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Rodgers Concordia 745 2 manual organ just arrived and being repurposed

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  • Rodgers Concordia 745 2 manual organ just arrived and being repurposed

    Our little Anglican church here in Augusta, GA is finally moving up up and away from its venerable Allen TC-3 ca. 1965 complete with inop Leslies and some tuning issues that have been an ongoing battle. A few weeks ago, I found a very nice and good working Rodgers 745 2 manual with factory MIDI to replace it, which arrived yesterday. I connected the old Rodgers speakers to it then replaced two of them with some good old audiophile Bozaks I had laying around. It sounds good but is gutless; the Rodgers has a 3 channel internal amplifier that is not that impressive in terms of output. I suppose it's OK with the swell cranked to at least 50%, but it may not keep up without being above that all of the time.

    I have not yet taken the back cover off the organ yet.

    Can anyone point me to where this organ's line level outputs are, if at all? I suppose I can use a powered input amplifier or converter to mix it down to two channel stereo and then simulate 5 channel through a home theater amp, but am unsure where that will get me.

    All suggestions are welcome!
    Thanks
    Chip

  • #2
    Here is the brochure for that organ--note it is "Concord", rather than "Concordia". http://www.rodgersinstruments.com/up...s/pdfs/745.pdf

    The internal amps are 100 watts, and unless you have extremely inefficient speakers (which is unlikely), they should be sufficient to provided plenty of volume. I suspect you just need to turn up the volume on the various preamps inside the organ. You will need to open up the back to do this.

    The circuits inside this organ are located on one or two racks that swing out like doors. The outer rack, upper right hand corner as you face the back of the organ has the preamp board where most of the voicing and volume adjustments are made. There will be tie-down screws at the top and bottom of the rack, and an offset or stubby phillips screwdriver will be handy to get the top one loose. After opening up all the racks, on the back of the knee panel there should be an output panel which is where you can pick up line level audio if you must--but using it will be more difficult and likely not to be any better than the internal amps. Rodgers used 5-pin DIN connectors for the line level, and it's best to just get some of those if you want to tie into the line level and make custom cables. I don't remember the pin layout of those connectors (and there are at least two different 5-pin layouts based on the alignment of the pins)--look to see what they are and get the ones that match. I suspect they are 180 degree types.

    There will be main and antiphonal line level outputs, make sure to use the main ones.

    There is probably a voicing chart for this organ, which would be very useful for you. I don't have a copy of it or I'd post it here. Maybe someone else has one. If not, you could contact your local Rodgers dealer who might be able to get one for you.

    Comment


    • #3
      There should be output jacks for each of the three channels located on an output panel inside the console. They may be large round sockets with 5 pins, or they may be the more modern type, which are DIN style jacks similar to MIDI jacks. One pin in each jack carries the audio, another is the ground, and two are for operating the relay found in every Rodgers amp for turning on the amp when the organ powers up.

      Not sure I'd run these into a mixer though. Your best bet would be to send each of the three channels into its own high powered amp, and direct the output through high quality speakers. Two of the channels need full-range speakers, and one of them carries only frequencies below about 100 Hz (derived from the other two channels). While the organ could actually be played without even hooking up that bass-only channel, it is easier to balance the tone with that channel operating through a big subwoofer. The level control for that channel then serves as a "bass boost" control for the organ as a whole. And with the sub, you don't have to use enormous speakers for the other two channels.

      There may well be a chart inside the organ, possibly glued to the reverse side of the back panel, which shows where all the level controls are. Some stops are unit stops, and there are level controls for these unit ranks. Other stops are independent, and will have a level control somewhere. Some level controls are on the keyer boards though, rather than on the output preamp.

      You may notice that all the voicing pots are marked with a bit of paint. These marks make it possible to return the pots to the "factory" position, if the voicing gets so messed up that you can't straighten it out. I generally begin voicing a Rodgers of that era by returning all the pots to factory, then making minor adjustments only as needed to suit the organist's preferences or the building's acoustics.

      This organ may not be a whole lot to write home about, but it is a couple decades newer than your TC-3, so it should be in better condition. I'm not sure that it actually will sound "better" because the TC-3 was a truly awesome analog organ when it was all working. Unfortunately, Rodgers has near zero support for these old models, and should the CPU fail, for example, you'd just have a pretty boat anchor.

      Despite the fairly primitive technology, the 80's Rodgers analogs can sound quite spectacular when properly installed and voiced, and when the acoustic surroundings are favorable to organ tone. You should read up extensively on this forum, looking for posts about speaker placement, and perhaps some detailed instructions on voicing a Rodgers of that era. You might find posts referring to the Rodgers 740 or 755 or 650 or 705 to be helpful, as these are sister models with much in common with your 745.
      John
      ----------
      *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

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      Comment


      • jbird604
        jbird604 commented
        Editing a comment
        I see that toodles was posting as I was typing, so take his post as the really authoritative word on this model!

    • #4
      Thank you both. I'll get into the back later today and poke around.

