 mins off suggestion.

My belief is that the slight metalic edge comes mostly from the bootstrap cap. For a while I even ran "Super E" connected Blackgate Ns for the bootstrap cap which addressed just this complaint (the metalic edge during bed in) BUT once bed was achieved I found I preferred the simple single bootstrap cap solution. I ran about 6 weeks in each configuration.

The BG web site say quite clearly that their caps take 40 hrs to bed in. I found that I was noticing further improvements out to 100 or more hrs. Relax and be patient - the longer its on the better it gets.
 
As described above the "dead black" background of the Nivarna Plus modification not only reveals additional music detail which was previously masked be low level broadband noise (the bane of ALL amps and of which you were'nt even aware coz your brain tunes it out) but will also reveal any minor (or major) problems with your music source equipment.

Cheers,
Ginger

[andyr]

Paul, ....

Benny, a session with a dB meter is very instructive. There are peaks and troughs all over the spectrum; it makes you cry. This is the reason speaker placement makes such a difference. ...

I have recently been experimenting with my dB meter - the purpose being to (attempt to) measure the natural LF rolloff of my Maggie panels, so as to decide how they would best mate with subs.

I was told that I would see a peak at the panel resonance and then a decay at probably 12dB per octave.

I put my db meter about 100mm from the centre of one base panel and had the IC plugged directly into one 100N channel (ie. bypassing my active crossover).  I used Stereophile Test CD #2 which has 1/3rd octave warble tones going down to 20hz.

Plotting the results on log graph paper, from 400hz to 100hz I got an up-and-down curve but only 3dB p-p ... ie. +/- 1.5dB.  Then, sure enough, there was a 5dB peak at just under 60hz.  Below this it fell at just under 12dB per octave to 40hz - then 30hz was the same value, then it dropped away again.

The dB reading at 30hz was only 3dB down from the average between 100 and 400hz ... I hadn't thought my Maggies did that well!

Here's the plot:  http://home.comcast.net/~dreite/Temp/SPL.JPG

Then I put the dB meter at my listening position and had both both base panels going.  With the magic of dipole cancellation now coming into play, the 60hz peak had flattened ... 'xept the plot now showed a 6dB null at 100Hz, caused by speaker placement.

So ya can't win!

Regards,

Andy

[Occam]

....
I was left with an impression, however, that the speed of bedding in was related to the number of times I turned the amp on and off. That is, each time I turned it on for a session I thought it was better than last time. ...

Thanks a bunch Ginger. I've been running the amp 24/7, but when I read your post I turned the amp off.  So now I play the amp for an hour or two, turn it off for an hour, repeat as audiophile nervosa dictates.  She Who Must Be Obeyed is getting really ticked off that the alarm goes off at 3 hour intervals throughout the night.
Now I've got to go into therapy to reconcile the guilt of such poor service to the touring amp...

I'll add some more ancecdotal fuel to this fire.  Our references to the breaking in process have been tonal in nature. But from my very limited sample size, 1, I'd guess there is a very specific event that signals the transition from scizophenic breakin to normal breakin. The most annoying thing about the adolescent N+ is its treble. Hugh has made the reference to its 'steely' characteristic. He is far too kind. Indeed, that characteristic can be explicitly shown by listening to music with a high content of high-hat brushwork, snare drum, those instuments with substantial treble transients and decay. I believe the technical adjective would be 'sucks'. This is accompanied by a stubborn refusal of treble content to leave the speakers, i.e. while the imaging and soundstaging of the bass and midrange follows a relatively linear maturation process, the treble content stubbornly refused to psychoacoutically to leave its physical origin, prompting despair. I'd already composed the email to Hugh in which I reccomended that this amp not be sent out on tour. I fixed myself a cuppa, sat on the couch and pondered what to do. And then I noticed it. I was thinking -

'Golly, that high-hat sounds good, and accurate! (this was listening to Sondheim's 'Assassins') And I can actually place the drumkit both laterally and by depth. Sonofabitch!"

That was the singular event that signaled (to me) the transition from scizophrenic breakin to normal breakin. Go figure.  It also gives a plausable (but unproven)  explanation that this hinkey behavior is specifically attributable to phase anomolies associated with reactive behavior of those bespoke capacitors in the N+ prior to 'bedding in'. [and given Ginger's post, I'm now obscessing whether I'd turned the amp off.....]

One thing I want to make perfectly clear is that these anomolies with regards to breakin are transitory. What I have described took place over a period of about 8 days of being under power and about 35 hours of actually playing music through the amp. At that point the amp is, IMO, clearly superior to the standard Nirvana, and has not fully experienced that 200hrs of breakin suggested by Hugh.  My comments are specifically intended as reassurance to those who build or upgrade to the N+, lest their initial impressions lead to a massive case of buyers remorse.  Possibly, Ginger's regieme might accellerate the breakin process, but verification would require 2 separate amps to attempt to empirically verify the best breakin process, and while I like and admire Hugh, there are limits.... and after 30+ years with my wife, I know her limits and the potential reprecussions.