Need help connecting speakers to Rodgers Concord 755

[Neumie]

This weekend a church gave me a Rodgers Concord 755. Nice instrument, with MIDI. My much older 750 is now in the garage, ready to be tossed out.

When the older 750 was in the house, I had two simple round organ plugs in the back going from the jacks to my speakers. I use two large powered JBL speakers, no external sub. Just simple two-channel audio is all I need.)

This is what I saw when removing the back off my OLD organ. This photo shows additional plugs, but in fact I only used two.



I naively thought that when I popped the back of this newer Concord 755, that I would see the same jacks and just be able to plug in my two JBLs and continue playing. No such luck. There are no organ jacks at all on the 755, just pressable tension connections for speaker wire. They are also not names the same names as on the 750. Instead, they are just called channel one, two, etc. The hacked off speaker wires were still attached to the back of the organ when it was delivered to my house, so that helps me zero in on what jacks I'll be using. Although here there are four wires connected, not two ... so I need a little coaching what jacks to hook up to duplicate my old setup.

First photo is a wide-angle of the four wires and their destination. The other two photos are closeups. In the second photo below, I see a row of channels 1 through 5, plus another connection for speakers.

In the third photo, I see a connection for "signal out" and "gnd" something-or-another.

My previous 750 did just fine using only two outs ... and since I didn't use a pedal jack, it had some way of funneling the pedals into the same signal as the left and right out. My 750 also didn't have anything that said "signal out" or "gnd".

It seems like the common sense thing to do is to disconnect all four of these lines and plug my left powered speaker into channel one and my right speaker into channel two. So questions are:

1) Is that the right thing to do?

2) Will this newer 755 mix and send the pedals to the L-R lines, since I'm not plugging anything into the "pedals" jack? Same as my 750?

3) What is that fourth "signal out / gnd" jack and can I leave it connected to nothing? I'm thinking gnd means ground and that perhaps that is/isn't important? I had no such jack on my 750, so I don't even have a guess what this is or what to do with it.








Again, the whole goal here is to get rid of the four old wires coming out of the organ and have just my two previously existing wires in use, one to each speaker.

[jbird604]

Unfortunately, you have changed to a much different type of audio setup. The old 750 had the "classic" Rodgers analog audio setup, with no power amps in the console. Nearly all Rodgers organs built before the 1980's had the same setup, so the speakers were transferrable from one to another. Not so with organs built in the 80's and later.

Your 755 and others of that era have the power amps IN the console, not in the speaker cabinets. So you no longer need your powered speakers, and it would be a stretch to get your organ to work with them. Not saying it couldn't be done, but unless you have some good technical skills you won't be able to make up the complicated mixing and level-matching circuitry that would be required.

I suggest that you just get some inexpensive standard speakers and use the JBL's for something else (or sell them).

To explain the wiring and outputs you now see.... The 755 was sold either as a 3-channel organ, or optionally as a 4-channel organ. Yours was apparently just three channels, or at least they seem to have only had three speakers attached. Channels 1 and 2 would carry the manual stops (or more correctly, the upper frequency ranges of the stops), each channel carrying a different mix of the stops. So the speakers required for those two channels would be relatively small, at least in a home setup. Rodgers originally supplied M-10 cabinets with the organ for these two channels. The M-10 consists of an array of 6x9 speakers and some tweeters. But you probably can't find any of those. Just use a pair of good quality full-range speakers. I've used low-cost commercial sound speakers with 8" or 10" woofers and some small cone or horn tweeters. You could also use some decent home stereo type speakers for these channels. Not "cheap" ones, but decent ones.

Channel 4 should be the bass channel. (I'm pretty sure about this, but it's possible that channel 1 is the bass channel. You can easily tell which one is putting out almost nothing except the lowest bass frequencies). You will need some kind of hefty speaker cabinet to handle this channel. Rodgers would have originally equipped the organ with one of their HUGE "P-32" cabinets for this channel, an enormous box with two 15" woofers and a large port. You probably don't want or need such a thing in your house.

There are decent PASSIVE subwoofers available from various sources for not too much money. I see them on MCM Electronics for under $100. What you do NOT want to buy is a "powered" sub such as you see everywhere, designed for home theater systems. Not that these woofers couldn't do the job, but they contain built-in power amps, and therefore not meant to be used with a direct speaker signal output like your organ has. All you really need is a 15" good-quality woofer in a box.

More bad news. You will almost surely need to do some voicing of the organ to make it usable in your home. The sound will probably be way too loud, if it was previously installed in a church. Some of us here can probably tell you where to look for the controls in the console. Unfortunately, there is not a "master volume" or even some obvious volume knobs. Just a group of level controls (thumbwheels) on the output preamp that must be properly adjusted and balanced with one another.

So, that may sound like a pain to you, but you will be pleased with the way this system works. Your two manual speakers need only be decent and small and can be placed where you want them. The woofer probably needs to be on the floor.

Good luck!

[toodles]

JBird is right--the 755 has the amps in the console, not in the speaker cabinets. But using the 755 with powered amps isn't that difficult, since the output panel already has connections for doing that; these were intended for supplementing the main speakers when required.