      I suspected as much regarding the 3rd bass-only channel, I have isolated it at the output buss bar. Thanks for confirming this.

      It is an amazing improvement over the old Allen, which we need to find a new home for very soon. Anyone need a home organ / project / small Hauptwerk console to convert?

      Comment


      • #5
        Since you are in a small church, the internal amps should be more than adequate if they are working correctly. As toodles suggests, you may need to adjust the output levels on the preamp board. Per my suggestion, do start by returning ALL thumbwheel pots throughout the system to the factory spot. You may find that a previous tinkerer has severely messed them up, if the sound is "gutless". This organ really should roar, even though it's smallish by Rodgers standards.

        The internal 3-channel amp is on a single pc board with some socketed power transistors on a large heatsink. Sometimes the legs of the transistors don't make perfect contact in the sockets, resulting in distortion or weak power output. You may need to clean those sockets and make sure the transistors are solidly plugged into the board. But once cleaned up, the internal amp should be very powerful and clean.

        And it may be best to use the standard Rodgers speakers as well. You should have received a pair of "M10" units, which are relatively shallow 3/4" particle board enclosures with six 6x9 speakers and four horn tweeters in each one. These are extremely efficient (LOUD) and do a good job of projecting the organ tones into even larger spaces. The third speaker is probably a huge subwoofer, perhaps a P32 with two 15" soft-suspension woofers in a ported box. The speakers should surely have been replaced by now, as the originals were probably foam-surround, and the foam would have rotted out long ago. Hopefully you have rubber-surround woofers in there now, or at least the foam has been replaced. This subwoofer is also extremely efficient, and should fill a good-sized church with HUGE bass, doing justice even to the 32' pedal stops.

        Glad that the organ sounds better that your old Allen TC-3. Yes, that one was getting old, and perhaps developing a lot of troubles. The Rodgers was about as advanced an analog as anything ever done, and by the late 80's when the 745 was produced, Rodgers had really perfected their analog reeds. And they were using a very sophisticated system for blending in chiff and air sound with the flutes and principals to make some interesting tones. Not as "authentic" as the digital organs we're so accustomed to today, but quite nice in their own right.

        Speaker placement is critical, so be sure to try different locations. Analog organs often sound best with the speakers on their backs facing up at the ceiling so the sound can "sweeten up" a bit before it gets out into the church. The subwoofer should be on the floor or at least solidly mounted somewhere. If it's near a corner the bass will be reinforced.

        Good luck!
        John
        ----------
        *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

        https://www.facebook.com/pages/Birds...97551893588434

        Comment


        • #6
          I only wish we had gotten such terrific speakers as you suggest; this organ came out of another small church and only with two small Rodgers bookshelf-size speakers and one larger one for the sub-bass. I substituted a pair of good older high power Bozak audiophile speakers for channels 1 and 2 which will do for now until I come up with something else.

          I pulled the back cover off, quickly discovered the output preamp board and boosted channels 1 and 2 as well as the pedal channel, which made quite a big difference. Tweaked a few other things as well, mostly returning it to stock tune throughout, though I turned up (slightly) all the air and chiff puffs! 8-)

          Couple of questions, what would the ANT output be? There's a phono plug on this board right by the ANT LVL and ANT TREB potentiometers. Also one there for REVERB - was there some sort of external reverb module?

          Anyone have any idea where I could find a more extensive technical manual for this organ? Would be nice to study.

          Sure I can't interest you in a nice TC-3? Help us remove it...

          Thanks again
          C
          Last edited by Chip Lamb; 02-23-2019, 02:25 PM.

          Comment


          • #7
            Antiphonal output would be on the same panel where the other output channel connectors are, and would be another 5-pin connector. However, the antiphonal out on this organ is a plain MONO signal, a blend of all the channels. Properly used, with a speaker in the rear of the church, it could be used to throw some sound back there for special purposes. But not suitable as a primary output.

            There might or might not already be a spring reverb installed. Often the reverb tank is just hanging there on the generator rack, suspended by some springs. A few late analogs were shipped with some sort of digital reverb, I think. You should be able to spot it if present, and you'll definitely hear the difference.

            The two RCA jacks are for connecting a reverb unit. The sending jack has a mono blend of all the stops that goes out to the spring or input of the digital, the other receives the reverbed signal and mixes it into the output channels just ahead of the amps. It's possible that the signal coming out of the send jack is very hot, as it may have been intended to drive a spring reverb. If so, you need to insert some series resistance ahead of a digital reverb such as a Nanoverb. And, the output of a Nanoverb may be too high a level to send into the recovery jack, as that circuit may be expecting only the low level signal produced by the pickup on the other end of the reverb spring. If so, you would need some series resistance there as well. Try about 100K and see if that works.

