Don Noon

Don Noon's bench

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Moving on...

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The beginnings of my microviola, which will be just a bit over 15".  A few reasons for such a small viola:

- I can use my processed violin wood

- An experiment to see how much low-end power I can get out of it

- There might be a niche market for these

- A precursor to making a 5-string violin/viola, to see what body size I want to go for... and maybe it will be the same mold.

 

As this is a da Salo inspired instrument, and I might only be making one, I'm not getting all precisely tooled up to make anything accurate.  And I'm going to have to try antiquing it, for which I'm getting a $44 white violin for antiquing practice.

 

In case anyone's curious about the "upper ctr." and "lower ctr." holes on the mold, those are the centerpoints of the endblock outer radius.  I put a pin thru those holes into a fixture attached to my spindle sander, and pivot about the pin to quickly and accurately trim the blocks.

 

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I'd guess there are more 5 string "fiddle" players around than 5 string "viola" players. I see no reason not to build a fiddle sized instrument. But the sound had better be what these accomplished players are used to hearing.... I vote for a traditional fiddle with an extra string!

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I wonder if there might be an interesting in-between size, where you're not sure if it's a large violin or small viola.  I'll probably put some violin strings on my 15" viola when I'm done with it, just to see what it sounds like.

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Fiddle #16 is now a little over 2 weeks old after first post-varnish stringup, so I looked at what happened to the impact response over that time:

post-25192-0-15834500-1399591138_thumb.jpg

-The bridge hill has formed more of a hill shape, instead of the sloping plateau.  I have seen this often before, but have no idea why this occurs.

-Most of the peaky resonances are lower, especially everything below 1 kHz.  A0 and the B modes too.  That's actually a good thing, as it was a bit bottom-heavy.

-It doesn't show on the impact graph, but the CBR resonance went from 386 to 398 Hz.  It actually is a fairly strong sound producer under bowing, but not impact... I also have no idea why this is.

-The bowed scales (not easily interpreted, so I'm not showing them) confirm the changes.

 

I would say that half of the change is due to bridge and soundpost adjustments, and the rest just due to settling-in.  Of course, I don't really remember what it played like two weeks ago, but I'll say it's better now.

 

 

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-The bridge hill has formed more of a hill shape, instead of the sloping plateau.  I have seen this often before, but have no idea why this occurs.

 Sure looks like the spectra of a master violin to me! Tell me again how you did that.....

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-\Sure looks like the spectra of a master violin to me! Tell me again how you did that.....

 

It's hasn't quite reached what I'd like... there's just a bit too much strength in the 900 Hz region and not enough toward the high end, with some dropouts in the bridge hill.  The changes over time appear to be going in the direction I want, and perhaps after a few years it will be even better, I hope.

 

I don't need to tell you again how I did it (presumably you are asking about how the violin was made, not how the spectrum was taken,)   If you start back at post #61 (page 4) of this thread, you can read about it.

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post-25192-0-27763100-1401327964_thumb.jpg

 

After the $44 violin diversion, and then messing around with bridges and soundposts for a few days (above is my latest attempt at carving a bridge), I'm finally getting back to making chips on the viola.  I might get slowed down by 5 tons of concrete blocks arriving Friday for my garden wall project. 

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Fiddle #16 is now a little over 2 weeks old after first post-varnish stringup, so I looked at what happened to the impact response over that time:

attachicon.gif2 week comparison.jpg

-The bridge hill has formed more of a hill shape, instead of the sloping plateau.  I have seen this often before, but have no idea why this occurs.

-Most of the peaky resonances are lower, especially everything below 1 kHz.  A0 and the B modes too.  That's actually a good thing, as it was a bit bottom-heavy.

-It doesn't show on the impact graph, but the CBR resonance went from 386 to 398 Hz.  It actually is a fairly strong sound producer under bowing, but not impact... I also have no idea why this is.

-The bowed scales (not easily interpreted, so I'm not showing them) confirm the changes.

 

I would say that half of the change is due to bridge and soundpost adjustments, and the rest just due to settling-in.  Of course, I don't really remember what it played like two weeks ago, but I'll say it's better now.

Are you sure that the moistire content of the wood is the same in the two cases, Don? Different MC would affect the resonances quite much alone. 

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attachicon.gifbridge.jpg

 

After the $44 violin diversion, and then messing around with bridges and soundposts for a few days (above is my latest attempt at carving a bridge), I'm finally getting back to making chips on the viola.  I might get slowed down by 5 tons of concrete blocks arriving Friday for my garden wall project. 

