Steve Bench's KT88 Matrix Amp
Ross Matheson
While I've collected all the parts for a possible 5894 version of the
original matrix amp, last year I was lucky to acquire 3 nos TT21.
I have a marine radio that uses one. I was hoping to get a quartet.
(The marine radio TT21 is well worn, but I'm in no hurry to fix it up.)
I am now thinking I'd like to make a TT21 version, but not with 6MB8.
Or, I do have 4 well-worn KT88, but a top-cap version could be neat!
I could use my 12W 7k/3.75-15 Beacon OPT's modularly perhaps!
I wonder about using other tubes I have for the front end - 6SN7, 6SL7,
even 1629 magic eye too. I have no spice yet. Not sure how to design.
Mind you I haven't given it a great deal of attention yet. ~26V drive?
Just a thought, logged. Surely it doesn't have to be a pentode driver?
While we're on that, and the triode festival - this vacuum state amp
looks as though it could be an incarnation of the above - was it?
http://www.triodefestival.net/atf2003/pictures/jim/allen/IMG_3375.JPG
Ross
Patrick Turner
Ross Matheson wrote:
I see you have posted a picture of an Allen Wright designed power amp based
on his
slightly new idea of PP, for which he claims sonic superiority, which isn't
unusual.
This is achieved by using a CCS sink to the commoned cathodes of the output
tubes,
which makes the output stage act as a class A amp only, and incapable
of class AB.
The first 10 watts are the most important, and they are precious, and need
our
care and respect, and using a CCS makes sure the turn off current of one
output
tube exactly equals the turn on current of the other.
To find out if Allen's ideas are beneficial to the sound, build one to find
out.
Meanwhile David Crittle at www.retrovox.com.au
might have quite a few TT21 for sale at reasonable prices.
Allen Wright's design would have nothing in common with
http://members.aol.com/analogengineer/kt88mat.htm
Patrick Turner.
Steve Bench
>even 1629 magic eye too. I have no spice yet. Not sure how to design.
>
>Mind you I haven't given it a great deal of attention yet. ~26V drive?
>Just a thought, logged. Surely it doesn't have to be a pentode driver?
>
>While we're on that, and the triode festival - this vacuum state amp
>looks as though it could be an incarnation of the above - was it?
Hi Ross,
Pentode drivers work better for the Matrix. You're looking for
linearity in the local feedback loop. There was a discussion
on that topic a while ago in this forum.
Although there was a Matrix amp at the triode festival, the pictured
KT88 amp from Allen isn't it. The Matrix at the festival was
7695 based and tiny (<200 cu inches) producing 3-4 watts per
channel from 7695 pentodes.
Best Regards,
Steve
Check my web page .. <A
HREF="http://members.aol.com/sbench101/">http://members.aol.com/sbench101</A>
Remove the .gov to EMail me
doug
"Steve Bench" <sbe...@aol.com.gov> wrote in message
news:20040113100550...@mb-m02.aol.com...
the website as posted doesnt work
http://members.aol.com/sbench101/
look up matrix in the list
Doug
Ross Matheson
: Pentode drivers work better for the Matrix. You're looking for
: linearity in the local feedback loop. There was a discussion
: on that topic a while ago in this forum.
Yes I recall now, thanks. Sorry! I have all that saved, too.
: Although there was a Matrix amp at the triode festival, the pictured
: KT88 amp from Allen isn't it. The Matrix at the festival was
: 7695 based and tiny (<200 cu inches) producing 3-4 watts per
: channel from 7695 pentodes.
I realised as I posted that it was unlikely to be, and that I could have
checked his site - besides, they looked like twin triodes in front.
I did see the little matrix amp pic and d/l the pdf notes but hadn't read
them then - am just going through them now. I see the combos tried.
I'll try it as is when I get a round tuit ... Thanks! RdM