Hey, its my first time posting here so might as well introduce myself. I'm Jeff, from New Zealand. I haven't spent much time playing resonators, but I've recently started building one. I've got a few questions that I haven't been able to answer with a google search, hopefully some of you knowledgeable folk might chime in.
- How much compression can be expected from the cone under string tension? Scale length is 25”. Tuning will be DGDGBD, possibly DADF#AD, strings are 12’s. Cone is national biscuit hot rod. I know this is also dependent on the break angle over the saddle to the tailpiece, I haven't made that yet, so that is still up in the air. I don't have access to a resonator to look at and measure compression, so a ballpark idea of what can be expected will help me to work out how deep to make the well.
- What effect does the vent hole area of the cover plate have on the sound? I'm making the cover out of a piece of copper, cutting a design into it, at the moment there is probably less vent hole area than typical. Is there a sweet spot for this? It is an electric instrument with a fishman nashville biscuit piezo pickup, so the acoustic volume is not super important. I don't want the cone to be damped out by restricting air movement, also maybe less vents would have a positive effect regarding feedback?
Jeff: You're asking the right questions regarding cone compression, break angle, coverplate opening area. Trouble is, I don't know of a source for those numbers other than experimentation to provide the values for your particular setup.
I'd suggest getting the National-style blueprint from Resophonic Outfitters so you can get a good starting point, setting up with temporary bridge saddles and other parts to fine tune the setup. Good luck with your project!
I know that the Jerry Douglas signature Beard coverplate supposedly was designed specifically for its impact on tone...at least that is what they say...certainly I can hear the difference between screens and screenless soundholes on the bass side...
Thanks daver and gzerninplatz for the replies. Can anyone give a rough indication as to cone compression just from observation when changing strings? Or do most people change one at a time? Ok, so the cover plate does impact tone, are there any generalizations that can be made ie more holes = louder etc?
Paul Beard is the master of cover plate design. He's indicated that it must have the "correct" ratio of open/closed spaces and they must be in the correct placement.
Also structurally viable.
He doesn't say much beyond that! ;-)
I see you ae going for biscuit bridge. Copper may not be rugged enough as a cover plate. I'd just go for an imported cover plate and call it a day.
Edited by - hlpdobro on 07/02/2022 12:21:35
'Cover plate history..' 22 hrs
'Demo of travel dobros' 1 day
'Best pick up for a dobro' 2 days
'Travel Dobro' 2 days