Check out that peak at ~440Hz. That's likely your problem...
In the 2nd Edition, Section 22.3.4 shows an example of how to fix this sort of problem on the 2nd partial (not in the 1st Edition). Also likley in the Modal Tuning Course notes.
Search found 1604 matches
- Sun Jan 16, 2022 11:06 am
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: Intonation Problem
- Replies: 10
- Views: 16018
- Fri Nov 26, 2021 8:16 am
- Forum: Instrument Builders Forum
- Topic: Schertier Slot Head Tuners
- Replies: 5
- Views: 4761
Re: Schertier Slot Head Tuners
I haven't used them either, but I would drill full depth at 6mm then open out for the collar with a metric step drill that has (at least) 6, 8 and 10mm steps. Picking up the original 6mm bore with the 6mm step should keep everything concentric. Best done with a pillar drill to keep the bores square ...
- Thu Nov 25, 2021 8:33 am
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: Air, Top and Back Resonances, Coupled and Uncoupled - Untensioned?
- Replies: 17
- Views: 41121
- Fri Nov 12, 2021 8:52 am
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: Target Plate Thickness for 0/Parlor Guitars
- Replies: 7
- Views: 18128
Re: Target Plate Thickness for 0/Parlor Guitars
I measured 9 top plates today and calculated targeted thicknesses for 343 mm wide 0 guitars. Adirondack, Engelmann, Lutz and Sitka. I look a random 10% stiffness reduction considering the top width. If you're using the formulae in the books for the elastic constants, measuring them correctly and ap...
- Thu Aug 05, 2021 7:07 pm
- Forum: Instrument Builders Forum
- Topic: West systems GFlex or Titebond original
- Replies: 2
- Views: 3304
Re: West systems GFlex or Titebond original
If you're looking for a gap filling glue, avoid Titebond. The thinner the Titebond glue line, the stronger it is. I would also avoid liquid epoxies, which is what G/Flex appears to be. You need the glue to stay where you put it. So I would suggest using Techniqlue (an epoxy), which is thixotropic, s...
- Sun Aug 01, 2021 11:37 am
- Forum: Instrument Builders Forum
- Topic: Torrefied Tonewood
- Replies: 24
- Views: 27295
Re: Torrefied Tonewood
No, I haven't done any objective tests.
- Fri Jul 09, 2021 12:31 pm
- Forum: Instrument Builders Forum
- Topic: How do you profile your bridge?
- Replies: 10
- Views: 7219
Re: How do you profile your bridge?
Page 20-8 in the Build book. Make a convex sanding form by either laminating veneers into the top dish that you used (then dress any spring-back by sanding in the dish) or just sand a block from scratch in the dish. I start with 80 grit and it never takes very long (no more than 5 minutes total) to ...
- Fri Jul 09, 2021 9:40 am
- Forum: Instrument Builders Forum
- Topic: New Gore Guitars website
- Replies: 7
- Views: 5323
Re: New Gore Guitars website
The UK is quite a low proportion of sales, which was a bit surprising as I know there is a lot of interest there. I think VAT and import duties really loaded up the price. The USA is a big market (no import tax/duties) and also Canada, which does have import taxes. There has been good interest acros...
- Wed Jul 07, 2021 7:56 am
- Forum: Instrument Builders Forum
- Topic: Falcate Bridge Plate Thickness
- Replies: 6
- Views: 4511
Re: Falcate Bridge Plate Thickness
1.5mm as per the second edition. Apologies for the typo that got through in the 1st edition.
- Thu Jul 01, 2021 9:12 pm
- Forum: Instrument Builders Forum
- Topic: New Gore Guitars website
- Replies: 7
- Views: 5323
New Gore Guitars website
When you've had a website up and running for a dozen or so years it can get quite big. I hadn't realised how much stuff I had there until I got a message from my hosting service saying they were going to switch off the content editor. That was about 6 months ago, so my website has been frozen in tim...
- Sat May 08, 2021 5:39 pm
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: Confused about frequency response in my first TG style falcate
- Replies: 20
- Views: 24954
Re: Confused about frequency response in my first TG style falcate
Nice guitar, Martin. Regarding the changing frequency responses, your early responses without the neck mean you couldn't have had strings on, and you may not have had saddle and bridge pins in. Just adding the mass of the strings can make quite a difference which people often put down to loading the...
- Tue Apr 27, 2021 9:55 am
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: Bolt On Neck truss Rod
- Replies: 3
- Views: 5732
Re: Bolt On Neck truss Rod
I haven't found much info in the book regarding truss rod extension pocket for BO. :o !! Section 18.9.1 I wonder about where to place the adjuster nut Fig 18-7 Also when the fingerboard is finally glued down, how to stop glue entering the rod channel. Section 18.6, esp. 2 lines up from the bottom o...
- Tue Apr 20, 2021 1:02 pm
- Forum: Instrument Builders Forum
- Topic: detached bridge
- Replies: 5
- Views: 4736
Re: detached bridge
This may not be the only problem, but certainly looks like one of them... Looking at the thickness of the residual glue on the tail side of the detached bridge, that glue line looks way too thick, to the extent that the the joint looks like it wasn't properly closed. There could be numerous reasons ...
