MIMF

Probably I am not the first to think about these variations in archtop bracing, however I have not met anyone mentioning it:
- One bracing is glued all along and the other overarching it in the middle
- Both braces form an arch above the middle area (although they are joined in the middle)
See schematic pictures. Grey represents gluing surface, white is non-contact, bridge is marked with red.
It frees the middle area, mimicking a bit paralel bracing. Anyway, I do not start hypothetising the effect these options might have on the sound. I hope that someone has experienced with or read about it. Any remark is welcome.

Hi Ferenc, welcome to the new MIMForum!

a few years ago I used some bracing like this. In '98 I used bracing of this type for the very light back plate to good results. For tops I have used this style of brace for only 2 instruments. As long as the glue joints are strong there is no detrimental result that I know of. I leave one brace complete uncut, and the other brace is cut and fitted to join the first brace, then a "jumper" or cap of spruce is glued across the joint and smoothed nicely. It is very strong if the joints are well fitted and glued.

I can't say if there is much difference in sound produced but it is interesting to look at.

Michael Lewis wrote:a few years ago I used some bracing like this. In '98 I used bracing of this type for the very light back plate to good results. For tops I have used this style of brace for only 2 instruments. As long as the glue joints are strong there is no detrimental result that I know of. I leave one brace complete uncut, and the other brace is cut and fitted to join the first brace, then a "jumper" or cap of spruce is glued across the joint and smoothed nicely. It is very strong if the joints are well fitted and glued.

I can't say if there is much difference in sound produced but it is interesting to look at.

Michael, what were you trying to achieve with the "very light back plate" with bracing? Reduced feedback?

Ken Parker's archtops have bracing that cross but do not touch each other...

Nelson, I was trying to make a very light instrument, and to that end I carved the back considerably thinner than usual and put in the bracing to stiffen the now floppy plate. It worked very well but the weight saving was not worth the effort. It looks really cool if you look in a sound hole.

Thank you all for the comments and also for drawing my attention to Ken Parker's guitars. In the meantime I was also considering mixing somehow X-braces and parallel.
However, finally I decided to use traditional parallel bracing to focus on "projection".