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Thomas Organ Conversion

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  • Thomas Organ Conversion

    Is it worth attempting to convert a Thomas VL3 organ into a guitar amp? Currently there is power to the organ, but no sound. All of the tubes tested ok in a tube tester. The caps look okay. I will post pics if this generates interest. It has a Leslie style speaker cabinet as well.

  • #2
    I turned an old gulbransen, which was beyond repair into a cool, low watt leslie. I used the cherry wood from the organ. I recapped the amp, added proper grounded plug and fuse, and changed the phono input to 1/4 inch. By rebuilding around the Leslie section and its louvers, the result is a sweet sounding, nice looking "end table" you can plug a guitar into. Not for gigging, but for around the house people get a real kick out of it. I even wired in a momentary foot switch, so you can use the one speed leslie motor as sort of an expression pedal.



    • #3
      I had great luck converting a Thomas AR-1 into a 17 watt "Marshall-style" guitar amp, and others have, too, so a big YES to your question. The result really depends on how much effort and thought you put into it. I am generally in favor of using the chassis, tube sockets, and transfomers but replacing the passive components - resistors, pots and capacitors - and rewiring it using a known, proven circuit.

      Some have had okay luck changing a a few things around but keeping the essence of the organ circuit, and this will work to a degree but can result in lots of troubleshooting, bad components, etc, and it might come out still sounding like ... an organ amp.

      Having the Leslie is huge. One speed motor or two? Mounted on a verticle board with the foam baffle? You can have a lot of fun with those, especially if you have the slow speed. Make a foot pedal with a fast-slow push button and an on-off button and you are good.

      I see that your organ appears to have been made in '63. What tubes does it have? Yes, pics are always welcome.



      • #4
        How to post pics

        I have pictures of the Thomas VL3. I would like to post them here. How is this done?


        • #5
          When you reply, go down below the Preview and Submit to Manage Attachments. Follow the prompts and find the pics on your computer, then upload them.

          Like I did with Big Ol' Lucille:
          Attached Files


          • #6
            how to post pics? you could go to and register for a free picture hosting account.

            "Stand back, I'm holding a calculator." - chinrest

            "I happen to have an original 1955 Stratocaster! The neck and body have been replaced with top quality Warmoth parts, I upgraded the hardware and put in custom, hand wound pickups. It's fabulous. There's nothing like that vintage tone or owning an original." - Chuck H


            • #7
              Thomas Organ Pics

              One of several
              Attached Files
              Last edited by Audie1966; 04-21-2010, 12:10 AM.


              • #8
                Nice. A couple of ceramic Jensen 12s - those also confirm the 1963 date.

                Amp looks to have four 6BQ5s or 7189s and five small signal tubes, a 5U4 rectifier. This would be a perfect candidate for the 36 watt amp project over on It is also the basis for a Vox AC-30 and its many variants. Lots of documentation available to make this into a guitar amp.

                The general idea with these is to use what you've got in terms of chassis, transformers and tube sockets, and then replace the passive components and rewire it as you do to a known guitar circuit. A little cabinet work, either head or combo, and you'll have something you can enjoy and be proud of.

                On that Leslie it is hard to tell from that angle whether its two speed or one. The two speed units have a smaller motor mounted on top of the main motor, and when you switch between them it engages one or the other. We also can't see which speaker was firing into the Leslie baffle.

                Lots of good stuff to work with!


                PS On further inspection it looks to be a stereo power amplifier, with one phase inverter tube for each pair of power tubes. Still could do a 36 watt amp but you might possibly need a different output transformer. Or you could do two 18 watt amps. In the organ, I guess one of the amps powered the two Jensens and the other one powered the Leslie speaker.
                Last edited by RWood; 04-21-2010, 03:53 PM.


                • #9

                  The Leslie is a two speed system. I t turns as it should when the switch is flipped on, and changes speed as it should. I do not have enough knowledge yet to do a safe conversion, though I am working on it. Resources and information are what I am seeking for now.


