Ebay Classic organs

Collapse

Announcement

Collapse
No announcement yet.

Hammond Reverb Units for M-3 and S-6

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Hammond Reverb Units for M-3 and S-6

    I'm just wondering how these work. From some pictures I've seen, the Music Rack Model doesn't have much inside other than the speaker and a control for the amount of reverb. Pretty much the same with the Floor Model. Anyone know of a schematic for either one of these to see how the reverberation is created? I also don't see any power line for these, so are these just connected to the speaker outputs of the amp?

    I'd like to add reverb to my M-3, and am looking for the simplest way to do that (also least expensive). I'm not seeing any of these reverb units for sale other than one Floor Model listed on reverb.com, but that one is very pricey. Can I easily make something that will give the same effect? I've attached a picture of these units from a Hammond brochure.

    Click image for larger version

Name:	Hammond reverb color.jpg
Views:	109
Size:	449.5 KB
ID:	786570
    1959 Hammond M3, Roland D-50

  • #2
    1) they incorporate a 12 watt amp so they are mains AC powered
    2) they'll use a reverb unit, no doubt a spring line, given the small size
    3) short of paying the price and buying one - or trying to build one, your best option for reverb is probably to find a small digital reverb unit that can emulate a spring line. There may have been some threads on this before now, so probably worth a search through the forum.
    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 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

    Comment


    • #3
      There is a floor Hammond reverb speaker for sale on Denver Craigslist, $100. Still needs the amp and reverb spring to make it happen. The simplest way is like Andyg said ,with an reverb/ effects unit that can be inserted into a lineout or an effects loop . I use a HallofFame reverb pedal ,to make the internal speaker have reverb but also to put reverb in the lineout as well.

      Comment


      • Sweet Pete
        Sweet Pete commented
        Editing a comment
        Next tour of Norman Petty's? Have a look at the chamber with cinder blocks and steel plates and a 604E at the end! It's in the annex building IIRC.
        Had it powered with a Macintosh and used a Pultec eq/pre.Best chamber I've ever heard to this day.He built it.Sir Paul McCartney loved that chamber!
        Heard everywhere as a model plug-in these days.

    • #4
      The advertised system shown was basically the exact same reverb system you find in the A100. I think it was called the Hammond "ETK" kit. The spring reverb unit would have been either the necklace type or the now-standard reverb tank, driven from the organ's speaker output with the AO35 reverb amp (later the AO44) driving a speaker used only for the reverb signal. That speaker could either be in the floor-standing cabinet shown or in a smaller box atop the organ. The reverb amp was mounted in the M3 cabinet where there was plenty of room.

      The schematic for the whole thing may be in the M100 service manual.
      I'm David. 'Dave' is someone else's name.

      Comment


      • #5
        OK, thanks everyone, that makes sense now. So apparently the original "kit" for these included a reverb amp that was installed in the M3 cabinet - I now understand why you don't see any electronics in the speaker cabinet, itself.

        Hmmm... so, this is going to take installing a line out, getting some kind of reverb effect box, then either feeding that back to the M3 speaker, or sending it to a separate amp/speakers. All of the Hammond Floor Model reverb cabinets I've seen are missing the amp, which means the box is just the speaker and the control.

        I had been thinking about adding a line out to the M3, then purchasing a 70's era reverb box (such as a Sansui RA-500), then feeding that to an amp/speakers. My hesitations is that when you add all that up, it will cost well more than the organ is worth. Just the reverb box alone will run me $50-100. I was hoping for something less expensive/involved to add reverb, but maybe there is not?
        1959 Hammond M3, Roland D-50

        Comment


        • #6
          I think the cost of the effects loop and reverb unit would increase the value of the M-3. The reverb unit can be used for other instruments as well ,for example an extra manual keyboard 's output ,sitting on the top or side such as a Wurly can now be put into the rca input on the Hammond. This gives a nice tube warmth and reverb to your Wurly. I know some smarter people can put together an amp , spring tank, and speaker to build a reverb system to be used with the M-3's amp. If you can get the parts cheap the rest is labor.

