Help with Rodgers 755 Concord organ

[Guest]

I have some questions about our organ. The subwoofer in the balcony is vibrating with the 32' Bass... can i adjust this to balance out the sound??

All the the MIDI on the great does'nt work... is this flawed by design??

[jbird604]

Jim,

Unless the woofer cones have been changed out, an organ of that age almost surely has foam-surround woofer cones, and the vibration you are hearing is probably the cones rattling in their suspension. This situation should be addressed by a competent tech ASAP before damage to the amplifier occurs. Check with the local organ dealer or a trusted tech. If you don't have one, go to www.mitatechs.org and search for a tech near you.

Of course I may be wrong and the cones could be fine and something else in the balcony is vibrating. In that case, you can indeed adjust the volume of the 32' stop to minimize the rattling. You'll need a chart of the voicing controls, which may actually be found taped or glued inside the back cover of the console. I think a 755 will have note by note leveling for the lowest two octaves of the 32' stop, but I can't recall just how that is laid out. There should also be an output level control for the subwoofer channel and there may be separate level controls for the various pedal stops.

Please be aware that it is possible to really mess up the voicing and balancing of an analog Rodgers if you are not very careful. You must always be sure that you are listening to the note and stop that you are adjusting. If you turn a control and don't hear any change, put it back the way it was immediately! Otherwise you may be throwing something really off and not even know it until you get the organ all closed up and try to play something.

When a Rodgers with voicing pots left the factory, the controls were probably marked with a silver paint to show the factory default settings. These default settings are not always perfect for a given installation, but will usually be very close to correct and will at least be safe. If someone has tinkered with the controls and moved them way off the factory settings, you might try returning some of them to the marked positions to see if that improves things. (But observe the warning above -- don't move anything unless you are listening to the exact note and stop affected!)

[jbird604]

Regarding the MIDI ... A 755 would have "Phase II" MIDI implementation. The Great manual could be set to transmit data on any of the 16 MIDI channels, so it's possible that someone has set the transmitting channel to something other than 1, 2, 3, or 4. Check the owner's manual to discover how to reset the channel to match the channel assignments of the external MIDI device that you are driving.

[toodles]

1. Check the subwoofer itself, make sure it's stable, level, and nothing has been placed on top of it that could rattle. Check the cone out, too, as John suggests. The 32's on that series usually and note-by-note levelling pots, so if it is just one note, you can adjust it.

2. No, the MIDI functioning as you indicate is not by design.

Toodles.

[Guest]

Alright, so i looks like i have some questions to present to my church about our current organ tech. I am very computer savy (it's my day job), and i would love to find the amp for this..
As far as the bass, it's almost as if not sound but just rattling is happening with the speaker. It's not bussted, we have replaced it since i've become on staff (i pushed for perfect equipment to work with.... lol)
also, the antiphonal speak isn't designed to handle bass i assume, it's so high in it's location that can't just service that by myself. I hear the horns and stuff going to it (it's located at the back of the church), but again, sending the 32' to the back or Subbass is a no no..... I'm still learning balancing.....

thanks guys!!! :)