Looks pretty nice! Are you using any kind of oil or shellack or something to tan the bridge? - Or is it just exposed to UV light?

 

Looks like your tools are pretty sharp. :-)

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Anders,

 

Moisture content is usually not much of a concern with the (relatively) uniform weather here.  However, this last month has been a doozie, swinging back and forth a few times from 60% to 6% RH and daytime highs from 68F to 100F.  I don't know how the wood moisture content followed those swings, but I continued to monitor spectra on a frequent basis.  There were some variations, but not of an obvious cyclical nature.  The bridge hill shape never flattened out to the original plateau.

 

The bridge shown is thermally processed, lightly, and then I rubbed on some tung oil, also very lightly.

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Anders,

 

Moisture content is usually not much of a concern with the (relatively) uniform weather here.  However, this last month has been a doozie, swinging back and forth a few times from 60% to 6% RH and daytime highs from 68F to 100F.  I don't know how the wood moisture content followed those swings, but I continued to monitor spectra on a frequent basis.  There were some variations, but not of an obvious cyclical nature.  The bridge hill shape never flattened out to the original plateau.

 

The bridge shown is thermally processed, lightly, and then I rubbed on some tung oil, also very lightly.

Thanks Don. That is an enormous swing in RH! @ 60 % RH the Equilibrium Moisture Content is 11 % ish and @ 6 % RH the EMC should be around 3 %. I do have some data from an experiment with one violin body. A change like that (8 % lower EMC) should give a variation in the resonance frequencies of about: 20 Hz for the B1 modes and even more for the C4 mode. The damping will also change, less damping at lower EMC. But this is at equilibrium. Did you happen to weigh the fiddle the same day you made the impact spectra? I would suppose about 10 g lower weight for a 8 % change in MC.

 

The source for my data can be found in a simple article at the site knutacoustics.com: Humidity and acoustic experiments with violins

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Ok, yesterday was thunderstorms and my fiddle sounded terrible. As a player what I perceived was a high degree of damping, ie very little ring. It just goes thud. That is not a surprise, but for us easterners, where over 60% RH is common, do any of these techniques minimize the problem? I am running out of dessicants.

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Anders,

No, I didn't weigh the fiddle during the wild temperature and humidity swings.  It might have been interesting.  However, I know that spruce billets take several weeks to stabilize, so I would expect the thicker parts of a violin (neck, scroll, fingerboard, blocks) wouldn't change too rapidly.  Our weather swings lasted less than a week.

 

Roger,

The only way I know of to minimize the effect of weather on the violin is to use processed wood, where the EMC is significantly lower.  I suppose there might be a way to treat wood with some hydrophobic microcoating... or make an instrument out of metal.

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The Kreutzer isn't off my chart... it's just waaaay at the bottom left, with a very light weight and a taptone far lower than anything else I've made or come across.

 

The only two recordings I could find on the internet were in suspiciously lively (extremely so) rooms.  Joshua bell only played on the G string, and described it as "rich, warm".   I would be interested to hear what this fiddle sounds like in a more neutral environment, or better yet in comparison with other known soloist Strads.   From the clues mentioned (and the taptone), I'd think the Kreutzer was very bottom-heavy, and might not have much high-end power.

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I see that the Kreutzer violin has resurfaced and is going on auction. Maybe now someone can figure out why it is off your chart of weight/M5 response.

 

The Kreutzer going on auction is dated 1731.

The weight/M5 data you refer to may relate to a different violin; i.e., that played by Vengerov (dated 1727).

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Thanks John.  Yes, that appears to be the case.

 

Whose bright idea was it to have the same name for two different fiddles?  One of them should be Kreutzer Jr. or something.

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I really need to get moving on my viola for the VSA.  I had intended to practice antiquing on my $44 Chinese fiddle, but I probably won't have time for that.

I shouldn't post photos until after the competition, but I can post other stuff.

 

I did get the back of my viola complete.  Dimensions are 384mm length, 229 lower bout.  

 

Back

~4.8mm center thickness, down to ~2.5 in the bouts.

105.8 grams

105 Hz mode 1

130 Hz mode 2

323 Hz mode 5

Maple is .50 g/cc density, I believe it's red maple, unprocessed but probably ~30 years old, from Bill Fulton.