          Comment


          • #7
            Thought I'd contact a local guy who deals in vintage stereo/electronics equipment. As fate would have it, he had a Gibbs Reverberator unit:

            Click image for larger version

Name:	89E700DF-0ADC-4F1D-982C-5F62A0D46531_1_201_a.jpg
Views:	104
Size:	414.1 KB
ID:	786607Click image for larger version

Name:	4FF12559-E760-4DC7-BC36-4407F6B8A277_1_201_a.jpg
Views:	106
Size:	444.0 KB
ID:	786608Click image for larger version

Name:	961CF4E4-D6E2-45A5-8479-0C110B64D36E_1_201_a.jpg
Views:	104
Size:	521.5 KB
ID:	786609Click image for larger version

Name:	3E2B363A-884A-426D-AC44-E2BE5EFE79C4_1_201_a.jpg
Views:	103
Size:	469.6 KB
ID:	786610Click image for larger version

Name:	8BDC1355-BE69-4228-B164-823FA3120C7D_1_201_a.jpg
Views:	104
Size:	481.3 KB
ID:	786611

            We tested it and it did pass a signal from a radio out to a speaker. So, appears it has a small amp inside. Looks like it was designed to input one or two signals, add the spring reverb, then output to a single speaker. Is this as simple as taking the speaker signal from the M3 and connecting to the "Input from Amplifier" on the Reverberator? I'd leave the M3 speaker connected.
            1959 Hammond M3, Roland D-50

            Comment


            • #8
              I'd never even heard of a Gibbs Reverberator prior to this post. Maybe a manual survived somewhere. It was apparently also sold as the Lafayette R777. There's one on eBay at the moment.

              Since A and B are used for Left and Right in the stereo world, I would guess it was designed to accept stereo speaker level inputs and drive a dedicated reverb speaker. But that's just an educated guess.

              Edit: Be aware that early solid-state amps usually didn't have any protection circuits for the outputs. I would check to see if there is any DC at the outputs before hooking it up to a speaker I cared about.
              I'm David. 'Dave' is someone else's name.

              Comment


              • #9
                Originally posted by David Anderson View Post
                I'd never even heard of a Gibbs Reverberator prior to this post. Maybe a manual survived somewhere. It was apparently also sold as the Lafayette R777. There's one on eBay at the moment.

                Since A and B are used for Left and Right in the stereo world, I would guess it was designed to accept stereo speaker level inputs and drive a dedicated reverb speaker. But that's just an educated guess.

                Edit: Be aware that early solid-state amps usually didn't have any protection circuits for the outputs. I would check to see if there is any DC at the outputs before hooking it up to a speaker I cared about.
                I saw that Lafayette too. This one looks identical to the pictures in that listing. I would agree there is nothing that looks like a protection circuit in there, no relay. I've got cheap test speakers I use for these situations. My main question is whether I can just connect the M3 speaker output to the input of this Reverberator unit, or do I need something to attenuate and/or filter the signal? I really have no idea if the A and B inputs were for a stereo signal or if the intent was the ability to mix two signals if desired.
                1959 Hammond M3, Roland D-50

                Comment


                • #10
                  Originally posted by KeithB View Post
                  My main question is whether I can just connect the M3 speaker output to the input of this Reverberator unit, or do I need something to attenuate and/or filter the signal? I really have no idea if the A and B inputs were for a stereo signal or if the intent was the ability to mix two signals if desired.
                  I have no clue about how it's supposed to be hooked up other than what I've already said. When you have screw terminals like that, they're typically for speaker wire, but, again, that's just an educated guess, combined with the knowledge that Hammond's reverb tanks of that era were sometimes driven by the speaker output of another amp.

                  It's certainly not a stereo reverb, so the A & B connections may be mixed in some way inside the unit to produce a summed mono reverb signal.

                  I'm David. 'Dave' is someone else's name.

                  Comment


                  • #11
                    Understood. I hooked it up to the output of a CD player, but that signal was clearly too low, so I connected it to the speaker outputs of a small amp. Good sound out of the Reverb unit speaker terminal. Varying level of reverb worked well. I then just aligator clipped onto the speaker terminals in the M3. Works as expected! I have to have the volume turned all the way up on the Reverb unit to get enough volume from the one speaker connected ot the reverb, but it's clearly giving me reverb on the organ signal. I measured DC offset at the speaker terminal on the reverb unit, and I was getting about 0.1 volt. Seems high, and there is a small amount of hum from the speaker I've connected. Is there a way to minimize that hum? I doublt there is an adjustement in the reverb unit, but I'll have a look.
                    1959 Hammond M3, Roland D-50

                    Comment


                    • #12
                      In terms of hum, if there is a power transformer near the output pickup of the reverb tank, the output transducer can pick up hum from the transformer's field. This is one reason why in Fender amps, the amp itself is at the top of the cabinet while the reverb tank is located in the bottom.

