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    V series amp tweaks?

    Even a rebuilt V series preamp seems too tame.Really don't need to alter the way this BV sounds overall from the MT. Wes uses one i think?
    This late V has smooth playing keys,hooray!Never seen one before.91 tone genny too.

    Maybe the AO10 or 28 with a doghouse expression would make it more robust?
    Must be a way to hang that style arm from the V rod?
    Some M3 perc switches still in the cheek block on a snake,from the blank chorus drawbar hole,resting on the lid.(seen it before)
    Great non invasive mod IMO!

    Obtained,unloaded it untested,have open service manual to 3/69......#49 is missing everywhere.Front corner of the filter deck at least....
    Can't remember if V has a resistor inside the vibrato switch? Geo helped me with the -2~! Will look it up!
    Will clip to bar 6 on the panel to test when I get back to it. (3/78)

    The 122 hangs off it fine,just the usual 'no dynamic range' compared to the A100/B2 here.
    Opening the rheo might find 'polite' hookup?Wes?

    Thanks in advance for your input.
    sigpic A100/251 A100/147 A102/222 B2/147 BCV/122 M3/145 M102/145
    Various modern keyboards and modules.

    #2
    This is how I connected the swell arm to the long rod in my BC ... a small hose clamp Click image for larger version

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    Current organs: AV, BC, A-100
    Current Leslies: 22H, 142, 147, 760
    Organs in the past: L-100 (several), M-100 (x2), T-100, E-100, CV
    Other keyboards: Roland FP-4, Yamaha DX7, Yamaha TX81Z, Yamaha Motif ES Rack, Korg Krome, Novation Mininova

    Comment


      #3
      Wes and I had a lot of discussions on here about CV preamps in the past. The upshot is that the design of it doesn't make it easy to increase its overall gain or output. It's a peculiar and somewhat inflexible circuit, driven by design considerations that Hammond abandoned with the 2-series (no electrolytic capacitors). Much of the gain happens in the first 6SJ7 stages. The output to the vibrato line box is pretty high, probably higher than in the later organs, but there's a lot of signal loss in the vibrato circuit, and the dry signal path has to be padded down to match. My sense is that Hammond didn't want organists to be able to overdrive the Hammond tone cabinets of the 1940s.

      Probably the only easy way to increase the output is to increase the input by taking the highest amplitude signal possible from the rheostat box. Or, just thinking about it, you could run the preamp's output into an audio step-up transformer. You wouldn't need a huge amplitude boost.
      I'm David. 'Dave' is someone else's name.

      Comment


        #4
        Thank you for reminding me about the vibrato return amp factor David! When last I modded a V a quarter century ago the AO43 supplied my B+(vibrato circuit)!
        Will hang this AO43/8000(Porta B) kit off the existing preamp,and have a look at the gain structure!
        Tried unsuccessfully to hang V vib circuit off AO43 back then,still ended up using it for perc and verb though!
        sigpic A100/251 A100/147 A102/222 B2/147 BCV/122 M3/145 M102/145
        Various modern keyboards and modules.

        Comment


          #5
          Peter -- after working with David that summer on this, I wound up with a really good-sounding preamp with lots of balls.

          Want to know something funny, though? I pull a CV out of mothballs the other day to help me troubleshoot a delay line issue on my gigger. I'd never even turned it on before, I added a quick tone cab outlet and plugged a 22H into it, damn if it didn't sound good and strong! I should pull that one and see if it's ever had any work done...

          My notes from a few years back:
          - update the amp to code -K (especially make sure there is no C12).
          - Add a cathode bypass for the 6SN7s -- I used 100uF. They share a common cathode resistor so the cap does both.
          - Change R4 in the rheostat box to roughly 100K.

          With those changes, it will drive a Leslie to full output without issue. R4 obviously has minor side-effects w.r.t. tone shaping and preemphasis, but I can't hear a difference. The main effect is to control how loud the pedal will get. Doesn't really affect the quiet end at all.

          I'm testing tone 25 (key 25 at 16'), at R4=100K I get 2Vrms out into one G.

          The limit in the amp is the 6J7, if you run too much into it, it will distort the waveform it is inverting. There is a ton of headroom in the amp, though. With R4 removed, I can get 9Vrms @ 150Hz into a Leslie and still not see any distortion from the preamp.

