Upgrading a VOX AD50VT Valvetronix

Discussion in 'Amps & Cabs' started by Dorian, May 8, 2005.

  1. ess

    ess Guest

    ya wouldnt want to lose, er i mean win errrrr :lol: :lol: :lol: :lol:
     
  2. Dorian

    Dorian Active Member

    Joined:
    May 8, 2005
    Messages:
    650
    Likes Received:
    189
    Location:
    LA area
    While you were all having fun (or at least I hope you were), I was listening to the same set of chords, lead, and simple fifths that I played in a similar way through all 11 amp models of the AD50VT set at the "factory default settings" with effects turned off. These recordings were made first with the Electro Harmonix 12AX7 and next with the Telefunken 12AX7. Each little snippet was about 15 seconds each, but listening to the same thing 22 times, repeated several times, was about all I could stand to hear of my guitar work. (It is true that there can be too much of a good thing.)

    I don't expect that I will do this again soon, but I have to say that not all results are conclusive. A solid conclusion is that the AD50VT amp electronics are well matched to the Electro Harmonix tube. The loudness of the amp was significantly lower with the Telefunken tube (in the range of 3-6 decibels). This is easy to adjust in the recording, of course, and I did so to make a fair comparison of the tones.

    The tonal differences with the two tubes was the more important question, of course. For the cleaner and Fenderish amp models, counterclockwise on the amp model selector switch, there was not a very big difference in the tones for the two tubes. There was a difference, but I can't really describe it in words, and I do not expect that everyone would prefer the same tube in a blind test. For the Marshall, Mesa, and Peavey high-gain sounds, located more clockwise on the selector dial, the Telefunken tube gave the tones that I preferred. The Telefunken tube gives something a bit richer and clearer in the midrange. The sound is warm and fat, but there is less harsh buzz than with the Electro Harmonix tube. I think most people will prefer the sound of the Telefunken for these amp models, but perhaps not everyone. The effect is not really very big, but it is definitely there.

    Let me summarize what I have done to upgrade my AD50VT amp, or at least what I think I have done. I have to rate the speaker replacement as the biggest improvement. The clarity and articulation of the Eminence Tonker is significant, and the bass is a bit better than the stock VOX/Celestion. The next biggest improvement, but definitely a notch or maybe two lower in importance, was the replacement of the Electro Harmonix tube with an old Telefunken. (Maybe I will sometime try an old GE that I have also found, but I won't get to this for a while.) Finally, slowing the fan was useful, but not entirely successful in reducing noise for recording. My next project will be to replace the fan entirely, but this will have to wait. I really enjoy playing the faded special through this amp, and I want to enjoy it a while longer before I make any more changes.

    Thanks for all your comments, although I don't claim to understand all of them :wink:
     
  3. Voxman

    Voxman Moderator Staff Member

    Joined:
    Dec 11, 2004
    Messages:
    14,240
    Likes Received:
    581
    Location:
    LINY and Satillite Beach
    I'm curious as to what the results would be if the Telefunken ecc83 was of an unused NOS variety? No matter thanks much for your
    time and posting the most interesting results! Efforts appreciated here.... :lol:
     
  4. skidshark

    skidshark Active Member

    Joined:
    Dec 12, 2004
    Messages:
    8,439
    Likes Received:
    6
    Location:
    tenn-O-see
    thank you very much dorian!! we need more reports like that!!
     
  5. ess

    ess Guest

    i can hereby verify that the VOX ad30vt doesnt work without a tooby in it :lol: :lol:
     
  6. Spunky

    Spunky Active Member

    Joined:
    Dec 12, 2004
    Messages:
    4,109
    Likes Received:
    1
    Location:
    Redondo Beach, California
    Ess,

    What? You tried to run it without a pre amp valve?.....LOL

    It won't work without the speaker hooked up too.....!

    :lol:
     
  7. ess

    ess Guest

    thats right! :lol:
     
  8. skidshark

    skidshark Active Member

    Joined:
    Dec 12, 2004
    Messages:
    8,439
    Likes Received:
    6
    Location:
    tenn-O-see
    i think the tube is actually used in the power amp circuit guys....
     
