Need help to choose a Pass amp

Hello Passlab diyer's .
I'm new to diy ,but have friends that can help .
I'm tri-amping an new speaker and I'm using 300B SET's for the
Tweeter & mids .I need something for the bass driver which is a
PHL 12" 4530 ,94db ,[email protected] 250hz .Xover point is 350hz.
Is the A40 to old a design and how would the F4 go I think my pre has a gain of 20 .I sit about 3 to 4 metres away from the speakers .
Any help much appreciated ,

With a fairly efficient woofer you're not going to need all that much power. The A-40 can be built, but the output devices were rare even when the design was new--impossible to find now. I believe Nelson posted some suggestions as to what devices might make good substitutes, but I have no idea how to tell you where to find that post.
More buildable designs would include the A-75 and the smaller Alephs. Note that the output stage of the A-75 can be scaled up or down if you want more or less power. However, my experience (I'm quad-amped and my main midrange amp is tubed) is that the Alephs are pretty decent matches for tubes, as they have a somewhat warmer sound. Your candidates there would be either of the Volksamp versions--a 30W and a 60W--or the 'normal' Aleph 3 at 30W. There was a 60W Aleph, but I can't remember the model number at the moment. It was either the 4 or the 5.


Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
Depending on what kind of hurry you're in, I do have a new
DIY amp coming up that would take the place of an A40. It's
going to be a very simple design.

The PHL 4530 is particularly easy to drive, so almost anything
will do the job.

What are you going to use for the mid and top drivers?
jupiterjune said:

WooHoo! can't wait to see it!!!!!!!

I think this thread must have escaped everyone's attention, or there would be alot more excitement about this!


you think?

seems to me that - in last few yrs - greedy boyz are at least two amps after Papa ........... mebbe they are just scarred


besides that - I'll be glad to see it ...... new spark ;)
Magura said:

Depending which greedy boys you're talking about, and which branch of amps :D

Magura :)

lykkedk said:
Hey... cool it ... :D ... It might be, that it's CHOKE loaded :D :D :D


you two aren't in counting ......... not even remotely .... even from different reasons ........