Gee that's a big guitar

Allen · Post by **Allen** » Wed Mar 19, 2008 6:12 pm

Silky Oak bends like butter when I've done it. Just for purfs mind you, but I didn't break one, and I've broke plenty of others types.

ap404 · Post by **ap404** » Thu Mar 20, 2008 7:21 pm

Silky Oak bends like butter

Cheers Allen, good to know that, that's just what an Australian guitar forum's for.

I've loved it since my Queensland childhood sleeping in a silky oak bed and staring into the rays ... and always wanted to use it.

I should have started stockpiling right there and then. The good deep red stuff doesn't just grow on trees anymore

A.P.

Paul B · Post by **Paul B** » Thu Mar 20, 2008 7:38 pm

That's interesting A.P.

My bedroom furniture when I was a kid was made from silky oak as well - I always thought that that furniture looked as cheap as the stuff it was made from. It's tainted silky oak for me for life.

Oh, the pain....(think Dr Smith - Lost in Space)

matthew · Post by **matthew** » Fri Mar 21, 2008 12:08 am

The linings for this bass, and the purfling too, have come from a silky oak bedhead thrown on Old Canterbury Road.

Love the stuff. Never looks cheap to me if the rays are broad.

Tigermyrtle · Post by **Tigermyrtle** » Tue Mar 25, 2008 3:44 pm

Well matt, for someone self taught you sure are doing a beautiful Job, that is one beautiful instrument, regards Bob,

matthew · Post by **matthew** » Sun Mar 30, 2008 12:46 am

here's a quick clip of me graduating the top

By the way Bob, the youtube tag doesn't seem to do anything ...

[youtube]http://www.youtube.com/v/PRlMqavfZqc[/youtube]

youtu.be/

Try that Matt,

Cheers

Kim

matthew · Post by **matthew** » Wed Apr 02, 2008 12:16 am

After marking the thicknesses with a dial caliper I highlight the "go" and "no-go" areas in blue and pink chalk

Dennis Leahy · Post by **Dennis Leahy** » Wed Apr 02, 2008 1:10 am

Matthew,

Thanks for including the video clip. That's fun to see.

You're right: that is a BIG guitar!

Dennis

Allen · Post by **Allen** » Wed Apr 02, 2008 6:37 am

Is there suppose to be a nice even graduation of thickness from the center to the outer edge, or do some areas get thinned more than others for tonal reasons, such as the treble side being thinner than the bass side?

How about from top to bottom?

Interesting stuff there Matthew. Keep posting progress picts.

matthew · Post by **matthew** » Wed Apr 02, 2008 8:16 am

there are various styles. "french" graduation is often even acrss the top, about 6mm for spruce. Usual graduation is thicker in the middle. I prefer this latter style, I think it gives the top more inertia once the vibrations have started up. The measures I am using for cedar are: the edge is about 7.5mm , thinning at the low part of the channel to 6mm if I dare (sometimes 4.5-5 for spruce) and gradually increasing to about 10mm along the centre. As cedar is lighter than spruce I think weight in the centre is going to help, too. Just a hunch. we often think of the top as across between a speaker cone (flexible edges, stiff centre to pump the air) and a tabla drum (weighted skin). I might try a bit thinner on this bass. But I don't want to be too adventurous, as the only bracing inside is a spruce bar running from upper to lower bout on one side.

Funny thing is, violin family instruments are assymmetric in the way they vibrate due to the sound post connecting top and back, yet few makers seem to graduate the tops assymetrically - which you think would be a good idea??? I've been puzzling over this a bit.

I'm going to try to document the flexibility of this top using mode 2 and 5 chladni patterns. Never done this before.

Craig · Post by **Craig** » Wed Apr 02, 2008 10:47 am

G'day Matt.,

Superb workmanship as usual Matt . I've found your thread to be incredibly interesting and really look forward to the instrument being completed.

I keep thinking a soundport would work well on one of these instruments, but I'm guessing most acoustic bass players prefer keeping to tradition ?

Great ,and exciting work mate.

Cheers , Craig

matthew · Post by **matthew** » Wed Apr 02, 2008 10:51 am

I agree a soundport is tempting. However this bass is a copy of a master bass and I want to keep it as original-looking as possible ...

