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Radford STA 15

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Some interesting comments and very high praise indeed for this amp that was recommended to me by Mike Murray, former owner of Stereo-Electrics of Horwich Bolton with, I dunno - maybe 40 years experience in the trade at the time (Sincerely hope he's still with us). I'd taken a Musical Fidelity A100 (Good amp) in for repair when Mike had closed the business down but was still doing repairs, and when I went in to pick it up, I cheekily took the opportunity to pick his brains and ask, in his experience, which amp and speakers were his no' 1 choice. Without hesitation Mike suggested a partnership btw a Radford STA-15 and Tannoy Reds, Golds, or HPD'S. I was already aware of the Radford's at the time and asked him if there would be a preference for the MA15 mono-blocks. He saw no great advantage going down that route and gave me some technical reason why but I can't remember what it was - maybe something about them having the same transformers?.

Many months later I got into an auction battle with some Yank and I was determined, come what may, to beat the bastard and keep this amp in the UK.

Original Mullards, very lightly used and presented on Ebay on a bloody wonky ironing board outside in the garden! Well I won the amp with a rather spendy bid and it arrived a little later in a cardboard box wrapped in a lumberjack shirt! valves still in position in the amp and totally unmolested.

Hooked the thing up to my Tannoy Ardens and I just couldn't believe how good it sounded. This was the first time I had ever arrived in the premier league. I concede that I lost a little bass to my previous NAIM 140, but in all other departments - just something else. Really, soOOO sweet, soOOO clear - such an airy sound.

Rather pleased with myself I took another look at my purchase on Ebay, and couldn't believe it - the guy from Wolves I'd won the amp from had another for sale - absolutely identical. So guess what? - I bought that little ****er as well!

So 15-20 happy HiFi years down the line and I am wondering how I could upgrade. Judging by the enthusiastic answers so far it seem like I may as well buy another guitar instead...or maybe a Leica........unless anyone has an STA-12 for sale?
 
Well done bagging your Radford.

I'm equally happy with my STA25 into my mk1 Ardens. Stop worrying about upgrades and enjoy it.

What are you using for the preamp?
 
I've used them with a variety of speakers, as have my clients. Whilst they work well with Tannoys they sound equally sublime with other makes. I'd probably avoid very current demanding speakers as with most valve amps. Tannoys are a peculiarity as it's all about damping factor-not too much not too little-rather than current delivery
 
Martian Sunrise said:
does everyone use them with tannoys? anyone using other speakers?
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Much to my astonishment reviewer David Prakel (DGP here) actually used an STA25 to drive Gale 401s, which are a notoriously obnoxious load (excellent speakers though). A pair of EL34s in a good amp with excellent transformers is a very powerful amp. A lot more grunt than the little EL84 Leaks or KT66 Quad IIs. All these amps routinely get partnered with ESLs, LS3/5As etc, so you needn’t fear low efficiency assuming the load is sensible. By saying that I bet a Radford would drive things like Magneplanars, Martin Logans etc assuming you didn’t want to blow the windows out.
 
Mike - my most recent acquisition was a Lightspeed passive pre that I have yet to test with the Radfords. Its currently in the Tannoy system with an Audionet Amp1 v2 - a currenty German tranny (No, not a Berlin prostitute!)

Other than that its a bog standard Quad 33 which is certainly not reference standard, but not too bad either. I'm well open to suggestions in this area, however I must say the match with the Amp 1 & LDR is very good indeed.

Tony - interesting that you mention the Gales, Maggies & MLS's because they have all been on my radar recently.

wd40addict - I can assure you that the Radford - Arden tandem would keep any spliff smoking Rasta dub reggae aficionado happy - very happy.:)
 
i have a rothwell indus into my 25 into cheviots, which works well. i would like to try the phono stage in the indus for sale on aos. and some esls, too.
 
I think my Radford SC22 works very well indeed with the STA15. If the whole thing is too sensitive for more modern sources you can fix that using the line input pots on the back of the pre (which I’m ashamed to say I had forgotten about until Mike P reminded me last year.) At the moment I’m using a Khozmo as being able to feed two separate amps is handy, and I’m getting lazy in my old age and appreciate the remote control. All this into HPDs.
 
I'm using a transformer volume control type passive pre (Glasshouse Audio) with my STA25 and with my efficient Tannoys it works very well indeed.

I've also got an SC22 in the back of the cupboard.
 
