Whats what and which

Bksabath

Banned
2007-12-01 11:21 pm
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?
 

Bksabath

Banned
2007-12-01 11:21 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.
 

Bksabath

Banned
2007-12-01 11:21 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.
 
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.


You will need almost a 1KW to get 105 db @ a listening distance of 9ft from that speaker......With 64 Watts you will get 93 db...

Figure on 81-82 db nominal in order to have good transients and dynamics from 64 watts .......
 
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Bksabath

Banned
2007-12-01 11:21 pm
Tanks Wayne I was Just triing to keep thing simple so just one chanel at one meter.

Eventualy I will mesure the SPL or to keep it simple the RMS V at a confortable listening level.

As I started this post this is a briliant site but all the god information is burried under loads of dross.

I am realy chuffed to have already a pointer from (if I may) Papa Nelson...

What I dont need is pointers to spell cekers or such.

Yes I know there are loads of mistakes but as long as my math is right I dont realy care.
 

Bksabath

Banned
2007-12-01 11:21 pm
I have managed to take a reading of the output level to the speakers at a comfortable level +some more.

I got 8.29 V RMS listening to a decent Hi Dynamic record (Black Sabbath Vertigo VO6 847 903 VTY)

This put things a bit more in prospective and maybe I don’t really need the 100 w amp I was thinking about.

So far after few hours reading trough the Post I have found same good information from Blitz a Grollins.

As Nelson recommended the F75 is the target but first I will give a stab at

Aleph J F5 Aleph XJ the Hi powered aleph xj and BA2.

As usual I am writing on the fly but I will put a few pointers of my findings on the post, as I would like this to be a guide of what is what and which.

Pointer 1: you may think that you need something really powerful to drive your speakers in truth a well built amp 1/4 of that may be just right.
 

Bksabath

Banned
2007-12-01 11:21 pm
Tanks Eyoung

Agree with you 100 %

Planning an F5 Just to wet my appetite still be nice to get a link or 2 to where the skematics and mod/ construction notes are kept hidden.

EG I read that there is a WIKI regarding the ? XJ 100XJ but can not find it

Cuould any one please drop in the Jucy links and short cuts please?

JJ maybe wire crossed some where I feell thet the A75 is going to be my targhet.

You quote Russel

I beliewe he was hinting that he would be moderateley happy if big Papa had a look at the A75 to take it up to date.

Personaly I would suggest that the "moderatley" may be taken as a joke.

Personaly as Londoners do it be good to get a revision for the A75 "thas all right in it'

Maybe we should start a new tread

314159265358979323846264.... good rasons why Papa should have a play with the A75.

As I started this is meant to be a ussefoul place for info altrought with loads of TYPO or bad spelling notting is more usefoull or used then the number abowe.
 

Bksabath

Banned
2007-12-01 11:21 pm
Same rusults at last.

Being working a 62 hours week most of the rest looking at this site.

So far then:

F5 nice and easy loads have beeing built same realy good pictures on tread

25 W Push Pull suply + / - 24 V consumption 160 W

(vannilla version)

Article on AudioXpress May 2008

Article construction notes First Watt site

Schematics this site F5 Power Amplifier Nelson Pass Full schematic page 9 post 89
Revised schematics revised parts please drop the links here.

To follow Aleph JX Aleph JX 100 Burning amp 2 A75 eventualy