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Thread: Croft 25R Preamp Tube rolling

  1. #41
    Join Date: Nov 2014

    Location: SE London

    Posts: 135
    I'm Oliver.

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    I found the JJECC83S valves to be more dynamic in the phono stage of my 25R, than the NOS Mullards, TJ Full Music, and Genelex Gold Lions I tried at the time, and recall reading somewhere that the JJ's have higher gain than the standard 100, so thought at the time that was the reason for what I heard.

    I must confess to swapping out the supplied regulation JJ's, for the NOS Mullards i already owned, before listening to them, so will give them a try this week.

    I recently replaced the supplied JJ ECC83S with a NOS Mullard M8137 (CV4004) in my Series 7, & that increased the dynamics & punch a notch or 2, or maybe what I heard was reduction of the noise floor

  2. #42
    Join Date: Jan 2013

    Location: Birmingham

    Posts: 4,976
    I'm James.

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    Quote Originally Posted by OD1 View Post
    I found the JJECC83S valves to be more dynamic in the phono stage of my 25R, than the NOS Mullards, TJ Full Music, and Genelex Gold Lions I tried at the time, and recall reading somewhere that the JJ's have higher gain than the standard 100, so thought at the time that was the reason for what I heard.

    I must confess to swapping out the supplied regulation JJ's, for the NOS Mullards i already owned, before listening to them, so will give them a try this week.

    I recently replaced the supplied JJ ECC83S with a NOS Mullard M8137 (CV4004) in my Series 7, & that increased the dynamics & punch a notch or 2, or maybe what I heard was reduction of the noise floor
    I think a lot of folk, including myself, have dismissed the JJ ECC83S valves supplied with the Croft amps and automatically popped in some NOS ECC83's. It was only by chance I popped some JJECC83s valves back in the regulation stage did I appreciate just how good these valves are and they cost peanuts in comparison to any of the NOS valves available.
    VPI Scout 1.1 - Ortofon 2M Black FGS - Croft 25R+ - Croft Series 7 - Spendor SP2

  3. #43
    Join Date: Feb 2014

    Location: Indianapolis, Indiana USA

    Posts: 562
    I'm Timothy.

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    I agree with that, the stock JJ's are indeed pretty darn good. Good enough to keep me from continually messing around, especially at the price. More music, less faffing around....
    Holbo TT-Nag 110-Croft Micro 25 pre-phono/Innuos Zen MK2/LinnenberG Telemann DAC-Preamp/LinnenberG Allegro monoblocs/Duevel Venus/LinnenberG Maestro SE-Senn. HD580
    Equipment on BASE Isolation platforms/DH Labs cabling

  4. #44
    Join Date: Jan 2013

    Location: Birmingham

    Posts: 4,976
    I'm James.

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    So I decided to try rolling the tubes in the Croft 25R back to the original JJTesla ECC83S tubes it came with. I have had great results in the regulation stage so I thought lets try the phono stage.

    The JJ Teslas did not even last the night! Popped the NOS Tesla ECC83 37,s back in. MASSIVE difference. No comparison at all. They slaughter the JJ Teslas on every account! Won't be doing that again. :roll eyes:

    Whilst I had the lid off decided to use some tube damping rings. 2 on the line stage tube and 1 each on the phono stage tubes. I have read I would loose some dynamics and detail but this is not what I have found. The tube rings have given the sound more precision and image stability.

    More listening required.

  5. #45
    Join Date: Nov 2015

    Location: Wolverhampton

    Posts: 10,107
    I'm Oliver.

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    Quote Originally Posted by Jimbo View Post
    So I decided to try rolling the tubes in the Croft 25R back to the original JJTesla ECC83S tubes it came with. I have had great results in the regulation stage so I thought lets try the phono stage.

    The JJ Teslas did not even last the night! Popped the NOS Tesla ECC83 37,s back in. MASSIVE difference. No comparison at all. They slaughter the JJ Teslas on every account! Won't be doing that again. :roll eyes:

    Whilst I had the lid off decided to use some tube damping rings. 2 on the line stage tube and 1 each on the phono stage tubes. I have read I would loose some dynamics and detail but this is not what I have found. The tube rings have given the sound more precision and image stability.

    More listening required.
    Yup, Valve rings do bring the precision. I love them. JJ valves aren't at the level of the original Tesla's or Telefunken.
    Analogue: Technics SP10 MK2 > Phonomac AT-1010 MK6 tonearm > Ortofon Kontrapunkt b > SIMaudio Moon LP5.3RS
    Digital: Orchard Audio PecanPi with JRiver
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    Amplification: Neurochrome Modulus 686
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    Alternative reading: http://www.audioaddictsforum.com

  6. #46
    Join Date: Jan 2013

    Location: Bristol

    Posts: 6,054
    I'm Justin.

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    Quote Originally Posted by Jimbo View Post
    Just had chance to try a nice NOS Raytheon 12BH7a in the Croft 25R+ line stage. Big rich soundstage with great detail and a tad more warmth than the Brimar. Listening with the 2M Black on the front end gives a great analogue experience.

    So after trying a Westinghouse, Brimar, GE, RCA and now a Raytheon I would say my preference would be for the RCA. This 12BH7a has everything. Unfortunately mine is coming to the end of its life so now need to source another beauty.
    I tried loads of 12BH7As years ago.

    My faves were RCAs - mid 70s Mexican production grey plates were good, but even better were the older RCA black plates which I think were 1960s. The plates are longer than the Mexican ones and a shiny metallic black. Ace I reckon.

    The Tesla gold pin yellow print 32 factory ECC803S is probably a bit better than the one you are using. Just a suggestion.

  7. #47
    Join Date: Jan 2013

    Location: Birmingham

    Posts: 4,976
    I'm James.

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    Quote Originally Posted by User211 View Post
    I tried loads of 12BH7As years ago.

    My faves were RCAs - mid 70s Mexican production grey plates were good, but even better were the older RCA black plates which I think were 1960s. The plates are longer than the Mexican ones and a shiny metallic black. Ace I reckon.

    The Tesla gold pin yellow print 32 factory ECC803S is probably a bit better than the one you are using. Just a suggestion.
    I agree with you regarding RCA 12BH7a - superb. I had gold pin Tesla 32s but they were not as good as the 37s I am using.

  8. #48
    Join Date: Jan 2013

    Location: Bristol

    Posts: 6,054
    I'm Justin.

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    Quote Originally Posted by Jimbo View Post
    I agree with you regarding RCA 12BH7a - superb. I had gold pin Tesla 32s but they were not as good as the 37s I am using.
    Interesting re 37s. Were the 32s actually ECC803S though? Or ECC83?

  9. #49
    Join Date: Jan 2013

    Location: Birmingham

    Posts: 4,976
    I'm James.

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    Quote Originally Posted by User211 View Post
    Interesting re 37s. Were the 32s actually ECC803S though? Or ECC83?
    The Gold pin Tesla's were ECC83's

  10. #50
    Join Date: Jan 2013

    Location: Bristol

    Posts: 6,054
    I'm Justin.

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    Maybe try the ECC803S 32 at some stage. It is as good as the Telefunken ECC803S. You may read differently elsewhere but I struggled to tell the two apart after days of trying. Weeks actually now I think about it.

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