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Blues Junior Power Tubes

Discussion in 'Amp Central Station' started by Cyberi4n, Dec 14, 2020.

  1. Cyberi4n

    Cyberi4n Tele-Meister

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    About to do the power and bias mod on my Blues Junior.

    what power tubes are people on here using (and can recommend)?

    Mine’s a blues jnr3 tweed with the Jensen speaker.
     
  2. braveheart

    braveheart Tele-Afflicted

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    Tubes/bias mod ....Read THIS (no1):

    https://www.eurotubes.com/store/pc/fender amp page.htm
     
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  3. marshman

    marshman Poster Extraordinaire Silver Supporter

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    EL84 amps are notoriously hard on their tubes in general (hopefully those mods help with that), so I’ve never felt the desire to install high-dollar A/NOS in those for general purpose playing. And I’ve not got a lot of experience with new production tubes, but I’ve never been disappointed with JJ. I get mine from Antique Electronics, and their service has always been exemplary, as well.
     
  4. Chiogtr4x

    Chiogtr4x Doctor of Teleocity

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    I used to change my power tubes in my 1999 BJ w/o checking/adjusting bias as I always read this was OK- but honestly my results were hit and miss with tube performance and longevity. I used EHX EL-84's

    Then I had some other issues ( power switch/ input jack) requiring our wonderful amp tech's help, and he recommended he install a bias adjustment pot w/resistors ( I think) and I now run JJ EL-84's in it, big and powerful.
    He basically said self-adjusting bias did not mean what we think it did.

    So my answer is a BJ does need bias adjustment either by owner or a tech, for best performance
     
  5. Cyberi4n

    Cyberi4n Tele-Meister

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    Intersting, thanks. What exactly are the BillM mods? I cant seem to find anywhere in detail that explains what his mods are? The ones I've been recommended are as follows

    • Swap white (and black stripe) lead from input switch with the black one to P6 in order to make the amp happier with 240v (UK market) as amp is currently 230v
    • Install a 33k resistor into R52 instead of the 22k one currently there.
    https://ratvalveamps.com/fbj-lifesaver
     
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  6. Andy B

    Andy B Friend of Leo's Silver Supporter

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    Any of the Sovtek manufactured tubes. My favorites are the Tung Sol RI.
     
  7. Chiogtr4x

    Chiogtr4x Doctor of Teleocity

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    I can't find my BillM BJ mods bookmark anymore and don't see the original website when I Google.

    But when I do Google ' BILM Blues Junior Mods' there are video and other article links, that may help

    I know there are mods to make the tone Stack act more like a BF Fender/Twin tone Stack ( so, more real range in those knobs)- I had this one done to mine, as well as other ones than quiet down hum or noise from the Reverb circuit - also done.

    I'm not a tech guy, I just read the stuff, and let someone competent work on my amps!
     
  8. Cyberi4n

    Cyberi4n Tele-Meister

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    Sorry I should be clearer about my intentions.

    I purchased a new BJnr3 tweed in August. In November it was sent back for repair as it was making a loud popping noise on startup. It came back after three weeks but within a week had developed the same noise again and so the store swapped it for another amp. A search on the internet revealed plenty of threads about how the BJnr3 is problematic for the UK market because of a combination of both the voltage being too low, and because the fixed bias combined with that lower voltage caused the amp to eat power tubes.

    I’d like to mitigate that risk by correcting any issues that may exist, hence my interest in these two mods.
     
  9. archetype

    archetype Fiend of Leo's

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    Here's a 'wayback machine' capture of the billm site back in 2016. It probably has what you want to find. Beware, the site performance is s-l-o-w. Be patient.

