It is the model I drew up that is in between a Gagliano cello, and a Gagliano violin. It looks like a Grancino. As such, I gave it a thick center 7.5 mm, and the wood seems to like it. I wrote the free plate tap tones on the chart as well. I can keep the charts for my referance, and note areas where I took stock off after gluing up, and maybe the tap tones when glued up, and then after tuning. The belly has no bass bar yet. The archings are very low, 16.5-17 mm. Like a del Gesu viola.
The other is a del Gesu violin. The belly is very stiff, even at 63 grams and no bass bar. The back seems fairly stiff as well, and has a maximum thickness of 5.1, but I cn't get a real ring tone out of it. Maybe an Eb.
This one I didn't put the purfing in, or the undercut. Besides in the corners, there really isn't much of a recure in it. The edges are quite thin, and just a scant overhang, I'll do the purfling when it is assembled. It won't be exactly Cremonese; I won't nail the neck on first; but the procces should be close to what they did.
Today I cut two bass bars, trimmed them close to size, and glued the little guides for fitting them. Took about an hour. I found an easy way to rough the bottom out. Clamp a board on the belly so the bar will lay flat on it when in the right spot. Mark the bottom with a washer, and trim. Do it again and it makes a mark on the shallow del Gesu. Remove the board, and place it the other side, and mark it the same way. Trim both sides to the same distance from the line, and you are close enough to start chalk. The viola needed two roughings, and then both side. Really easy. I also found that the extra length of the bar was easily sawn into guides. Why didn't I think of that before.
Tomorrow I'll start fitting.
About the Eb tone you think you have..... that could be 307hz to 327hz or so. If your plans are for a 355-357mm length wouldn't that tone be low for a back?
ReplyDeleteI don't know why it is so low. The wood rang at first, and now it doesn't even do that. I've never had a peice of wood that won't ring. It is basically the same thickness pattern as the viola, and it rings at F2, F3, and C4. I don't have any more wood besides cherry, poplar, and sycamore for violas. It doesn't seem flimsy in any sense of the word, I used birch, and it had a low tap tone, maybe this peice just wants to ring low? What would the repercussions be for the belly to ring a third higher than the back?
ReplyDeleteFrom what I'm been studying about m/c the tops frequency will more or less skyrocket if one is not careful as compared to the back wood m/c . If I'm not mistaken the top should ring lower than the back, right? I'd have to do some more reading elsewhere to be sure.
ReplyDelete........here's something that may work for trying to find the ring tone. Type in Online Frequency Generator. Pick the one that has the orange colored background screen. Adjust the hz level down to anywheres around 90hz - 110hz. It'll be a real low octave you're hearing when tapping your wood in the edge area of a lower bout while putting pressure above an upper corner with the other hand. Match the low pitch using headphones covering 1 ear partially on low volume. When you pick the best hz tone multiply the number x3. Hopefully you'll be around F#-Gb hz numbers instead of Eb.
ReplyDeleteWOW, the tone generator is the way to go! My notes were off. For the violin back I found 222, 340 and 490! The A and the E were right, but I wasn't hearing the overtone, only the interference of the E. Thanks
ReplyDeleteWhere did 490 come from? Is the wood weighing over 200 grams or so presently? To tune plates I might add you'll need a quite place, good hearing and not posess a severe case of tone deafness. If the wood is close to weight pick a hz number from that frequency website to start with or go to the right column they have there and pick your note you want your wood to be and adjust to their hz level. Don't start with anything over A440hz. I'd feel bad if I didn't reply to the last comment thinking 490hz is what your plates are going to be before gluing to the ribs and have you thinking you did great. Tap the wood in the same place 5-10 seconds. Start the tone frequency/headphones for a few. Tap the plate again. Headphones again. After a few back and forth series you should be able to pin point the exact hz number of the plate. Hopefully it'll ring from D# to F# depending on what you want for a sound.
