Marchbanks
Hat and Beard member
I used to get a tiny amount of hissy shash from my STA15, which disappeared after it was serviced IIRC. Either that or my tinnitus worsened and covered it up.
Radford STA 15
- Thread starter Axe.al
- Start date
topoxforddoc
pfm Member
Mike,
Yes, the STAs are ok with normal sensitivity speakers. No problems with my LS3/5as (obviously not as efficient as Tannoys). But I was trying to illustrate the differences between the STA15 and the TRON.
Arkless Electronics
Trade: Amp design and repairs.
STA25 over Tron for me.
Radford designed their own OPT's which are some of the best there's ever been.
Personally I'm not a fan of the "obsessive" neatness of the Tron's (very well done as it is). It add's nothing whatsoever to sound quality, reliability or longevity (in fact the neatest layout is never the best electrically). Extreme neatness designed to give "eye appeal" is NOT the same as good build quality, Tron manages both but the neatness thing must double the labour costs involved.
Radford designed their own OPT's which are some of the best there's ever been.
Personally I'm not a fan of the "obsessive" neatness of the Tron's (very well done as it is). It add's nothing whatsoever to sound quality, reliability or longevity (in fact the neatest layout is never the best electrically). Extreme neatness designed to give "eye appeal" is NOT the same as good build quality, Tron manages both but the neatness thing must double the labour costs involved.
montesquieu
pfm Member
I have owned STA25 and STA100 (twice now) as well as all sorts of PP valve amps from EAR (890, 509, V20, 861), Leak (Stereo 20, Stereo 60 and TL12 monoblocks), Leben (CS660p, 1000p), and the fabled Tim de P/Andy Grove 300b amp for WAD, and at one point not just a pair but a quad (for by-amping) of Audion Silver Knight PP300b, just to name a few.
I'm not the biggest fan of single ended amps, mainly because neither Tannoys nor Quads like them very much. I know some people are very happy with them on high efficiency horns and the like. But for me they hold little interest, having been round the houses with them over many years. I've had a few, most recently Silvercore 833C which used transmitter tubes, several 300b amps (including Audion again, Tekton and Audio Note), Unison Research S8 (845 tubes - possibly the worst amplifer I've ever owned) and assorted other 2A3 and 45 flea power custom jobs. None of which could come anywhere close to the performance of a Radford STA25 into Tannoys.
The STA25 is a fantastic all rounder. The STA100 beats it, the main difference being the bass performance, more 3D depth and detail in the soundstage, and the ability not to run out of steam with tougher speakers than the STA25 is happy with. But the STA25 still manages to run it very close as an overall proposition, so likeable is it and so few its actual flaws. It's just fabulously musical. The STA15 is a great amp too, sounding very similar if a touch sweeter, though facing slightly more limitations when it comes to the speakers it can drive. I believe the main difference is the use of a valve rectifier vs solid state in the STA25. Possibly with a really easy 16 ohm load - vintage Tannoy reds - it might just be the pick of the crop.
I think the STA25 is underrated for two reasons: first and by far the main reason is price. People often like to to pay more in the expectation that they will get more for the money, but the fact you can still get a very good one for under £2k, or a brand new one for not a huge amount more from Radford Revival, means they don't get accorded the esteem they deserve. The fact is into the vast majority of speakers out there (90%+ I would suggest) it will easily toast £15k worth of blingy single ended amp. (I've sat and heard that time after time, to the point where it's quite amusing). By toast I mean provide a far more musical experience, in particular better rhythm, timbre and bass control. Far too many people buy with their eyes - either looking at the casework, or reading the specification or theory behind it - rather than their ears. The second reason is the name. STA25 is not a 25 watt amp, it's a 35watt amp. This does make a difference.
I recall being very deflated once, well over 10 years ago now, in a shootout into some freshly rebuilt Quad ESLs, of an STA25 Mk3, Leak Stereo 20, Quad II monoblocks, and my then-new EAR V20 (its retail price being four times what any of the vintage amps could be got for at the time). I assumed the EAR would easily come top (I was using it myself into Quads at that point). Well it didn't. It came a creditable second (in my view anyway), but the STA25 absolutely walked it. The Quads and the Leak were each pleasant enough (the Quads running my EAR fairly close), but nowhere near the Radford in terms of all round ability or sheer musicality. I got a big lesson that day.
