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converting a 251 amplifier (6C) to behave as a 122 amp (6H)

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  • converting a 251 amplifier (6C) to behave as a 122 amp (6H)



    A couple days ago I had a friend let me know that his church was selling a leslie, and I came to find out that it was a 251--and they sold it to me for an extraordinary deal. The problem is that I've been using a 6122 connector kit on my A-100 to connect it to a 21-H (with a carribean controls 2-speed upgrade) for the past year or so. I saw online that somebody had converted a 251 amplifier "into" a 122 amplifier--or at least changed the wiring so that it would be compatible with a 122 style connection. Does anybody have any insight on performing such a conversion?</P>


    Also, the 21-H has an output that allows for daisy chaining leslie speakers together. Assuming that everything works out well converting the 251 amp into a 122 amp, and since the amp in the 21-H is also 6H style, would I be able to run the organ into the 21-H and then into the 251 (converted to look like a 122)? That would be sweet. I know that I would need to get a power relay before daisy chaining any leslie together.</P>


    Any insight is greatly appreciated. </P>


    Thanks mates.</P>


    Oh, another idea I've been playing with is simply purchasing a 122 amp and installing it in place of the 251 amp. I read that all the components of a 251 are identical to those in a 122, with exception of the amplifier. Could I simply just perform this swap?</P>


    Thanks again.</P>

  • #2
    Re: converting a 251 amplifier (6C) to behave as a 122 amp (6H)



    I'd recommend replacing the amp outright - rather than carve up a perfectly good 251 just to accomodate the switch on the organ. Either that, or do some work with the switches.</P>


    The switching for the "H" and the "C" type is incompatible for the "daisy chain" setup. Each Leslie would require it's own cable from the organ.</P>


    Buy a 122 amp - that'll do everything you want. Send me the 251 amp, I'll dispose of it properly.</P>
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    • #3
      Re: converting a 251 amplifier (6C) to behave as a 122 amp (6H)



      I have the exact situation...so far the feedback I got was replace the amp, or get schematics for both and have a tech sort it out. Unfortunately, my electronics skills are limited.
      I was rather hoping that someone out there had made this modification, and had a feel for what was involved...or better yet a parts list, so I could save the cost of having a tech having to sort things out. I have not been successful in locating this information anywhere as of yet.
      Exchanging the amp is certainly the easy option...but it is also the most expensive...the 122 amps I have seen so far are rather pricy, and the market for 251 amps is not that great.</P>


      Please letme know what solution you come up with.</P>


      Bob</P>
      In theory, there is no difference between theory and reality.
      In reality, there is.
      '54 C-2 & Pair of 122 Leslies
      H-324/Series 10 TC
      '35 Model A (Serial# 41) with a 21H
      Look at some of my rescues:
      https://www.flickr.com/photos/58226398@N03/albums

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      • #4
        Re: converting a 251 amplifier (6C) to behave as a 122 amp (6H)



        Changing the switch on the organ would be the most economical way to use the 251 - I can't think any good reason to hack up the amp.</P>


        Also, daisy chaining a 251 with a 21 H just ain't gonna happen w/o some major surgery.</P>


        The "H" type uses DC current to signal speed changes, the "W" and "C" models use mains current. Hook 'em up without a total understanding, and POOF! Out comes the smoke. Balanced/unbalanced signal - again, it's doable to use both, but the answer is in the switching from the organ.</P>


        While I'm not a total purist about things, there's also the idea that they just don't make those 251 and 21H amps anymore... at some point, the "vintageness" of those amps should prolly be considered somehow.</P>
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        • #5
          Re: converting a 251 amplifier (6C) to behave as a 122 amp (6H)

          I think this has been covered over on the Hammondzone Yahoo group. If you haven't looked there yet, it's worth doing so. A post there is sure to get a response from Chris or Harvey, who know their stuff when it comes to all things Hammond and Leslie.
          It's not what you play. It's not how you play. It's the fact that you're playing that counts.

