Multiple resonating chambers ?

[Chuck Morrison]

Historically there are a few instruments that have additional resonating strings, like Hardanger fiddles, harp guitars, Sitars and so on. These are strings whose purpose is just to resonate when their frequency(s) is played on the main strings. I was wondering if anyone could point me to an instrument(s) that utilizes several resonating air chambers (columns, tubes ...) rather than strings ? I would guess that a pipe organ with lots of banks of pipes would by default have background resonances occurring on/in unused pipes of the same or related frequencies which may contribute to the massive tonality they can have. But that would be more by accident than by design. I'm wondering about instruments that utilize multiple chambers by design. I'm sure I'll have a "duh!" moment when someone points out the obvious.

[Chris Reed]

Vibraphone?

[Chuck Morrison]

True, a vibraphone would qualify, at least as much as a pipe organ would. Not quite what I'm looking for though. Still, that may be mostly what there is...

[Yuri Terenyi]

Marimbas. (yes, that's just another kind of a vibraphone but older)
There are some very early clavichords that have two air chambers. One where you expect it, under the bridge, and a separate one running the lenght under the keyboard, from the left side to the beginning of the main air chanber. This one is invariably shallower than the main one.
Some experimental guitars have been made with two backs. The idea was to prevent the body of the player dampening the back plate. So in effect thre are two resonating chambers, though the air can flow through by means of yet another hole inthe "middle" back plate.
There also is in existence a late 18th c. guitar (or early 19th) that has a little oblong box with strings stretched over it, in the manner of a tiny dulcimer, built into it. It sort of was slipped into th body of the guitar from the part where the block would be, and then sealed by a wooden plate. Probably the strings were tuned to something like a chromatic series, and then the maker hoped for the best, as there was absolutely no way of keeping the strings in tune after the box was sealed into the body of the guitar. There was an article on it in I think the Early Music magazine.
When it comes to organs, most pipe organs have the pipes enclosed in a box. The older ones certainly all have it like that. Larger organs have more than one box, the most obvious is the kind where there are what looks like two organs hanging over the balcony. The "smaller one" is part of the whole, of course, but is normally played from a different keyboard from the "main" one. The cases (boxes) act as resonators and blenders.
There are a few travelling harpsichords in existance that are composed of three hinged boxes, each in fact a small, truncated harpsichord, that fold out to form a complete one. But they still have three independent resonators.

[Yuri Terenyi]

Actually, just remembered yet another one.
In the Middle Ages there existed an instrument of which there aren't any remaining examples, but plenty of depictions. It consists of a combination harp-psaltery. Imagine a small "normal" harp, but run a separate soundbox along the triangular space denoted by the body-pillar-neck triangle, and instead of hitching the strings on the top to the neck, as normal, run them over a bridge, and hitch on the top, beyond the bridge. So in effect the sound is simultanously made by the two ends of a given string, one end harp-fashion, the other psaltery. And more tan likely the harp body was separated (acoustically) from the psaltery body.
Hope it made sense.

[Stephen Bacon]

The veena in its various forms has a hollow neck and two resonating gourds at either end.

[Chuck Morrison]

Thanks for the interesting responses. I do recall seeing Veenas and didn't make that connection. The Veena is similar in some ways to the American guitar experimenters who have used hollow necks, although I haven't seen that they go to the extent the Veena does.

Marimbas, vibraphones, organs, all have tubes dedicated to a specific note, although Organs use the tube to generate the notes and the Marimba/vibraphone uses it for support, more similar to what I'm thinking of.

Specifically I'm looking at experimenting with a multi-chambered stringed instrument. In principal there would be several air chambers with different (tuned) resonant frequencies to selectively boost specific harmonic regions (series, regimes, call them what you may). The "double back" guitars I've seen don't do this as they tend to mirror the top with similar size and placement of sound holes. They also induce their own resonances which I don't want to deal with. For experimentation, at least, I'm looking at these chambers being able to be tuned to specific frequencies on the fly. Probably more a science experiment than a viable instrument.

This has been helpful though, many thanks for the input.