Radical new design

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Nick
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Radical new design

Post by Nick » Thu Nov 20, 2014 12:42 pm

Latest build from the 'shed' is this deep bodied instrument, it's a radical departure from normal luthiery methodology and flies in the face of conventional guitar building wisdom, even the materials are different for me. It's designed so that even a monkey can build one, well I managed to build it so what more proof do you need? :wink: it also has an exagerated Manzer wedge profile to it.
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:lol: :lol: :lol: No, actually it's called a Cajon.....not cojones, they're different animals altogether, warm round and fluffy, this is a box drum originally from Peru (Cajon being the Peruvian for box). It has a front 'head' a "Tapa" and behind that are drum snares. When it's hit near the top it sounds just like a snare drum and a move down more toward the centre and a flatter palm approach gives you the deeper kick drum sound. My step son was originally wanting to build one but the poor bugger's been working two jobs saving for his wedding next year, so seeing as it was his birthday last week I decided to knock one of these up for him. It took a little longer than I first anticipated but has been fun working on it. Traditionally they are made square and the player leans it back to make the front face more accessible but I've noticed a few manufacturers now angling the face so that's a feature I incorporated into my build.
Here's a few pics I took during the build.
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'frame' made from construction grade 12mm ply and a 22mm dowel carries the snares (a 13" snare cut in half), I made it so that the handle/knob on the left clamps the snare bar in position and the right one adjusts the bar so the snares can be 'disengaged' just by loosening the left and turning the right knob.
With the front 'tapa' in place.
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From what I can make out commercial ones use 3mm ply, the closest I could find here in Un Zud was 4mm Marine ply so I used that but ran it through the thickness sander, it would have worked leaving it at 4 but I felt the snares became a little more active at the lesser thickness. Because my step son is right into his music and sometimes records with DJ's e.t.c (actually does a mean beatbox!) I added an internal mic and wired the XLR output into twin plugs, a balanced XLR for going straight into a P.A or desk and a 1/4" jack for amping
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I used a stereo jack socket so that it didn't cancel out the balanced line signal at the XLR (usually you bridge terminals 1 &3 when going into a mono signal) with terminal 1 going into what would be the ring on a stereo jack but the earth on a mono.
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A bit of 'tidying' up the frame by rounding corners and a sand, a quick wipe with some half strength black stain so as not to hide the grain on the ply and a few sealing coats of lacquer and the body has what my workmate termed "Speaker Black" (apparently all the speaker cabinets in the 70's had a similar appearance :shock:, I'd forgotten!). I left the front and rear faces natural added an "Oliver" signature sticker to the front face (have plenty left over from the vibraphone I made as I had to order at least 50 before the sign company would do the job!) and voila........
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and here's a clip of a guy that knows just how to play one!

youtu.be/
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charangohabsburg
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Re: Radical new design

Post by charangohabsburg » Sat Nov 22, 2014 12:19 pm

That's a quite clever and versatile design, and very nicely executed Nick! :cl :cl

Years ago I made one with some massive spruce for top, bottom and sides, and some birch plywood rests. For the back (the part with the soundhole) I used 1.5mm ply which I thought would have been too weak for the top, and for the top I used the next thicker plywood I had at haand, which was 6mm, haha! I ended up removing 3 of the 5 layers of the 6mm ply, which is now a 2.5 mm top. The thing is quite ugly compared to yours, and sounds a bit loud now - which is the reason why I mostly use it as a stool. :lol:
Markus

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Re: Radical new design

Post by Kamusur » Sat Nov 22, 2014 4:42 pm

Oh yeah, definitely *****5 star cool.

Steve

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Dennis Leahy
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Re: Radical new design

Post by Dennis Leahy » Mon Dec 08, 2014 5:07 am

Nice job, Nick!

I bought a snare about a year ago, and still haven't gotten around to building the cajon yet. I came to the same conclusion on the angled shape, giving the wrists less of an angle to have to make in playing it.

I saw a design (maybe on YooToob) that had the snares mounted on a rotatable dowel with a spring to engage and a string and knob at the back to disengage, but your system to set the amount of snare (or none) is better (simpler, more elegant) than what I saw.

