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Help - 122RV = mounting the tank

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  • Help - 122RV = mounting the tank

    So about a year ago, I picked up a B3, a 147, and a 122RV - all of established historical significance.

    These had been sitting in cold storage for three decades. Just a little bit of clean & lube, and they were at least working. Over the ensuing months, I have been going through them bit by bit, getting them mechanically and electrically up to snuff. Just a few things left to do...

    My inquiry today concerns the 122RV. This had the reverb amp included, as well as one 6x9 in a inner compartment, but was missing the reverb tank. Some spelunking here on the forum taught me the characteristics of the tank I needed. I was able to find a suitable replacement. Some electronic work and patching, and I now have reverb emanating from the side of the cab. (Despite other reports here, I think the reverb sounds quite good. The mix control is poorly placed, but whatevs...)

    My question is in regards to the mounting of the tank. I can see screw holes on the inside lower area of the middle compartment cover. So I think I know where it belongs. But I know that guitar amps typically do not hard mount tanks to the cab, in order to eliminate feedback from the speakers into the springs.

    So should the tank just be screwed to the rear panel or should it be mechanically isolated with rubber grommets or somesuch?

    As long as I am asking - the interior of the cab has some bracket assemblies on the opposite side - as if to attach another sub-compartment for another 6x9. But these only came with a single 6x9, right?

  • #2
    Yes, the reverb tank should be acoustically damped and isolated to the extent possible. The biggest problem with them is their tendency to pick up the EM fields from the slow motors.

    There was only a single reverb speaker, but it was made so that you could switch it from one side to the other, based on the installation.
    I'm David. 'Dave' is someone else's name.

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    • #3
      Thanks for that last piece of info, David. That's been driving me crazy.

      Comment


      • #4
        Here are a couple of pics of my 147RV that may help you. The first one shows the mounts used for the reverb tank on the inner lower part of the middle back panel. The second show the extra shielding on the lower rotor's small slow speed motor. It is strange that the larger fast speed motor in this stack does not have extra shielding even though it is physically located closer to the tank (the tanks is located almost next to it). I wonder if anyone can explain this. (These pics were taken when I first purchased the 147RV and before I did a thorough cleaning of its insides, so my apologies about the dust)
        James

        Click image for larger version

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        Jimbo_____________________________________________ ________________

        Korg BX-3 & BPX-3 Bass Pedalboard, early 80's bastard child
        147RV blueblood born Feb 7, 1973
        125 bourgeoisie born Oct 1, 1969

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        • #5
          Originally posted by BX3guy View Post
          It is strange that the larger fast speed motor in this stack does not have extra shielding even though it is physically located closer to the tank (the tanks is located almost next to it). I wonder if anyone can explain this.
          It seems counter-intuitive, but because of the winding geometry of the fast motors vs. the slow motors and the fact that the fast motors are inherently better shielded by their bearing flanges than the open-construction slow motors, the slow motors radiate a considerably stronger 60Hz electromagnetic field than the fast motors.
          I'm David. 'Dave' is someone else's name.

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          • #6
            I hope that you find it worthwhile. We have a couple of 122RVs, and the reverb in them sounds pretty bad. The vintage and TrekII reverbs we have in a couple of our B3s sound decent (though a bit long for many types of music).

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            • #7
              I think there is a reason most 122RV have been stripped of the parts and made into 122, just my thoughts, not the best leslie idea? Not the worst either 900 was pretty sad .......other 900 series were way better
              1956 M3, 51 Leslie Young Chang spinet, Korg Krome and Kronos

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              • #8
                Thanks David for drawing attention to the slow motor isolation on the lower stack in BX3's picture 2.
                Proximity to the tank must warrant the extra 'cage' on that lower stack.

                Constant moving and jarring of anything over 100 pounds creates mechanical issues too.
                Probably fine for an install,not suited for road duty so much.

