Lowrey Berkshire Deluxe TBO-1 Arpeggio Function

[Drawbar Dave]

I've got a TBO-1 where everything seems to work fine other than (possibly) the Arpeggio function. what is it supposed to do? The owners manual is not very helpful on this function. The AOC works perfectly well as it should and I'm guessing that the Arpeggio should behave in a similar way.

[andyg]

Head scratching time here! Last time I played a TBO-1 was 40+ years ago! IIRC, this isn't connected to the AOC side of things but more connected to the repeat and marimba repeat. If you turn it on and play a chord, does it strum it from bottom to top?

[Drawbar Dave]

No it doesn't do anything like that. It's strange because the marimba repeat and AOC work fine! I'll have to try cleaning the switch contacts again.

[JQA]

This section from Richard Dorf's Electronic Musical Instruments, 3rd Edition (1968), which describes the Theatre Spinet model H, may be relevant:

The Arpeggio effect is closely related to the AOC and it is obtained by adding nothing more than a tablet and its switching contacts.

The Arpeggio tablet does two simple things. First, it turns on the AOC even though the AOC tablet may be off, by effectively shorting its contacts. Second, it removes the keying potential from the upper-manual diode keyer busses.

The total effect is to have AOC but no normally operated melody notes. That is, when the upper-manual keys are pressed, you will hear notes corresponding to any you are holding on the lower manual, but not necessarily the note of the key you are actually holding down.

Suppose you hold a C chord on the lower manual. Now you just run a finger up the keys of the upper manual in the manner of a long glissando. You will hear the C's, E's, and G's of the C chord following you up on the scale, and nothing else, just as if you had manually played a long arpeggio. As with normal AOC, the voices and pitch registers heard will correspond to whatever upper-manual tablets are on, since the normal diode keyers are being keyed and feeding their normal voicing networks. (For some reason, the Owner's Manual says the normal voices are cancelled; this is an error.)

So, it is not the same sort of arpeggio effect as found on e.g. later Japanese organs and synthesizers! More versatile, but not automatic.

[Drawbar Dave]

Thank you very much. Yes that describes what happens when I switch it on so it must be working normally. Although mine does defeat the upper manual voices when it is on.