The terminals to which wires are already attached are the direct amp-out speaker connections. By the way, the wiring on those is TERRIBLE! You don't wrap extra strands of wire around the main set of strands, all strands should be twisted together, and inserted into the terminal.

For connecting powered speakers, use the DIN jacks labelled Channel 1, Channel 2, Channel 3, and Pedal Channel which are also on the output panel (in about the middle). These provide audio driver outputs which would connect to amps or powered speakers. You just need to make adapter cables to go from the large, tube-plug type connnectors to DIN plugs, or cut off the tube-plug type connectors and wire DIN plugs right onto your cable. Since the existing connectors are now very expensive, and DIN connectors are cheap, I would make adapters in case the old style connections are ever needed, but the choice is yours.

It is odd, however, that your system has Channel 3 speaker connectors, but the levers to use those connections seem broken off.

It is also very odd that you have an antiphonal channel amp connected from the output panel to the amp. You'll need to figure out what that is about.

The model number nameplate might indicate the number of channels originally included but a "dash" number, like 755-3 or 755-4--I think that is what Rodgers did at that time.

The DIN connectors have the usual Rodgers wiring: two 12 VDC power wires (+ and -) and a single shielded signal audio signal, and a "no connection" pin. The tech manual provides the pin out. The page with the output panel connections is attached.

[Neumie]

FIrst of all, a fat THANK YOU for the knowledgeable replies, both of you. I don't know what I would have done without you. Well, yes I do. I would have had to get out a checkbook and call in a Rodgers fellow from 150 miles away.

So Toodles, I'm reading that my solution is to remove the wires from the amplified lines and instead use (line level wire) in what you call the DIN jacks, the small round jacks?




1) That means that, as the speakers are currently wired, channels one and two of the amplified outs are for the two mains. And the one marked "pedals" is obvious. I'll just be pulling those wires out and replacing them with line level wire to the DIN equivalents right nearby? Also then, no need for new speakers (other than a passive or active sub, depending on which jack I plug it into).

2) Toodles, you wrote that you don't understand why Antiphonal2 DIN is connected to a second antiphonal amp. Is that not straightforward? The antiphonal doesn't use the main amp, so we're sending a DIN level signal to the 2nd dedicated antiphonal amp and then an amplified signal from the "signal out/gnd" to a passive cabinet in the back of the room?

3) Also, must I actually have a sub? I didn't on the older 750. Even though there was a pedals jack on that organ, I just hooked the two mains up to my powered JBLs and the pedals came through plenty clear together with the manuals. Is there anything about the newer 755 that forces the pedals to remain separate? Or can I again just hook two speakers to channels 1&2 (DIN) and get the full range of sound? (My JBLs have plenty-big woofers, adequate sound for an unrefined amateur like myself.)

4) John, you referred to a thumbwheel. I looked back there this morning and did see an large assembly that, judging from the cooling fins, I assume is the amp. I see three canisters down the left side, and each canister has a little thumbwheel beneath it. Are these the volume thumbwheels? If so, do I only see three because I also see pressure-jacks on the audio-out panel for channel1, channel2, and pedals? Three wheels for those three powered-outs? (Antiphonal has its own amp & channel3 seems to be broken or unused.) If that's correct, Rodgers installed an amp to match the audio-out panel - ie, unusued channels 3&4&5 means no thumbwheels for those channels.

And would these thumbwheels even be in use, if Toodles is correct and the DIN jacks send out an unamplified line level and I do USE the DINs? The DINs would bypass the amp and the thumbwheels entirely, correct? (Although even then, an organ still needs to be voiced. How then does Rodgers intend me to do it? With the volume knob on each powered speaker? That would make sense.)

[toodles]

The DIN jacks, circled in red, are the un-amplified outputs (line out); except that the upper right hand corner is an antiphonal channel, the others are "main".

The separate amplifier with the "signal out/gnd" is a generic amplifier, not specific to this model or application. For example, if you bought a 770 (larger model like the 755) you got one of the amps for external mounting for the pedal channel. This is why it labelled generically. To find out how it is used here, follow the input plug back to its source


The "signal out" wire on the amplifier on the right is just the amplifier output. This was a generic Rodgers amplifier, so it isn't labelled specifically for the organ . This should be the output to the aniphonal speaker system. You can figure out that it is for the antiphonal by following the input plug cable back to the output panel.

If you aren't going to do an antiphonal channel, you have a spare amplifier.

[Neumie]

I'm getting so close here, Toodles. You've been so helpful. Thank you.

Please stay with me for the home stretch. Do you think that if I use the DINs, then that bypasses the voicing thumbwheels? No need to touch those? All voicing is done externally, on the outside amps or powered speakers?

And if ultimately, I'm using nothing but channels 1&2 ... then the organ will mix the pedals into those channels, just as my old 750 did?

(Let me tell you how appreciative I am to learn that those were powered line-outs. Thinking I had another organ just like my 750, I was so close to hooking those up to my powered speakers and likely ruining them. Very grateful you and jbird (John) are on this forum.)