Anyway call me a Radford fanboy if you like, I don't care!
My (new) STA100, rebuilt/restored by Will at Radford Revival:
I'm not the biggest fan of single ended amps, mainly because neither Tannoys nor Quads like them very much. I know some people are very happy with them on high efficiency horns and the like. But for me they hold little interest, having been round the houses with them over many years. I've had a few, most recently Silvercore 833C which used transmitter tubes, several 300b amps (including Audion again, Tekton and Audio Note), Unison Research S8 (845 tubes - possibly the worst amplifer I've ever owned) and assorted other 2A3 and 45 flea power custom jobs. None of which could come anywhere close to the performance of a Radford STA25 into Tannoys.
The STA25 is a fantastic all rounder. The STA100 beats it, the main difference being the bass performance, more 3D depth and detail in the soundstage, and the ability not to run out of steam with tougher speakers than the STA25 is happy with. But the STA25 still manages to run it very close as an overall proposition, so likeable is it and so few its actual flaws. It's just fabulously musical. The STA15 is a great amp too, sounding very similar if a touch sweeter, though facing slightly more limitations when it comes to the speakers it can drive. I believe the main difference is the use of a valve rectifier vs solid state in the STA25. Possibly with a really easy 16 ohm load - vintage Tannoy reds - it might just be the pick of the crop.
I think the STA25 is underrated for two reasons: first and by far the main reason is price. People often like to to pay more in the expectation that they will get more for the money, but the fact you can still get a very good one for under £2k, or a brand new one for not a huge amount more from Radford Revival, means they don't get accorded the esteem they deserve. The fact is into the vast majority of speakers out there (90%+ I would suggest) it will easily toast £15k worth of blingy single ended amp. (I've sat and heard that time after time, to the point where it's quite amusing). By toast I mean provide a far more musical experience, in particular better rhythm, timbre and bass control. Far too many people buy with their eyes - either looking at the casework, or reading the specification or theory behind it - rather than their ears. The second reason is the name. STA25 is not a 25 watt amp, it's a 35watt amp. This does make a difference.
I recall being very deflated once, well over 10 years ago now, in a shootout into some freshly rebuilt Quad ESLs, of an STA25 Mk3, Leak Stereo 20, Quad II monoblocks, and my then-new EAR V20 (its retail price being four times what any of the vintage amps could be got for at the time). I assumed the EAR would easily come top (I was using it myself into Quads at that point). Well it didn't. It came a creditable second (in my view anyway), but the STA25 absolutely walked it. The Quads and the Leak were each pleasant enough (the Quads running my EAR fairly close), but nowhere near the Radford in terms of all round ability or sheer musicality. I got a big lesson that day.
Anyway call me a Radford fanboy if you like, I don't care!
My (new) STA100, rebuilt/restored by Will at Radford Revival:
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Mike P
Trade: Pickwell Audio
I have owned STA25 and STA100 (twice now) as well as all sorts of PP valve amps from EAR (890, 509, V20, 861), Leak (Stereo 20, Stereo 60 and TL12 monoblocks), Leben (CS660p, 1000p), and the fabled Tim de P/Andy Grove 300b amp for WAD, and at one point not just a pair but a quad (for by-amping) of Audion Silver Knight PP300b, just to name a few.
I'm not the biggest fan of single ended amps, mainly because neither Tannoys nor Quads like them very much. I know some people are very happy with them on high efficiency horns and the like. But for me they hold little interest, having been round the houses with them over many years. I've had a few, most recently Silvercore 833C which used transmitter tubes, several 300b amps (including Audion again, Tekton and Audio Note), Unison Research S8 (845 tubes) - possibly the worst amplifer I've ever owned - and assorted other 2A3 and 45 flea power custom jobs. None of which could come anywhere close to the performance of a Radford STA25 into Tannoys.
The STA25 is a fantastic all rounder. The STA100 beats it, the main difference being the bass performance, more 3D depth and detail in the soundstage, and the ability not to run out of steam with tougher speakers than the STA25 is happy with. But the STA25 still manages to run it very close as an overall proposition, so likeable is it and so few its actual flaws. It's just fabulously musical. The STA15 is a great amp, too sounding very similar if a touch sweeter, though facing slightly more limitations when it comes to the speakers it can drive. I believe the main difference is the use of a valve rectifier vs solid state in the STA25.