                  • #10
                    It works

                    I got the unit to make sound as an organ. Though it is very weak and still needs more cleaning. The leslie turns at 2 speeds and does its job as it should. I am trying to decide if it is worthwhile to attempt to make a guitar amp from the thing.


                    • #11
                      Similar - Thomas VT-2, Leslie 10B rotating speaker

                      I'm real glad to find this thread--I bought a Thomas VT-2 maybe 6 weeks back at an estate sale for $15, because it has that rotating Leslie (model "Leslie 10B"). Mine is a 1 speed, it's a single mono amp, and I supposed the organ is a generation older than yours, Audie.

                      Glad to hear you got yours working! I'm just starting the disassembly on my electronics, hoping to salvage the amp & any controls & effects that aren't part of the main big boards. BTW it seems a shame--this organ sounds (well sounded) waaaaay cool, but they are cheap & plentiful on craigslist.

                      RWood, your comments are extremely helpful & confirm a few of my ideas--but I suspect I'm way behind both of you in my knowledge--so I'll be back asking a few questions, I suspect.

                      Here's my pics...thanks again for your knowledge. Tom in Denver
                      Attached Files
                      Last edited by tstockma; 05-09-2010, 02:05 PM.


                      • #12
                        VL3 and VT2

                        Looks almost exactly like the one I have here. Though it made sound it was very weak. Still needs more cleaning. It sat in a garage for years. I rescued it just recently. It was, and may still be, my intention to convert this into a guitar amp. Never having done that before, I appreciate any and all advice on the matter.


                        • #13
                          re: VL3 and VT2

                          Audie, our organs look similar--but yours has a much stouter heart, plus the double rotating speakers (mine has only one). Also, please forgive me if I'm misinterpreting, & telling you some very obvious things...I'm thinking when you say you have it working but with weak sound, you mean the organ itself, not that you've disassembled components & got them working. (If the latter, then you're way ahead of me & this post is foolish!)

                          This project is going to be messy, if someone who hasn't done much wiring takes this on, I would be surprised to see it done. I've built my own computers (boards & plug-in stuff is easy), of more importance is that I've tracked down lots of electrical issues on older cars using circuit diagrams & done lots of modifications on them too. And my plan for this organ still looks pretty brutal to me.

                          If we find one, a real schematic for this organ would be a _nightmare_ to fully trace--however--it's possible that to salvage a few effects out of this thing, that schematic would give us enough clues. As I started my disassembly, I'm tracking some individual wires & controls that I know I want--volume control knob, volume pedal, a few of the electronic effects I hope are either hosted inside the amplifiers or perhaps a few simple hardware parts. I am ripping out big chunks of unwanted electronic hardware & hoping I don't throw out something I want; even just cutting the wrong wires makes tracing something important an impossible task.

                          OK, the basics.

                          RWood has it right, but he's clearly a wiz & I'm a noob--you might be too--his description is for someone who already has a lot of knowledge. RWood, please offer corrections & comments as you see fit.

                          Originally posted by RWood View Post
                          Amp looks to have four 6BQ5s or 7189s and five small signal tubes, a 5U4 rectifier. This would be a perfect candidate for the 36 watt amp project over on It is also the basis for a Vox AC-30 and its many variants. Lots of documentation available to make this into a guitar amp.