                      You could also have hum from >50 year old electrolytic caps in the unit's power supply.

                      As for the DC offset at the output, 100mV is not too bad for a unit of that age, depending on the circuit. Some were single-ended with capacitor-coupled output (positive supply only), and some had bipolar supplies (positive and negative). No idea what's in yours.
                      I'm David. 'Dave' is someone else's name.

                      Comment


                      • #13
                        Originally posted by David Anderson View Post
                        In terms of hum, if there is a power transformer near the output pickup of the reverb tank, the output transducer can pick up hum from the transformer's field. This is one reason why in Fender amps, the amp itself is at the top of the cabinet while the reverb tank is located in the bottom.

                        You could also have hum from >50 year old electrolytic caps in the unit's power supply.

                        As for the DC offset at the output, 100mV is not too bad for a unit of that age, depending on the circuit. Some were single-ended with capacitor-coupled output (positive supply only), and some had bipolar supplies (positive and negative). No idea what's in yours.
                        There certainly is a transformer in there near the tank as seen in the attached photo. Agree the old e-caps could be causing trouble too.

                        Click image for larger version

Name:	s-l1600.jpg
Views:	53
Size:	305.7 KB
ID:	786717

                        I'm used to ±10mV for solid state stereo equipment DC offset, so 100mV seems high, but it is likely due to age. For the time frame of this unit, I'd say it's cap-coupled, but I'd have to do more investigating to determine.
                        Attached Files
                        1959 Hammond M3, Roland D-50

                        Comment


                        • #14
                          It should be easy to tell whether the outputs are DC or capacitor-coupled to the speakers. If they are DC-coupled, the output transistors will connect fairly directly to the speaker terminals. If capacitor-coupled, there will be a large-value capacitor in series with one of the speaker terminals.

                          And the power supply -- does it have one main power supply capacitor or two, with one grounded on the positive terminal?

                          Designers usually try to orient a power transformer and a reverb tank to minimize interaction, but chassis size can limit placement options. When I had to build a replica F/AR power supply for my Farfisa Compact Duo, including the stock reverb tank, my first version suffered from transformer-induced reverb hum even though I thought I'd laid it out to avoid that. I had to experiment with PT placement to find the best solution. I ended up putting one PT inside a steel shield.
                          I'm David. 'Dave' is someone else's name.

                          Comment


                          • #15
                            Here are pictures of the inside.

                            Click image for larger version

Name:	IMG_1097.jpg
Views:	41
Size:	423.7 KB
ID:	786855Click image for larger version

Name:	IMG_1098.jpg
Views:	41
Size:	411.9 KB
ID:	786856Click image for larger version

Name:	IMG_1099.jpg
Views:	41
Size:	436.0 KB
ID:	786857Click image for larger version

Name:	IMG_1096.jpg
Views:	41
Size:	425.9 KB
ID:	786854
                            I tried following the speaker terminal connection on the PCB, but not easy to see under the board even with all the mounting screws removed, as the wiring is a bit "tight." Looks like + speaker terminal goes to a resistor (and fuse?), but could not see enough to follow after that. I've not seen something like this from my vintage stereo experience. That single board has to be a combined power supply and amplifier. I can only guess the power rating must be just a few watts. As you can see there is a "large" transformer and a smaller one mounted on the PCB. I count 5 e-caps: two 2000 µF 25V, two marked 1022, but can't see the printed rating data (might be on the side facing the PCB), and one marked Suzuki 100 µF 6V. Has a few of the "red" caps. Seeing only two transistors: round black body marked 6135 839. Has a silver can on lower left of PCB that looks like it could be an axial capacitor, has "W Germany" on it but can't fully make out the other markings. Might need to desolder some wires to get a full view of the underside.
                            Attached Files
                            1959 Hammond M3, Roland D-50

                            Comment

                            Working...
                            X