A40 PCBs

[Nelson Pass]

You can use anything that will source a couple mA and not break. With a
resistor in series, you can use lower voltage parts, as the resistor will take
up some of the rail voltage.

If you get desperate, just use a resistor and no JFET.

 

[jam]

Mr.Pass,

Do you not think that we are ready for an A-40 Mk2?

Regerds,

Jam

 

[amp_guy]

So since there are no pcb's from audioexpress Iam considering doing up a new one. So any changes to recommend?
Will be adding an offset trim pot and probably degeneration resistors on input stage. A ccs other than the hard to find jfet might be in order as well.
Also may be going to mosfet outputs as well.
Screw terminal blocks for connections are to go on too.
Hmmm this is beginning to sound like a whole new design.
Still think this would be a good pick to drop into a Hafler
And much less $$$ than the musical concepts pcb.

 

[Bigun]

I wonder if we have such a great line up of MOSFET based amps from Nelson that it's better to keep the A-40 bipolar. It's a 'blast from the past', a time when Nelson 'did' Bipolars ???

 

[amp_guy]

Ahh but a Burning amp with bipolars has been prophicised.

 

[eyoung]

Thats right... An Amp with current dumping that you can crank a car forget about welding. I'm all in a whole flock of bipolars. Keep me posted.

see the glo, Elwood

 

[amp_guy]

I wonder if we have such a great line up of MOSFET based amps from Nelson that it's better to keep the A-40 bipolar. It's a 'blast from the past', a time when Nelson 'did' Bipolars ???

Actually the A40 is not all bipolar.
it has a jfet ccs

 

[djk]

My A40 boards ended up with between ±57~±95V on them, the latter with six pair of MJ15024/25 doing 600W/4R (class AB).

RE: a new board,

The Vas and its ccs need to have an extra pad so TO-126 devices may be used, as well as EBC parts (I used MPSU10/60 and 2N3440/5415)

 

[m0rten]

Maybe this thread is dead now... but I want to build the A40. Mostly because I came across a bunch of original output transistors. And I have this vacant chassis...

Anyone knows where to buy a set of PCBs?

Thanks for any help!

(In the meantime I'm building the Aleph 5, will I be disappointed with the A40 in a direct comparison?)