          Note that 6SJ7s are microphonic, and this is worsened somewhat when you upgrade to code -K, since that gives that stage about another 4dB of gain.
          (Note that 9Vrms is WAY too much, you could easily damage components sending a Leslie a signal that hot)

          Comment


            #6
            Overall this late BV is really nice.Tone 49 fix is next....
            Thanks Wes,will have a good look at those cathode bypass caps and the R4 rheo resistor.
            I know where my other working V preamp is.....will have to try it out.

            This Porta B preamp/Leslie kit sounds great so far with ANY Hammond I've tried through it.Runs a pair of 'H' style boxes.
            Last time I did this, it kept the V vibrato out of the L100 perc circuit by using the stock V pre; adding an AO43 to 'mix' the signals.
            I wonder if M3 perc switches will hang off an AO43? Likely they will.




            sigpic A100/251 A100/147 A102/222 B2/147 BCV/122 M3/145 M102/145
            Various modern keyboards and modules.

            Comment


              #7
              I haven't studied the problem at all, so take this with a grain of salt, but I think you'll be able to make the M3 switches work with the L100 amp with the addition of a couple of resistors. I'm pretty sure the level-setting resistors are on the switch itself in the L100.

              That said, the L100 percussion circuitry is in the AO42, not the AO43.

              If you want L100 percussion, power amp, and reverb -- maybe you could use the AO42 and AO43 together in the BV. Bypass the vibrato amp circuit path with a short RCA jumper cable and leave it out of the organ. Finally, connect the rheostat box to intercept the signal between the AO42 and the AO43 the same way the L100's expression pedal is plumbed in. Then adjust R4 in the rheostat box to give you the correct drive (I believe the value affects the curve as well as drive - hopefully you don't need to change it too much).

              Oh crap. That will cost you vibrato.......*thinking* ....maybe the BV preamp can go where the AO41 normally does in an L100? The signal levels are similar. You might need to bleed some level on the way out. Easy enough.

              Wes

              Comment


                #8
                Why would anyone want L-100 percussion?? (puzzled)
                Current organs: AV, BC, A-100
                Current Leslies: 22H, 142, 147, 760
                Organs in the past: L-100 (several), M-100 (x2), T-100, E-100, CV
                Other keyboards: Roland FP-4, Yamaha DX7, Yamaha TX81Z, Yamaha Motif ES Rack, Korg Krome, Novation Mininova

                Comment


                  #9
                  Wes,
                  I used the AO43 vibrato B+ (210V) to power up the V preamp.Then I mixed the AO42 and V preamp at the rheo.
                  Just never thought the 100K pre 'mix' through at the time.Will need to mix V,and AO42 at the rheo input.
                  Decent AO43 'verb too!
                  The V premp as I recall did a great vibrato/chorus,after all it was the 'new thing' they wanted it to be its best!
                  Those big first series lineboxes really shimmer when working right.
                  The V has lots of personality.I can source some 'drive' for it it elsewhere(FX loop)....

                  An AO43 and AO42 are sitting right here working.I can try this non-invasive mod.The V preamp becomes the 'AO41' in the block.
                  An AO43 already lives in this Sears Craftsman tool box that I haven't finished yet....it won't live inside or on the BV.
                  A little electronics...and metal fab.'Verb spring sits in box lid too!
                  Little carpentry( one connector visible) at music desk chorus drawbar plumbing,start switches stay. Reversable mod!
                  AO42 sits on other side of rheo just fine.
                  Wiring a snake from an outboard AO43 should be easy.
                  Will have a look at suitably rated connectors.


                  enor,
                  I saw you hanging M3 perc switches off an E100 so what is so different about an L100?
                  I played both and they are at least tolerable.
                  The M3 perc tabs still in a cheekblock on a cable will sit comfortably on the BV lid,or on a sliding
                  'rythm II' type holder below the deck....
                  A removable connection/plug for moving/closing fallboard.
                  Those M3 perc switches should hang off an L100/AO42 just fine.
                  If this sounds bad when I'm done I'll use an AO28.....I would rather leave the V 'deck' alone!
                  I love the sound of the original vibrato boxes.
                  Never found the L100 perc that bad compared to stock E/T/H type circuits?

