Finished with my valve junior...for the moment

Discussion in 'Amps & Cabs' started by acdcrocker, Jul 11, 2006.

  1. Bonfire

    Bonfire Active Member

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    Thanks for that 1Way! I'm glad you found a little gem! You will have to get pictures up here, ASAP!!

    Yeah, it is alot smoother, but as I said....it just isnt bright enough for lead....great chord crunch....its awesome...but more bite is needed... i'll head down to the shop later and get some caps to try out....





    those tubes better be here soon.......
     
  2. Spunky

    Spunky Active Member

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    Keep it up the Bonfire,

    Use one of the switches for the bright switch and the other for the gain.
    That way you can have a clean or dirty amd.
    Dark or bright.

    the tubes will make a big difference but the biggest is the output transformer.
    The 125DSE seems to be the most popular but I used the 125ESE in both the VJ and the Galaxie 10....
     
  3. Bonfire

    Bonfire Active Member

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    Time for an update!!

    Ok, today I added the bright switch with two caps, a 42pF and a 100pF. Theyre on a DP3T switch, so centre is dark, up is 100pF, down is 42pF....its good like that i find....if only they were on a foot switch!! lol

    here is a shot of the inside:
    [​IMG]

    and another:
    [​IMG]

    now, when i was drilling the hole in the chassis for the bright switch, i was doing so while the PCB was still in there....now i knew this, so i was not pushing down, and just taking it slow...even so, the drill flew right into the board when the hole went through....so lesson no.1:

    TAKE THE BOARD OUT WHEN DRILLING THE CHASSIS!!!!

    i was lucky to have no component damage, only a few legs being torn off:
    [​IMG]

    i also decided to switch the MV pot from 500k log to 500k linear...now, this made a difference...but in the wrong way!! it was even harder to keep the volume down....you see, at 0, it is silent...no sound....you move it fractionally up and you have little quiet lacking tone sound...a fraction more, and its world war 3......so i switched it back to the log pot, which is a tad better, but by no means ideal...

    so can anyone (i'm looking at you CB....you suggested this MV config!!! :p) give me some suggestions on what to try....do i try spunky's way? (the 220k resistor with a 250k pot) different pot value?? different taper (even though ive tried both...and no-one here know what the hell i mean by reverse log....)??

    so here is the finished front....well...i need to improve the labels...but when im completely done i will!

    [​IMG]

    comments? suggestions? criticisms?
     
  4. 1Way

    1Way Active Member

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    This is really impressive! Love the pics. I will have to get myself a digital camera and join in this graphic stuff! I'm getting psyched to mod up my amp too.

    [quote author=Bonfire link=topic=9380.msg134489#msg134489 date=1158643475]
    so can anyone (i'm looking at you CB....you suggested this MV config!!! :p) give me some suggestions on what to try....do i try spunky's way? (the 220k resistor with a 250k pot) different pot value?? different taper (even though ive tried both...and no-one here know what the hell i mean by reverse log....)??
    [/quote]

    I think I understand your dilemma and reverse log idea. I assume there are (basically) two kinds of pots, linier (electrically consistent sweep range) and audio taper (sonically consistent sweep range). For general reference, sound volume is not linier to electrical power, i.e. a 50watt amp is not half as quiet as a 100 watt amp, a 10watt amp is half as loud as a 100watt amp. I think that relationship is a log, but don't quote me on that.

    Anyway, that's why they make audio taper pots, so that the entire sweep range is much more consistent and useful from min to max. By your description, I'd assume that the first pot was the right taper type, but with the wrong specs between itself and the resistor.

    So, you might try different resister specs to see if you can dial it in closer.

    Sorry if I've not helped your situation. I like to get involved in these sorts of matters so that hopefully I can learn something.
    :roll:  ;)
     
  5. Bonfire

    Bonfire Active Member

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    i think tomoz, i'll jump in again and wire the pot backwards, so its reverse log....even though it will turn backwards....we'll see....

    Thanks 1way!!


    p.s. oh, and i think its spelt resistor..... ;)
     
  6. 1Way

    1Way Active Member

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    You bet and thanks for the correction. I hope the Club 20 does not need much for mods. Hoping that plugging in some sweet NOS tubes and a 2-12 cab will suffice... Maybe I can get a decent pic from my cheapy camcorder, but I have not used that function yet... Dang it, I guess I need to read the manual to learn how to get the close-up pic function to work.

    Before I start digging into it much, I need to find out how to safely discharge the stored electrical charges... If I remember right, you get an alligator clip test lead with some sort of resistor or cap or whatever, and connect that to a ground source, so as to safely bleed off the charges. (???)
     
  7. skidshark

    skidshark Active Member

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    works good if you hook the other clip end to any dental work!! ;D
     
  8. 1Way

    1Way Active Member

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    Hmmm, by looking at your personal avatar, I'm not so sure. ;D (Just pullin your fin!)

    I've been zapped enough times with different appliances to respect the safety issues involved. Since my (ancient) apartment has no ground in the outlets, I suppose I'd have to run a wire lead from the water inlet or sewage piping in the basement.

    Any suggestions on how to best run a ground into my apartment?

    Is it as simple as connecting(soldering?) a wire lead solidly to a water pipe and then run it upstairs? Not sure I'd trust connecting it under the kitchen/bathroom sink as the old house has a variety of pipes and patch jobs on the water and sewage lines.

    Is there a recommendable way to test the ground from a kitchen sink pipe?
     
  9. skidshark

    skidshark Active Member

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    ;D ;D ;D

    i would go to the cold water pipe......then to the dental work. if the lights in your apt. go out, then it works...if YOUR lights go out it don't.... ;) ;D
     
  10. 1Way

    1Way Active Member

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  11. Bonfire

    Bonfire Active Member

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    you should be fine if you have a 5 watt wirewound resistor (i dont know what value...) connected to two aligator clips, clip one end to the negative lead on the cap, the other connect to a screwdriver with a plastic handle, and then touch it on the positive end...i believe someone here suggested that....
     
  12. Spunky

    Spunky Active Member

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    That is a 1 megohm 5 watt resistor, either wire wound or ceramic......
     
  13. Bonfire

    Bonfire Active Member

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    thnaks spunk!!
     
  14. 1Way

    1Way Active Member

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    Uhm, but, don't I need a ground source you guys??? I thought you were supposed to bleed the charge to a ground source so the charge leaves the amp...
    :?
     
  15. Bonfire

    Bonfire Active Member

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    if you bleed it to its reletive ground source, thats ok....as in, the ground source of the amp...hmm........ clarification spunk? ceebs?
     
  16. skidshark

    skidshark Active Member

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    now if it was me i'd poke the other end into a kumquat and see what happens, but that's just....me!! ;)
     
  17. *ess*

    *ess* Member

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  18. Spunky

    Spunky Active Member

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  19. 1Way

    1Way Active Member

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    ess, correct me if I am wrong, but I just scanned your document, which linked to another page for the safety/shock side of things, but there, they did NOT explain how to bleed off potentially leathal charges, they showed you how to measure residual charges...
    I think that is the procedure for FINDING a ground fault. In this case, we always know that because of the high voltages and electronic design of a guitar amp, there should be (potentially) leathal charges stored in some of the components, and they NEED to be safely discharged, not tested for charge... Next time, lets quote from a safety source that works with guitar amps as the primary default assumption...
     
  20. Bonfire

    Bonfire Active Member

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    :?
     

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