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  • Valvetronix mods - 6v6 power amp, midi stuff

    I have enjoyed the vox valvetronix AD120 amp very much for the last 3-4 years, but just never seemed to get a great sound out of it. I tried different tubes, thought it was my guitars, I changed speakers (which made a difference definately) to a Celestion Vintage 30 and a G12H30, made a baffle to make it closed back (this was before they had the VTX series), used an eq to add lows, but it still didnt sing like I wanted it to. Course I know I have picky ears...but anyhow....

    Now, I havent changed the preamp tubes inside for a while, maybe they are fine, I just never was truely satisfied though, so I found an old reel to reel player/recorder from my church that used a 1 6v6 single ended power amp, had the power amp modifyed, and now i run the line out from the pre-amp to the tube power amp (5 watts I think...basically what the atomic amp does), and back into the speakers in my valvetronix, and WOW ....WOW WOW WOW. There it is. After 4 years, I am now using my EQ on each valvetronix amp as an tool for art rather than trying to "fix" the sound by adding the lows I thought needed to be there, or whatever. Just my two cents. Anyone else had a similar scenerio?

    Maybe I just had bad 12AX7's the whole time...who knows.

    Anyhow, I am looking now for more info because I am a moddifier at heart and like to tweak with stuff. Does anyone know how the foot controllers work for this ( I have the small one VC12 I think)? Does it send a midi type signal to the amp over the CAT5? I found a topic/article about this a long time ago and cant find it anymore. Any help on this? Does anyone know how it communicates at all? Links?

    Or any comments at all?

    Kurt

  • #2
    you may want to try searching around on these forums to get the info you are looking for

    http://www.patchtronix.com/

    or

    http://www.valvetronix.net/

    good luck
    Agile AL-3000 Prestige (Cherry)
    Epiphone DR 500MNS
    Ibanez GAX 30
    Hohner 300G acoustic
    VOX AD120VTX
    VOX DA-5
    Digitech RP300a
    Behringer EQ700
    BOSS OS-2

    Comment


    • #3
      Originally posted by rattleandhum123 View Post
      I have enjoyed the vox valvetronix AD120 amp very much for the last 3-4 years, but just never seemed to get a great sound out of it. I tried different tubes, thought it was my guitars, I changed speakers (which made a difference definately) to a Celestion Vintage 30 and a G12H30, made a baffle to make it closed back (this was before they had the VTX series), used an eq to add lows, but it still didnt sing like I wanted it to. Course I know I have picky ears...but anyhow.... <BR /><BR />Now, I havent changed the preamp tubes inside for a while, maybe they are fine, I just never was truely satisfied though, so I found an old reel to reel player/recorder from my church that used a 1 6v6 single ended power amp, had the power amp modifyed, and now i run the line out from the pre-amp to the tube power amp (5 watts I think...basically what the atomic amp does), and back into the speakers in my valvetronix, and WOW ....WOW WOW WOW. There it is. After 4 years, I am now using my EQ on each valvetronix amp as an tool for art rather than trying to "fix" the sound by adding the lows I thought needed to be there, or whatever. Just my two cents. Anyone else had a similar scenerio? <BR /><BR />Maybe I just had bad 12AX7's the whole time...who knows. <BR /><BR />Anyhow, I am looking now for more info because I am a moddifier at heart and like to tweak with stuff. Does anyone know how the foot controllers work for this ( I have the small one VC12 I think)? Does it send a midi type signal to the amp over the CAT5? I found a topic/article about this a long time ago and cant find it anymore. Any help on this? Does anyone know how it communicates at all? Links? <BR /><BR />Or any comments at all? <BR /><BR />Kurt
      I can't believe it... I have a Vox ad120VT and I want to modify the amp just like you did. Please explain me what I need and how I'm supposed to do this thing. I can pay a little money (around 30 dollars) if you really want for the information. I really need it: I've got just this amp and I haven't thousands of dollars to buy a Friedman amp or something like that. I would be very grateful if you can explain it to me. Thanks in advance, Nicholas

      Comment


      • #4
        Originally posted by rattleandhum123 View Post
        I have enjoyed the vox valvetronix AD120 amp very much for the last 3-4 years, but just never seemed to get a great sound out of it. I tried different tubes, thought it was my guitars, I changed speakers (which made a difference definately) to a Celestion Vintage 30 and a G12H30, made a baffle to make it closed back (this was before they had the VTX series), used an eq to add lows, but it still didnt sing like I wanted it to. Course I know I have picky ears...but anyhow.... <BR /><BR />Now, I havent changed the preamp tubes inside for a while, maybe they are fine, I just never was truely satisfied though, so I found an old reel to reel player/recorder from my church that used a 1 6v6 single ended power amp, had the power amp modifyed, and now i run the line out from the pre-amp to the tube power amp (5 watts I think...basically what the atomic amp does), and back into the speakers in my valvetronix, and WOW ....WOW WOW WOW. There it is. After 4 years, I am now using my EQ on each valvetronix amp as an tool for art rather than trying to "fix" the sound by adding the lows I thought needed to be there, or whatever. Just my two cents. Anyone else had a similar scenerio? <BR /><BR />Maybe I just had bad 12AX7's the whole time...who knows. <BR /><BR />Anyhow, I am looking now for more info because I am a moddifier at heart and like to tweak with stuff. Does anyone know how the foot controllers work for this ( I have the small one VC12 I think)? Does it send a midi type signal to the amp over the CAT5? I found a topic/article about this a long time ago and cant find it anymore. Any help on this? Does anyone know how it communicates at all? Links? <BR /><BR />Or any comments at all? <BR /><BR />Kurt