I think the STA25 is underrated for two reasons: first and by far the main reason is price. People often like to to pay more in the expectation that they will get more for the money, but the fact you can still get a very good one for under £2000k, or a brand new one for not a huge amount more from Radford Revival, means they don't get accorded the esteem they deserve. The fact is into the vast majority of speakers out there (90%+ I would suggest) it will easily toast £15k worth of blingy single ended amp. (I've sat and heard that time after time, to the point where it's quite amusing). By toast I mean provide a far more musical experience, in particular better rhythm, timbre and bass control. Far too many people buy with their eyes - either looking at the casework, or reading the specification or theory behind it - rather than their ears. The second reason is the name. STA25 is not a 25 watt amp, it's a 35watt amp. This actually makes a difference.
I recall being very deflated once, well over 10 years ago now, in a shootout into some freshly rebuilt Quad ESLs, of an STA25 Mk3, Leak Stereo 20, Quad II monoblocks, and my then-new EAR V20 (its retail price being four times what any of the vintage amps could be got for at the time). I assumed the EAR would easily come top (I was using it myself into Quads at that point). Well it didn't. It came a creditable second (in my view anyway), but the STA25 absolutely walked it. The Quads and the Leak were each pleasant enough (the Quads running my EAR fairly close), but nowhere near the Radford in terms of all round ability. I got a big lesson that day.
Anyway call me a Radford fanboy if you like, I don't care!
My (new) STA100, rebuilt/restored by Will at Radford Revival:
Crikey! That STA100 is a beast!
Raoul Duke
pfm Member
Thought I'd try keep this thread going as I've just finished off my STA-15 which I bought back in 2019. The restoration took a little longer than planned! Right off the bat I am incredibly happy with this amp playing through my 12" HPDs.. Having had a fully rebuilt Stereo 20 in the system for the past month, I really feel the STA-15 to be a substantial upgrade. More accurate timbre, a sweeter more pronounced liquid midrange and a bit more power on tap. Yes the mains tranny hums and yes it gets even hotter than the ST20 but this is the proverbial keeper! Have been using a simple passive pre and now just hooked up an Audio Research LS-7 which is working out to be a great partnership.
On valves... I have some old Mullard EL34 in the amp at the moment which measure ok but need a backup set... I have heard good things about the JJ KT77, could anyone chime in as to reliability and sound quality in the STA-15 or if I should hunt down Svetlanas or similar?
20210620_125758 by Jonathan Chiles, on Flickr
On valves... I have some old Mullard EL34 in the amp at the moment which measure ok but need a backup set... I have heard good things about the JJ KT77, could anyone chime in as to reliability and sound quality in the STA-15 or if I should hunt down Svetlanas or similar?
20210620_125758 by Jonathan Chiles, on Flickr
snowman_al
pfm Member
That is looking good, a really nice out come.
Have you got any before pictures?
How 'spooky' too that I was posting another STA15 restoration thread at the same time you posted here!
My favourite EL34 apart from the Mullards, are / were the Svetlana winged C, but they are getting hard to find now sadly.
Have you got any before pictures?
How 'spooky' too that I was posting another STA15 restoration thread at the same time you posted here!
My favourite EL34 apart from the Mullards, are / were the Svetlana winged C, but they are getting hard to find now sadly.
Raoul Duke
pfm Member
Cheers snowman_al 
It did work out well in the end, and very worthwhile I would say!
