Search found 1604 matches

by Trevor Gore
Thu Feb 23, 2023 8:13 am
Forum: Instrument Builders Forum
Topic: Repairers in Darwin
Replies: 5
Views: 3548

Re: Repairers in Darwin

You could try Jim Scofield, Darwin Strings and see if he is interested. Jim has been a frequent contributor to the forum.
by Trevor Gore
Tue Feb 14, 2023 8:08 am
Forum: Instrument Builders Forum
Topic: Action & relief for C# open setup
Replies: 6
Views: 6992

Re: Action & relief for C# open setup

The amplitude of oscillation is entirely dependent on the pluck displacement. Of course, it takes less force to displace a lower tension string for the same oscillation amplitude of a higher tension string. For the same feel you have to go to a higher tension string set, i.e. heavier strings, which ...
by Trevor Gore
Mon Jan 16, 2023 7:32 pm
Forum: Instrument Builders Forum
Topic: Heelless neck joint
Replies: 8
Views: 8513

Re: Heelless neck joint

Not my idea, and no pictures, but you could do a tapered sliding dovetail into what I call the neck block top plate, with a single screw accessible from inside to stop it unplugging. Fully fit the dovetail before you glue the fret board on.
by Trevor Gore
Mon Jan 16, 2023 8:43 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Vibrational stiffness freq for ukulele?
Replies: 4
Views: 10395

Re: Vibrational stiffness freq for ukulele?

You might find some relevant information in this thread. Otherwise, try to track down Clancy.
by Trevor Gore
Wed Dec 07, 2022 8:25 pm
Forum: Instrument Builders Forum
Topic: Frets causing back bow
Replies: 8
Views: 11819

Re: Frets causing back bow

My fret saw is 0.5mm, my fret tangs are 0.5mm wide so why when I install the Frets do I get a back bow on my fretboard I wonder? I'm guessing that the 0.5mm measurement doesn't include the barbs (or the frets would just fall out). The barbs will force a bit of back bow, especially if you're frettin...
by Trevor Gore
Sun Oct 16, 2022 11:34 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Top thicknesses :)
Replies: 6
Views: 12641

Re: Top thicknesses :)

The deflection method will also not work on those. Is there any way to still use them? It's still possible to use the deflection method if the cupping is not too bad. Basically, pre-load the panel with enough weight to flatten the cupping, zero the deflection gauge, then add more weights to take th...
by Trevor Gore
Sat Oct 15, 2022 11:04 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Top thicknesses :)
Replies: 6
Views: 12641

Re: Top thicknesses :)

At the moment my guess is there was some problem with the tap testing. Some of those tops were slightly bent in the short axis (cross grain) while being totally straight in the long grain direction. That would explain things. Cupping across the grain will make the long grain Young's modulus measure...
by Trevor Gore
Thu Oct 13, 2022 7:18 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Live back too low when uncoupled
Replies: 8
Views: 11129

Re: Live back too low when uncoupled

Gluing fiber carbon over a X-Brace to increase stiffness would be an option? I don’t know if anyone tried before. See page 11-12 in the Build book. What is the consequences of having the main frequency too low? "Low" is a matter of taste. The lower you take the main resonances, the more bass you ge...
by Trevor Gore
Tue Oct 11, 2022 9:25 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Live back too low when uncoupled
Replies: 8
Views: 11129

Re: Live back too low when uncoupled

If the back has the radial bracing plus main brace over lower bout then you have the option of reducing stiffness of the back by taking material out of the centre of the back brace. That's correct, but reducing the stiffness will reduce the T(1,1) 3 frequency. The OP wants to raise it. To raise sti...
by Trevor Gore
Tue Oct 11, 2022 9:11 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Curious about a mode at 146-ish Hz
Replies: 11
Views: 16034

Re: Curious about a mode at 146-ish Hz

That's an interesting mode, Jim! All I can think of is that it might be a "corpus" mode, and maybe asymmetrical because of the offset excitation. The first corpus mode is the marimba bar mode of the whole guitar. It has a node usually somewhere between the nut and first fret with the other node bein...
by Trevor Gore
Tue Oct 11, 2022 8:57 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Top thicknesses :)
Replies: 6
Views: 12641

Re: Top thicknesses :)

Jurgen, I put your numbers through my spreadsheet and got 3.15mm for the Sitka (twice) and 3.22mm for the Engelmann. So I suspect you may have got the data entry wrong on the Sitka, unless the data you posted is your actual spreadsheet, in which case something really weird is happening. As for alway...
by Trevor Gore
Tue Sep 27, 2022 8:53 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Tap testing the panels - help, what am I seeing?
Replies: 2
Views: 8630

Re: Tap testing the panels - help, what am I seeing?

