Search found 1507 matches

by Trevor Gore
Tue Jul 21, 2020 6:13 pm
Forum: Instrument Builders Forum
Topic: Classical Build (s) - Hopefully falcate!
Replies: 94
Views: 20117

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:
by Trevor Gore
Fri May 29, 2020 6:41 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: having a go at spectrums
Replies: 11
Views: 1915

Re: having a go at spectrums

The extra "grass" looks like you managed to score two taps in one buffer. Also possibly a bounce (essentially the same as two taps per buffer). One tap per buffer definitely gives cleaner plots. It takes a bit of practice.
by Trevor Gore
Fri May 29, 2020 6:31 pm
Forum: Instrument Builders Forum
Topic: The order of things ...
Replies: 14
Views: 1814

Re: The order of things ...

I wonder is it a steel string vs classical guitar thing? I k no w no-one who frets before gluing the fretboard? Yes, you do! :D One of the reasons for going to the BOBO neck joint (steel and classical) was so that I could fret the board fully before gluing it on. It is much easier to keep everythin...
by Trevor Gore
Mon May 25, 2020 9:40 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Starting out on J45
Replies: 43
Views: 15716

Re: Starting out on J45

Ed Haney wrote:
Mon May 25, 2020 3:33 am
I still wonder what value of E was used for J-45 in the Book.
10GPa. Don't go less than that, but stiffer is OK as you can always shave a bit off the tops of the two lower bout braces.
by Trevor Gore
Sat May 09, 2020 9:56 am
Forum: Instrument Builders Forum
Topic: Quality Machine heads
Replies: 16
Views: 2185

Re: Quality Machine heads

For steel string, I've bought one set of (old) Schallers ever, one set of Schaller Grand Tune ever (had to give them a second chance after many years) one set of Grovers ever, Waverly's only when the customer insists and countless sets of Gotohs of all sorts and never had a mechanical problem with a...
by Trevor Gore
Fri Apr 17, 2020 4:43 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Starting out on J45
Replies: 43
Views: 15716

Re: Starting out on J45

Best just to download Visual Analyser (for free) and follow the instructions in the Appendix. If you're using a Mac, you'll need an emulator type program so you can run Windows apps (Parallels or Wine seem to be the popular ones) or buy a cheap Windows PC. If you need further instruction, you can ge...
by Trevor Gore
Thu Apr 16, 2020 8:12 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Starting out on J45
Replies: 43
Views: 15716

Re: Starting out on J45

I must have read that bit last time and gone with the traditional 4 transverse braces of 6.3 wide on 2.8 mm thick mahogany - which, I hadn't understood, gives a 'live' back after all - a contribution to the sound from back vibration - which I take it is better and richer in complexity as long as (i...
by Trevor Gore
Thu Apr 16, 2020 8:36 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Starting out on J45
Replies: 43
Views: 15716

Re: Starting out on J45

In Section 11.2.2.13 I talk about the details of J45 back bracing. The "real" J45 has a live back and the live back is important for the reasons given in that section. So if you want to improve over your previous J45 I'd recommend going for a live back and the details of how to do that are also disc...
by Trevor Gore
Wed Apr 08, 2020 8:19 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Help to find details of Rosette Router Jig
Replies: 5
Views: 1116

Re: Help to find details of Rosette Router Jig

The "first block" (with the arrows drawn on in black felt tip) has a through hole for the shaft. The nuts are locked to the shaft, so the shaft is a tight rotating fit through that block. Both nuts in the larger central block are captive (and have Belville washers) so when the shaft is rotated this ...
by Trevor Gore
Tue Apr 07, 2020 9:56 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: having a go at spectrums
Replies: 11
Views: 1915

Re: having a go at spectrums

Depending on which version of Windows you have, there are different ways to control the gain. For VA 9.0.6 (which I use most of the time) the level controls in VA only work in Win XP. In later versions of Windows, you have to go to the Windows sound controller or other installed app (e.g. DTS Audio ...
by Trevor Gore
Mon Apr 06, 2020 9:10 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: having a go at spectrums
Replies: 11
Views: 1915

Re: having a go at spectrums

I made an attempt at spectrums just now and really don't know where to start... You can download the VA setup instructions from my website here . That should at least get you started! There is definitely quite a bit of "grass" on those plots, possibly due to too much gain as John suggested, but als...
by Trevor Gore
Mon Apr 06, 2020 8:49 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Abalone rosette measurements
Replies: 2
Views: 747

Re: Abalone rosette measurements

On a steel string with a 102 mm sound hole (in the plan)... The falcate plan has a 95mm sound hole, which is what I had in mind when suggesting "something around 115mm". Your 121mm former should be OK for a 102mm sound hole, but best to get a compass and a piece of paper and draw it out to make sur...
by Trevor Gore
Mon Apr 06, 2020 8:38 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Help to find details of Rosette Router Jig
Replies: 5
Views: 1116