            There may not actually be a full service manual for this model, though toodles is the guy to tell you for sure. Rodgers just about stopped making service manuals by that point in analog production, relying on older manuals that contained similar circuits. Old-time Rodgers techs didn't really need a manual, as these organs were all so similar, and the system was rather redundant.
            John
            ----------
            *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

            https://www.facebook.com/pages/Birds...97551893588434

            Comment


            • #8
              There are no readily accessible amphenol connectors on the output board - the single RCA/Phono jack here by the ANT pot makes that make sense though as it's just mono. I'll send you a pic when I've got the back off of it again. The reverb pot and its associated RCA/Phono jack (1 again) is quite a ways away from the ANT. Hmmm.

              Comment


              • #9
                Originally posted by Chip Lamb View Post
                Sure I can't interest you in a nice TC-3? Help us remove it...
                Chip,

                If you're requesting assistance, it would help if you provided your approximate location (i.e. State or region).
                If you are trying to re-home your Allen TC-3, you should post a classified in that section of the Forum with the details of the acquisition (i.e. price, location, etc.).

                That Rodgers will certainly be a big improvement over the Allen, as you now have Mixtures and other niceties at your disposal. When you mentioned how there was little or no oomph to the sound, I wondered if the woofer surrounds needed to be replaced, or if when they were re-connected, they were wired backwards, which will almost certainly result in phase cancellation: Net result–no bass.

                Best with the new instrument for your church.

                Michael
                Way too many organs to list, but I do have 5 Allens:
                • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
                • Lowrey Heritage (DSO-1)
                • 9 Pump Organs, 1 Pipe Organ & 6 Pianos

                Comment


                • #10
                  Thank you, Michael. I need to update my profile. The Allen is in Augusta, GA 30909, right off I-20 at the GA/SC state line.

                  The output levels were turned down and I am "under-speakered" at present... working on improving the latter as the former is fixed for the moment.

                  Comment


                  • #11
                    All the line level outputs will be grouped together on a common connection panel. In late analog models like yours, it was usually on the inside back of the knee board, so you'll have to swing the generator racks out of the way to see them. You should see three "Main" outputs -- Ch 1, Ch 2, and Ch 3 (one of which is the bass channel, but I don't recall which one) and also one output marked "Antiphonal" with an identical 5-pin connector.

                    These five-pin connectors are meant to go to individual Rodgers S-100 amps, which require a 15 volt relay voltage to switch them on with the organ power. So two of the pins are the relay + and - power. One is the audio signal, and one is signal ground. The fifth pin is unused.

                    The two RCA jacks you see, regardless of where they are located, are almost surely the OUT and IN connectors for a reverb unit. I've never seen any other RCA jacks on a Rodgers preamp board. The Reverb OUT jack is actually a nice place to pick up a Mono mix of the whole organ, if you should need that type of signal for some reason. It is "on" all the time, unlike the Antiphonal output, which is only live when the Antiphonal control is lit up. It is of course intended as the drive signal for a reverb unit, since organ reverb systems always start with a mono signal.
                    John
                    ----------
                    *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

                    https://www.facebook.com/pages/Birds...97551893588434

                    Comment


                    • #12
                      Neat info. Thanks. I think with better speakers (chasing a set of correct M10s and the sub) the onboard amp will be sufficient.

                      Comment


                      • #13
                        Update - we now have 2 M10 cabinets and a P16 with new drivers. Each M10 crossover unit has two speaker inputs on the board, one right next to the other, neither of which is marked. Any tips as to which is + and which is - ? (inboard or outboard)

                        The P16 sounds terrific, I can't wait to get this organ installed; it's only work.

                        Comment


                        • #14
                          If there is a "C" next to one of the terminals, that is the Common or negative. If there is a paint dot next to one, that is probably the positive. If you can't find any markings, just connect both of them the same way. They do need to be in phase with each other, as all the tones are derived from the same rank of oscillators, and there would be some loss of tonal richness if they were out of phase.

                          After you connect the M10's, have someone hold a note on a 16' pedal stop at B1, then try the phasing of the P16 both ways to see which one produces the most FUNDAMENTAL output. You may not hear any difference except a very slight increase in the "body" of the tone when the P16 is in phase with the other speakers. Or you may hear no difference at all. The M10's don't contribute very much bass to the sound anyway. If you don't hear any difference, then don't worry about it.

                          Glad you got the proper speakers. The P16 was actually designed for organ models with 16' pedal stops as the lowest, and the P32 was supposed to be used when 32' stops were present. But I would guess that in later production a lot of organs with 32' stops got installed with P16 subs, as they were obviously quite a bit smaller and no doubt less expensive. Still a very nice subwoofer, even if the 32' stop may not shake the church quite as effectively. The P16 may actually be a little bit more efficient, giving you more oomph on the 16 footers.
                          John
                          ----------
                          *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

                          https://www.facebook.com/pages/Birds...97551893588434

                          Comment


                          • #15
                            John - thanks - the - was marked COM so I connected it properly.

                            Bit more hiss from these than I'd like to have. Any suggestions for noise cancelling? I've tuned the treble back at the organ preamp and at the tweeter adjustment on the M10 crossover to 2/3.

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