        i, I've seen your post on the net about your modded Vox valvetronix...and I registered just to talk with you. I have a Vox Valvetronix AD120VT and I need improvements from the sound quality. I need your help because that's my only amp. Please explain me what i need and what i'm supposed to do. I would be very grateful if you help me out. Thanks in advance, Nicholas

        Comment


        • #5
          I wouldn't count on the preamp tubes varying the tone in valvetronix amps very much. The tubes use a very low voltage to make them operate and they are mainly used to color the sound. Normal tube amps use up to 240v volts on the preamp to make them operate normally. In starved circuit designs they often make them run with a low and a plate voltage between 9~12 volts. This isn't nearly enough to get any kind of decent harmonics or compression and what you're mainly hearing nearly all solid state with some tube coloration which isn't always better then using just solid state all; the way through.

          If you're looking for a good tube option in these kinds of starved voltage circuits I did allot of experimentation with different tubes. I tried at least a dozen different Soviet and Chinese tubes and found the Electroharmonix is one of the best sounding. Most of the Sovetec tubes sounded pretty muffled in comparison. In my Marshall Valvestate head I wound up using a 5751 tube which cleaned up the drive a bit.

          I had a Few, a GE, a Sylvania and an RCA which I had hanging around in my collection but some of the newer tubes sounded better then those (just because they are vintage doesn't mean they are good. With the exception of Military grade tubes, you actually had more bum tubes back in the day then you do now because the quality standards were not very good for commercial quality tubes and any old stock you may find may be just old tube junk tubes cannibalized from old gear with unknown burn hours on them. Tubes are good for maybe a year in guitar amps before they become microphonic from vibrations and heat. Low voltage designs may last as long as 5 years or more because they run at low voltage and low heat).

          Comment


          • #6
            Originally posted by WRGKMC View Post
            I wouldn't count on the preamp tubes varying the tone in valvetronix amps very much. The tubes use a very low voltage to make them operate and they are mainly used to color the sound. Normal tube amps use up to 240v volts on the preamp to make them operate normally. In starved circuit designs they often make them run with a low and a plate voltage between 9~12 volts. This isn't nearly enough to get any kind of decent harmonics or compression and what you're mainly hearing nearly all solid state with some tube coloration which isn't always better then using just solid state all; the way through.
            They are used as diodes for clipping just like the diodes in some solid state amps.


            you can't control the wind but you can learn to sail

            contentment is true wealth

            Comment


            • #7
              I have had a AD 120 VTH (120 watt stereo head version) since they were introduced. I found the best sound comes out of it when it is loud.
              So no real (bedroom level) benefit from THAT amp. But it sounds great when turned up and the power scale is at least at 30 watt (x2).
              It has also been a BEAR to keep working. I've found a LOT of cold solder joints in the power section. Then I've had to do the old
              Deoxit in ALL the input jacks and there's a LOT of them on this amp. But yeah... turn that sucker up on a quality speaker cab and it delivers quite well in the toan dept.
              If only I was all thumbs

              Comment


              • #8

                Originally posted by onelife View Post

                They are used as diodes for clipping just like the diodes in some solid state amps.
                On my Marshall valve state the tube is wired in two low gain stages in series.

                http://elektrotanya.com/PREVIEWS/634...100w.pdf_1.png

                In the Vox AD120 they seem to use something called a valve reactor circuit and use a push pull dual triode configuration and the tubes produce about 1w or power into a transformer which drives the power amp. The tubes must be getting some higher voltages to get 1 watt and the amp does have a fairly good sized power transformer.

                Couldn't find a full schematic but according to this. http://www.voxshowroom.com/uk/amp/ad120vtx_hood.html

                They use this circuit. http://www.legendarytones.com/vtSchematic.gif





                Comment


                • #9
                  AD120V(tx) pretty sure had a 200+ Vdc plate. It isn't a starved design. 1W though is right. Then it's coupled via PT to a SS output circuit.

                  Link to the print:
                  http://www.valvetronix.net/docs/AD12...l_Complete.pdf
                  Last edited by HKSblade2; 09-18-2014, 05:31 AM.

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