Juancho

Radford STA 100 Monoblocks

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Superb looking amps and a credit to you.  Obviously a lot of clever thought gone into making these by starting with the much loved and revered Radford and improving it.  Love the addition of chokes and the use of modern high quality components not available to Radford at the time, valve positioning and heat dissipation, ease of servicing, compact size etc and yet retaining the benefits of simple but clever circuitry, point to point wiring, no printed circuit boards, no chips, no unnecessary add-ons.  What's not to like?

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Super Wammer
3 hours ago, rabski said:

I'm usually the first one to say that particular valves don't have a 'sound', but circuits do. However, there are generalisations that hold true to a degree and I'm about to break my own rule and say that I agree with a couple of comments here. I don't like KT88s as push-pull pentodes. And that comes from someone who has a few NOS GECs in the pile and a spare pair of monos that were designed to run KT88s. I much prefer those with the wick turned down and running 88s as strapped triodes or even with some more serious changes and running KT66s.

Okay I can feel duly chastised but what is the main difference between a KT66 and a KT88 and in this case I am only talking about GEC items whichthe oiriginal Quad II was fitted with by Quad . As I understand it a KT66 is similar to 6LG6 but different and the the KT88 is simialr to a 6550 but different .

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Super Dealer
3 minutes ago, bencat said:

Okay I can feel duly chastised but what is the main difference between a KT66 and a KT88 and in this case I am only talking about GEC items whichthe oiriginal Quad II was fitted with by Quad . As I understand it a KT66 is similar to 6LG6 but different and the the KT88 is simialr to a 6550 but different .

Do you mean sound/construction/electrical characteristics? On the latter, the anode and screen voltage ratings are way, way lower, so without a fundamental re-design there's no way you can use them in these amps. But for me it all goes to the resulting sound. This amp was designed around the Radford circuit with a few improvements, one being speccing it for KT120s which can far better stand the high 630v HT and screen voltages the STA100 uses. When I first decided to build these, I always said that it was a shoot out sound quality between these and the Leben cs1000p which also uses KT120s (or EL34s, KT88s etc) and this amp won, hence I went to sell the Leben but ended up swapping it for the two Silvercore monoblocks. So comparing it to the Silvercore 833 valved Class A amps and  my wife's Mastersound 845 PSE monoblocks, those that have heard the comparison all agree the Radford monos are the best of the bunch across a wide range of music. All very subjective I know but an indication of how well the amp performs with its KT120s.

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