A Radford STA15 restoration story - diyAudio
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Old 20th October 2010, 05:02 PM   #1
bigwill is online now bigwill  United Kingdom
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Smile A Radford STA15 restoration story

The amp first came to me in quite a mess...

The metalwork had HOLES in it, it was rusty, filthy and the wiring was shot.
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Old 20th October 2010, 05:04 PM   #2
bigwill is online now bigwill  United Kingdom
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A complete strip down was required.
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Old 20th October 2010, 05:10 PM   #3
bigwill is online now bigwill  United Kingdom
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The old PCBs were pretty shot with broken traces so I put considerable effort into making a prototype new design (using the original Radford circuit), with a few tweaks (CCS cathode biasing which turned out to be a more trouble than it was worth) and a better physical layout.

Meanwhile the metalwork I sent off to be chromed came back.
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Old 20th October 2010, 05:14 PM   #4
bigwill is online now bigwill  United Kingdom
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Here are the runners with new valve holders and sockets installed. I even managed to use the original spacer with a new gold plated RCA/Phono socket!
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Old 20th October 2010, 05:15 PM   #5
kevinkr is offline kevinkr  United States
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More, more, more!! Definitely want to see how this turns out..
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Old 20th October 2010, 05:16 PM   #6
bigwill is online now bigwill  United Kingdom
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A while later I got the chassis resprayed in a car auto place up the road
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Old 20th October 2010, 05:22 PM   #7
bigwill is online now bigwill  United Kingdom
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Whoops this is backwards, but before I got the painting done I had to see to those pesky holes. The welding and grinding were not done by me

Also I feel silly for posting the previous pictures already because it gives the game away so quickly
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Old 20th October 2010, 05:23 PM   #8
bigwill is online now bigwill  United Kingdom
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I have to go and do something outside but I will be back soon with more pictures!
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Old 20th October 2010, 05:44 PM   #9
Xoc1 is offline Xoc1  United Kingdom
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Looks great with all the metalwork chromed, The pressings holding the valves are only zinc plated standard, and they easily stain with any moisture that gets on them.
My STA 15 had MK4 upgrade PCBs fitted and then stayed in my audio system for a pleasurable 20 years of use before exploding an electrolytic. It now sits on the shelf waiting to be repaired.
The Mk 4 PCBs are very similar to the Mk3 but had added bi-pass polypropylene caps on most of the electrolytics. Other mods that were recommended were hard wiring the output transformer impedance tap without the selector switch. They also supplied a new input socket, and heavy duty binding posts.
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Old 20th October 2010, 05:55 PM   #10
kevinkr is offline kevinkr  United States
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Quote:
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I have to go and do something outside but I will be back soon with more pictures!
It looks really excellent, looking forward to seeing more pictures soon.

Will also be be quite interesting to read your impressions of the amplifier's performance once completed and put back into service.

That's real dedication to bring something back from the brink like this. I think many would have scrapped it for the transformers.
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