My series III amp came to me with a Woodside PC board conversion done, and a remade rear panel (OPTS 8ohm tap hardwired to binding posts, voltage selector and octal for pre connection also not present) One of the boards was slightly charred from a cathode resistor and the wiring and solder joints were a bit messy. I then noticed I had a slightly warped chassis and a bent top plate.. so it became a full redo top to bottom using the Radford Revival boards that I populated myself. Will was very helpful and generous with sharing his enormous experience with these. My first choice if I was in the UK would have been sending the amp to RR for reworking. A few before pics:
20190801_104827 by Jonathan Chiles, on Flickr
20201011_131326 by Jonathan Chiles, on Flickr
20190731_164128 by Jonathan Chiles, on Flickr
It did work out well in the end, and very worthwhile I would say!My series III amp came to me with a Woodside PC board conversion done, and a remade rear panel (OPTS 8ohm tap hardwired to binding posts, voltage selector and octal for pre connection also not present) One of the boards was slightly charred from a cathode resistor and the wiring and solder joints were a bit messy. I then noticed I had a slightly warped chassis and a bent top plate.. so it became a full redo top to bottom using the Radford Revival boards that I populated myself. Will was very helpful and generous with sharing his enormous experience with these. My first choice if I was in the UK would have been sending the amp to RR for reworking. A few before pics:
20190801_104827 by Jonathan Chiles, on Flickr20201011_131326 by Jonathan Chiles, on Flickr20190731_164128 by Jonathan Chiles, on Flickr
eguth
pfm Member
Thought I'd try keep this thread going as I've just finished off my STA-15 which I bought back in 2019. The restoration took a little longer than planned! Right off the bat I am incredibly happy with this amp playing through my 12" HPDs.. Having had a fully rebuilt Stereo 20 in the system for the past month, I really feel the STA-15 to be a substantial upgrade. More accurate timbre, a sweeter more pronounced liquid midrange and a bit more power on tap. Yes the mains tranny hums and yes it gets even hotter than the ST20 but this is the proverbial keeper! Have been using a simple passive pre and now just hooked up an Audio Research LS-7 which is working out to be a great partnership.
On valves... I have some old Mullard EL34 in the amp at the moment which measure ok but need a backup set... I have heard good things about the JJ KT77, could anyone chime in as to reliability and sound quality in the STA-15 or if I should hunt down Svetlanas or similar?
eguth
pfm Member
YOUR QUERY AS TO VALVES
I am not the best person to respond, because:
1) years ago, I had a home demo of an original STA 15 and sent it packing in favour of my STA 15/III. Far too coloured (sweet). I once heard an STA 15 that had all wiring changed for pure silver wire. Even sweeter. Even more unacceptable, so far as I am concerned.
That said, and (some of) my prejudices off my chest, I can say I have used JJ KT77 for many years. First of all, they are reliable- at least as reliable as any other valve I have used.
Since you like AR gear, do you know that the head of AR has said that GE KT77 is the best valve ever made? I bought sets from Graves- Morris (GE Chief Engineer) when the factory closed. I still have some matched sets.
I have used Gold Lion KT77 for years. JJ KT77 are the closest to these I have used - very close- and this subject to the proviso that YOU OBTAIN YOURS FROM THE AMERICAN IMPORTER, AND GET MATCHED SETS. Believe there is good reason for this!
No EL34 I have used or heard comes close to good KT77s for realism.
Good luck with your search.
I'm off to study audio psychology, by reading pfm.
I am not the best person to respond, because:
1) years ago, I had a home demo of an original STA 15 and sent it packing in favour of my STA 15/III. Far too coloured (sweet). I once heard an STA 15 that had all wiring changed for pure silver wire. Even sweeter. Even more unacceptable, so far as I am concerned.
That said, and (some of) my prejudices off my chest, I can say I have used JJ KT77 for many years. First of all, they are reliable- at least as reliable as any other valve I have used.
Since you like AR gear, do you know that the head of AR has said that GE KT77 is the best valve ever made? I bought sets from Graves- Morris (GE Chief Engineer) when the factory closed. I still have some matched sets.
I have used Gold Lion KT77 for years. JJ KT77 are the closest to these I have used - very close- and this subject to the proviso that YOU OBTAIN YOURS FROM THE AMERICAN IMPORTER, AND GET MATCHED SETS. Believe there is good reason for this!
No EL34 I have used or heard comes close to good KT77s for realism.
Good luck with your search.
I'm off to study audio psychology, by reading pfm.
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eguth
pfm Member
Bad error in my post (above). It should read: "...sent it packing in favour of my STA25 III" (NOT STA15 III)!
Update on info: U.S. importer of JJ KT 77 is Eurotubes inc. They are located in Oregon. They will test and match sets, and provide a burn -in service. I have used them in past (on purchases from here in England) and found their service excellent. No amount of time and trouble is too much. The KT77 valves they send are every bit worth what they charge.
Update on info: U.S. importer of JJ KT 77 is Eurotubes inc. They are located in Oregon. They will test and match sets, and provide a burn -in service. I have used them in past (on purchases from here in England) and found their service excellent. No amount of time and trouble is too much. The KT77 valves they send are every bit worth what they charge.
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