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Spare set of output valves for Radford STA25

Just heard from my Russian friend in Moscow - she says that they make the best valves in the world, because they are Russian, and why make bad ones - they use them themselves, so don't want them going wrong (she's a world expert in explosive technology, so she probably knows things we don't!). EH now on order from Thomann and I saved a bit by buying non matched - I'll check them in the amp on arrival, then put them on the shelf.

I've been saying "buy Russian" when it comes to valves for years!:)
 
It's all very confusing - there are manufacturers, and there are brands and actually working out what is what is a nightmare. There is an assumption that 'they don't make them like they used to' but in my youth I had all sorts of valve things, like radios etc, and valves going pop was almost the norm, and those must be the valves from the 50s and 60s, so I'm not really prepared to pay a premium for something made years ago and stored in a drawer somewhere. I'd like to think that modern manufacturing could make good quality valves as they are no longer a mass product and they sell into a non-price sensitive market. I could (and probably am) be wrong, but at the moment I like what I'm hearing from my EH=Sovtek valves so I may well just get those - I can get a set for about £80 so that is ok. Can someone confirm that I don't need matched valves in the Radford as long as I bias them on installation?
Hello I am Simon, new here this is my first post but I have experience of JJ valves in my 2 1/2 year old Radford Revival STA15. I assumed because Will fitted JJ valves that they were okay sadly it has not been the case as two E34L valves have failed and the GZ34 went very quickly. This isn't my only power amp so they hadn't had excessive use. I switched to N.O.S Svetlana winged C EL34 and the have been no problem and sound better. The biggest surprise was putting Mullard GZ34 in place of the JJ GZ34 make a bigger improvement to the sound than changing the EL34 output valves. I realise Jem your amp doesn't use a rectifier valve but it shows current production valves just don't seem to be as good as N.O.S valves. Tony knows this and is fortunate to have a good stock of spares for his Leek Stereo 20. Good luck finding some, hopefully will improve the sound from your STA25.
 
I'm not really looking to improve the sound of my STA25, it maybe isn't perfect, but it drives just the panels of ML Summits so it has nowhere to hide and sounds as good as any system I've ever heard at any price. I just need a spare set, just in case something fails, as they inevitably will as we listen to it for fifteen hours a day, seven days a week. I'm not looking for a valve 'sound' I just want total realism, and I think I've got that. I've decided that the sovteks are fine, so I've ordered a new set. When they arrive I'll fit them, test the bias, and hope they sound the same. If they do, they will go in the cupboard ready for the day that one of the EL34s dies. They have been more reliable than the KT90s in my EAR890 already.
 
I'm not really looking to improve the sound of my STA25, it maybe isn't perfect, but it drives just the panels of ML Summits so it has nowhere to hide and sounds as good as any system I've ever heard at any price. I just need a spare set, just in case something fails, as they inevitably will as we listen to it for fifteen hours a day, seven days a week. I'm not looking for a valve 'sound' I just want total realism, and I think I've got that. I've decided that the sovteks are fine, so I've ordered a new set. When they arrive I'll fit them, test the bias, and hope they sound the same. If they do, they will go in the cupboard ready for the day that one of the EL34s dies. They have been more reliable than the KT90s in my EAR890 already.
Hello again, I understand and you are very lucky you can listen to it for 15 hours a day, seven days a week clearly you are enjoying your Radford a great deal just as it is. As a matter of interest which pre-amp do you use with it ? I used to partner my STA 15 with an EAR 868 pre but now use a Nagra Melody and find that a better combination.
 
I have the luxury of two buildings, two systems and only two sources, so I don't need a preamp in my main system. It's both simple, and complicated!

My main, 15 hrs a day music system is digital. I have maybe a thousand CDs ripped to my server in the loft, running LMS and several Squeezebox devices, but the source in the main system is a Raspberry Pi, running PiCorePlayer connected by USB to an Audiolab MDAC modified by the designer John Westlake. This is a USB DAC with digital volume control. This goes via XLR balanced connections to a a box that has a miniDSP balanced unit in it. The analogue full range signal goes to the STA25 then via a passive x-over to the Martin Logan Summit electrostatic panels. The Bass side of things is via the miniDSP unit that corrects some bass resonances and then uses the built in bass section of the Summits to do bass - flat to 20Hz in room with no peaks (some troughs that are difficult to fix). So the Radford only has to be transparent and dynamic from 270Hz upwards - it doesn't find that a challenge.
I've never found a preamp that actually adds anything (how could it?) and when I replaced a Naim NAC82 + 2 x Hcap + NDAC with the stock Audiolab I was absolutely astounded. I'd discovered many years ago that analogue volume controls seem, to me, to have more influence on sound quality than quite a lot of other stuff so when I finally accepted that a digital volume control (within limits) is ok, and actually listened, I realised that maybe less is more. So the STA 25 is basically the only thing between the analogue output of my DAC and the panel. I'm hoping that maybe the next SQ lift will be a better DAC, but maybe we are quite near the top of the tree already - the difference in quality between recordings completely swamps all other factors. Some recordings are sublime, but some are really dire. We mainly listen via Tidal now. Good 16/44 is actually ok, though 24/96 would be nice.

Our analogue system is in a different building - Transcriptors Skeleton/Vestigial Decca London Gold "Naim" boards phono amp with Supercap PSUs, Radford SC22 with custom PSU, Gainclones and Quad ESL57s (and a few other bits).