The cross grain mode is definitely the most difficult to get. However, the thickness result does not depend very heavily on it, which I guess is the good news! I hold the panel about a third of the way down the long edge and tap at the same level down with the mic immediately behind the tap position...
by Trevor Gore
Sat Sep 10, 2022 8:44 am
Forum: Instrument Builders Forum
Topic: Running VA software with Windows 11
Replies: 3
Views: 2636

Re: Running VA software with Windows 11

VA will run on anything from Win XP to Win 11. I still use v. 9.0.6, which has a couple of draw-backs listed here , but these are less hassle (to me) than using later versions. After XP, for v. 9.0.6 the mic levels need to be set up in Windows, as after XP the Windows I/O protocol changed which is t...
by Trevor Gore
Wed Sep 07, 2022 10:39 pm
Forum: Instrument Builders Forum
Topic: The Caldersmith Papers
Replies: 6
Views: 20292

Re: The Caldersmith Papers

I understand that Graham Mc. had some difficulties obtaining permission to publish a number of papers jointly authored by Graham C. and Tom Rossing. Prof. Thomas Rossing was one of the greats of musical acoustics and a friend to many, including me. It is with considerable sadness that I have to repo...
by Trevor Gore
Tue Aug 23, 2022 8:37 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Wood species for Falcate braces
Replies: 37
Views: 56128

Re: Wood species for Falcate braces

I recently bent some Engelmann spruce into falcate braces - by far the easiest spruce I've ever bent. That was the first time I've tried bending Engelmann, so I don't know if that is representative of the species. What's the general experience of bending Engelmann by you falcaters out there?? Thanks.
by Trevor Gore
Tue Aug 02, 2022 8:30 am
Forum: Instrument Builders Forum
Topic: Epoxy, brushes, CF tow, oh my!
Replies: 10
Views: 6166

Re: Epoxy, brushes, CF tow, oh my!

It's best not to buy tow, but to buy cloth and pull threads from the cloth. The cloth spec. is in the book. I get mine from these guys: https://allnex-brookvale.business.site/ . I use artist brushes from Bunnies or try a $2 shop. Use WEST epoxy, 105 resin and 207 hardener (the 207 can be used when g...
by Trevor Gore
Sat Jul 30, 2022 11:00 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: DIY Sig Gen/Amp unit for Chladni patterns
Replies: 33
Views: 139844

Re: DIY Sig Gen/Amp unit for Chladni patterns

With only 4 W RMS power, I don't think that's enough (c.f. 30 W RMS on the unit I built). You can probably get away with 15 W RMS. Modifying this unit for more power would require a new power supply and power amp module, or putting the output through a cheap stereo amp (e.g. like this or this).
by Trevor Gore
Thu Jul 28, 2022 7:59 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: DIY Sig Gen/Amp unit for Chladni patterns
Replies: 33
Views: 139844

Re: DIY Sig Gen/Amp unit for Chladni patterns

On the note of people blowing their speakers I was wondering if you think this Griffin signal generator with amplifier will work? Hard to say, Dave. The specs just say sig gen and amplifier. A bit like saying car with engine. See if you can get more detail out of Griffin, such as frequency range an...
by Trevor Gore
Wed May 11, 2022 8:23 am
Forum: The Gallery
Topic: Figured Koa Acoustic
Replies: 7
Views: 12337

Re: Figured Koa Acoustic

Nice work! Definitely one for "The Book" gallery!

The guy who inspired your rosette was "Tricky Fish".
by Trevor Gore
Tue Apr 26, 2022 8:25 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Un-coupled top frequency
Replies: 2
Views: 10066

Re: Un-coupled top frequency

Hello, I'm determining the monopole mobility of a just finished steel string. I need to find the UN-coupled tops main frequency. The strings are off, and the sound hole is plugged with a cut off sour cream container. When I tap it into the analyzer with no saddle or bridge pins I get 188hz. With a ...
by Trevor Gore
Fri Apr 01, 2022 8:29 am
Forum: Instrument Builders Forum
Topic: Applying G&G techniques to a kit guitar
Replies: 14
Views: 8937

Re: Applying G&G techniques to a kit guitar

The main reason for routing the saddle slot after gluing down the bridge is because the bridge is pre-positioned by the bridge pin holes on falcate braced designs, as there is little latitude for error due to the proximity of braces if the pin holes are drilled in the closed box. If you have the rig...
by Trevor Gore
Fri Mar 11, 2022 8:21 am
Forum: Instrument Builders Forum
Topic: 0 Taper Bridge Pins
Replies: 19
Views: 13147

Re: 0 Taper Bridge Pins

They also have no taper at all, the shaft measures 4.7mm the whole length. As such, neither my 4.5mm or 5mm drill bits are suitable... 4.7mm is 3/16". You should have no trouble finding a 3/16" drill if you want to use the supplied pins. A 3/16" drill is also a good size to use as a pilot hole for ...
by Trevor Gore
Wed Mar 02, 2022 3:13 pm
Forum: Instrument Builders Forum
Topic: Saddle Compensation
Replies: 10
Views: 5829

Re: Saddle Compensation

Hi Trevor, thanks for the response mate, You will note that I simply excluded the 3mm for nut compensation in my calculation, does that now make my numbers correct? Definitely not! Adding nut compensation, in very approximate terms, halves the amount of saddle compensation you need. So just excludi...
by Trevor Gore
Wed Mar 02, 2022 9:15 am
Forum: Instrument Builders Forum
Topic: Saddle Compensation
Replies: 10
Views: 5829

Re: Saddle Compensation

Steel string, Falcate braced, 645.2mm Scale Length, no Nut Compensation. I have read and re-read sections pertaining to Saddle Compensation and I am terribly confused about Saddle Location. If I use a 5mm Saddle, straight not slanted, the front of the saddle slot should be (from page 20-19, section...
by Trevor Gore
Fri Jan 21, 2022 7:56 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Intonation Problem
Replies: 10
Views: 16000

Re: Intonation Problem

I've not applied any more thought to this (a bit busy at the moment), but have you got some sort of tail piece resonance going on?