PaX amplifier: invitation to discussion

[mick.carrick]

As the author of the email Jan mentioned, I should perhaps elaborate a bit on why I like this amp so much.

It excels particularly at revealing subtleties of the music in a very relaxed and enjoyable way. There is absolutely nothing Hi-Fi about it in the sense of being "in your face" but it reproduces the music in a very natural way. I find I am being absorbed into the music and thinking about and enjoying music rather than an amplifier. It appears to add no character of its own to any of the various kinds of music I have listened to so far, but reveals the space in which it was recorded in a very satisfying way. It sounds expensive like some amps I definitely can't afford such as Mark Levinson, Pass Labs and others. Its power is there when called for but it has a single ended Class A sort of refinement that makes listening a genuine pleasure.

So don't hesitate to build a pair. Jan has been a great help and although it is an unfamiliar design, it is not difficult to get it right. The only caveat is to suggest that you follow Jan's advice to build and test each stage in the order he has outlined in the Construction guide. Trouble shooting should then be easy. I built mine with regulated power supplies (Boak style from AA) as a twin monoblock. The regulators were mainly to tame an overvoltage raw supply but I am sure they do no harm. The only other point is that the bias adjustments take a while to settle and its easy to get a bit carried away and raise the bias too fast (and consequently too high). In its final setting, it took several hours to stabilise.

Thanks to Jan for a brilliant design.

[obi-wan]

Just a quick comment, since the issue of using balanced amplifier inputs was brought up here:

My own system, in the design phases now ( I plan to use several Elektor designs as modules, including the "High-end Preamp" and the "Crescendo Millenium Amplifier), will use balanced interconnects between all components, in part to eliminate so-called "ground loops," and in part due to a lot of RF interference in my area. I'm not happy about adding unnecessary stages, either, especially as I will hear most of my music from my computer via Elektor's "Winamp Controller" through your "Audio DAC 2000" and "96KHz Sampling Rate Converter"--needless to say I'll be trying to keep every signal as pristine as I possibly can!

I intend to use THAT 1200s or 1206s (with the bootstrapped inputs) as component input stages, with Neutrik NC3FAV connectors, and for component output stages, simple impedance-balanced outputs since to gain the advantages of balanced interconnects I don't really need to drive both the + and - audio lines, especially into the THAT 1200 series. If I actually wire an analog signal across my living room I may drive that with a THAT 1606, but between components in the main system rack I see no advantage to doing so.

Good luck!

-klo

[thanx]

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[thanx]

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[pat75]

somebody to have the complet schematic of the pax amplifier
thak you in advance
patrick

[janneman01]

Hi Patrick,

You can download the complete articles for a few dollars from http://www.elektor.com/magazines/2008/april/pax-a-power-amplifier-with-error-correction-part.399028.lynkx .
Theres also an 'Audio collection 1' DVD that has the full articles, don't know the price.

I would advise to get the complete articles; this amp is bit different in concept than a 'regular' audio power amp and the articles gives some advise how to incrementally build it up and test in several steps to assure success.

best,

jan didden'

[neron]

hi my name is neron

[pat75]

thank you for answer ,but there is 4 pcb ? whom to have to utilize?

[janneman01]

Hello pat75,

Are you asking where to get the boards? There is one board pre amplifier channel, plus one board for the protection system per channel, indeed total 4.
I understand that Elektor provides boards through their PCB service. Also, Pilgham Audio (www.pilghamaudio.com) sells complete kits; I don't know if they will sell boards only.
I recently changed the protection board so if you are going to build this amp be sure to get the latest protection board from Pilgham.

best,

jan didden

[pat75]

dear jan i dont understand because there is 2 pcb no reflected and 2 pcb reflected for the pax amplifier?
whom to have utilized? 1and 2 or 1and 3or 1and 4or 2and 3 or 3and 4
thank you dear jan