    Edit: Well, the link took a hike somewhere. Here it is:

    http://web.archive.org/web/20161031185335/http://billmaudio.com/wp/
     
    Last edited: Dec 14, 2020
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  10. saltyseadog

    saltyseadog Tele-Meister Silver Supporter

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    I've had my BJr' since I bought it in 1999. Over the years I have tried many brands of EL84's, including Groove Tubes, JJ, Tesla, Gold Lion, Tung Sol, and several types of NOS bought in Ebay with various results. The best ones I have found are ones which I only found earlier this year which are the new version Electro Harmonix EL84's made in Russia. Much better than the similar priced Tung Sols also made in Russia. I have done many mods to my BJr' over the years but the best one was also done earlier this year when I took out the Fender tube pcb board and replaced it with the green board version from MOX amps. It is made from a much stronger material and I really am impressed by how cool my BJr' runs now even after several hours, I never bought the bias mod version just the standard one. I cannot recommend these boards highly enough. My link is the UK one but he also has a USA one as well. https://reverb.com/shop/mox-black-magic-amplifiers
     
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  11. zombiwoof

    zombiwoof Tele-Afflicted

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    I haven't heard any feedback on them yet, but Tungsol has a new 7189-spec tube that takes more voltage, at least on paper it sounds like it would be perfect for those amps that put stress on the EL84's. As I said, though, haven't heard anything about their sound or longevity.
    Al
     
  12. schmee

    schmee Doctor of Teleocity

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    I used mostly Jj EL84s in my amps that needed that tube. They seemed to work fine in high voltage amps.
     
  13. SlideGuy123

    SlideGuy123 Tele-Meister

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    Mine (BJr II from 2001) seems to like JJs for power and preamp. Sound fine and quiet than other brands.
     
  14. braveheart

    braveheart Tele-Afflicted

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    what do you mean exactly with "lower voltage" in the UK`???
     
  15. braveheart

    braveheart Tele-Afflicted

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    I also need new power amp tubes for my BJR3...
    The stock ones said goodbye with a beautiful "purple haze" glow...
    I will buy a matched set of JJ EL84 with lower power "for blues jr" and I also replace the preamp tubes with JJ ecc83s...but these are interesting,too https://www.eurotubes.com/store/pc/EL844-c57.htm
     
  16. Mr. Lumbergh

    Mr. Lumbergh Poster Extraordinaire

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    Cool, those are reasonable prices, too.
    As for the BillM mods site, it's down because he passed away a couple years ago. Fromel makes something similar that I want to try:
    https://fromelelectronics.com/products/bjr-mods
    One of the things it includes is a higher-value resistor for the bias circuit.
     
  17. VintageSG

    VintageSG Friend of Leo's Ad Free Member

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    The Soviet 6p14p-EV or -K are about as tough as you can get, and sound fine too. Prices vary enormously, so shop carefully.

    UK wall voltages are 240V+ whereas Fender and many others use European spec 230V transformers. This doesn't matter for switched mode supplies, or step-down transformers so much, but step-up transformers end up giving an overvolt which can and does affect certain items. I'm not sure of all Bj models, but a lot have multiple primary options for different markets and it's a fairly simple task to move a few connectors around to set it for 240V.
     
  18. T Prior

    T Prior Poster Extraordinaire

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    JJ's for me, the NON expensive ones. I have an early issue Bjr . I actually think the 12AX7s have more effect on the amps overall performance than the 2 x EL84's. I recently changed all the tubes, I noticed a bit more MID range HONK, as we call it, but I have not gone backwards to investigate why. I have had this amp for around 15 years, I don't think I changed tubes more than twice and I wouldn't have now if I didn't have some 12AX7 squeal.
     
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  19. Henry Mars

    Henry Mars Tele-Afflicted

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    I wouldn't go nuts trying to find the "right" pwr tubes. I have used several current production brands and NOS tubes. Most of them are rebranded Sovtec tubes. I normally use JJ's for power and pre-amp tubes Some times I use EH or TungSol all in all I cant hear the difference. This amp burns trough tubes unless you cool the bias. For longer life the NOS tubes seem to do a little better. All in all when I am using this amp or any amp with a 6V6 pwr tubes regularly they get replaced at least once a year.
    Back in the day we never worried about it but with the circuit design and crummy current production tubes they have these days you need to CYA.
     
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