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Bksabath 19th September 2010 12:03 AM

Whats what and which
Hi there just stubled on this site and have been reading quite a few posts.

But I am swamped by the large amount of information.

I would like to start building one or 2 of the Pass amplifiers but where to start.

Also how do you get papa Nelson to give you his blessings on doing so?

There realy is a lot to take in and maybe I am a bit to overconfident but would like to build somethink in the reagion of 100W My main speakers are Polk Audio Ls15 and they need quite a bit to be driven at a reasonable listening level.

I have tried the sudgen class a 25 W and altrought it sounded god at low level it could not cope I have also tried the Krell 400w??? integrated but did not like at all the way it sounded.

So I would like to try F5 AlephJ and XA.

Is the XA a couple of Aleph J bridged and conected so to achieve supersimetry?

Where could I find the skematics for those?

And I know I am asking for a lot but what is the best lates skematic eg sobstitutin of input mossfets with J fet appears to be caming up a lot?

Rodeodave 19th September 2010 06:29 AM


Originally Posted by Bksabath (
I would like to start building one or 2 of the Pass amplifiers but where to start.

By reading many of the Pass Labs: Technical articles (especially the zen series) and reading many manuals here: FIRST WATT PRODUCTS.

The rest you'll find by using the search function or google...

Bksabath 19th September 2010 11:16 AM

Just the kind of answer thats no answer.

As I said I am swamped by information.

Where is the schematic for the F5 to start whit?

Rodeodave 19th September 2010 03:49 PM

I think I answered at least one of your questions, no? I'll try again:
The F5 schematic is in the F5 product manual over at FIRST WATT PRODUCTS, including a complete and entertaining circuit description.

Nelson Pass 19th September 2010 04:15 PM

Unfortunately, the only diy amplifier of mine that can do the
100 watts is the A75, which is probably better for experienced

I should fix that one of these days.


Gyuri 19th September 2010 04:50 PM

And one well tuned up Aleph 2 would not be okay?
I want to say it two.

Bksabath 19th September 2010 05:09 PM

Hi Nelson
Tanks for pointer.

I had a look at the A75 and I will have a at it eventualy (started saving for tranies and caps )
That is a 1992 design and I was wondering if there has been any improvment in the last 18 years. any beter Mosfets or other power smiconductors.

I recon that to get 12 matched mossfets I will need to order a minimum of 100

As the expensive bits can be recicled I would try someting bit simpler to start.

Hem "I should fix that one of these days" Oh yes preaty please cant wait... any other interested

So nice to see you care so much about the comunity...

If you ever came over to Chester in UK drop as a line would love to buy you a pint or 2.

Again tanks Nelson

Hi Rodeodave

Thanks for info on F5 found straight away briliant Just the kind of pointer I was looking for.

Marra 19th September 2010 05:44 PM

If 60 watts is powerfull enough I can definately recommend the Aleph 5. Mines been running for 6 years now and goes plenty loud although my speakers are 90db's. I think the info is still on the Passlabs sight.

Bksabath 19th September 2010 07:40 PM

Ok Aleph 2 Aleph 5

Aleph 5 6o W
The room I am listening in is 22X14 fot
Polks Ls 15 are about 87 dB at one W this would give 105 dB at 64 W which is plenty loud I think but no head room.. Got to borrow the sound level meter from work and try and see what I am getting out of the Kandy I am using at present...

My tinking is 60 W may be enoug especialy considering the kind of power suply (600VA Trany) in Nelson amps.

As i said the 25 W sudgen sounded ok but could not cope, 3 more dB out of a 50 W maybe is a good start.

woodturner-fran 19th September 2010 10:49 PM

No one else going to say it?

You got to, just got to, fix your spelling!

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