Pass A40

[MEGA_amp]

I present my work in progress A40 (I'm actually planning on finishing this one), I know its old but it truly is a beast. alexcp was nice enough to create a 'new' board, which addresses the Q11 issue. In its place is a LM334 constant current source, which made it super easy. Used MJ11015/16 for the outputs. According to my non-scientifical research KSC1009YTA (Q1-Q4, Q6), and MPSA93 (Q5) are direct-ish replacements for the originals. R11 @ 6.8K gives me ~1.3A bias, and a 1000VA 25V trafo gives about 31VDC. This thing knocks the paint off the walls paired up with a set of Cornscala 'B'. Now, since my chassis is HUGE it barely gets warm after 12 hours of use. Of course I'd like to increase the bias, planning on putting back the 20K pot, however I'd like to know if this ~1.3 amp bias (per the article) is optimal with these type of outputs (i'm used to burning up mosfets). Is it the usual bias it until the sinks (or my hand) cant take it anymore?

Thanks Nelson!
John

 

[Nelson Pass]

What drivers in those speakers?

 

[osscar]

Very nice, A40 also in my wishlist 😀

 

[MEGA_amp]

What drivers in those speakers?

From what I could gather they are Crites's own drivers, not a ton of info on them.
Link: Cornscala Style B | Critesspeakers.com

Very nice, A40 also in my wishlist

DO IT!! Fell off the diy stuff for awhile, bought a Threshold 400A, and a Nak PA-7, and dare I say the A40 crushed them both. Although the 736,000uF of capacitance and 1000VA transformer in the A40 may have helped with that.

 

[Ultrasparc]

I built one 5 or so years ago using 2n5551, 2n5401, an NTE312 Jfet, and the same output devices you used, with a 24-0-24 1000va Transformer. It sounds very nice paired with my Paradigm Studio 60 Speakers and BA3 preamp..