The Ronzatori Intonarumori
I've started to build a Ronzatori Intonarumori. To help I can use the 'single extant photograph of the internal mechanism of any of the intonarumori -' Lucino Chessa¹.
However this photograph does need some interpretation.
Once we are told that there is the hammer mechanism from an electric buzzer against the drum skin and the main resonating string is tightened by means of the lever, it is easy to understand how the Ronzatori works, however there are other things happening in here which are less easy to interpret.
Russolo may give some clues in a letter.
The Buzzers [ronzatori] possess a timbre that is similar to the humming ofelectric motors; they are sweet and harmonious, very rich in harmonic sounds and are adapted with a pedal. Another timbre exists in the same instrument – that of the gurglers [gorgogliatori]. One can switch at will between the buzzer and the gurgler, which has the exact timbre of the gurgling of water in gutters. By means of two electric buttons one can, for example, hold a note of the buzzer and provide rhythm with the gurgler (that is to say, with the same note they can be sounded either together or separately, but when they are together the two timbres have the same note). There are three of these, but two have the same range, for which reason I would advise you to only use I – that is to say, the high. You can use it without fear, because both timbres are pleasingly sweet. You can also achieve staccato effects with these (unlike the howlers). They are also very well suited for legato. They lend themselves less well to singing, possessing a richly harmonic timbre that renders the note less certain. But they are full of charm and mystery.
So there is a switch 'between the buzzer and the gurgler' or both can be used together.
Here's what I think might be happening in this photograph.
I think the photograph was taken without the far side of the box on and using a flash hence the black area. The photograph may also have been taken during the construction of the Ronzatori showing the the structural supports E and F being positioned.
A. Electric Buzzer hammer mechanism to drum against the drum skin.
B. 'Gurgler' mechanism dangling against the main resonating string?
C. Electric mechanism to 'effect' the 'Gurgler'?
D. Main resonating string.
E. Upright supporting structure for the 'Gurgler' and electric mechanism.
F. Further support for E.
So the main mystery here is that of the 'Gurgler'. I imagine it to be a weighted metal rod which may be textured to rub or some how hit the main string. This may be pulled up and down by either a rotating cam or a similar hammer lever of a buzzer mechanism. Anyhow these questions may be answered by trying to recreate the Ronzatori.
Here's the start I've made.