I had envisioned laminating some cool veneer on the sides, and though I may still do that, your semi-transparent stain looks nice. I saw one person (somewhere online) that had thinned some spruce and made the tapas like a soundboard. Wonder how many smacks (or heel presses) before it cracked. All the commercial ones use 1/8" (3mm) plywood, though some do use swirly birch to avoid the plain tapas.

I "auditioned" a number of these by watching/listening to videos, and the video you posted does have a cymbal or high-hat in the audio mix (just in case anyone was wondering how in the hell the cajon made that cymbal sound - it didn't.)

Did you pad the top? Looks like you did.

One thing I may do is to add a curve where the back meets the bottom (a sort of "folded horn", like some speaker boxes) and port it out the front. Why? Oh, I don't know - I seem to have a need to complicate everything. :lol:

Thanks for showing yours! Looks very professional.

Dennis

p.s. Oh, one last thing: what is the logic of why you arranged the tapas screws as you did (with an area not screwed down)? Did you see that done by someone, or is that your own intuition, or...?
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Nick
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Re: Radical new design

Post by Nick » Mon Dec 08, 2014 12:30 pm

Dennis Leahy wrote:Did you pad the top? Looks like you did.
Yeah just a small amount of cushioning for the backside Dennis :wink: It's a bit of 1/2"thick high density foam. Interestingly enough when running the Cajon through an amp, if you hop off it and hit the padded top it gives you yet another sound! More of a muffled 24" kick drum without any of the snare action.
Dennis Leahy wrote:One thing I may do is to add a curve where the back meets the bottom (a sort of "folded horn", like some speaker boxes) and port it out the front. Why? Oh, I don't know - I seem to have a need to complicate everything. :lol:

I've seen a commercially made model with the front port (rectangular opening at the bottom of the Tapa Cajon Rock was the brand https://www.youtube.com/watch?v=FTwFA8EsGBw) and considered that feature for this but then decided against it, the idea of the rear facing port is typically a drummer is at the back of the stage or room you use the wall behind to gain projection. But if you built in a horn then you probably wouldn't need the wall to get any of that out of it, it has it's own projector built in! Let me know how you get on if you decide to make it 'forward firing' :D
Dennis Leahy wrote:p.s. Oh, one last thing: what is the logic of why you arranged the tapas screws as you did (with an area not screwed down)? Did you see that done by someone, or is that your own intuition, or...?
Cheated and copied others Dennis :wink: The idea is with no screws is to allow the tapa to sit off the box slightly at the corners so that when you hit it it gives a slight tapping/clicky or slapping sound similar to a rim hit, so another flavour to add to the sound. The guy I saw doing it actually "tuned" the gap slightly by adding shims under the higher screws on the side, this altered the amount of slap sound it produced.
The sound is crap on this clip but gives you the idea

youtu.be/
and here's a really good one to give you an idea of the different sounds from different parts of the Tapa, although his Meinl utilises screws right across the top and he just 'loosens' up the corner screws to achieve the same goal.

youtu.be/
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Re: Radical new design

Post by kiwigeo » Mon Dec 08, 2014 1:21 pm

Good ol' boys!!!!! :D
Martin

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Dennis Leahy
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Re: Radical new design

Post by Dennis Leahy » Wed Dec 10, 2014 3:29 am

Thanks for the follow-up answers to my questions, Nick.

Interesting that I watched a dozen cajon videos, a few cajon-building videos, found some on-line plans, (thought I had) carefully visually examined the commercial ones - and never noticed the upper corners of the tapas being deliberately left loose. (I don't think all the builders do this - some of the videos show players getting the "straight" snare sound from the upper corners, not just the upper middle.) Once it is pointed out, it's easy to hear the sound, an extra timbre from the instrument. Now I have to decide if I like that extra sound and want to incorporate it. Do you feel like you can easily get a "tight snare" sound or is there always a hint of a 'buzz' from the loose corners?

As an aside, there was a Paco de Lucia concert (it may have been posted here) that is such a joy to hear, and has other virtuoso players playing along with Paco - including the cajon player (might be Piranha Israel Suarez Escobar.) Here's the link, in case you missed it, or as a second dose if you didn't miss it the first time: http://www.youtube.com/watch?v=nux5LzzxT3o

Dennis
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