Don Noon

Don Noon's bench

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At this moment, my unheated shop (garage) reads 53%RH and 69F.  It's a few degrees cooler than summer.

 

The EMC of the processed wood is definitely much lower than unprocessed, so I would expect less varaibility due to atmospheric gyrations.

 

That's a killer back. Top is not too shabby either.

 

The next one will be better.

 

as usual

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Back and ribs glued on, now for my favorite part... carving the top.

 

You can see my extra-wide, contoured block, and the bass side struts for side-mount chinrest support.  They're just pieces of lining material, mitered into the normal linings.  The ribs are extra-dark on the inside, partly due to a light coat of casein/ammonia.  That's mostly to make the inside a little darker and more even, and it doesn't do any acoustical harm.

 

  post-25192-0-70179900-1392271217_thumb.jpg

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Don,

 

Would you care to test the "coupling frequencies" of back/rib structure. There should be two frequencies.

Hold it with your tumb inside at lower block and knock in the middle. Then hold it at upper block and do the same.

 

Peter

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Would you care to test the "coupling frequencies" of back/rib structure. There should be two frequencies.

 

300 and 351 Hz.  I see both peaks no matter how I support it.

 

Recall Bissinger's A1 cavity mode, Don. If you think it is important, then do contoured blocks such as yours reduce the strength of such a standing wave? Does it matter?

 

 

I don't think of A1 as a "standing wave" so much as a Helmholtz-ish cavity mode, with the two bouts acting as cavities.  The A1 is around 470Hz normally, which is an air wavelength bigger than the body.  So small features like the shape of the block won't have any effect.  I am more concerned about higher bending waves of the plates.

 

But, even if the blocks DID have an effect on A1, it wouldn't matter, because A1 almost never does anything anyway.

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I suspected this top wood (.36 density, C-5900+m/s) would show high taptones and low weight, and it looks like I was right.

 

Presently down to 3 - 3.5mm thickness, 65.7g. M5=374Hz.  That's WITHOUT the bass bar.  At this weight, it's the highest taptone I've ever measured.  Hopefully that means it's a good match for the back :)

 

For unbarred plates, I have never made anything above M5=340Hz, and the highest of the Cremonese in Curtin's article are just over 330Hz.  So, my approach will be to keep thinning until M5 gets under 340Hz, although I don't want to get much below 55 grams, either. 

 

This is shaping up to be another experiment in extremes; hopefully extremely good.  For sure it will be light.

 

 

edit:  after some more carving and planing, the top is 58.4g, M5=344Hz.  The weight is about where I stopped on my previous 2 fiddles, but the taptone is much higher.  Also, a static bending test showed it is indeed stiffer in an absolute sense.  It should lose another few grams and Hz with some smoothing with the scraper and edgework, which I think will be where I want it.

 

another note:  this wood density is the same as reported for the Titian, and my thicknesses are very close to what's shown on the Titian poster.

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another note:  this wood density is the same as reported for the Titian, and my thicknesses are very close to what's shown on the Titian poster.

 

Hi Don, do you happen to know the weight of the Titian top?

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It is measured to be 61.7 gm without the bassbar.

 

See here.

 

By "measured", that means CT measurements of density multiplied by CT measurements of volume.  I couldn't tell quite how much error there might be in this way of coming up with weight, but I would bet that the actual weight is several grams lighter. I base that on several things:

-My plate, slightly larger and approximately the same average graduations than the Titian, is well below that value (even adjusting for the fact that my wood is 2% less dense and has no varnish yet).

-I just chatted with George Stoppani, who has made 3 Titian copies, and all of his tops were lighter than that WITH the bassbar.

 

I suppose it is possible that some of the weight is around the edges and corners, which don't show on the Strad poster graduation maps...  but currently my plate is 8.2g lighter than the "measured" Titian plate, and I can not imagine where I could put that weight without a major change in thickness, density, or size.  Yeah, I know I said I didn't want to go below 55 grams, but I almost always get carried away.  Oh, and I still have a little bit of edgework to do.

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Ha! Maybe some people noticed that I changed that verb from calculated to measured. In any case, we understand what was involved with determining this number.

 

I do agree that the weight does seem to run on the high edge for what I normally get.

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I'm calling the top plate done (without the bass bar)

 

53.1 grams, M5=320Hz

 

Definitely on the low edge of what I have been doing lately, but not worrisome.  I will put in a slightly stronger bass bar.

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That was the going-in idea, and picking out what I thought was going to work best acoustically.  However, it remains to be seen how this one actually sounds.

 

If it has problems, I'll go with #15, which I think sounds very good.  There's still no real hope for a workmanship medal, so sound is the only thing I'll use to decide.

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It is measured to be 61.7 gm without the bassbar.

 

See here.

 

Thanks Michael. I wonder if anyone has verified these CT calculated weights and densities. It would seem easy enough to do with a new violin with known weights and densities. I also wonder about how much all of this changes over time. Don's wood treatments have shown that wood has a potential to reduce in density.

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Top with bass bar:  57.2g, M5=359Hz  Still some edgework not done, but close enough.  If nothing else, this should have really quick response. 

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Body assembled.

 

The body-only modes look normal-ish, 480/600 for B1-/B1+ for the bare body, and 437/559 with a chinrest (and a spool clamp on the top block for simulated neck mass).   Body-only mass is 203g, which is abnormally light, even for me.

