Accordeon, With regard to your post of using accordion reeds for a concertina, you can cut every accordion reed plate to a smaller size. Time consuming but it works well. Or contact the Melodica makers in France to get their more narrow reeds which now have stainless steel reeds. These are nice and flat and easy to work with. The main problem hasn't been addressed and is very important. I have seen many new, very well made concertina's but often the sound is mediocre. This has to do with the size of the reed compartment. Too small and it will 'choke' the sound. Too large and the sound gets tardy and subdued. Many years ago on my bi-annual trips to the accordion factories in Italy it finally clicked. I wanted a special button accordion made from C/G to D/G. The factory refused, telling me the C/G was especially made for a C/G to get optimum sound and turning it into a D/G would stifle the sound projection.. As I was also making wind instruments at the time I applied this knowledge to my instruments which worked very well and got some extra technical literature from about 1850 which confirmed it. Wind turbulation and air compartment size are a most important aspect to produce a purer and richer sound. With my own instruments, concertina and accordions, I re-adjust reed compartments volume where needed. It is time consuming but in the end very worthwhile. Also important to remember is the air pressure you are working with. I have taken many air samples from England, France, Germany, Austria and The Netherlands and found tuning variations in each of these countries from A440 showing as A438 to A442 so don't be surprised if your instrument is out of tune playing in different countries or even close to 1km up in the mountains. Playing up in mountains, 1km high and higher, can mean your instrument does not show the same tuning reading as at sea level. Overall I found the English air pressure playing havoc with tuning and tuned my instruments at A443 in Australia at sea level to have them playing at A440 in England. A concertina not sounding bright, slow in response or just not sounding good enough may well mean for you to check out the reed compartment. Just even out the tuning won't fix it. Sorry about the long blurb but nobody seems to address this that I know of.
