Re: Audio Cyclopedia - A highly recommended book



"Patrick Turner" <info@xxxxxxxxxxxxxxxxxx> wrote in message
news:48918BD4.553416BB@xxxxxxxxxxxxxxxxxxxxx


I've never seen the actual winding plans for the Radford amps.
Old secret stuff. Bah, let them keep thie bloody secrets, I don't care,
what I will wind will be better anyway.

All good coilwinders are very careful about giving away too
much information. I suppose that's understandable really. It's
their living and they have had to learn what they know the
hard way.

I once talked to Dr. Gavin Sowter about cloning a Radford
OPT. He said, "Hmm, quite a challenge. It is extremely
complex.

In the spec for the STA100 which Radford wrote
for the BBC, he stated, "the amplifier can run
indefinitely at full power into an open or short-circuit
load. I have never seen such a claim from any other
maker!


I am, not sure about the situation in the US
but in the EU out of some thirty or so commercial transformer
manufacturers, there seem to be only two that can work to such a high
standard.


Lundahl and Sowter?

Indeed.


I have just nearly completed reforming a VAC 7070 amp with a quad of
300B per channel.

The brand of OPT used is unknown, but they do seem to have a big
simularity
to something made by Hammond, which is the brand used by many
hobbyists in the US and elsewhere.

Hammond ain't the cream though.

They seem to have several different standards of transformers for differing
requirements. A chap I once spoke to at an audio fair, who made
very handsome custom-built Williamsons told me that he had never
been able to make one work properly with a Hammond. I have used
Hammond iron (mainly mains xformers), and found them to be OK,
but their regulation is not as good as the more expensive makers.

Feel free to wind anything you fancy at my website such as OPT No1.

An acquaintance of mine has been looking for a coilwinding machine for
several years. He come accross all kinds of junk, but never a hig-quality
machine. AVO in the UK used to make one, I think it was marketed
under the name McCade or something similar. It could wind four
bobbins simultaneously. I have never seen one, especially for sale.

I have a feeling that the Radford machines were built in-house. I
rememember on a visit to the Ashton Vale factory seeing three or
four machines.

Clever dicks will do a lot better than I have.

I doubt that many people have enen an inclination to try
Those of use who fettle tube amps have little enough spare time
as it is, without dabbling in the black arts as well:-)

Regards to all
Iain



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