Although I don't have the circuit, I assume bandwidth is important?
If so, then the capacitance and leakage of the tranny/choke must be
considered. Maybe leakage isn't crucial...depends.

Simulation would be dead easy for anyone with a circuit and the
right valve models. Unfortunately no EL86 in my library.

As Ross says, Sowter could undoubtedly help if they knew what it is
for. They may well have a stock interstage transformer that would
do the job, or they can wind an OPT without the secondaries,
presumably. They don't charge extra for one-offs, or for advice.
They can take a long time to deliver though...

cheers, Ian


"Ronald" wrote in message
...

"Lemoncha" schreef in bericht
om...
Hi group,

I bought some EL86 recently, and want to build an OTL amplifier
for my
800 ohm speakers. Does anyone have some cheap, quality 60Hy
double
chokes to spare for this application, or can anyone tell me
where to
have them made? I discussed this matter with Sowter
Transformers but
they don't know what a double choke is. The Philips book says
to use
60H double chokes. There is also a EL86 SPP article in the May
2003
issue of Audioxpress which tells me to use 30H (I think there
will be
less bass if a 30H DC is used). Both authors never specify the
details about this double choke. I need more details about
them, ie
winding details.

Thanks a lot!

I had a look at the file Ross was talking about and there it says
2 x 5H is
enough
for 30Hz .
So the first thing that came to mind was using 2 power trannies
and try to
get both
primaries on one bobine/core .
That wouldn't be to hard if the trannies have 2 chambers and a
core that can
be taken
appart (not welded or something) .

Ronald .