 

Per my normal routine of playing James Ehnes through the body via a voice coil driver, it sounds OK, similar to #15 (which I'm antiquing currently), and nowhere near as colored and muddy as a cheap old German fiddle I have hanging around as a low quality reference. 

 

So, no obvious problems that I can find, so it's on to the scroll carving. 

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Looking around for things to do to avoid carving the scroll for #16, I found a few.

 

Regraduation of #10, my 2012 VSA fiddle.  The recent discussion about high-density backs got me thinking about this, as the back was of moderately high density (.62) and on the heavy side.  The G and D strings seemed relatively low on power to me, so I took it apart and scraped a few grams out of the back.  Signature mode frequencies dropped slightly, A0 and B1- strengthened slightly, and everything else stayed about the same.  So it seems a little nicer to me.

 

Violin #15 needed a final setup and fittings, and I got tired of looking at the uniform-looking varnish.  So I practiced my antiquing techniques.  My varnish probably isn't the most antiquable (I'll coin that word), as it is very hard and tough.  It doesn't come off gracefully, if at all.  But I messed around with it for a while as best I could.  Not meant to fool any experts (and it won't), but I find it more interesting to look at, and probably more easily sold at the mid-levels, so I've been told.  You can compare it to the original look in post #47.

 

By the way, the completed weight, without chinrest, came out at 366g, my lightest so far, even with ebony pegs and tailpiece.  I wasn't trying for super-lightness; it just came out that way mostly due to a low-density neck billet.

 

post-25192-0-43363300-1394321418_thumb.jpgpost-25192-0-38725600-1394321416_thumb.jpgpost-25192-0-08135000-1394321420_thumb.jpgpost-25192-0-08857600-1394321423_thumb.jpg

 

Yeah, I gotta mow the lawn.  But it was too hot today for that.

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Looking around for things to do to avoid carving the scroll for #16, I found a few.

 

Regraduation of #10, my 2012 VSA fiddle.  The recent discussion about high-density backs got me thinking about this, as the back was of moderately high density (.62) and on the heavy side.  The G and D strings seemed relatively low on power to me, so I took it apart and scraped a few grams out of the back.  Signature mode frequencies dropped slightly, A0 and B1- strengthened slightly, and everything else stayed about the same.  So it seems a little nicer to me.

 

Violin #15 needed a final setup and fittings, and I got tired of looking at the uniform-looking varnish.  So I practiced my antiquing techniques.  My varnish probably isn't the most antiquable (I'll coin that word), as it is very hard and tough.  It doesn't come off gracefully, if at all.  But I messed around with it for a while as best I could.  Not meant to fool any experts (and it won't), but I find it more interesting to look at, and probably more easily sold at the mid-levels, so I've been told.  You can compare it to the original look in post #47.

 

By the way, the completed weight, without chinrest, came out at 366g, my lightest so far, even with ebony pegs and tailpiece.  I wasn't trying for super-lightness; it just came out that way mostly due to a low-density neck billet.

 

attachicon.gif140308 front.JPGattachicon.gif140308 back.JPGattachicon.gif140308 scroll.JPGattachicon.gif140308 side-back.JPG

 

Yeah, I gotta mow the lawn.  But it was too hot today for that.

Looks beautiful.

 

The green background looks wonderful too.

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Suspend with rubber bands or string, tap with an eraser.  Should get the modes.  If you want to see modes closer to what the finished fiddle will be, put on a chinrest, and a spool clamp or two at the neck block.

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I finally ran out of diversions, and got back to working on #16. 

I won't bother posting in-the-white photos, mostly 'cuz it looks dull like every other unvarnished fiddle.  And I'm mostly interested in how it sounds, anyway.

 

It has the usual fuzzy, somewhat wild character that I usually find in my unvarnished fiddles, especially when I first string them up.  The impact spectrum looks like this:

post-25192-0-09346100-1396586448_thumb.jpg

 

I highlighted two areas:  on the low end, between 300 and 400 Hz, the dropout is ~3db less severe than usual, giving more power on the fundamental of the D string.  Around 1300Hz, there is an unusual amount of stength; normally there is a weak zone here.  I have seen this effect once before, on my #8 fiddle, and then as now, I have no good explanation for this feature.  It doesn't seem to be a tonal detriment, though, and I expect things will smooth out after varnish and I get around to doing a proper setup. 

 

I also did a bowed spectrum, and the results verify what is on the impact spectrum

 

For the modal frequency fans,

A0=272

B1-=434

B1+=541

A1=459

CBR=371 or 401, there are two CBR-like modes here

 

These are all about where I like them to be, although I'm sure they'll go up a few Hz after varnish. 

I think that's pretty good considering how thin and light this fiddle is.  Without chinrest, it's 366g

 

In summary, I'm happy enough with what it sounds like now:  huge sound, decent tone, but a bit raw as unvarnished instruments usually are.  I'll have to wait until after varnishing to decide if I want to enter this one or #15 in the VSA competition.

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I have noticed that the lighter the instrument is, B1 modes tend to fall more whith chin rest, especially B1-, even if the endblock and thicknesses is ok in the lower regions. Have you tested with and without CR on this extremely light instrument?

 

My last soundbox was ~215 g (65, 95, 55)

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Yes, I noticed a similar trend.  This one (body=204g) had B modes:

450 / 557 Hz without chinrest

420 / 535 Hz with a very heavy (76g) ebony chinrest

 

measured today

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