Allen TC3 into TC4 = possible?

[toasterDude]

It is feasible to add an additional rank to an Allen analog organ--if there is physical space for it. The reed ranks used the basic sine wave oscillator (same as the flute), passed it through a diode to rectify it and add harmonics, then had a filter for each note.

Interesting... this is precisely what happens in the reed "trunk" on the T15 etc. Allen called this diode circuitry a "tone changer". I guess I assumed the reed generators per se (i.e., on a TC-4) might've been done differently, by generating a square wave or sawtooth wave or something, then filtering it down. ...So it sounds now like this would be possible to do, but would require essentially sacrificing a T15's entire tone generation system.

Either way you're right: space may be an issue anyway. I hadn't really gotten in there to look; I was still just at the speculative "I wonder if it would be possible to..." stage. But I pushed the TC3 out today for a look: darn! There's considerable empty space, but not such that I can see any way to fit another generator rack in there. The space just isn't configured right. So the only way might be to go with external generators... rats.

Anyway I appreciate the lively discussion!

[m&m's]

Either way you're right: space may be an issue anyway. I hadn't really gotten in there to look; I was still just at the speculative "I wonder if it would be possible to..." stage. But I pushed the TC3 out today for a look: darn! There's considerable empty space, but not such that I can see any way to fit another generator rack in there. The space just isn't configured right. So the only way might be to go with external generators... rats.

Anyway I appreciate the lively discussion!

You might have to move the existing middle set of oscillators up or down some, but space can be found for the additional set of oscillators, as the TC4 used the same console, and had the additional set of oscillators.

Where there's a will, there's a way....

[toasterDude]

Good point. I guess if I were to tighten up the spacing of the individual generators within the rack, then it might be possible to do.

But I'm confused now. If the reed voices on a TC-4 were derived by taking the notes from a flute (sine wave) generator and running it through Allen's "tone changer", i.e. the clipping diode circuit mentioned before... then how much of a difference is that over the TC-3? --Since again, the TC-3 already does the same thing. It sounds like the main difference is that in the TC-4, the tone-changer/reed section has a flute generator all to itself, so to speak, whereas on a TC-3 it has to share the flute generator with the flutes themselves. So does this mean on a TC-4 the corresponding flute *doesn't* sound along with the reed voice, as it does on a TC-3 (and on a T15 for that matter, I suppose TC-1 also). If that's the only difference then it may not be worth all the work to add another generator.

On the other hand, the old Allen brochure someone was kind enough to share on here says the following about the TC-4:

"Each tonal family, produced by a separate source, retains its own characteristic attack which serves to enhance the superb full organ ensemble." Does that mean the TC-4's separate reed circuits also have a provision for a different ADSR envelope? Or is this just marketing-speak for "on this one the reeds can sound without the flutes tagging along"?!?

Well, this is all highly interesting to me anyway... :-)

[nullogik]

Hi Toasterdude and Circa,

You should have an email and a PM from me respectively. I have some scanned Allen docs which might be of interest to you both which I can email.

I'm working on uploading the TC4 and TC6 brochures which should be done sometime today and will appear soon depending on when Admin authorises them.

Nu

[toodles]

Good point. I guess if I were to tighten up the spacing of the individual generators within the rack, then it might be possible to do.

But I'm confused now. ... So does this mean on a TC-4 the corresponding flute *doesn't* sound along with the reed voice, as it does on a TC-3 (and on a T15 for that matter, I suppose TC-1 also).

...


"Each tonal family, produced by a separate source, retains its own characteristic attack which serves to enhance the superb full organ ensemble." Does that mean the TC-4's separate reed circuits also have a provision for a different ADSR envelope? Or is this just marketing-speak for "on this one the reeds can sound without the flutes tagging along"?!?

Well, this is all highly interesting to me anyway... :-)

1. Note that the TC4 reed oscillators had ONE FILTER PER NOTE; this is note-by-note voicing capability. I don't think the "flute trunk" did that (to me "trunk" = "bus" and that means all note outputs consolidated); I think it was a lumped filter (but I don't have my schematics in front of me). Even if the flute trunk approach did note by note filtering, as far as registration, you would get the reed along with the flute for every flute and reed pitch level selected, and that is very much different than flutes at specific pitches and reeds at others.

2. Yes, the keying envelope would likely be different between flutes, principal, and reed ranks. The reeds would have a faster attack than the flutes.

Yes, adding a separate reed rank would be valuable. It would give a bigger ensemble and allow indepenent selection of flute, principal, and reed pitches.

Toodles.