ReplyDeleteThe 490 must be an overtone. I was just leaving for work, and was in a hurry. I hear the tap around E/Eb, with the belly being around F#/F without a bar. The I'm not tone deaf, but ratios give me a lot of problems. I can hear when they are off, but thirds, fifths, fourths? I fave to mentally go note by note up to where they are to find them. With the generator set on 2%volume and my computer set at the lowest bar, I hear the tone from 200 to 3100. That is with the commputer speakers. If I turn the generator volume to max, then most of it is way too loud, but I will hear from the lowest note up to 12000 in on ear, and 10000 in the other with headphones. Not too bad for almost 60. I do have ringing in my ear, but I don't notice it unless it is quiet, and it doesn't bother me. I'll have to get the bars in, and glue them on. Free plate tuning may get you close as far as not being too flimsy; but I think that tuning when assembled is the way to go.
ReplyDeleteI re-read you earlier comment. Are you suggesting that the ring mode is generally a 12th above the fundamental? It seems to be true for the violins. C3-F#(without a bar) for the belly, and A2 to E4 for the back. The viola back is that way too, F2 to C4, but the belly is a different animal. It seems to span 2 full octaves. A little higher than B1-3 when brought up from the basement at 55% humidity to C2-4 today after being upstairs in the desert for a day. Funny, the belly SOUNDS lower than C4 when tapped after the back, but it because the modes under it are lower. The belly rings at an even C where the back has the F chimeing in making it sound higher.
ReplyDeleteNo, I'm not suggesting the 12th/fundamental. I don't know what that would mean. I suggested using the lower hz tone {headphones} to help find the sound of your wood since you weren't sure about what tone the plate was making before I commented. I found if the main mode sound of my plate is at a certain hz, it will also have a 2 octave lower tone in the same ballpark notewise, just lower sounding, give or take a few hz either way.
ReplyDeleteWhat does the C3 mean when written C3-F# and the A2 and E4? Are those tone notes you found or is that part of a plate tuning method? I'm 11-12 years younger than you and I tested right past 14000. So I'd think your hearing is fine and I may of even been slow to hit the stop button when I couldn't hear anymore.
A twelth is what a clatinet plays when it hits the register key; low F (written a note below the G on a violin) changes to C5 I played clarinet. All other instruments overblow an octave. The A2-E4 would be low A and middle E for the mode five; a twelfth. I clamped the back to my building board, and thinned the center of the upper bout some to even the tap tones out. Now it actually rings! And it actually rings about F. When the belly and the back are clamped around the edge the both sound around E. Cool.
ReplyDeleteThe clarinet- what an invention. You mentioned tap tones and flimsy plates. That may be something a more experienced maker may keep in mine while working but getting tap tones right being brought up in books, website-forums and blueprints may have more to do with beginner/rookie makers so they don't leave to much wood in the plate.
ReplyDeleteDon't know if what I post here today will be of any help because I don't know if you have done any gluing yet but here goes- We know by taking a note of the starting hz, then by cutting and shaping the f holes that the tone of the wood will go lower. Then find the new hz number and write it down. It will be lower than when we started cutting. Then glue and shape the bass bar to bring the hz number back to where the plate was at before f-hole cutting. Now I find after reading elsewhere that the only way to lower the hz number after bass bar gluing/shaping is to thin the areas at the end of the bar by taking wood from the plate in that vicinity. Enlarging and removing wood from underneath the f-holes will raise the frequency instead of lowering it. Seems to me that removing wood would continue to lower the frequency instead of raising it. What do you think. Ken?
ReplyDeleteI will try to remember to write down how the frequencies change. I put my f holes in very early, and make them an integral part of the arching, so I don't really know what the tap tone was before they were in. It seems odd that enlarging the holes, and taking material out in the middle could raise the frequency. I also think that you need to have a bass bar in place to get the tuning really right.
ReplyDeleteKen, we should talk. Drop me an email. stephenkperry@gmail.com Haven't read through all the blog, but you're doing nice work. There are some things to consider, and probably will come up with more as I wade through your work.
ReplyDeleteI've been visiting Ken's blog for a couple of years now. He's seems to give a good and honest effort.
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