Re: Help to find details of Rosette Router Jig

Well, there's the pics in the 15th Aug 2018 post and also some in a post on Apr 7th 2018 and I think that is all I've posted on the subject on this forum. Anything on other forums will be much the same. I've never made drawings of the jig, but you should be able to replicate the main features from t...
by Trevor Gore
Mon Feb 03, 2020 9:52 am
Forum: Instrument Builders Forum
Topic: Qualities of Spruce
Replies: 17
Views: 6457

Re: Qualities of Spruce

Thanks, DaveO. ...But I have noticed slightly (non significantly) higher E long results comparing thin bracewood to wider soundboard stock, when comparing population with a simple t-test. My charts are from data made up primarily of sound board samples planed to ~ 4mm thick and measured for the elas...
by Trevor Gore
Sun Feb 02, 2020 11:35 pm
Forum: Instrument Builders Forum
Topic: Stain on soundboard
Replies: 11
Views: 4614

Re: Stain on soundboard

Bruce, I suspect that kind of staining came from the gig bag. Some time back a manufacturer was offering a "protective wrap" for a guitar for inside the case and it left marks like that, but fortunately it wasn't on one of my guitars. Whatever it was came out of the wrap and into the finish, though ...
by Trevor Gore
Thu Jan 30, 2020 10:18 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: High frequencies
Replies: 2
Views: 2959

Re: High frequencies

I was always lead to believe that anything above 1K really isn't worth worrying about. Happy to be proved wrong. Trevor?? It's certainly difficult to target specific modes of vibration up beyond 1k Hz, so it's down to doing things that support high frequencies generally, like keeping monopole mobil...
by Trevor Gore
Thu Jan 30, 2020 9:06 am
Forum: Instrument Builders Forum
Topic: Qualities of Spruce
Replies: 17
Views: 6457

Re: Qualities of Spruce

Thanks for posting that DaveO. I have a similar chart with a tighter spread, which just indicates that a lot of selection has gone into the wood before I measure it (so not a random sample). Also, the regression line is lower down the page in my results, indicating lower measured E long values. I pr...
by Trevor Gore
Fri Jan 03, 2020 8:44 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: VA plots for tap test on plates
Replies: 13
Views: 5783

Re: VA plots for tap test on plates

Were any of the panels not flat enough?
by Trevor Gore
Wed Jan 01, 2020 12:06 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: VA plots for tap test on plates
Replies: 13
Views: 5783

Re: VA plots for tap test on plates

Fdiag should be an easy one to get, assuming you have the VA set up right. Hold the panel in the middle of the long side edge, tap lightly on a lower corner with the mic right behind the corner you tap. Often the problem is due to tapping too hard or not putting the mic where it can "hear" the vibes.
by Trevor Gore
Tue Dec 31, 2019 9:01 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Latest build final tap results
Replies: 1
Views: 2368

Re: Latest build final tap results

That looks close enough to ideal to leave it as is. Well done, Chris!
by Trevor Gore
Mon Dec 23, 2019 1:03 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Unusual Panal Size
Replies: 6
Views: 3429

Re: Unusual Panal Size

Sorry about the typo. Should have been p 4.39.
by Trevor Gore
Mon Dec 23, 2019 8:38 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Unusual Panal Size
Replies: 6
Views: 3429

Re: Unusual Panal Size

For non-rectangular pieces, e.g. a rectangle with a corner cut off, choose a part of the panel that is rectangular and do a three point bend test on that part. Page 4.30 Design.
by Trevor Gore
Thu Dec 05, 2019 7:38 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Spectrum change with age
Replies: 5
Views: 3610

Re: Spectrum change with age

I've found that if I use "old" wood (that I've had for at least 5 years), the guitar seems to get louder with age but the spectrum remains much the same. If I use "new" wood, cut and dried for less than 2 years, the guitar gets stiffer as it ages and whilst the shape of the spectrum remains recognis...
by Trevor Gore
Fri Nov 22, 2019 7:57 am
Forum: Instrument Builders Forum
Topic: Searching for Carbon Fiber for a Falcate Guitar Build
Replies: 4
Views: 1985

Re: Searching for Carbon Fiber for a Falcate Guitar Build

These guys keep changing their name but are still in the same business and is where I've bought the CF products called for in the books. The cloth (1m wide) is much more economical to buy than tape (or was!). Give them a call and see if they still stock CF. https://allnex-brookvale.business.site/
by Trevor Gore
Wed Nov 20, 2019 9:45 am
Forum: Instrument Builders Forum
Topic: packaging tape for binding
Replies: 12
Views: 3506

Re: packaging tape for binding

I am looking for a source of the reinforced packaging tape to use for binding work...any recommendations? What are you using and do you find that the tape is strong enough by itself or do you still bind with stretchy cord or rubber as well? Cheers! Ross I use the two-way filament tape from these gu...