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Allen TC1 wiring

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  • Rick Jay
    replied
    John,

    Thank you for that advice. I wired in a couple of 47k ohm resistors tonight and all is well.

    GREAT ADVICE!!! :)

    ~Rick

    Leave a comment:


  • jbird604
    replied
    About 22K to 47K of series resistance between the Allen outputs and the input to your mixer will restore the operation of the expression pedals. The original amps used by Allen on these old analogs has an input impedance of around 75K, I believe, so the input of the amp doesn't load down the expression cells and keep them from working. Modern equipment has lower input impedances which tend to obscure the changes in resistance of the LDR's in the expression shoes as they are exposed to more or less light. Thus the need for isolating series resistance.

    Leave a comment:


  • Silken Path
    replied
    Hi, Scott - This is the afore-mentioned Lamar in Georgia. I have two TC-4s, which are simply TC-1s with four generators. If you could take a picture of the floor where the long terminal barrier block is and the adjacent area, we can suggest more, but John is (almost always) right, God bless him, and the coax coming from the pedal to the floor terminals are the ones you want. On my TC-4s, it's a separate block from the gryo-control, power-distribution long fore and aft block. The speaker wires end in a small RF-looking connector that is OBSOLETE now and can only be replaced with used parts.

    I'm going to get a little mixer for the three channels in mine so I can use headphones. This is the convenient way to do it, since the amps are high-impedance. They can also go in parallel to the speaker wire and amps, which I can turn off with a power strip when I want to use headphones. You can also mount one under the panel to make the headphone jack easy to get to. The pedals light on mine is an easy through-point. The Rolls MX-II is what I'm considering - it has the headphone jack on the front.

    The 110-carrying wires on mine are not large and don't look much different from the speaker wires.

    The info pack from Allen is good to have. It's a subset of the Analog Technical Manual, which is pricey and overkill.

    Make friends with John, by the way. This old organs need TLC.
    Last edited by Silken Path; 03-13-2019, 07:23 PM. Reason: Changed "Hi, Rick" to "Hi, Scott" as I am easily confoosed (and Rick was probably wondering why I was answering HIM)

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  • myorgan
    commented on 's reply
    Rick,

    I believe you can direct your question to member, Silken Path (Lamar) from Georgia. He has a couple of TC-3 organs, and may be able to help you from the resources he has. Of course, John is a good resource too....

    Michael

  • Rick Jay
    replied
    John,

    Above you stated: "For headphone use, just pick up the two channel audio on the coax cables and run it into a small tabletop mixer (less than $100), using a microphone level input if possible, so as to preserve the operation of the expression pedal. (For many technical reasons I won't go into, the input needs to have a high impedance, otherwise there will be little or no volume change when you move the expression pedal."

    I'm in the process now of temporarily reconnecting our old TC-1 while I get the ADC-6000 installed. I connected the outputs to a Mackie 1202 Micro mixer which has 10k ohm input channels and I am experiencing the limited volume change you mentioned. When I connect the organ directly to my Bose L1 Compact system, the volume range is much better, but I can't find the published Zin spec for the Bose inputs. The lowly L1 Compact doesn't have the oomph needed. The mic inputs on the Mackie are all XLR and rated at 2.5k ohms. I haven't tried those yet as I'd have to rig up a cable, plus they are lower Z than the 1/4" inputs. So according to you post they shouldn't work as well as the 10k inputs I'm trying to use.

    So, does the TC-1 really need a higher amplifier Zin than 10k, or did you mean lower Z in your original post?

    Thanks,

    ~Rick

    Leave a comment:


  • Guest
    Guest replied
    Thanks for the informative and speedy reply!

    The organ didn't come with speakers or any external amplifier. So, if I have this right: the TC1's thick wires coming out were not likely speaker outputs, but as you say are relay control wires and the like. So I should just remove those and use the coax. That's pretty simple -- I suspect I can get that done simply. (I'm an EE by training, but usually work in the digital micro controller world, not the power or audio/video world).

    Thanks again!

    Leave a comment:


  • jbird604
    replied
    For headphone use, just pick up the two channel audio on the coax cables and run it into a small tabletop mixer (less than $100), using a microphone level input if possible, so as to preserve the operation of the expression pedal. (For many technical reasons I won't go into, the input needs to have a high impedance, otherwise there will be little or no volume change when you move the expression pedal.)

    The rest of the wires will have no use in a headphone setup, as they are relay control wires, turning on the remote amps, changing the gyro speeds, operating antiphonal relays, and such. Be aware that there MIGHT be live 110 volt AC on one of those cut cables though.

    You don't need to hook up the old amps, and they are in fact quite useless for headphone playing. Just get a little mixer that already has an headphone jack, and it will also make it easy to pan and blend the two channels, adjust the bass and treble, and otherwise tweak it to sound good in headphones. Some little mixers even have built in reverb.

    Leave a comment:


  • Guest
    Guest started a topic Allen TC1 wiring

    Allen TC1 wiring

    Hi folks,

    My sister's husband just acquired a Allen TC1 removed from a church. There is no manual and cut wires. I know I can get a $50 info pack from Allen, but before I do that I'm just wondering if anyone can give me a little help:

    1) basic pin-out of the terminal block.

    2) confirm my understanding that the Coax wires are outputs that can be attached to an amp

    3) If we hook up an Amp, can the speaker wires be left 'open' or will this cause any damage.

    4) Any other tips to bringing this unit back into basic service.

    The desire is to only hook up headphones for practice.

    Thanks in advance.

    - Scott
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