Mini-A boards

[MikeW]

I am finished with my mini-A experiments. I see some people are still interested in boards. I will gladly donate the films for the boards to the DIY forum for a group buy. These boards can be cut in half to do other Alephs.

[MikeW]

board

[Panelhead]

What is your next project?

George

[MikeW]

I am sworn to secretcy until it is finished.
If I build two I will send you one.

[jam]

Big Brother is watching you!..............................

[MikeW]

My E-mail got kicked back. The board is for a stereo pair. I sent out maybe 15 boards. If someone isn't going to build a mini please send a board to Stabist.

[Stabist]

Originally posted by MikeW
My E-mail got kicked back. The board is for a stereo pair. I sent out maybe 15 boards. If someone isn't going to build a mini please send a board to Stabist.

Hi!

Yes, I apologise - but my email server is apparently down I've discovered that after sent you a pm ...

Oh, THANKS!! Well - if someone will be so kind - I'll be really glad

[JacekPlacek]

Originally posted by MikeW
board

Hello Mike !
I made few copies as a monoblocks similar to Your( I have greater DC bias current) circuit so I have question about dumping factor in Your circuit. Did You measure it ? With Aleph active current source "iron" condition that AC current flowing through output sense resistor should be two times greater that AC current flowing through Aleph current source I got dumping factor about 40 for 8 Ohm load resistance not at least 100 as in original Aleph. In Your circuit it should be even much less because You work with DC bias not 2A but I suppose about ( taking into account components values) 1A
In original Aleph3 there are two mosfetes that creates current source each of them giving 1A what totally gives 2A of DC bias current. In my circuit IRF044N works with DC bias current about 2A. Taking into account characteristics IRF244 with 1A and IRF044N with 2A I think that sensitivity ( total gm of two parallel IRF244 with 1A for each is about gm of one IRF044N with 2A) of these current sources should be similar but unfortunately real world turned out to be different.
I was taking with Nelson Pass but I did not get satisfied answer. Doing some experiments I got very good characteristic of dumping factor but I had to significantly change mentioned Aleph current source condition. I changed relation between output current and Aleph current source current from 2:1 to 1.2:1. With such relation I got excelent dumping factor ( much above 100 for 8 Ohm and about 100 for 3.4 Ohm - it is lowest impedance of my speakers). Nelson unfortunately said that I should stay by 2:1 condition because relation 1.2:1 creates more distortions. Unfortunately , I have not equipment to measure distortions. On osciloscope of course I always get nice sinus signal

Have You any expieriences concerned with the matter ?

Reagrds
Jacek

[MikeW]

No, I did not measure it. Mark asked me to put the pot in the current source for adjustment. I don't know if he measured his.