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Thread: Croft 25R Preamp Tube rolling

  1. #1
    Join Date: Jan 2013

    Location: Birmingham

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    I'm James.

    Default Croft 25R Preamp Tube rolling

    I know this subject has been covered many times way back on the forum but I though I would just post up an interesting observation regarding the Croft 25R preamp tubes.

    I initially bought my Croft 25R with all JJTesla ECC83 S tubes included, one or two of them were cryogenic. I was soon keen to fiddle and mess and so bought a couple of 1970's NOS Tesla valves which were ok but not dramatically better but here lies the conundrum, were they really NOS "New" or just NOS having been rolled a number of times over the last decade, who knows. You have to rely on the word of the vendor unless you have a valve tester.

    I knew Tesla NOS valves were some of the best sounding out there so I endeavoured to purchase some more. This time they were with gold pins and had 32 after the ECC83... Well they were OK and better than the JJTesla ECC83's but not significantly better. I then purchased some more NOS Tesla from a very reputable dealer and they were stunningly good these had the 37 code after ECC83. I stuffed my preamp with these and have been happy for a couple of years. I know preamp tubes can last 10,000 hours but recently one of mine started to sound like an out of tune FM radio. This was positioned in the regulation section.

    I decided to replace these with a couple of NOS valves so had a good read round the net and to my amazement the JJTesla ECC83 S tubes were recommended over a lot of tubes including Telefunkens which I have seen go for 1500 a pair recently! JJTesla ECC83S goes for around 10. Investigating further I found the JJTesla ECC83S was an upgraded replacement for the JJTesla ECC83 and a number of dealers thought very highly of them. So I decided to pop some back in the regulation section of the Croft and wow, I was very surprised indeed. Dynamics were restored and on nearly every level they contributed a superb sonic oomph to the sound. Again I have read of other folk who have found this to be the case.

    I think I may have been to quick in my initial assessment of the JJTeslas and even though the NOS Teslas were running under par, I have been very impressed with the JJ version. Obviously Glenn used the JJ valves to build the sonic performance of the Croft 25 so I should not really be surprised they performed very well.
    I did try them in the phono stage but here I found them a bit bright and forward compared to the NOS Teslas.

    I will be keeping the new JJTesla ECC83S in the regulation stage from now on as they have performed so well in this position. Sometimes it's good to go back over changes you have made as sonic memory is not always great. I recommend to any Croft owners out there to have a go with the JJTesla ECC83S in the regulation stage, you may be as surprised as I was and you will save yourself a few bob!

  2. #2
    Join Date: Jan 2013

    Location: Bristol

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    I'm Justin.

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    I had a pair of Telefunken ECC803S and a pair of Tesla ECC803S, yellow print, 32. Just as good as the Teles I was actually unable to hear a difference I could be sure of, which is very rare for me. Sold the Teles and made money.

    I still personally rate the Tesla's as fantastic. But no experience of the Croft and there is no accounting for personal taste and how things will react in various different systems.

    One thing I will say with valve rolling is a change is as good as a rest sometimes, and the hallmarks in the sound of a particular set of valves can wear thin, in preference to a set you have just swapped in, only to discover in a month or two that actually you've decided you really preferred the original option. Been there, done that. More than a few times.
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  3. #3
    Join Date: Jan 2013

    Location: Birmingham

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    I'm James.

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    Good to hear your views Justin as I know you do a fair bit if tube rolling! Certainly is worth revisiting the past sometimes as it can throw up some surprises.

  4. #4
    Join Date: May 2008

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    I'm David.

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    Has anyone thought to ask Glenn himself? I mean, I'd suspect he'd 'voiced' the 25R to sound as right as possible with the valves he supplies, wouldn't he - he's not daft?
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  5. #5
    Join Date: Sep 2014

    Location: Northern Ireland

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    I'm John.

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    Quote Originally Posted by User211 View Post
    One thing I will say with valve rolling is a change is as good as a rest sometimes, and the hallmarks in the sound of a particular set of valves can wear thin, in preference to a set you have just swapped in, only to discover in a month or two that actually you've decided you really preferred the original option. Been there, done that. More than a few times.
    Agreed

  6. #6
    Join Date: Apr 2011

    Location: Dublin

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    I'm Simon.

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    Quote Originally Posted by DSJR View Post
    Has anyone thought to ask Glenn himself? I mean, I'd suspect he'd 'voiced' the 25R to sound as right as possible with the valves he supplies, wouldn't he - he's not daft?
    I had a short email exchange with Glenn on the subject of valves for my 25. His view was everybody has different preferences.

    I have a NOS mullard in the line stage presently and it sounds lovely.

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  7. #7
    Join Date: Jan 2013

    Location: Birmingham

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    I'm James.

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    My line stage is upgraded to the RS spec so I run a 12Bh7a in this position, a fabulous NOS Brimar from Anthony at Tube Distinctions.

    However when I had a regular line stage I did try all sorts including Mullards but I found a GE 5751 worked well for me.

    Listening to the Croft 25R+ this afternoon and there is information in the recording coming across I was not aware of before. Hard to think that the regulation valves could be that influential to the over all sound. I thought the line stage and certainly the phono stage was more important. Just goes to show you can learn something new all the time even with equipment you have had for years!

    Maybe a techy could explain what the significance is of good valves in the regulation stage. I feel no matter how much you read or what folk tell you at the end of the day your own experience matters most, especially mucking about with valves.

  8. #8
    Join Date: Aug 2009

    Location: West Yorkshire

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    I'm Stephen.

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    Yep I have. His view is that he can source as many new JJ's as he needs and they are always a known quantity whereas it's impossible to source volume NOS valves of any stripe which he also opines are highly variable in quality and performance and as Simon also says personal sonic preference is highly variable. By sticking to JJ's (standard or gold) there will be minimal sonic variation between his individual amps.

    FWIW and after swapping more tubes than I care to remember(Tesla, TFK, Phillips, GE, Amperex, Mazda, Full Music, Mullard, Brimar etc etc) I have settled on NOS Siemens for phono and regulator and Raytheon 12BH7A line stage in my 25RS. I've kept the JJ gold ECC99's in the 7 monos. I don't claim this combo is "better" than any others rather it just produces the sound I like.
    Always a little further

  9. #9
    Join Date: Jan 2013

    Location: Birmingham

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    I'm James.

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    Yes it is all about personal choice and what sound ticks the box for you. I have found that Valves can influence the sound from hyper detailed to rich and mellow. The JJ Teslas veer towards the top end in detail and strong dynamics and as you mentioned Stephen, Glenn uses them because there is consistent availability. However as I have found in particular the ECC83 S sounds very good indeed, even compared to some of the great NOS valves.

    Interestingly I have a NOS Raytheon 12BH7 winging its way from the states at this moment which I ordered a couple of weeks ago. Looking forward to what it achieves in the line stage compared to the Brimar.

  10. #10
    Join Date: Aug 2009

    Location: West Yorkshire

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    I'm Stephen.

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    Quote Originally Posted by Jimbo View Post
    Interestingly I have a NOS Raytheon 12BH7 winging its way from the states at this moment which I ordered a couple of weeks ago. Looking forward to what it achieves in the line stage compared to the Brimar.
    I think you will find the Raytheon more musical and enjoyable than the Brimar. I always find Brimars sound too "dark" for my tastes. Likewise GE and RCA (other than the 1950's RCA long black plates which I like very much)
    Always a little further

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