Search found 1531 matches

by Trevor Gore
Sat Jan 30, 2021 10:18 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Intonation and Flamenco guitars
Replies: 4
Views: 388

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...
by Trevor Gore
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: 4748

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...
by Trevor Gore
Fri Jan 15, 2021 8:52 am
Forum: Instrument Builders Forum
Topic: Red gum
Replies: 15
Views: 1679

Re: Red gum

peter.coombe wrote:
Thu Jan 14, 2021 10:53 am
Not too shabby under varnish.
Yep, that looks fine. Gerard would have been using nitro over a grain filler, which may well look different from an (oil?) varnish.
by Trevor Gore
Wed Jan 13, 2021 8:19 am
Forum: Instrument Builders Forum
Topic: Red gum
Replies: 15
Views: 1679

Re: Red gum

Give Gerard a call. iirc, what he told me was a) it is not very stable in guitar sized panels, so prone to cracking and b) whilst the grain in most woods is enhanced with finish, in red gum any figure seems to disappear under finish. But best to check with Gerard as I have one set, but have not buil...
by Trevor Gore
Tue Jan 12, 2021 10:42 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Richlite & primary bracing
Replies: 4
Views: 776

Re: Richlite & primary bracing

I've never tried Richlite or Rocklite, so no view from me on that. Regarding the rebates, classical or steel string, they should be tight. Don't forget the thickness of the carbon cloth in the SS situation. One way of getting the rebates to fit well is to leave the braces a little tall, cut the reba...
by Trevor Gore
Wed Jan 06, 2021 9:00 am
Forum: Instrument Builders Forum
Topic: New Luthier Tips du Jour video - Cedar vs. Spruce
Replies: 12
Views: 2053

Re: New Luthier Tips du Jour video - Cedar vs. Spruce

Dave M wrote:
Wed Jan 06, 2021 3:37 am
Presumably it is picking out the highest volume peak...?
Yes, the highest amplitude peak. Useful for all sorts of things.
by Trevor Gore
Tue Jan 05, 2021 9:55 pm
Forum: Instrument Builders Forum
Topic: New Luthier Tips du Jour video - Cedar vs. Spruce
Replies: 12
Views: 2053

Re: New Luthier Tips du Jour video - Cedar vs. Spruce

I have some questions for Trevor....firstly, what VA setting give that particular frequency display. There's a row of tabs to the right of the ON button. One of them says "Freq. meter"... Second question, I have experimented with and measured as well as played a few guitars which have rather thin s...
by Trevor Gore
Mon Dec 21, 2020 8:58 pm
Forum: Instrument Builders Forum
Topic: Building a flamenco guitar
Replies: 9
Views: 1937

Building a flamenco guitar

A customer of mine decided to go the next step and build his own guitar, with a little help and advice from yours truly. Then he went one step further and made a compilation of the pics and vids he shot as he was building, and left us with some of his thoughts on the experience, for which I would li...
by Trevor Gore
Tue Nov 24, 2020 8:33 am
Forum: Instrument Builders Forum
Topic: More mandolin thoughts - the end result
Replies: 13
Views: 2602

Re: More mandolin thoughts - the end result

Nice work, Peter!
by Trevor Gore
Sun Nov 22, 2020 10:19 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: 1. falcate braced classical
Replies: 17
Views: 7682

Re: 1. falcate braced classical

JurgenV wrote:
Sat Nov 21, 2020 7:01 pm
But if I use a ltb the calculations with the typical values for EI would be valid?
Yes. But remember there's a very wide spread of results in Fig. 4-4-9, and the size of the LTB makes quite a difference.
by Trevor Gore
Sat Nov 21, 2020 10:42 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Bridge rotation too high... countermeasures?
Replies: 3
Views: 773

Re: Bridge rotation too high... countermeasures?