          New website now live - www.andrew-gilbert.com

          Current instruments: Roland Atelier AT900 Platinum Edition, Yamaha Genos, Yamaha PSR-S970, Kawai K1m
          Retired Organs: Lots! Kawai SR6 x 2, Hammond L122, T402, T500 x 2, X5. Conn Martinique and 652. Gulbransen 2102 Pacemaker. Kimball Temptation.
          Retired Leslies, 147, 145 x 2, 760 x 2, 710, 415 x 2.
          Retired synths: Korg 700, Roland SH1000, Jen Superstringer, Kawai S100F, Kawai S100P, Kawai K1

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          • #6
            Re: converting a 251 amplifier (6C) to behave as a 122 amp (6H)



            Find a 53-1 kit for your A100 and use the 251. I would not mod the 251 amp. Having the "correct" Leslie for an A100 is worth something, at least to me. The stationary channel for reverb is a nice thing to have. If you want to run two leslies, I would pick up a 122 amp and slide it in. Save the 251 amp for a rainy day. </P>


            H101</P>

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            • #7
              Re: converting a 251 amplifier (6C) to behave as a 122 amp (6H)



              I think I'll pick up a 122 amp (after saving up some cash for a little bit as to not break the bank) and hold onto the 251 ampif I ever wish to use it. One bit of confusion I develop after reading some of the responses is regarding the issue of running both leslies simultaneously. If I do swap out the 251 amp for a 122 amp, then both leslies should be running with a 6H setup. As such, would it be possible to perform the daisy chain operation off of the 21-H,considering its amp is also 6H like the 122's? I know that riverside had mentioned that daisy chaining the 21-H to the 251 would require some major surgery, but that's daisy chaining the 21-H amp to the 251 amp, yes? Would such major surgery be necessary if it were a 21-H amp to a 122 amp?</P>


              If daisy chaining doesn't work, would I install another 6122 connection kit in parallel with the 6122 connection kit already in the organ?</P>


              Thanks, this has been very helpful.</P>

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              • #8
                Re: converting a 251 amplifier (6C) to behave as a 122 amp (6H)



                122 to 21H (and vice versa) = OK</P>


                251 (C) to 21H (H) (and vice versa) NOT</P>


                Again, the speed relays in the "H" uses DC, in the "C" and "W" types, AC.</P>


                There are those who poo-poo daisy chaining at all -but that's another thread!</P>
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                • #9
                  Re: converting a 251 amplifier (6C) to behave as a 122 amp (6H)



                  The 251 is a great Leslie. What I recommend is that you use the 20 amp channel to pre-amp the 35 amp channel and you will have one of the meanest screeaming leslie's on the block. You can actually get the overdrive sound (if you play jazz, blues or rock) with the amp volume only half way up. A good tech can do the job and convert the pin assignment for 122 output. I have had several converted like this for local players and they love them. I suggest you join the Ham-Tech forum and post the question or search the archivesand you will get some great advice on how to do it. If your near Cleveland I can reccomend a localtech.</P>
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                  Good Luck, Mike</P>


                  www.mikesbarn.com</P>
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                  • #10
                    Mike could you tell me who you use for this mod? I just got a 251

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                    • #11
                      This thread is almost 4 years old and Mike only has 8 posts so I doubt you'll reach him on here. Try his website.
                      Hammonds: A; AB; B3; D; E; 6-M3's; 2-A100; T582C.
                      Leslies: 3-31H; 21H, 22H, 4-44W; 46W; 25; 47; 45; 125; 50C; 51; 55C; 2-120; 122; 122A; 145; 147; 245; 770; 825; 2-102; 2-103; 300.
                      Wicks 2/5 pipe organ; Yamaha upright; Kurzweil Micro Piano & Micro B with M-Audio Oxygen 61; Yamaha DGX520; Wurlitzer 4100 (it came with a Leslie!). Peavey KB100 keyboard amp. Peavey Bass Guitar. Yes, I have A. D. (acquisition disorder) and don't want it cured.

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                      • #12
                        will do thx!

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