Search found 460 matches

by johnparchem
Sat May 23, 2020 12:46 pm
Forum: Instrument Builders Forum
Topic: Test post
Replies: 9
Views: 790

Re: Test post

kiwigeo wrote:
Sat May 23, 2020 11:33 am
[youtube]https://www.youtube.com/watch?v=JBM5r5WnPOs[/youtube]

You still need to to it like this

Code: Select all

[youtube]JBM5r5WnPOs[/youtube]




youtu.be/JBM5r5WnPOs
by johnparchem
Sat May 23, 2020 6:29 am
Forum: Instrument Builders Forum
Topic: Classical Build (s) - Hopefully falcate!
Replies: 80
Views: 15995

Re: Classical Build (s) - Hopefully falcate!

Hello folks. I'm probably going to be shot down for this long and complicated post, but that's OK, if perhaps even a small part of what follows might be useful to someone. Perhaps I should post it elsewhere. I'll preface what follows with the statement that I have spent my previous long working lif...
by johnparchem
Fri May 22, 2020 1:54 pm
Forum: Instrument Builders Forum
Topic: Advice on removing HHGed binding
Replies: 3
Views: 770

Re: Advice on removing HHGed binding

If I am not saving the bindings I just pretend they are not there and recut the binding channels with my binding jig. If I want to save the bindings I start at one end and use a heat gun and a spatula to gently work the bind off. I just work along the binding heating and removing.
by johnparchem
Thu May 21, 2020 10:46 pm
Forum: Instrument Builders Forum
Topic: Classical Build (s) - Hopefully falcate!
Replies: 80
Views: 15995

Re: Classical Build (s) - Hopefully falcate!

Careful with the methanol it is very toxic, even the fumes. In the US cheap denatured alcohol is about half methanol. I avoid it for pure ethanol as I do not want to wear a mask through all the time it takes to French Polish. Methanol is highly flammable and toxic. Direct ingestion of more than 10mL...
by johnparchem
Wed May 20, 2020 11:15 pm
Forum: Instrument Builders Forum
Topic: Classical Build (s) - Hopefully falcate!
Replies: 80
Views: 15995

Re: Classical Build (s) - Hopefully falcate!

The guitar looks good. I also wonder about the consistent lack of T(1,1)1 on your plots. I just wonder in you setup something is filtering out the lower frequencies. It should be showing up very clear. You can hum into the box around the frequency you think it is an hear where it resonates. I have f...
by johnparchem
Mon May 18, 2020 5:59 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Establishing the target plate thickness for Flamenco guitars
Replies: 1
Views: 444

Re: Establishing the target plate thickness for Flamenco guitars

I had a very good Flamenco guitar in my shop with the back having a lower resonance than the top; a very thin back. I used Spanish cypress and use the same back vibrational stiffness that I use for classicals and pitched the back for semitones from the top. That might not be typical for a flamenco. ...
by johnparchem
Sun May 10, 2020 3:01 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Reducing BOBO neck weight
Replies: 9
Views: 1121

Re: Reducing BOBO neck weight

Just a thought, not my idea as it was posted on this site awhile back. Set things up so that you can install the bolt on neck sans fret board before gluing on the back but after gluing on the top. Then while gluing on the back you can set the forward angle by tilting the bolt on neck to the correct ...
by johnparchem
Fri May 08, 2020 11:58 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Reducing BOBO neck weight
Replies: 9
Views: 1121

Re: Reducing BOBO neck weight

Am I right in thinking that the 'wedge' for the BOBO classical neck might not be required for a flamenco, where the desirable saddle height is 7-8mm, rather than 10-11mm for a classical? I think you still need the wedge. Just imagine flat, no neck angle, with a 6 mm fretboard 2.5 mm of action will ...
by johnparchem
Mon May 04, 2020 4:40 am
Forum: Instrument Builders Forum
Topic: Best way to repair bent sides?
Replies: 10
Views: 1611

Re: Best way to repair bent sides?

Can anyone explain why a Ukulele should be tapered? Is there any Acoustical reasoning behind this, or is it just traditional? . They do not need to be and many traditional ukulele's are not. I think the tapered sides on a tenor looks better. It matters less to me with a soprano or true ukulele. I m...
by johnparchem
Sun May 03, 2020 11:46 am
Forum: Instrument Builders Forum
Topic: Best way to repair bent sides?
Replies: 10
Views: 1611

Re: Best way to repair bent sides?

This all looks normal to me. Agree with taper the sides, the block and the heel cap until all is in plane.
by johnparchem
Sat May 02, 2020 11:57 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Trevor’s video by Robbie
Replies: 10
Views: 1949

Re: Trevor’s video by Robbie

I have just gone through the video published by Robbie O’Brien of Trevor going through the whole process of analysing a guitar’s responses. It is incredibly useful. It is not a criticism of the book to say that a video of many of the processes involved is very powerful. Words can only take you so f...
by johnparchem
Thu Apr 09, 2020 5:40 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: 1. falcate braced classical
Replies: 10
Views: 2660

Re: 1. falcate braced classical

Thanks John. My bracing is going to be more or less the same as the steel string layout. I drafted my own but will amend it slightly. Im intending to put the lower TB in. 20200403_133723.jpg ... The lower transverse brace even an open will make a big difference when determining the height of the fa...
by johnparchem
Thu Apr 09, 2020 1:16 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: 1. falcate braced classical
Replies: 10
Views: 2660

Re: 1. falcate braced classical

After my actually quite nice results with a steel string falcate braced 000 style guitar I thought I can easily adapt a classical guitar to falcate bracing. Little did I know :) I should have believed John Parchem build description and stayed with the bracing height for steel strings. What I did wa...
by johnparchem
Mon Apr 06, 2020 8:04 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: having a go at spectrums
Replies: 11
Views: 1547

Re: having a go at spectrums

They look sort of noisy to me, like maybe your mic is clipping. You might turn down the gain. Because of the extra peaks I can not tell what the back might be.
by johnparchem
Fri Apr 03, 2020 7:48 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Closed box T(1,1)2 less than 200 Hz - Edge thinning
Replies: 3
Views: 810

Re: Closed box T(1,1)2 less than 200 Hz - Edge thinning

I think both of your guitars that came in around 195 Hz had a good chance of hitting 180 Hz once finished. It would have depended on the mass of the bridge and how much the bridge lowers the top's resonance. On the steel strings I have been seeing <-10 Hz adding the bridge and another <-5 adding the...
by johnparchem
Thu Apr 02, 2020 6:28 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Closed box T(1,1)2 less than 200 Hz - Edge thinning
Replies: 3
Views: 810

Re: Closed box T(1,1)2 less than 200 Hz - Edge thinning

Thinning the edges is a good way to Lower T(1,1)2 Lowering the braces is a real good way to Lower T(1,1)2 Having A thinner top is a good way to Lower T(1,1)2 The tops resonance is based on both stiffness and mass. In all the above three cases you are lowering the stiffness more than you are lowering...
by johnparchem
Wed Apr 01, 2020 2:57 am
Forum: Instrument Builders Forum
Topic: Bellied up top
Replies: 28
Views: 4228

Re: Bellied up top

I do not think changing the tone bars will do anything for you. The belly is from the nut side of the bridge rotating in. One fix I might try if I did not want to remove the top would be to sister taller braces on the over carved x-braces from the X to the finger braces on each side. Having said tha...
by johnparchem
Sat Mar 28, 2020 9:55 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: 1. falcate braced classical
Replies: 10
Views: 2660

Re: 1. falcate braced classical

Ok, old top off, new top on. Actually easier than I thought. Thanks the advice Jim. New values after binding and sanding: T(1,1)1= 90Hz T(1,1)2=195Hz T(1,1)3= 244Hz I had been wondering why the T(1,1)1 is so low until I checked the diameter of the soundhole... Great! Instead of 85mm I have just 79m...
by johnparchem
Fri Mar 27, 2020 2:04 am
Forum: Instrument Builders Forum
Topic: Bellied up top
Replies: 28
Views: 4228

Re: Bellied up top

I was taught not to start the scallop before the bridge plate for structural reasons. When I shift the braces toward the sound hole I am thinking about just the X not the entire scallop pattern. The low part of the braces are right where you need structural support.
by johnparchem
Wed Mar 18, 2020 8:24 am
Forum: Instrument Builders Forum
Topic: Carbon Graphite neck bracing, too much?
Replies: 6
Views: 4061

Re: Carbon Graphite neck bracing, too much?

Richard thanks for your reply, I had not thought about the creep factor over time. On many of my guitars I use a 2 way truss rod so I can dial it out. But for many of my classical guitars without a truss rod it is worth a thought.
by johnparchem
Wed Mar 18, 2020 7:47 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: 1. falcate braced classical
Replies: 10
Views: 2660

Re: 1. falcate braced classical

I have built all my falcate classical guitars without a lower transverse brace. Without a lower transverse brace, I am between 10 to 10.5 mm on the primary falcates and 8-9 on the secondary falcate braces to get the top strung up to resonate at 190 Hz and 200 Hz respectively. My first guitar had num...
by johnparchem
Wed Feb 26, 2020 11:23 am
Forum: Instrument Builders Forum
Topic: Why a neck volute?
Replies: 7
Views: 3953

Re: Why a neck volute?

The look good? I know that some of them were part of the headstock to neck joint. I believe a lot of them are decorative.
by johnparchem
Mon Feb 24, 2020 1:36 am
Forum: Instrument Builders Forum
Topic: Carbon Graphite neck bracing, too much?
Replies: 6
Views: 4061

Re: Carbon Graphite neck bracing, too much?

I have used carbon fiber rods in necks with truss rods, and have had no issues providing relief using the truss rod. Part of the reason for this may be that when the fretboard is glued on the rod is close to the neutral axis so it may not really be stiffening the neck all that much. After I was show...
by johnparchem
Mon Feb 03, 2020 3:15 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: cosed box Frequency response falcate OOO
Replies: 10
Views: 5101

Re: cosed box Frequency response falcate OOO

Very nice, my favorite steel string's spectrum graph is very close to your falcate 000. It compares well to any guitar I have heard, at least for my use as a fingerstyle guitar. The x braced guitar spectrum looks good to me. I built a few falcates with 180 Hz top and was very happy with them. I bet ...
by johnparchem
Sun Feb 02, 2020 1:54 am
Forum: Instrument Builders Forum
Topic: Stain on soundboard
Replies: 11
Views: 4429

Re: Stain on soundboard

It is hard to tell but an interaction with something in the gig bag. I wonder as the somewhat localized stains.