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Allen AP-3 Sub Bass connector

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  • Allen AP-3 Sub Bass connector

    I recently acquired a powered sub and want to connect it to my Allen AP-3. (Not sure why, but want to play with it). I got the connector for the Ch 4 sub bass output. It has 2 cables and on the cage it is marked Lo +/- and High +/-. I understand that the +/- are the signal outputs. I hooked it to the LO pins, and it does play but get a good bit of treble from the sub. My question is what are the Lo and High outputs? It was my understanding that the only thing that would come out of the Sub Bass output would be the Bourdon 16'. Is this a cross-overed output from Ch 4 that has the lo frequencies on the low and the highs from that channel on the high, or are they 2 different levels of Bass?

    I was expecting to only get Lows from the SubBass out.

    Would someone know what the 2 different outputs from this connector be?


  • #2
    According to the audio chart drawing on the Allen tech site, the P948 connection carries the same signal as the normal channel 4 output, but it goes through a frequency splitter and comes out as separate high and low frequency bands. So the portion of the connector marked "lo" should carry only the frequency band they thought should be produced by a dedicated subwoofer. Therefore, not only will you hear the lowest frequencies of the pedal stops, but the bass portion of all other stops that are in channel 4. (On the AP-3, which has only two audio channels by default, there are even some swell stops in that output, so you'll get the bass frequencies of those stops as well on that "lo" output.)

    BTW, you can ignore the "minus" pin when connecting the signal to your subwoofer's line level input. Use the "plus" pin for the inner (signal) wire on your RCA cable and connect the shield to the ground pin (the one not marked).

    Even though the "lo" output was intended for a subwoofer, there may still be a lot of higher frequencies present in the signal because it isn't a super steep crossover slope. Your powered sub probably has a control that allows you to change the crossover point. Adjust that control until you hear only the very lowest frequencies coming from the sub, since it is only the super low pedal frequencies that you want to boost with the sub.

    Also, play around with the "phase" control on the sub, if it has one. You may find that it makes a dramatic difference in how well it works, because if the phase happens to be wrong, it might actually work AGAINST the internal bass speaker and give you LESS bass than without it.

    As with many other Allen self-contained models, the AP-3 might actually benefit more from some TREBLE enhancement outside the console instead of some bass enhancement. The easiest and cheapest way I've found to greatly improve the sound of a self-contained Allen is with a pair of PP-3 speakers connected in parallel with the internals. Place the PP-3's on top of the organ, facing up at the ceiling. It really opens up the sound. The internal speakers are pretty lousy for projecting treble frequencies.
    *** 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!