Radford STA25

Agree it is yes. I’m going to have to make an effort and try and offload some excess kit 

Money well spent.

Keep it to yourself will ya, unless it’s good news for me 

Heard an STA 15 on several occasions at previous NEBO’s, excellent amp.

Cor that's a colour, think Id like one in British Racing Green that would be cool.

His builds really are totally impeccable.

Great choice.

Had mine (in gloss black) for over 4 years now, still on the same valves and never a moment's regret.  Possibly one of the best designed and most impeccably built valve amplifiers available at any cost.  Difference is with the STA25 Series V, is that you don't end up paying for a grand's worth of bling half inch thick alloy casework, vdu meters or any other gilding.  You get a thoroughly well made no frills power amp that out-classes as many SS amps (in measured response) as it does valve amps and sounds pretty epic.

The measured distortion at full chat on this amp is vanishing low, ridiculously low for any valve amp, and the damping factor on offer matches many SS amps, as output impedance as something like just 0.2 ohms.  The secret behind this is the huge amounts of negative feedback (28 or 29dB) possible whilst keeping the output stage fully stable.  Arthur Radford found a way of doing this in the feedback circuit (something to do with phase delay at frequency extremes) where everyone else failed.  Thing with feedback is that too little is worse than not using any at all, so all those amps using just 5dB or thereabouts could actually be making things worse instead of better.

One thing though (although I'm sure Will would have mentioned this), don't be tempted to roll the phase inverter valves (Phillips manufacture in the STA amps) as the amp is really fussy about these and they need to be specially batched and matched in order to achieve the best measured (and audible) performance.

Cracking amplifiers!

It'd be a brave man who sticks his neck above the parapets Scotty to deride the technical design and both measured/audio performance of any STA15 or 25 amplifier. The looks aren't for everyone but I quite like their industrial, honest charm. What they hide within is possibly one of the very best power supplies I've seen on any valve amp, very good output transformers and a build which is nothing short of tidy and pristine in appearance.

I know that some people like to roll output valves but this is unlikely (in this circuit) to make much, if any difference due to the feedback loop, save for a slight change in power output between the KT77s and EL34s. Personally, I like the rugged reliability of the JJs and they're not stupidly priced.