- Sat Apr 17, 2021 10:18 am
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: How useful is the CF under the brace?
- Replies: 15
- Views: 30553
Re: How useful is the CF under the brace?
I think you need to re-check the theory of composite structures... Hint: the CF is held in a matrix...
- Fri Apr 16, 2021 10:08 am
- Forum: Instrument Builders Forum
- Topic: Falcate Classical #2 Build (in NZ)
- Replies: 37
- Views: 24589
- Fri Apr 16, 2021 9:57 am
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: How useful is the CF under the brace?
- Replies: 15
- Views: 30553
Re: How useful is the CF under the brace?
One of the main reasons for adding CF to the structure is to control cold creep, so it allows you to remove a lot of wood that would otherwise have to be there purely to keep the stress levels down so there is less cold creep. Over time, as wood creeps, only having one layer of CF will likely come b...
- Fri Apr 16, 2021 9:31 am
- Forum: Instrument Builders Forum
- Topic: Problem with side mass not changing T1
- Replies: 2
- Views: 2994
Re: Problem with side mass not changing T1
Moving down 17Hz would take an awful lot of side mass. The critical thing for making side mass work is to make sure the mass is so firmly connected that it is essentially integral to the sides, because to work the mass has to move precisely with the sides. So if the hold-down bolts aren't seriously ...
- Fri Apr 16, 2021 9:17 am
- Forum: Instrument Builders Forum
- Topic: Paulownia Acoustic Top
- Replies: 10
- Views: 8256
Re: Paulownia Acoustic Top
Paulownia has a similar range in long grain Young's modulus as King Billy, but typically is around 75% the density. As ever, it's critical to measure the piece of wood you are about to build with, but I can't see why Equ. 4.5-7 wouldn't work to tell you how thick to leave it.
- Sun Apr 11, 2021 9:51 am
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: Specific mobility
- Replies: 3
- Views: 5551
Re: Specific mobility
The book says "Steel string guitars with monopole mobility greater than 14 x 10^-3 s/Kg are exceptional instruments indeed...." (p. 1-89) Note that in Fig 1.7-8 the guitars below 14 are all wood X-braced guitars and the one above 18 is falcate braced with CF. That tells you something about responsiv...
- Fri Apr 09, 2021 6:02 pm
- Forum: Instrument Builders Forum
- Topic: Finger pressure
- Replies: 6
- Views: 5480
Re: Finger pressure
If you have the 2nd edition of the books, check out Appendix V (not in Ed. 1) p. AV 2. You're probably better off measuring string displacement rather than pressure applied and p. AV 2 explains how to do this.
- Sat Apr 03, 2021 3:44 pm
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: Can you derive a freq plot from a sound clip?
- Replies: 8
- Views: 9001
Re: Can you derive a freq plot from a sound clip?
...And that got me thinking... can you use a high quality sound clip of an instrument and use it to figure out the freq plot?... As John Parchem has said, every played note contains an embedded impulse response. The best way I've found to derive a frequency response curve is to isolate a single not...
- Tue Mar 16, 2021 7:45 pm
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: Compenstaed nut jig
- Replies: 7
- Views: 8774
Re: Compenstaed nut jig
Trevor if by chance you read this I wonder what cutter you use? CMT 1/8" two flute solid carbide down spiral. A new one can be pretty aggressive, so I use ones passed down from other operations (e.g. rosette channel cutting). I run a low speed on Tusq, otherwise it melts. Bone could be run at a hig...
- Wed Mar 03, 2021 12:17 pm
- Forum: Instrument Builders Forum
- Topic: Airbrushing lacquer vs HVLP
- Replies: 17
- Views: 11801
Re: Airbrushing lacquer vs HVLP
I've sprayed lacquer with an airbrush, touching up the edges of fret boards. It works fine, but you need a big nozzle (for an air brush) and need to spray wet or the lacquer will dry before it hits the target. It's not the tool to use for a whole instrument, though. I've had an HVLP touch up gun (1....
- Sat Jan 30, 2021 10:18 am
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: Intonation and Flamenco guitars
- Replies: 4
- Views: 5784
Re: Intonation and Flamenco guitars
This type of discussion can get very fraught very quickly. The outcome of the argument depends on what going-in assumptions you consciously and/or unconsciously make. Consider a couple of things: 1) Nut compensation works because it means you have to change the string tension (re-tune) to get the op...
- Mon Jan 18, 2021 9:12 am
- Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
- Topic: Plate target thickness of non rectangular plates using deflection testing
- Replies: 11
- Views: 15270
Re: Plate target thickness of non rectangular plates using deflection testing
It's not that hard to get the cross grain stiffness using deflection methods. The pics here are of my old deflection jig as they show the technique better. First the jig. Note that the support tubes themselves are longer than the panel is. DSCF6101s.jpg Here's the normal arrangement for measuring lo...