[toodles]

VOICING
There is no voicing done after the tumbwheel pots--those affect both the regular speaker outputs and the DIN audio outputs. If the amps in your speakers have some tone controls (they do not usually on Rodgers amps) they they would affect the tone. And any tweeter adjustment on the speakers would affect.

CHANNEL MIXING
The organ was built as a 3-channel or 4-channel organ (see attached brochure). I don't think it is set up to do channel mixing other than allowed by the base configuration (3 or 4 channel). There is no mixing by virtue of using the line (DIN) outputs. Any mixing has to be done on the preamp board.

Your organ seems odd in that the 3rd speaker connections are present but not used and look broken. Perhaps it was converted from 4 to 3 channels at its former installation. You really need to know what was done here to know if you have a 2-channel plus bass or 3-channel plus bass organ in order decide if you need another audio channel or 2.

Pedal Channel
The main organ channels are full range--i.e., the bass frequencies are incorporated into those directly. If your speakers are capable of producing that range of frequencies, then you don't really need the pedal channel.

The "pedal" channel sums the bass range from all the channels, and the idea was to use speakers that were weak in bass (i.e., smaller) for the main channels and then supplement the bass as needed with the "pedal" channel. Callling it "pedal" is a Rodgers misnomer--it's really just a woofer channel (or subwoofer). There are internal adjustments on the preamp board to control how much bass the channel gets from each of the audio paths.

In other words, if your main speakers provide enough bass, you don't need a pedal speaker.

Finally
I have the tech manual as a PDF that I can send to you in pieces--most email servers limit the size of attachments--but you'll need to send me a private message with your email address. The forum doesn't allow sufficiently large attachments for me to post it to this message. This includes voicing instructions and detailed info on where different adjustments can be found.

Note that certain voicing can be done from the front of the console: some voices (unit flutes, unit diapasons, unit reed voices) have a loud and soft setting, and these can be chosen at will from the front of the console; likewise, octave by octave chiff levels can be set. The Continuo Range can be set, as can be the solo coupler (if you have one). Choice of pipe/electronic voices is also done from the front.

[Neumie]

SO much helpful information. Thanks, T. Next step is to buy some DIN jacks. That might be a weekend thing.

Let me know if my private message did not arrive. I sent it, but it doesn't show up in my sent box. That might just take a while. You should have it though.

[toodles]

I got your PM--the manual is on its way to you in several messges. Radio Shack used to sell these plugs. There are multiple styles of DIN plugs/jacks, having to do with the angle between the connections. Note these use 5 pins across 180 degrees.

I don't know where you are located, but this should be the right plug: http://www.jameco.com/webapp/wcs/sto...10001_15879_-1

They delivery quickly to the west side of the US but have a small minimum order.

[Neumie]

Very cool, Toodles. Thanks for the link to the product. Radio Shack in my neck of the woods went belly up, but I have a Fry's I can visit this weekend. If that doesn't work, then I'll order from your link.

Will it be self-explanatory which of the five pins to hook up to my two wires in the speaker cables?

Eager to bring you a good report of a working organ by the end of the weekend.

[tucsondave]

Neumie,

Those thumbwheels you asked about on the power amp are not volume controls. They are bias controls. Do not move them.

If you are not going to use the antiphonal channel you could use the DIN cable that connects it. Cut the cable in half and splice the correct wires to your powered speaker wires.

td

[toodles]

If you have the large, tube-style 5 pin connectors on your current cables with amps in the speaker cabinets, then there should be 4-wires to connect, not just 2. The output panel drawing has the connections for the DIN plug in the lower left hand corner--if you have a technical manual for the 750, it should have the pin-out of the cables you now have. Connect appropriately. If you can't figure it out, maybe you shouldn't do this yourself???

As Tucsondave said, you can cut your DIN cable for the antiphonal in half to get 2 plugs.

[Neumie]

If you have the large, tube-style 5 pin connectors on your current cables with amps in the speaker cabinets, then there should be 4-wires to connect, not just 2. The output panel drawing has the connections for the DIN plug in the lower left hand corner--if you have a technical manual for the 750, it should have the pin-out of the cables you now have. Connect appropriately. If you can't figure it out, maybe you shouldn't do this yourself???

As Tucsondave said, you can cut your DIN cable for the antiphonal in half to get 2 plugs.

I did have the large 5 pin connectors on my 750, but I soldered the wires in myself. Someone on the forum gave me the pin numbers to solder to, and I took regular two-strand speaker wire and soldered it to two of the prongs. If I can find something in the manual, or someone here on the forum, that states what pins in a DIN jack to solder to, I can do the job again myself.

Yes, I could slice the antiphonal wire in half - and I will do that if I can't easily find DINs at my local Fry's the weekend. I'd prefer to have that premium extra long DIN cable intact for future use, but I'll use it if I don't find anything else local this weekend.

[toodles]

How do you switch on and off the amps in the JBL cabinets? That's what the other 2 wires do (the ones that aren't shielded audio).

[Neumie]

Good to know. No, I never used those other two connections. My JBLs are plugged into a switchable outlet in the wall. I hit the wall switch, turn on the organ, and play.