wood vs aluminum tone chamber

[debra]

I found this picture

That's the "Amplisound" extra sound chamber, used (exclusively) by Beltuna. It can be opened and closed so you get normal cassotto sound or the extra amplisound sound.

 

[Ventura]

in a way related, might interest some of you

i made many strap on microphone rails for personal use over the years
(gave a few to friends)
(these sat longways on top of the grille, elastic bands loop over the bellows snaps)
and experimented with various materials and shapes of the capture chamber
and numbers and spacing of the Mics

Some rails were curved (half round) mostly angled aluminum but some rectangular Steel and
one very heavy half round Copper

i lined some with veneer to alter tonality (mahogany seemed to work best) and
one rail i actually installed the Mics facing up, into the wood lined chamber
so that only reflections were amplified (the deepest tonality by far)

i honestly cannot say which were the best combinations of bounce and tone shading
except to say that my favourite ones through the years surfaced as the Primo rail i
lined with thin copper tape then installed 12 Panasonic Electret Mics with volume and
tone controls, then lined the outside of the rail with suede

i used this on my FisItalia woody mostly, partly because the suede complimented the
accordions wood finish, but they sound great too and were reliable and resisted feedback
it looks nice on the cream colored Accordiana and Guiliette too

then a simple felt lined rebuilt Sano rail with a standard Master Sennheiser kit retrofitted
inside, with the Bass mic wired in as well

i use that one on all the black accordions and it sounds great too

that crazy copper rail was bolted on the front of my Red Serenellini and used
Dynamic Mics butchered from an old Titano, eventually replaced with RadioShack electrets

this is possible for me as i have long installed independant mic systems on the bass
sides of any and every box i might use for a big Gig
(small gigs just have no need for amplified Bass or i use MIDI Bass)
and i have been using dual Wireless systems for big acoustic events for a very long time
so it is not difficult in practical terms

the takeaway from this, however, is the understanding that ANYTHING you do to alter
the Tonality physically is a PERMANANT change and can only REMOVE frequencies

you can also remove frequencies electronically, but then at other times you can
leave those frequencies in

so be careful what you wish for, considering that your excellent hand made reeds
and carefully engineered and crafted Accordion and chambers were designed to
give the RICHEST tone possible... so why would you want to reduce this with
some permanent physical alteration ?