  9. Spunky

    Spunky Active Member

    Joined:
    Dec 12, 2004
    Messages:
    4,109
    Likes Received:
    1
    Location:
    Redondo Beach, California
    Skids,

    I'll defer to VOX and CB but the tube in the 30 is pre amp and is the reason for the tone. The power amp section is the 30 watt transistor section. The tube being a 12AX7 could not possibly put out 30 watts. A pair of 6L6's, 5881, or other power tubes would work for power output. We get the tone off the 12AX7 and then the power section amplifies it.
    We can't get tube sag or tube rectification but we can get tube tone! :lol:
     
  10. skidshark

    skidshark Active Member

    Joined:
    Dec 12, 2004
    Messages:
    8,439
    Likes Received:
    6
    Location:
    tenn-O-see
    just quoting the manual spunk.....pg.1, first sentence under "main features...
     
  11. Spunky

    Spunky Active Member

    Joined:
    Dec 12, 2004
    Messages:
    4,109
    Likes Received:
    1
    Location:
    Redondo Beach, California
    Skids,

    you gonna make me look at the manual? :D

    I hate manuals!
     
  12. vic108

    vic108 Well-Known Member

    Joined:
    Dec 12, 2004
    Messages:
    6,846
    Likes Received:
    81
    Location:
    Chincoteague, VA
    So, ya think the MESA BOOGIE tube makes a difference Ess?
     
  13. ess

    ess Guest

    reckon so Vic, been playing thru it for the past 5 hours maybe more., overall better and sounding great.

    seems to have cleaned up my neck pup, less mud., no idea how or why.
     
  14. vic108

    vic108 Well-Known Member

    Joined:
    Dec 12, 2004
    Messages:
    6,846
    Likes Received:
    81
    Location:
    Chincoteague, VA
    So, how do ya get to the tube?

    From the baffle side or from the top?

    Do you have to take the side screws out in the process?

    BTW: The TUBE 10 speaker much heavier than the stock speaker!
     
  15. ess

    ess Guest

    unscrew the lot dudey. chassis sits on a shelf so wont fall. tube was a tight fit. not much room for manouvre :wink:
     
  16. vic108

    vic108 Well-Known Member

    Joined:
    Dec 12, 2004
    Messages:
    6,846
    Likes Received:
    81
    Location:
    Chincoteague, VA
    Man! That toob is a muddar to get out and getting
    the new one in, but I did it! Thanks Ess!

    I just leaned the amp on a flouresant light
    and back lit thru the grill and could see alot better!

    Now...putting it all back together!
    (there's more screws than in a Nevada ho' house!)
     
  17. vic108

    vic108 Well-Known Member

    Joined:
    Dec 12, 2004
    Messages:
    6,846
    Likes Received:
    81
    Location:
    Chincoteague, VA
    All together now (all together now...)!

    The tube switch was the hardest part.
    Not much womb ta work in at all!

    It sounds MUCH better!
    Between the new speaker and the new tube,
    it's smoother and has a more balanced tone.

    Thanks to CB, ESS, SGM, SPUNKY, etc...!
     
  18. Spunky

    Spunky Active Member

    Joined:
    Dec 12, 2004
    Messages:
    4,109
    Likes Received:
    1
    Location:
    Redondo Beach, California
    Now you have a kick butt amp.

    I want a new speaker but I think I'm gonna do a 12" upgrade!
     
  19. CharlieB

    CharlieB Active Member

    Joined:
    Dec 11, 2004
    Messages:
    6,128
    Likes Received:
    3
    Pssst... tellin ya.. BIG bottom can be had from Celestion V12-60 (a well kept sleeper of a speaker)
     
  20. Spunky

    Spunky Active Member

    Joined:
    Dec 12, 2004
    Messages:
    4,109
    Likes Received:
    1
    Location:
    Redondo Beach, California
    Vic,

    What is the impedance needed for the speaker to replace the stock one in the AD30VT?
    Is it 8 ohm?

    Thanks
     

Share This Page