Nak statis

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roddyama

roddyama

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Joined 2002
altor said:
What Nelson's designes were used in these 2x150w and 2x200w
Clfss-A amplifiers?

It seems to me, that for the "pure class A" - both of these amps are too small, at least - the first (Nakamichi), am I right ?
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Both of the amps had a reputation for running hot, but not for failure.

Nak also used Nelsons design in a couple of receiver amps.
 
roddyama

roddyama

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Joined 2002
altor said:


Yea, but according to the size of the heatsink - I can't imagine that they are possible to dissipate (2x150)x3=~1kW.....
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Maybe not what you might call over kill, but enough to keep the amp alive.
 

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A

altor

Member
Joined 2003
altor.co
Nelson Pass said:
I am not aware that any of the Nak Stasis amps were Class A,
having seen only high-bias AB models.
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Thats what I/ve said.

BTW, Nelson, I've read at one russian site that "X-1000 amplifier works in a Class-A only below 128W".

Is it realy?! How it possible? As I understand, X-**** are Super Simmetric based SE amplifiers, how in possible run then in another then "A" ???


P.S. Sorry for my not so clear English, but I hope you understand about what I'm asking.

Regards, Alex.
 
S

SI

Member
Joined 2004
PA-5 vs PA-5II

I have a Pa-5 and its rated at 100 wpc, I think the later version of the same amp with a little chasis mods PA-5II was rated at 150 wpc. The differance between Pa-7 and PA-7II were that the PA-7II had vents on the top panel and rated at 225 wpc instead of 200 wpc.

Regards.
SAAD//
 
Nelson Pass

Nelson Pass

The one and only
Joined 2001
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Originally posted by altor
BTW, Nelson, I've read at one russian site that "X-1000 amplifier
works in a Class-A only below 128W"....As I understand, X-****
are Super Simmetric based SE amplifiers, how in possible run
then in another then "A" ???
Click to expand...

The X series is Class AB, the XA series is Class A. The X1000
does about 125 (rms) in Class A, and twice that on peaks, both
figures into 8 ohms.
 
S

skilpad

Member
Joined 2003
I've owned a PA5 MKI for +/- 9 years and they do run very hot > 55C
They are not true class A but very close
They do sound great, the PA7 sounds even better
Could anyone please help me with sch info or a service manual
I intend to replace all the caps and generaly service the amp(PA5) but would like to re adjust the bais as per factory settings

Any help would be most welcome
 
Z

Zodiac

Member
Joined 2003
The PA7 bias is measured between two prongs on each side of the amp, you have to take off the top cover, they are about 1/3 way from the front of the amp to the back.

Disconnect speakers and short the inputs. Turn on and leave for an hour or so to heat up.

There are two sets of pots in the amp. One set to adjust the bias, VR102/202 and one set to adjust the DC balance VR101/201.

Connect voltmeter across the two prongs and adjust the bias pot until you read 40mV. This is equivalent to an idling current of 40mA. I actually replaced the pots that were in my amp with multi-turn ones because I found the bias point very hard to set accurately.

Anyone who would like to exchange emails about renovating these amps drop me a pm as I am about to embark on this project and I did, once upon a time open up a thread. See "renovating a PA7", posted in the solid state forum.

;)
 
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