On Jul 14, 4:32*am, flipper wrote:
On Sun, 13 Jul 2008 14:37:05 -0700 (PDT), bigwig
wrote:
On Jul 13, 3:51*pm, flipper wrote:
On Sun, 13 Jul 2008 06:14:42 -0700 (PDT), bigwig
wrote:
On Jul 12, 11:28*pm, flipper wrote:
On Sat, 12 Jul 2008 07:02:27 -0700 (PDT), bigwig
wrote:
Hello,
*Im new to the group. Has anyone built an amp. with or played with 5B
255M?. I have a load of these valves and would like to put them to
use. The curves seem the same as the 807/6L6 types. I would like to
know if anyone has had any experience with them before I go and build
something. I was thinking PPP class AB1 ultralinear.
*Thanks Matt.
Well, Brimar said it's electrically similar to the 807.
http://www.mif.pg.gda.pl/homepages/f.../5/5B-254M.pdf
The STC data sheet is more comprehensive
http://www.mif.pg.gda.pl/homepages/f...0/5/5B254G.pdf
*(612k)
RCA 807 for comparison.
http://www.mif.pg.gda.pl/homepages/f.../084/8/807.pdf
(1.7Meg)
Ok great thanks guys,
*I have a few 7N7s so I think I will build something along the lines
of a Williamson. Should look nice with all Loktal valves. PPP output
stage, 3.3K output transformer.
Thanks for your help with the datasheets.
* * * * * * * * Matt.
You're welcome.
I'm building a 'midget' Williamson (6 Watts from 13FD7s) and Patrick
Turner had an excellent suggestion. Long tail pair the post phase
splitter triodes.
If you use spice to simulate it won't look like that does much, unless
you simulate tube mismatch where it makes a world of difference.- Hide quoted text -
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Sounds good,
* I need to wind my transformers next weekend(if the wire turns up).
These will be the first OPTs I have wound and my first large valve
project.
Ah, in that case you might want to talk with Patrick Turner because
he's the OPT expert in here.
I built a small EL84 based amp a few years ago. It sounded
very good to my tone deaf ears.
My PP 6GK6 (EL84 clone) amp is my favorite. So far anyway 
I have built numerous MOSFET amps,
some with stupidly good specs. but they all sound a bit harsh to me.
So I need a reasonably sized valve amp, hence this project. Perhaps we
could trade notes as we go.
Be glad to. Not sure there'd be much correlation with my little pip
squeak but I suppose you never know. Ironically, I was thinking about
a 6BG6 '807 variant' amp when I switched gears and decided to build
this small 13FD7 feller for my sister.
The 'idea' grew from my 'PC Speaker' amp but that one is 6AW8s, using
the same basic topology as the 6GK6 amp, and I took a completely
different approach with this one.
Got pictures of the 'PC Speaker' amp (and others) on my homebrew web
server at *http://flipperhome.dyndns.org/*but the 13FD7 isn't there
yet because it isn't done yet There's a picture of the first
component fit on alt.binaries.schematics.electronic, though.
* * * * * * * * Matt.- Hide quoted text -
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Hi,
Sorry Im so late replying. You have some interesting stuff on your
pages. I have printed all of Patricks transformer and matching pages,
this is what I have based my plans on. I also have RDH4 and some other
transformer related books although these are mainly aimed at
industrial uses. Im hoping to wind somewhere near 6K or so. This will
let me configure it for half that for push pull parallel and also play
about with pure triode, pure tetrode and ultra linear. Im in two minds
at the moment I might even add cathode feedback windings but this
limits my options somewhat.
What transformers do you use on your amps? I would like to build a
smallish amp for a friend to play with. He seems happy with the 8-10W
class A transistor amp he built so I think he will like valves more.
Only trouble is he has really ineficient Mission bookshelves so push
pull is the only way (for a reasonable outlay). Im not a fan of single
ended anyway.
Matt.