I have a bass with laminated sides and back (common in "cheap" basses up to arount $3k) that I need to make a new top for. Maybe this is my chance to try a bunya top AND a soundport??

James Mc · Post by **James Mc** » Thu Apr 24, 2008 8:39 pm

Matthew mateâ€¦ took a while to read it all but itâ€™s been an education! Would now take five postage stamps the write the sum of my knowledge on building a huge guitar. Great post!

matthew · Post by **matthew** » Fri Apr 25, 2008 4:34 pm

Here are some more pics with the FFs cut and the top thinned more.

First, FFT analysis of tapping the lower bout

You can see distinct peaks at about 29Hz (dominant frequency) and at 58Hz (the first harmonic of 29Hz)

Next is with the plate suspended at blocks only. It shows a mode 1 pattern (twisting) and works best when the lower flank is excited by the speaker at 29Hz.

Next is almost the same frequency, but suspended at the outer edges, and responds when the lower block area is excited by the speaker:

This looks pretty much a Mode 2.

Next is 58Hz, a harmonic of 29Hz. You can see this is a combination of both the previous patterns!

FFT analysis of tapping the centre bout; there are peaks at about 76Hz and 113Hz.

These are the corresponding Chladni Patterns. Looks closeish to a mode 5 maybe?

Well; what do youse make of all THAT???????

jeffhigh · Post by **jeffhigh** » Fri Apr 25, 2008 5:40 pm

It looks sad at 58

matthew · Post by **matthew** » Fri Apr 25, 2008 9:03 pm

You would be, too ...

Colin S · Post by **Colin S** » Fri Apr 25, 2008 11:35 pm

Matthew, I'm just at the varnishing stage of my first violin, having built a whole load of guitars and lutes. Carving the plates on the violin was a daunting enough excerise, but scaling that up to a double bass size is nothing short of superhuman. I'm very, very impresed.

Colin

matthew · Post by **matthew** » Sat Apr 26, 2008 7:50 am

coming from a guy who can cut a rosette like in your avatar ... that's a nice compliment!

matthew · Post by **matthew** » Wed May 21, 2008 7:51 pm

The bass bar is fitted and more Chladni patterns on offer.

Look here: http://home.exetel.com.au/studio205/e10 ... 10#post_53

Allen · Post by **Allen** » Thu May 22, 2008 6:00 am

It looks like your making some great progress there. Besides raising the frequency, The patterns appear just a bit more defined as well.

Does any of this make sense to you yet, or is this data going to be used as a reference for subsequent builds?

matthew · Post by **matthew** » Thu May 22, 2008 7:53 am

I think I understand what the patterns are showing me. I'm not really confident yet about how what I am shaping is affecting the patterns, or more importantly, whether a certain "pattern" is desirable.

Luke · Post by **Luke** » Thu May 22, 2008 5:04 pm

that is some impressive work matt and an inspiration.
One of the guys I play music with is a excellent Bass player. He has a cheap double bass that he plays well, and it is always a pleasure when we have a gig that it will suit.

Have always been blown away at the cost of a decent double bass, another friend said you could pay $500 for a set of strings

One can see by your posts the amount of work to build one is huge!

Also curious as if you have time to gig and the style of music you are into.

matthew · Post by **matthew** » Thu May 22, 2008 8:41 pm

You can get strings for about $125 per set, but it depends what you want. Gut strings are $500 and upwards.

These days I try to play jazz and tango on the weekends with friends ... anything really... used to play in a salsa outfit for a while. I'd love to do some gigs again, best buzz. But honestly, I spend more time making than playing.

matthew · Post by **matthew** » Sun Jun 01, 2008 11:57 pm

Carving the decoration in the back of the scroll:

The main problem I have had is that the carving gets very "chippy" near the edges and is easily damaged.

It will probably sort out when I get all the edges nicely rounded and chamfered.

Allen · Post by **Allen** » Mon Jun 02, 2008 5:52 am

Your definitely a man of great patience Matthew. It's looking great. I imagine having chisels even more than razor sharp is trick to getting crisp carving. Just wish I could get them that sharp and have them stay that way.

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