                          The general idea with these is to use what you've got in terms of chassis, transformers and tube sockets, and then replace the passive components and rewire it as you do to a known guitar circuit. A little cabinet work, either head or combo, and you'll have something you can enjoy and be proud of.
                          Uh-oh...big stream-of-consciousness mind dump on the way...
                          • Your amplifier, the dusty metal box with tubes on the left, appears to RWood to _perhaps_ be the same one powering the classic Vox AC-30 guitar amplifier (see Wikipedia on VOX amps). (Mine's not cool like yours, it's mono, much weaker, other limits also.) You can use your amp plus some of the other components like transformers, follow RWood's suggestion to see
                          • My advice here--if you want to try that project--since you're currently getting weak sound, try to figure out if both sides aka channels of that amp are working. That thing should rattle your fillings. Get it to work right before disassembling the organ, it'll be much easier to debug.
                          • RWood's suggestion--which I love--is to get the speaker, amp, and a decent amount of the electronics into another cabinet--add extra parts as needed--add "the head" which is the extra circuitry needed to take your guitar input, convert that signal to correct input signal level into the old organ electronics. Viola! It's a great project.
                          • Here's a simpler idea--just take the Leslie rotating speakers into a separate cabinet, find an appropriate gutar amp to drive those speakers, call it done. If getting the proper amp for those old speakers is out, then replace those old speakers with modern ones that a modern amp will drive. The speakers IMO are less important to preserve than is the rotating hardware.
                          • My own project: I want that rotating speaker sound, with openings for external mics or...geeze how over the top can I go? Built-in internal mics?
                          • I'll use the old wood to make a speaker cabinet, the louvered wood panel on the most visible panel, fabric panels on either side, just oversized enough to house the old amp & parts...and make a detachable box for the ancient floor pedal volume control. I'll see if I can salvage a few control knobs & wiring--perhaps a bit more--to preserve a few effects, if those effects on my old organ are in smaller electronic components. Saving the big masses of sound producing boards, tubes, & circuitry is waaay beyond me.) Then I need to develop the "head"--take my input signal from the guitar & convert it to proper signal strength for the ancient amp. Other effects perhaps needed in the head, as well.
                          • I'll perhaps find other old junk furniture with similar wood & build another cabinet to house the 2 speakers that aren't part of the Leslie rotating speaker. The amp's already driving those too, may as well keep them. Sound quality might be pathetic (these are organ not guitar components), might be a waste of time. First I'll try to verify the amp can drive both Leslie speaker plus those extra speakers at the same time--perhaps the organ switches main outputs so they're mutually exclusive? Don't know.

                          Audie, if this sounds overwhelming, then go with your gut--it's a big project. The least ambitious project, a cabinet to house speakers & rotating hardware, even using modern speakers & amp, is still cool. But preserving the existing amp is really cool.

                          I'll take pictures & see about documenting my project, I've seen some similar web articles but not for my hardware.

                          Hope this helps! Tom in Denver
                          Last edited by tstockma; 05-10-2010, 01:35 AM.


                          • #14
                            Guitar Amp Project

                            I am not a noob. However I am no genius either. I do guitar rewiring, fix effects pedals, household wiring, installed network systems. Tubes are a different animal and I know this. I only wish that when my Dad was trying to teach a young fool, tube electronics many years ago, that fool had more interest and foresight. Such is the foolish ways of the young. I lucked into an old tube tester. The organ's weak sound has a lot to do with the key contact points needing cleaning. Many of the electrical contacts on all of the switches have suffered from being stored in a garage. I do wish to build a guitar amp from the poor old thing. I play mostly jazz and blues. No need for anything loud or crunchy. The cleaner the sound the better. I am on the lookout for a good book on guitar amp building and maintenance. Tube amps, that is. Your input is all very welcome and appreciated. I wait with baited breath on the progress of your own project. If I get anywhere with mine I will be sure to post each step as i have done for my other guitar mods.


                            • #15
                              re: VL3 and VT2

                              You _are_ way ahead of me! Nice. Thank you for being gentle. I never had the exposure to a mentor about this stuff, but even if I had I probably would still have pressed ahead boorishly, with trial & many errors...

                              I'll post as I go. That post above is my most serious thinking about this thing yet. My big question is going to be, how do I convert that input signal from the guitar to the correct signal level for the amp?

                              Maybe before I seriously explore that question, I should get the disassembly finished, & identify the input more thoroughly check the amp schematic, which is attached to the interior of the cabinet.

                              Thanks again, & I'll see how many pitfalls I can discover in the coming months.



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