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Thread: 6J1 Pre-amp modifications (hum removal)

  1. #41
    Join Date: Jan 2017

    Location: Kansas City, Missouri

    Posts: 590
    I'm Nathan.

    Default

    There's only one way to find out, but I would think it would be more noticable going into a solid state pre-amp than a tube based one.

  2. #42
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 3,383
    I'm Alan.

    Default Further modifications to the 6J1 pre-amp

    Having tried this now in various guises; gain stage - triode and pentode operation, buffer (cathode follower) operation, and finding very clean and transparent performance, I have added a couple more valves to try and give some 'tubiness' to the sound.

    I have fitted a couple of 6418 miniature pentodes, wired as triode gain stages before the 6J1's in buffer configuration.
    Looking at the spec sheet for the 6418 they show quite a lot of harmonic distortion, but listening through it gives a very satisfactory sound at typical CD levels.



    I think it's possibly what you wanted now Oliver

  3. #43
    Join Date: Nov 2015

    Location: Wolverhampton

    Posts: 2,199
    I'm Oliver.

    Default

    Quote Originally Posted by Firebottle View Post
    Having tried this now in various guises; gain stage - triode and pentode operation, buffer (cathode follower) operation, and finding very clean and transparent performance, I have added a couple more valves to try and give some 'tubiness' to the sound.

    I have fitted a couple of 6418 miniature pentodes, wired as triode gain stages before the 6J1's in buffer configuration.
    Looking at the spec sheet for the 6418 they show quite a lot of harmonic distortion, but listening through it gives a very satisfactory sound at typical CD levels.



    I think it's possibly what you wanted now Oliver
    Lol, we can test it tuesday ! I don't know how you think of these things

    Sent from my EVA-L09 using Tapatalk
    Mission 774 OG Tonearm > Toshiba SR 370 Turntable > ZYX R50 Bloom cartridge > Firebottle OTP Phono Stage > Firebottle Monoblocks > IXOS Speaker Cables > Pioneer CS-77A Speakers

  4. #44
    Join Date: Jan 2017

    Location: Kansas City, Missouri

    Posts: 590
    I'm Nathan.

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    Cool. I'm still waiting on mine to show up. The transformer is here, but that's the last piece I need. I should just do it point to point.

    Sent from my Z981 using Tapatalk

  5. #45
    Join Date: Jan 2013

    Location: Bristol

    Posts: 2,997
    I'm Justin.

    Default

    Posted this on the Wam 5 years ago. I am amazed the ebay link works now. It was about 50 then I am sure. High end then It broke very quickly unfortunately. One channel went.

    http://www.ebay.co.uk/itm/Valve-Clas...item1c27c0be9d

    Put this in front of the A500, with the volume pots on the A500 reduced, ignoring all the stuff about the distortion the Behringer pots introduce. Then rip out the Russian 6922 and put a Tesla gold-pin E88CC from 1972 in the headphone amp. If you ask, I'll sell you the Tesla, as I have one spare.
    The Tesla gives mad but good imaging in that precise headphone amp - dunno why but they do. I know cos I have done it and the results are surprisingly entertaining. I really enjoyed it feeding my little M&Ds. If the imaging gets a bit too insane, shove a Mullard 6922 in it, which I can also supply.

    Just ordered me a quad of the Teslas for the EAR preamp. Be interesting to see how they work in it.

    Obviously you need to use the headphone jack output into the Behringer, in case you were wondering. And don't blame me if the headphone amp stops working as mine eventually did.

    Trust me the results are REALLY nice - much better than you would expect. Much, much better.
    Until we get there... just let it flow.

  6. #46
    Join Date: Jan 2017

    Location: Kansas City, Missouri

    Posts: 590
    I'm Nathan.

    Default

    I don't think I could mount a Mullard on a PCB. That seems like sacrilege.

    Sent from my Z981 using Tapatalk

  7. #47
    Join Date: Jan 2017

    Location: Kansas City, Missouri

    Posts: 590
    I'm Nathan.

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    They sent me the wrong boards. This looks like a SRPP driver board. It should serve the same purpose. A wall wart isn't going to drive this one.





  8. #48
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 3,383
    I'm Alan.

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    It's not is it.

    Unlucky.

  9. #49
    Join Date: Jan 2017

    Location: Kansas City, Missouri

    Posts: 590
    I'm Nathan.

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    I ordered one full kit and some of the boards. Maybe the full kit will be right.

    This one doesn't look bad, but the transformer won't be cheap. I'll have to try and find a surplus one.

  10. #50
    Join Date: Jan 2017

    Location: Kansas City, Missouri

    Posts: 590
    I'm Nathan.

    Default

    I got the full kit today. The components look decent. It's definitely got more than $10 worth of parts in the bag.

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