                All the RV models have been downgraded if they see road work which is entirely likely.
                The extra room inside the upper rotor chamber is way better suited to a permanent mic install than a stock 147/122 etc.

                jdoc,Lee Michaels had a lot of 925's.
                Still working on the mall organ coffee table book for cork sniffers

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                • #9
                  Road duty is not an issue for an RV model. They have a little access hatch on the back panel that opens up into the back of the reverb tank (see pics below). This hatch cover can be rotated aside and you place a cylindrical packing (rolled up cardboard or wine cork, for example) into the access hole when you are moving the unit. This puts pressure on the reverb spring inside and prevents the reverb spring from bouncing around and getting damaged with the move. The previous owner of my 147RV used it at dozens of gigs with no problems or damage to the reverb tank. Of course, if the crew is clumsy, there's going to be damage, but not just to the reverb tank.
                  JamesClick image for larger version

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                  Jimbo_____________________________________________ ________________

                  Korg BX-3 & BPX-3 Bass Pedalboard, early 80's bastard child
                  147RV blueblood born Feb 7, 1973
                  125 bourgeoisie born Oct 1, 1969

                  Comment


                  • #10
                    Thank you for your pictorial clarifications! I wouldn't road a reverb model because of ergonomics.
                    Thank you Don Leslie for matching up the dimensions of the side of the 147 with the front of an A100.

                    That being said, the jury is still out on the reverb built into a Leslie, compared to a Hammond Tone Cabinet or an A100.
                    Still working on the mall organ coffee table book for cork sniffers

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                    • #11
                      925 was a good one Pete, had fast/slow on both rotors iirc, not so the 900
                      1956 M3, 51 Leslie Young Chang spinet, Korg Krome and Kronos

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                      • #12
                        I restored a 247RV a couple of years ago, and the cabinet's reverb sounded better than I'd been led to expect. It may have to do with the larger number of 6x9 speakers (two or three). Also, the RV amp needed a good bit of work. When I was done, I clocked it at 19 Watts clean.
                        I'm David. 'Dave' is someone else's name.

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                        • #13
                          I have heard before the the height of the upper shelf of a 147RV or 122RV is greater than in a regular 147 or 122, in order to make room for the Reverb Amp. The upper shelf in my 147RV measures as 6 and 1/4 inches (15.9 cm) high from the top of the shelf's "floor" to the bottom of the ceiling inside. Just curious, can anyone tell me what is the height in a regular 147 or 122?
                          James
                          Jimbo_____________________________________________ ________________

                          Korg BX-3 & BPX-3 Bass Pedalboard, early 80's bastard child
                          147RV blueblood born Feb 7, 1973
                          125 bourgeoisie born Oct 1, 1969

                          Comment


                          • #14
                            Not off the top of my head but one thing that is cool about the RV series....you can remove the horn without removing the V21.
                            Hammond B3 (55), B3 (70), B3 (72), B2 (51) conversion, A100 (61) chop, A100 (62), A105 (75), Northern BC (39) empty.
                            Pile of Leslies of various flavours, Minimoog, ARP Odyssey, MaxiKorg, Hohner D6, Rhodes 54, Rhodes 73, Wurlitzer A200, Wurlitzer A203W

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                            • #15
                              Originally posted by BX3guy View Post
                              I have heard before the the height of the upper shelf of a 147RV or 122RV is greater than in a regular 147 or 122, in order to make room for the Reverb Amp. The upper shelf in my 147RV measures as 6 and 1/4 inches (15.9 cm) high from the top of the shelf's "floor" to the bottom of the ceiling inside. Just curious, can anyone tell me what is the height in a regular 147 or 122?
                              James
                              The upper shelf on a 147/122 etc. has a 4 3/8" opening so to include the upper lip from 'deck to lid' would be 5 1/2".
                              Which is the main reason I don't have permanent mounted mics in mine.
                              There is a Backline 122RV around here with a Sennheiser MD421 mounted where the 'verb amp used to be.
                              Still working on the mall organ coffee table book for cork sniffers

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