The intention was to move the STA25 to the vinyl system, but this may not happen. My health situation doesn't support long term plans at the moment, so my main intent at the moment is to leave two useable systems. Rather than optimise them for the long term. My wife is unlikely to use thge vinyl system as much, long term, so I'm working on getting the digital system as good as possible, and properly documented for ongoing use.
 
Since the President of Audio Research declared that the GE KT77 is the best valve ever made (I used these for years, and when the factory closed in London I bought more sets from Mr. Graves-Morris , personally).

I stopped using them when their value escalated: regard them as an investment rivaling vintage port- so searched for the nearest best. I found JJ KT77 are just the job. I was advised by the Chief Honcho of the American importer that he ran extra tests before shipping them out from U.S., to cull the dodgy ones with the gremlins among his JJ imports. I found that what he said makes sense. From then on I bought all my JJs from U.S. importer direct. I had some cryoed here in U.K. ... not worth going to these lengths, in my opinion, if you are using bog standard Radford STa 25s- they have to be seriously upgraded if you are to be enabled to hear the benefits- rest of the system being capable of sufficient resolution.
 
I have the luxury of two buildings, two systems and only two sources, so I don't need a preamp in my main system. It's both simple, and complicated!

My main, 15 hrs a day music system is digital. I have maybe a thousand CDs ripped to my server in the loft, running LMS and several Squeezebox devices, but the source in the main system is a Raspberry Pi, running PiCorePlayer connected by USB to an Audiolab MDAC modified by the designer John Westlake. This is a USB DAC with digital volume control. This goes via XLR balanced connections to a a box that has a miniDSP balanced unit in it. The analogue full range signal goes to the STA25 then via a passive x-over to the Martin Logan Summit electrostatic panels. The Bass side of things is via the miniDSP unit that corrects some bass resonances and then uses the built in bass section of the Summits to do bass - flat to 20Hz in room with no peaks (some troughs that are difficult to fix). So the Radford only has to be transparent and dynamic from 270Hz upwards - it doesn't find that a challenge.
I've never found a preamp that actually adds anything (how could it?) and when I replaced a Naim NAC82 + 2 x Hcap + NDAC with the stock Audiolab I was absolutely astounded. I'd discovered many years ago that analogue volume controls seem, to me, to have more influence on sound quality than quite a lot of other stuff so when I finally accepted that a digital volume control (within limits) is ok, and actually listened, I realised that maybe less is more. So the STA 25 is basically the only thing between the analogue output of my DAC and the panel. I'm hoping that maybe the next SQ lift will be a better DAC, but maybe we are quite near the top of the tree already - the difference in quality between recordings completely swamps all other factors. Some recordings are sublime, but some are really dire. We mainly listen via Tidal now. Good 16/44 is actually ok, though 24/96 would be nice.

Our analogue system is in a different building - Transcriptors Skeleton/Vestigial Decca London Gold "Naim" boards phono amp with Supercap PSUs, Radford SC22 with custom PSU, Gainclones and Quad ESL57s (and a few other bits).

The intention was to move the STA25 to the vinyl system, but this may not happen. My health situation doesn't support long term plans at the moment, so my main intent at the moment is to leave two useable systems. Rather than optimise them for the long term. My wife is unlikely to use thge vinyl system as much, long term, so I'm working on getting the digital system as good as possible, and properly documented for ongoing use.
Hello again Jem, thank you for the very comprehensive reply. I am sorry to hear your health situation doesn’t support long term plans at the moment and hope things improve. It’s interesting you have two spaces and two systems as I am in the same situation but mine both use turntables and cd, not got into streaming and digital music yet. I have my main everyday system with Technics SP10r
Timestep 12 in arm / SPU 95 cart, Esoteric Cd Nagra Melody pre & Electrocompaniet power & Apogee Caliper Signatures. My second vintage system is a Schopper Thoerns TD124 , 12 in Ortofon arm from Alfred Bokrand Ortofon SPU GME cart, Cambridge 840c cd, Electrocompaniet preamp Radford STA15 from Will Moores ,Quad ESL57QA from Manfred Stein. It’s interesting to compare and contrast as both are very enjoyable they just do things differently.
 
Electroharmonix EL34s arrived today. As the amp was off at the time I removed the old valves and had a proper look at them. two have no identifying marks on the glass at all, one has what I interpreted as EH, but the fourth is a Phillips EL34. I don't know where Phillips fit in the panoply of the greats, but looking at the others I reckon they are all Phillips. On the same bias as the Phillips the EH were all around 2.5v rather than 2.0v so I tweaked the bias, left them for an hour, re-checked - all the same, so there is a small difference between the two sets, but not wildly so. Left the EH in and brought in the golden ears (wife) and she concluded there was no discernible difference (my view too) so I've left the EH in, as then we don't need to address the worn out valve issue for a few more years.
 
Rather than starting a new thread, I thought it best to bump this one.

One of the JJ EL34s has gone cloudy and I have a couple of questions.

Can I just replace one/two rather than all four?

How close do they need to measure before you notice a difference?

Ideally, I'd have 500 bananas to throw at a matched quad NOS Mullards, but alas that isn't the case.

If anyone has any interesting valves in their drawer - let me know!
 
I wouldn’t get too hung up about matching if I were you. I haven’t even got matching types on my Radford (three xf2s and one xf4) but it sounds great to me and (I’m told) everyone else who hears it.
 
The very first and as it happens only valve I have ever bought was a brand new Mullard UL41 when they were still being made back in 1965.

It failed heater cathode short after 20 minutes.....
 
Yes, another endorsement for the early 'Winged C' EL34s from me. Build quality, and reliability are excellent and they sound good as well. I have them fitted in my Radford STA12.
 


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