Radford: About Power Amplifiers

[Ali Tait]

Be nice to hear an SE amp with trannies of the same quality..

[blstransformers]

Hi Everyone,

I've just been searching on the internet for any information about Radford amplifiers. Someone has asked me to make him some power and output transformers for STA 15s and STA 25s. Does anyone know how large these transformers are? I've looked on Sowter's web shop and the designs they have for the outputs at least are massive. My initial calculations are showing DC resistances on the primary that are tiny and well below the 5-10% I work to when doing a "ground up" output transformer design.

If anyone's got any information at all, I'd be most grateful.

Simon

[spendorman]

Do you know this to be true? I can't find reference to it in the Gramophone link you provide, though it would not surprise me. I believe the secret to a good valve power amplifier does lay in the design of the output transformers. And yes, a lot of this sort of knowledge is being lost through lack of use. Most transformer manufacturers concentrate on power transformers; audio transformers, especially power transformers are a bit of a speciality

I've always been interested in this amplifier since reading about it in the late '60s. Does anybody out there have experience of one? (Andre? if your still reading AoS posts) It, along with the Radford 15 and 25 amps, the Lowther LL26 and Richardson MA135 or ST70, are all amplifiers using EL34s that I would love to get my hands on.

Regards

A little late!! lol, but proof here of the use of Radford transformers in the Rogers Master power amp:

http://farm5.staticflickr.com/4138/4...d12ffd5c_b.jpg

[electromuffin]

Hi Alex an aquantence also has a ST20 but the lettering has rubbed off of the first valve in both channels. As your freind has one can your possibly help please
Best regards Len
PS He lives some distance away so I have not seen this amp and he is not that technical

[The Grand Wazoo]

Len,
Take a look in th AoS Library, where you will find an article about Radford. There is a list of products with their valve complements itemised.