I've never heard an SC22 but had always heard it was not very good.......one simple upgrade I've done for clients is remove the speaker impedance selector switch and hardwired back to the output transformer. This is neat little tweak that generally gives a good improvement over a thirty year old switch. I've then fitted some decent carbon track pots in place of the switches so you get volume and balance all in one
 
Juancho said:
I've never heard an SC22 but had always heard it was not very good...
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I think that’s how a lot of accepted wisdom begins - no-one has actually heard one but everyone knows they are no good! Let me put it this way - I took mine off the shelf to try it when the STA15 came back from its service and immediately realised my Croft 25 was now superfluous.
 
You are absolutely right of course. One the one hand it would be surprising if a designer so good with power amps couldn't design a reasonable if not great pre. On the other hand the huge majority of glowing reviews are about the power amps not the pres........
David
 
The thing with preamps is the context has changed so much; most people are now dealing with 2V+ sources, when all of these vintage preamps dealt with a handful of mV, so the whole gain structure is wrong and you end up attenuating just to amplify and then attenuate again, then they tend to have complex and unneeded tone control circuits in the signal path, they add hiss and noise etc. That doesn’t mean they are ‘bad’, they are just starting from a place that no longer has much context.

Logically a TVC or really good stepped attenuator makes sense in most cases. I certainly can’t imagine using an active preamp with my crazy high-gain Leaks.
 
Marchbanks said:
I think that’s how a lot of accepted wisdom begins - no-one has actually heard one but everyone knows they are no good! Let me put it this way - I took mine off the shelf to try it when the STA15 came back from its service and immediately realised my Croft 25 was now superfluous.
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Marchbanks and I are perhaps the only members of the PFM SC22 appreciation society. However, I have to admit that I'm not currently using mine. I have given it a decent try though and it sounds perfectly decent to my ears and has a nice sounding MM phono stage too.

I think the SC22 suffers from comparison with the power amps which still offer cutting edge performance. The SC22 might not be cutting edge but it's a perfectly good and useable pre.

Maybe a couple of very vocal people have heard poorly maintained examples and got the wrong impression? There are A LOT of switch contacts inside an SC22 to get dirty and the smaller electrolytics in mine were WAY out of spec when I got it.
 
I also use an sc22 with a radford st25 series 5 amp. It has been serviced and updated by
Will at Radford Revival and sounds fabulous. I suspect all the original tubes in it help the sound but know
doubt Wills expertese in all things Radford plays a large part as does the seperate power supply he designed
and built for it.
Clive
 
I would have expected by now that someone would have put forward a leak TL 12.1 as a contender in the "what's better than a Radford STA -15" debate.
Not that i have heard one, but I am well aware of their reputation and s/h prices.
Anyone got an opinion? or is that a silly question :D
 
Axe.al said:
I would have expected by now that someone would have put forward a leak TL 12.1 as a contender in the "what's better than a Radford STA -15" debate.
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Different amp and context IMO. The TL12.1 only generates 12 Watts, so whilst lovely, is likely to end up in a different sort of system to an EL34 amp like the Radford. Whenever one sees pictures of old Leaks they are almost always in the context of big Tannoys or LS3/5As, that’s certainly where they end up in Japan, South Korea, Hong Kong etc. Radfords don’t seem to have such a clearly defined current context.
 
The Leak 12.1 is a very good amplifier. However, I think its prowess has been exaggerated somewhat over time through a deluge of internet hype. If you like the classic KT66 sound, then the top-range PYE power amplifiers from the 1950s ( PF91 and HF25 ) are IMHO better examples of the type.

If you fancy high end EL34 amplifiers then the Audiomaster 11A with Partridge output transformers is probably the best commercially built implementation of the classic / original Mullard 5-20 circuit.
 
brecklandboy said:
The Leak 12.1 is a very good amplifier. However, I think its prowess has been exaggerated somewhat over time through a deluge of internet hype. If you like the classic KT66 sound, then the top-range PYE power amplifiers from the 1950s ( PF91 and HF25 ) are IMHO better examples of the type.
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I suspect it is more down to quantity, availability and the collective knowledge that brings. The upmarket Pye and Audiomaster stuff are just crazy, crazy rare to the point if you found one you may not find its pair in your remaining lifetime. Beam Echo, RCA etc too. Leak and Quad sold in huge numbers right across the world, and whilst good clean TL12.1s are plenty spendy these days you can at least still hunt one down to make a pair!
 
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