It doesn't look like anyone else has had this problem, Jurgen. I haven't. My ~15 year old prototypes are still all fine. It sounds like an assembly issue, though hard to figure what went wrong.
by Trevor Gore
Thu Nov 19, 2020 7:37 am
Forum: Instrument Builders Forum
Topic: It’s not your fault but
Replies: 7
Views: 2188

Re: It’s not your fault but

Not quite the same, but close (and it works).
by Trevor Gore
Sun Nov 15, 2020 10:10 am
Forum: Instrument Builders Forum
Topic: Visual Analyzer set-up
Replies: 21
Views: 11862

Re: Visual Analyzer set-up

Also check out this thread and go to page 3: http://www.anzlf.com/viewtopic.php?f=33&t=3652
by Trevor Gore
Tue Nov 10, 2020 9:45 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: 1. falcate braced classical
Replies: 17
Views: 7682

Re: 1. falcate braced classical

But in general I would like to know why the spreadsheet didn´t work for the classical guitar. In the meantime I built 4 steelstring acoustics using the spreadsheet and I always get good sounding guitars with resonance frequencies in the target area. Any comments on that from Trevor? I think John (P...
by Trevor Gore
Thu Nov 05, 2020 1:59 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Scalloping the lower bout transverse brace
Replies: 6
Views: 1226

Re: Scalloping the lower bout transverse brace

If you don't know how far to go, don't scallop the back brace initially. Glue the back to the sides, take the assembly out of the mould and tap the back, which will give you the B(1,1) frequency. The B(1,1) sits a little higher in frequency than the T(1,1)3 on the fully assembled guitar. Scallop awa...
by Trevor Gore
Sat Oct 31, 2020 6:08 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Scalloping the lower bout transverse brace
Replies: 6
Views: 1226

Re: Scalloping the lower bout transverse brace

If you have the 2nd Edition, see Build, p. 12.11, esp. the last paragraph.
by Trevor Gore
Sun Sep 27, 2020 10:17 pm
Forum: Instrument Builders Forum
Topic: Repair in Melbourne
Replies: 2
Views: 1047

Re: Repair in Melbourne

by Trevor Gore
Sun Sep 20, 2020 12:51 pm
Forum: Instrument Builders Forum
Topic: Classical Guitar Tuners Creaking and Binding Up
Replies: 13
Views: 3087

Re: Classical Guitar Tuners Creaking and Binding Up

You can also lube the wood bearing surfaces with wax (candle, paste, bees, carnauba. All seem to work OK). Keep the hole clearances to a minimum, and make sure they're clear of finish, buffing compound etc.. Also, depending on your tuners, some (most) are 10mm diameter barrels and so need a 10.3mm h...
by Trevor Gore
Sat Sep 05, 2020 9:47 am
Forum: Instrument Builders Forum
Topic: Soundboard Sonic Signature
Replies: 17
Views: 4680

Re: Soundboard Sonic Signature

The bridge weighed in at 35 grams, so quite heavy... Yes, that's over double what mine typically weigh. Is it much heavier than the bridges on the other guitars? Have you and O’Brien rescheduled your class dates yet from July 2020, early days I guess? No, not yet. Still too many unknowns, unfortuna...
by Trevor Gore
Fri Sep 04, 2020 8:39 am
Forum: Instrument Builders Forum
Topic: Soundboard Sonic Signature
Replies: 17
Views: 4680

Re: Soundboard Sonic Signature

The figures from the walnut guitar seem to imply it has a heavy bridge (relatively low T(1,1)2, relatively high stiffness). A heavy bridge would explain the lack of excitement in the sound, as it will be less responsive to higher frequencies. How heavy was the bridge?
by Trevor Gore
Wed Aug 19, 2020 10:03 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Nut compensation
Replies: 3
Views: 1246

Re: Nut compensation

Any ideas on what I'm doing wrong and what direction to go in? You're not necessarily doing anything wrong. It's always worth understanding what the causes of intonation errors are and (if you have the 2nd edition of the book) this is explained quantitatively in Appendix V. One of the major causes ...
by Trevor Gore
Sat Aug 15, 2020 10:13 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: High frequencies
Replies: 4
Views: 4359

Re: High frequencies

Trevor, that was a great phone conversation! Very informative for a start. Thank you for your generosity! No worries, Ross! My guitar had resonances in pretty good places, and ate the Gibson for breakfast when compared! Mine was a a lot more bassy but not tubby, still a nice tight picking sound, so...
by Trevor Gore
Tue Jul 21, 2020 6:13 pm
Forum: Instrument Builders Forum
Topic: Classical Build (s) - Hopefully falcate!
Replies: 94
Views: 37676

Re: Classical Build (s) - Hopefully falcate!

seeaxe wrote:
Sun Jul 19, 2020 8:44 pm
... But I'm puzzled, as if I had reduced the top stiffness to achieve a more flexible top, and more bridge rotation, then how would I have kept its T1,2 up at 180-190?

Any suggestions/thoughts?
Resonant frequencies are proprtional to SQRT(stiffness/mass); so....... :wink: