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Big Mouth is born - Falcate-braced Dred
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Author:  SteveSmith [ Mon Dec 31, 2012 6:16 pm ]
Post subject:  Big Mouth is born - Falcate-braced Dred
If you're following the Challenge threads then skip this, you've already seen it. duh If you haven't checked out the Challenge threads then you should, there's some cool stuff over there.

This is my latest. I've nicknamed it "Big Mouth" because I made it with an oversized soundhole (4 1/4").

Some of the facts on this one:

Dred with Bubinga back and sides, Lutz top, BRW bindings and appointments. Bridge and fretboard are Bastogne walnut. EVO frets. Falcate braced with bolt-on butted neck joint with a bolt-on fretboard extension. Finish is Zpoxy fill, shellac sealer, and PolyWhey waterborne. Everything came in at just under $150 for materials.

My goal was a dred with volume, enough response to play fingerstyle or with a pick, and a better balance between treble and bass than one usually gets with this body style. I think I got reasonably close to my goals.
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And the video. Build photos with 3 sound clips, one each fingerstyle, flatpicking, and strumming:
Author:  Pat Hawley [ Mon Dec 31, 2012 6:30 pm ]
Post subject:  Re: Big Mouth is born
Looks and sounds really good Steve. What a great guitar for less than $150.

Any more impressions of the PolyWhey? The longer my test board sits by my bench, the more impressed I become with it. I've tried cracking the finish by flexing the board several times about an inch but the finish seems quite flexible. Also, although I haven't made any serious attempts to scratch it, I have been hitting it with my fingernails about as hard as I think someone would be hitting it with a pick and have been making no marks. This stuff is definitely the hardest of any water-based coating I have tried. In fact, I think it's harder than anything I've tried except for polyester.

Pat
Author:  Mike OMelia [ Mon Dec 31, 2012 6:40 pm ]
Post subject:  Re: Big Mouth is born
Very nice!

OK, I gotta ask. How do you justify those 4 diagonals on the back and that one outlier on the top (near the butt block)

Mike
Author:  SteveSmith [ Mon Dec 31, 2012 6:46 pm ]
Post subject:  Re: Big Mouth is born
Hi Pat, thanks - I'm real happy with the guitar.

So far I'm impressed with the PolyWhey and I'm looking forward to seeing how it holds up over the next few years. I think the cracks I saw in the headplate were caused by a split in the BRW under the finish. I'm also not seeing what I thought was a bluish tint on the headplate anymore now that I've got it out of the shop (where it was under T12 fluorescent lights). I have two more guitars that should be ready for finish soon and I'm going to use the PolyWhey on them too.
Author:  Jeff Highland [ Mon Dec 31, 2012 7:21 pm ]
Post subject:  Re: Big Mouth is born
Looking and sounding great Steve.
Since Dreadnought size is out of the scope of Trevors book, do you mind sharing some details?
Falcate brace size and tow weight, air, top, and back resonances achieved?
Author:  Tom West [ Mon Dec 31, 2012 7:36 pm ]
Post subject:  Re: Big Mouth is born
Steve: Excellant........Congrats. How do you rate this guitar compared to conventional X braced. I really like the sound but it's hard to get a complete sense of the instrument without having it in hand . Any details on sound comparisons appreciated. Thanks in advance.
Tom
Author:  LarryH [ Mon Dec 31, 2012 8:08 pm ]
Post subject:  Re: Big Mouth is born
Wow really nice Steve. Sounds very good - for $150? Simply amazing. Also curious about the bracing.
Author:  Trevor Gore [ Mon Dec 31, 2012 9:17 pm ]
Post subject:  Re: Big Mouth is born
Nice work, Steve. A great all-rounder!

Got to be happy with that.

Good recording, too. What did you use?
Author:  Quine [ Tue Jan 01, 2013 9:59 am ]
Post subject:  Re: Big Mouth is born
Great sounding dred!! Just about blew out my speakers with that big bass
Author:  WaddyThomson [ Tue Jan 01, 2013 11:05 am ]
Post subject:  Re: Big Mouth is born
Looks and sounds great! Nice job!
Author:  SteveSmith [ Tue Jan 01, 2013 1:37 pm ]
Post subject:  Re: Big Mouth is born
Thanks everybody and Happy New Year to all! Let me try to address some of the questions.

First of all I built this based strictly on the the plans for a falcate braced top with a live back from the Gore/Gillet Contemporary Acoustic Guitar bookset. I did adjust the design to fit the dred shape, basically, the sizes weren't all that different so I made the braces the same size but then made sure they ended the same distance away from the linings to allow the top to resonate. I maintained all of the other spacings but did modify the bridge plate slightly to fit my bridge shape. I also had to modify the soundhole patch area somewhat since I used a bigger soundhole. As far as drawings go I did all the nut to saddle spacings for neck and fretboard on a piece of freezer paper taped to the bench and I did the top layout on the top. ;)
Here's part of the freezer paper.
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It's a very worthwhile experience just to build the guitar in such a different manner. The only drawback is that it takes quiet a bit longer to build the top than with a conventional X-brace.

How do you justify those 4 diagonals on the back and that one outlier on the top (near the butt block)

If you look closely at the center of the bottom cross brace on the back you'll see it is notched down to around 7mm or 8mm. This is designed to create a live back which will couple to the top. I think of them as radial braces somewhat like a speaker cone with the bridged connection between two of them allowing some adjustment.
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The little outlier brace was on the plan so I put it in ;) I can only guess it's function at this point since I had to quit studying the design book so I could get it built for the Challenge. I do think it provides some cross-grain stiffness for the the structure at the top join. Perhaps Trevor can step in and answer this question.

Since Dreadnought size is out of the scope of Trevors book, do you mind sharing some details?
Falcate brace size and tow weight, air, top, and back resonances achieved?

Main and secondary falcates were 5mm wide and 7mm at the highest point. Both were a 3 layer red spruce/epoxy laminate.

I used a CF cloth fabric I found on ebay - 2x2 Twill 3K - 5.7 oz. The weave was much too coarse on this but it was on ebay and it was cheap. The tow for the tops and bottoms of the braces I took from the cloth. Next time I'll get something with a finer weave. The epoxy I used was System III T88. I would like to find something a bit less viscous next time.

My measurement capability is limited right now but best I can tell on the resonances is main air = 80 Hz, top = 157 Hz, and back = 197 Hz. Main air is kind of low but I attribute that to the oversized soundhole.

How do you rate this guitar compared to conventional X braced. I really like the sound but it's hard to get a complete sense of the instrument without having it in hand . Any details on sound comparisons appreciated.

For comparison to an X-braced I think it should be compared to a Dred of the same shape so I tend to think of the HD28 I played for many years. The top is much more flexible and vibrate more readily. This guitar has more treble with plenty of bass on demand, more balanced across the frequency range, much more responsive to the pick attack; where the HD28 just quits driving without enough energy, this one gets quieter and sweeter. The sound is different, to my ears it is more complex with more harmonic content. I originally strung it with Martin SP phosphor bronze mediums (my go to strings for the HD28) but they were just too jangly so I went to the D'Addario phosphor bronze flat top mediums which I've found to be a mellower sounding string. The D'Addario's are what I used on the recording.

Good recording, too. What did you use?

Thanks Trevor - and thanks for some awesome books, I've learned a bunch so far just by doing something so radically different. Even if I build all the rest of my guitars with X-braces (I don't think I will though) working with the falcate braces has really added to my understanding of how guitars work. Now I can go and read some more in the design book and what I read will make more sense now that I've built one.

The recordings were done with an Olympus LS-10 recorder sitting on my music stand about 2 feet from the soundhole. I used Audacity to remove the clunks and bangs before and after the songs but otherwise the frequency response is as recorded.
Author:  Tom West [ Tue Jan 01, 2013 5:31 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
Steve: Thanks for reply. That tends to reinforce my general feeling about the sound. I'm am getting more and more tempted to give one a try.Thanks again.
Tom
Author:  Trevor Gore [ Tue Jan 01, 2013 11:58 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
SteveSmith wrote:
My measurement capability is limited right now but best I can tell on the resonances is main air = 80 Hz, top = 157 Hz, and back = 197 Hz. Main air is kind of low but I attribute that to the oversized soundhole.

Those numbers didn't look quite right to me, Steve, nor did they equate to the guitar sound I was listening to, so I took the liberty of measuring off your recording. I got 87-90Hz for the main air (88Hz if I had to pick a single number) and 165-167Hz for the main top (165Hz if I had to pick a single number), which aligns a lot better with what I hear in the recording. If you make the sound hole larger, the main air resonance goes higher rather than lower. Your responsive top and live back will bring the main air resonance down and the larger sound hole brings it back up again, so it measuring up in the 87-90Hz range (as best as you can do that from a recording) makes sense.
SteveSmith wrote:
The recordings were done with an Olympus LS-10 recorder

Thanks for that, Steve.
Author:  klooker [ Wed Jan 02, 2013 8:48 am ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
Wow, that's inspiring. [clap]

Thanks for taking the time to put together the recordings & slide show.

Kevin Looker
Author:  SteveSmith [ Wed Jan 02, 2013 9:10 am ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
Trevor Gore wrote:
Those numbers didn't look quite right to me, Steve, nor did they equate to the guitar sound I was listening to, so I took the liberty of measuring off your recording. I got 87-90Hz for the main air (88Hz if I had to pick a single number) and 165-167Hz for the main top (165Hz if I had to pick a single number), which aligns a lot better with what I hear in the recording. If you make the sound hole larger, the main air resonance goes higher rather than lower. Your responsive top and live back will bring the main air resonance down and the larger sound hole brings it back up again, so it measuring up in the 87-90Hz range (as best as you can do that from a recording) makes sense.


Thanks for the numbers Trevor, I've been working to improve my technique for to determine resonance frequencies on the guitar and still haven't got it down (obviously). Funny, since my day job is as an electronics hardware design engineer working on RF stuff (at the moment, anyway) so I understand resonance and spetra fairly well. I made the larger soundhole decision quite a while ago based on a discussion at the MIMF. The idea was that soundhole size didn't make that much difference so might as well make it big enough for your hands and I have big hands. I need to study the design book some more to understand this better as I'm starting to feel that everything makes a difference.

I took about 15 seconds of the third recording and did an analysis in Audacity (I got similar results in about 10 samples of varying length). The first 4 peaks, from left to right, are 86 Hz, 128 Hz, 158 Hz, and 195Hz. The main air peak seems to be working out for me but I have nothing at 165-167 Hz and would be curious as to how you're seeing that number? I'm using the original file, is it possible that processing into the video has shifted the frequencies a few Hz?
click on the plot for a larger version.
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Author:  Darryl Young [ Wed Jan 02, 2013 12:38 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
When and how did you take that plot? After strung up with the strings deadened? Is it from a tap on the bridge?
Author:  SteveSmith [ Wed Jan 02, 2013 1:12 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
Darryl Young wrote:
When and how did you take that plot? After strung up with the strings deadened? Is it from a tap on the bridge?


This one was taken from the recorded music only because Trevor said that's what he used to get his information. I'm trying to see how he got what he got - a learning opportunity, I hope.
Author:  Darryl Young [ Wed Jan 02, 2013 2:33 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
Interesting. It seems adding the strings and their harmonics would complicate things but adding a lot of information to the graph........so it's more difficult to identify what frequency peaks are caused by the body and what is from the strings.
Author:  Trevor Gore [ Wed Jan 02, 2013 5:35 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
SteveSmith wrote:
The main air peak seems to be working out for me but I have nothing at 165-167 Hz and would be curious as to how you're seeing that number?

