Hello,

I'm currently building a Gec 30w KT88 / 6SN7 amp.
(http://tdsl.duncanamps.com/schematics2.php?make=GEC)

In fact i have all the parts now at home and will start prototyping in
the next days.

I wanted to buid quad ii replicas, but stopped because of the compexity
(price :-(( ) of the output trannies.

I have bought 6k 60w UL pp otp
(http://www.die-wuestens.de/dindex.htm?/atrafo.htm) and ww2 power
transformers
(http://cgi.ebay.fr/ws/eBayISAPI.dll?...tem=3018270367)

What i'm looking for is real rexperience on this gec 30w design.

I have found :
http://personales.ya.com/lcardaba/projects/GEC/GEC.htm

He gives helps on HF stability (problem with GFB).

Anybody has advice on this design and on stability?

Please explain things simply i'm a beginner and don't speak tubes
fluently yet ;-)

Have fun folks !
Best regards,
Luc D.

wrote:

Hello,

I'm currently building a Gec 30w KT88 / 6SN7 amp.
(http://tdsl.duncanamps.com/schematics2.php?make=GEC)

The link doesn't work in netscape or IE.



In fact i have all the parts now at home and will start prototyping in
the next days.

I wanted to buid quad ii replicas, but stopped because of the compexity
(price :-(( ) of the output trannies.

I have bought 6k 60w UL pp otp
(http://www.die-wuestens.de/dindex.htm?/atrafo.htm) and ww2 power
transformers
(http://cgi.ebay.fr/ws/eBayISAPI.dll?...tem=3018270367)

What i'm looking for is real rexperience on this gec 30w design.

I have found :
http://personales.ya.com/lcardaba/projects/GEC/GEC.htm

This design is a Williamson design.



He gives helps on HF stability (problem with GFB).

Anybody has advice on this design and on stability?

It looks OK.
Stability depends on the OPT quality, and things you have not learnt yet.



Please explain things simply i'm a beginner and don't speak tubes
fluently yet ;-)

We don't speak spanish or german either, so maybe we can teach you slowly
by sending you smoke signals, and you can send some back
when you hook up the amp.

Also see

http://www.turneraudio.com.au/htmlwe...0ulabinteg.htm

Patrick Turner.



Have fun folks !
Best regards,
Luc D.

Thank you for your answer.
Here the link is working, i tried it again.

I don't speak spanish too but diagram are universal !
and the german site is in english (partly) too ;-)

Ok, patrick i'll send you smoke signals when i'll fire it up.

I saw your 5050 a few months ago.
More complex for me, maybe i'll try it in a second time, when i'll be
more experienced.

Can you explain for a beginner what are the pros and cons of your
"5050" design against the "gec 30w" or "gec 30w improved by Luis" ?

Anyone has experience with Gec design ?

Thank's,
BR,
Luc.

wrote:

Thank you for your answer.
Here the link is working, i tried it again.

I don't speak spanish too but diagram are universal !
and the german site is in english (partly) too ;-)

Ok, patrick i'll send you smoke signals when i'll fire it up.

Cheaper for you if you don't.



I saw your 5050 a few months ago.
More complex for me, maybe i'll try it in a second time, when i'll be
more experienced.

Can you explain for a beginner what are the pros and cons of your
"5050" design against the "gec 30w" or "gec 30w improved by Luis" ?

The GEC at the spanish site is more complex than mine, but then
I have a transistor CCS, and that trips up anyone who likes
real simplicity, since the very idea
of a current that is constant is hard to grasp.

The overall complexity of the GEC and mine is about the same though.
I have a separate line stage preamp, gain control, source switch included
in my
schemo though.

Anyone has experience with Gec design ?

The first power amp I built was just like the GEC, but with a quad of
EL34.
I switched to the desighn I use now because its slightly simpler,
with slightly less RC couplings, and thus slightly easier to stabilise.

Ppl must re,ember that the GE or Williamson drive amp
circuit has slightly wider bandwith than an input triode + LTP
because the concertina phase inverter acts like a buffer stage between
the input stage and the balanced voltage
amp driver stage.

There are a few tweaks for the GE / Williamson circuit to optimise it.

I'd allow for the use of two octal or nine pin sockets for the drive amp.

Thus 2 triodes are possible in each socket, for a total of 4,
or a pentode used and a triode in one socket, plus two triodes as an LTP.

Allowing 3 tube sockets allows for a pair of EL84 or
6V6 to be used as each 1/2 of a voltage amp, or LTP,
with the 3rd socket for an input tube.

This makes *the* best driver amp, imho.

Patrick Turner.




Thank's,
BR,
Luc.

wrote:

Hello,

I'm currently building a Gec 30w KT88 / 6SN7 amp.
(http://tdsl.duncanamps.com/schematics2.php?make=GEC)

In fact i have all the parts now at home and will start prototyping in
the next days.

I wanted to buid quad ii replicas, but stopped because of the compexity
(price :-(( ) of the output trannies.

I have bought 6k 60w UL pp otp
(http://www.die-wuestens.de/dindex.htm?/atrafo.htm) and ww2 power
transformers


They have several Hammond part numbers listed, ie 1650N, Etc. When you
go to the photo the end bells & any ID marking has been removed from
whatever transformer is exhibited. I wonder what that means!!
JLS

(http://cgi.ebay.fr/ws/eBayISAPI.dll?...tem=3018270367)

What i'm looking for is real rexperience on this gec 30w design.

I have found :
http://personales.ya.com/lcardaba/projects/GEC/GEC.htm

He gives helps on HF stability (problem with GFB).

Anybody has advice on this design and on stability?

Please explain things simply i'm a beginner and don't speak tubes
fluently yet ;-)

Have fun folks !
Best regards,
Luc D.

On Thu, 17 Mar 2005 02:00:44 +0000, luc.destomb wrote:

I have found :
http://personales.ya.com/lcardaba/projects/GEC/GEC.htm

He gives helps on HF stability (problem with GFB).

You can translate this page at:
http://ets.freetranslation.com/

"Enchufar" is Spanish for "plug in"

These articles might be of some help:

http://www.triodeel.com/images/willimp.pdf
http://www.triodeel.com/hipower.html

--
Ned Carlson Triode Electronics Chicago,IL USA
www.triodeelectronics.com

Thank you everybody,
this one was missing to my collection ;-) :
http://www.triodeel.com/hipowe=ADr.html

Anyone real experience on 'improving the williamson as described there ?