                  Must be a way to tweak L100 decay,and ping/bonk? Too slow an attack,sped up it would mimic the M more.
                  sigpic A100/251 A100/147 A102/222 B2/147 BCV/122 M3/145 M102/145
                  Various modern keyboards and modules.

                  Comment


                    #10
                    Agreed, the E-100 perc sounds sort of like the L-100 perc does even after modifications - but not quite as bad. All I'm saying is, if one is to add perc to a -V, there's really no point choosing a difficult method that's bound to be bad sounding. Just pop an AO-28 in there, or a TREK perc kit. Sounds much better and is much easier.
                    Current organs: AV, BC, A-100
                    Current Leslies: 22H, 142, 147, 760
                    Organs in the past: L-100 (several), M-100 (x2), T-100, E-100, CV
                    Other keyboards: Roland FP-4, Yamaha DX7, Yamaha TX81Z, Yamaha Motif ES Rack, Korg Krome, Novation Mininova

                    Comment


                      #11
                      Point well taken enor.While I have the V preamp/rheo out of there no harm in trying an AO28 with a hose clamp attachment.
                      Overall very clean BV,I did encounter one surprise when I took off the music desk.Thought these drawbars felt too smooth to be ratchets!
                      So far,#49 fixed at the manual strip....all working again.Nice to have a manual to remind me of the procedure to locate and repair....
                      threaded the test lead through the top with the manuals lifted and found the broken solder joint fast.

                      Smooth edged keys,smooth drawbars already! Next will replace the chorus resistor.
                      Attached Files
                      sigpic A100/251 A100/147 A102/222 B2/147 BCV/122 M3/145 M102/145
                      Various modern keyboards and modules.

                      Comment


                        #12
                        You're just a preset panel, a transformer and an AO-28 away from full B-3 functionality then!
                        Current organs: AV, BC, A-100
                        Current Leslies: 22H, 142, 147, 760
                        Organs in the past: L-100 (several), M-100 (x2), T-100, E-100, CV
                        Other keyboards: Roland FP-4, Yamaha DX7, Yamaha TX81Z, Yamaha Motif ES Rack, Korg Krome, Novation Mininova

                        Comment


                          #13
                          That cabinet looks great Pete. Is that the BCV in your signature or a completely new organ?
                          Hammond BC/Leslie 147 (UK 50Hz)
                          MK2 Farfisa Compact Duo/Binson Echorec 2
                          Yamaha KX88
                          MK1 Korg CX3/Neo Ventilator

                          Comment


                            #14
                            enor,
                            The vibrato return cable is different on a V than a -3.Easy to swap for testing though.
                            Also have an A100 switchplate/vib line,sans drawbars,and a B3 music desk.
                            Will 'mock it up' after i recap the TWG filters.

                            Taking my time on the BCV, which is almost done.
                            DrawbarDave.....
                            The BV wil be modded,the BCV will remain a BCV!

                            The BCV has a recapped genny that is so smooth and non brittle I surprised myself.
                            Followed Wes and Kon's advice.Non tapered manuals can be too brittle on the top octave,not this one!
                            A true 'antique' with only the 1950 upgrades,scanner and smooth playing keys.
                            Really too much history here to mod,after all it is a Northern that still works as intended!

                            The BV will be modded though.Wanted a late one (49) for the 91 tone genny and smooth keys.
                            Had never encountered a V with these keys before.
                            It all works,will be easy to restore that filter set on the genny.
                            Second time in a row working on the old 'wide top' trays.Got it down pat.
                            The old vibline on there? Great chorus in a few extra sections. Hope it likes the AO28?
                            If not,there's a redcapped A100 line here.

                            I'm in no hurry.Will let the oil take the genny to a place it needs to be.
                            sigpic A100/251 A100/147 A102/222 B2/147 BCV/122 M3/145 M102/145
                            Various modern keyboards and modules.

                            Comment


                              #15
                              Awesome! Lucky you. How do you like the chorus generator on the BCV? I love the effect on all 8’s especially when I’m playing Santana.
                              Hammond BC/Leslie 147 (UK 50Hz)
                              MK2 Farfisa Compact Duo/Binson Echorec 2
                              Yamaha KX88
                              MK1 Korg CX3/Neo Ventilator

                              Comment

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