Every pluck release is similar to a tap on the bridge, so you get the guitar's frequency response embedded in every note. With a bit of practice, you get to be able to just hear that. The challenge, of course, is to separate the guitar's response from the note(s) being played. Sometimes, depending on what's being played, you can get it from a long period spectral analysis of the playing, (like you tried), but it is usually better to pick a single high note, of a pitch which you think the guitar is NOT tuned to (e.g. if you think the top might be tuned somewhere around A, say, pick a high C note) and look for the body transients at the start of that note. This is easy to do in Audacity, harder to do in VA, but VA tends to give cleaner results, IME. It takes a bit of experience to separate the artefacts from what you think is the real stuff, so I could be wrong (has been known!!)

If you have the guitar, it is much easier just to tap the guitar, of course. Again, I get cleaner results from VA (Visual Analyser) and it's quite easy to use (and is a free download).
SteveSmith wrote:
is it possible that processing into the video has shifted the frequencies a few Hz?

Possible, but unlikely. Your played notes seemed to be at the right frequencies.
Author:  SteveSmith [ Wed Jan 02, 2013 11:25 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
I've got the VA installed but I need to figure out how to get the samples I want. I'll look at that in the morning.
Author:  SteveSmith [ Sat Jan 05, 2013 11:14 am ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
Trevor, I'm still playing with VA but I think I'm seeing more like what I'm supposed to even with Audacity. The big change I made is moving to a real mic duh . Now I'm running a Behringer mic that has a freq response down to 60Hz through a Tascam USB audio interface. Makes a huge difference in the signal. Here's what I'm seeing with Audacity which lines up better with what you are seeing but still seeing a peak closer to 160Hz than 165/167 Hz. Hopefully VA will let me get closer results.
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The spectral components seem to agree well in VA I just need to learn how to manipulate it so I can read the peaks better
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Author:  SteveSmith [ Sun Jan 06, 2013 2:37 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
Those of you using Visual Analyzer - How are you reading the peak values accurately? There are some things about this software that I'm finding non-intuitive.

I know I can narrow the frequency range down in the main spectrum window and then do an average and a hold to get a data sample. I've found the capture window to be pretty useless only because it wants to plot the entire 0 to 20KHz spectrum and, at least to me, it does not always look like the spectrum in the main window. I'm wondering if the capture function samples the current signal and not the averaged signal on the display?

I suppose if I selectively narrow the freq range I can zoom in on the measurement. Is this how you read the peaks?
Author:  Trevor Gore [ Sun Jan 06, 2013 8:22 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
I use VA version 9.0.1 because I find it easier than more recent versions and I think it is still available. You need to set the FFT sample size and the sampling frequency; instructions here. Also set the Capture Spectrum to 10. When the capture window pops up, you can move the frame by "grabbing" with the "wrong" mouse button and zoom by "boxing" with the "right" mouse button. As you move the mouse/cursor, the X,Y coords appear in the lower left corner, so you can get the frequency of any peak you place the cursor on. If you save the file from the menu in the pop up window, you automatically save the pic that is on your screen and a text file of all the numbers. You can search the text file for peaks to find what the real data is (rather than the graphic interpolations) and you can import the text file into Excel (or whatever) if you want to do other operations on the data.
Author:  SteveSmith [ Mon Jan 07, 2013 1:35 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
Thanks Trevor that's very helpful. I also discovered that the VA help function is window specific so have found more info there too. Now I just need some more time to play with it - I have been frustrated with this whole frequency measuring thing for way too long and need to get it nailed down.
Author:  Alexandru Marian [ Mon Jan 07, 2013 6:25 pm ]
Post subject:  Re: Big Mouth is born - Falcate-braced Dred
Steve, you need to select 16k for the "size" in Audacity, gives a much more detailed graph. Go lower only of the signal is poor (usually not the case with recordings you make yourself).
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