 

No, I have no idea what I'm doing, other than trying to make a small, extremely light viola with a powerful low end... and hopefully good elsewhere, too.

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To give my wrists a break from scraping the top of my viola, I thought I'd start laying out the scroll.  That's when I discovered that the oversized violin block was nowhere big enough for the da Salo scroll.  Scrounging through my pile of stuff, I found a short block big enough for the scroll, and figured I'd do a graft. rather than just glue on a hunk to make the neck block bigger.  

 

As I have never done a graft before, and didn't want to take on such a potentially time-consuming fit-up, I resorted to machinery.

 

First I laid out the graft cuts, and sliced up some tapered clamping blocks cut the the same angle as the graft.  That way, I could hold the blocks in my milling vise, cut one side of the taper, then flip the blocks around to cut the other side in perfect symmetry.  

post-25192-0-45322000-1406171588_thumb.jpg

 

The end part, where it stops between the G and D strings (viola, remember), I had to trim out by hand and chalk-fitting... but at least the large surfaces were done and accurate.

post-25192-0-46729200-1406171590_thumb.jpg

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To give my wrists a break from scraping the top of my viola, I thought I'd start laying out the scroll.  That's when I discovered that the oversized violin block was nowhere big enough for the da Salo scroll.  Scrounging through my pile of stuff, I found a short block big enough for the scroll, and figured I'd do a graft. rather than just glue on a hunk to make the neck block bigger.  

 

As I have never done a graft before, and didn't want to take on such a potentially time-consuming fit-up, I resorted to machinery.

 

First I laid out the graft cuts, and sliced up some tapered clamping blocks cut the the same angle as the graft.  That way, I could hold the blocks in my milling vise, cut one side of the taper, then flip the blocks around to cut the other side in perfect symmetry.

 

attachicon.gif140723 1.JPG

 

The end part, where it stops between the G and D strings (viola, remember), I had to trim out by hand and chalk-fitting... but at least the large surfaces were done and accurate.

attachicon.gif140723 2.JPG

Don, I don't know if you seen it or not but there was an article in Strad magazine, I believe, about this. Whoever did the article made a couple jigs for routing this out of both pieces. He just glued paper to the peg box part and glued the jig to it. It looked pretty nice. I like to make and use jigs if I can.

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Berl,

No, I didn't see (or forgot I saw) the Strad article.  I am very much a fixture-oriented maker, but only when it makes sense.  In this case, it's a 1-time job, and having a milling machine is a much different condition than only having a router.  I got the job done way faster than it would have taken to make a fixture. (you could consider the tapered clamping blocks to be a fixture, which just took a couple of minutes to make)

 

 

Back to the plate:

The top plate is DONE.  It came out even lighter than I had initially estimated, as is usually the case for me.

Reminder: this is a 15" viola top of .31 density Engelmann:

63.9g (no bass bar)

M2 119 Hz

M5 280 Hz

Graduations are approximately 3 in the center, down to 2.6 in the bouts (this is ~20% thicker than the da Salo small viola graduations).

 

Interestingly, this viola top is 6 grams LIGHTER than my regraduated $44 Chinese white fiddle project, and during the thinning process, when the tops were equal weight, the taptones were also nearly identical.  That says something about the difference in stiffness/mass of the wood.

 

edit:  with bass bar, 68.6 g, M5 317 Hz

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 I like to make and use jigs if I can.

 

Yeah, me too.  More than once I have made handy little jig for something, only to discover that I had already made one before, and it was sitting on the shelf.  That just happened again last week, for a jig to trim off the ends of the fingerboard.  My new one is better, though.  I don't know if is jigaholism, or senility.  Or both.

 

 

The neck is now attached on my VSA viola.

 

Normally at this state I would string it up and play it for a week or two to decide if anything needs a tweak before varnishing, but I don't have the time to mess around with that.  Only about a month to go before the competition, and I need to do a full 400-year's worth of antiquing to this thing.  And I'd like at least a couple of weeks strung up for the usual early-life roughness to smooth out.  And besides... it's a viola, so I really don't have a clear idea of what the goal is, anyway.

 

I did, however, play some music through the body (with a voice coil driver) while I was working on the neck, per my usual habit.  It sounds more comfortable playing viola music than violin, which I suppose is a reasonable thing.

 

I also looked at the signature modes with the neck on... nothing unexpected, about a semitone or two below violin frequencies.  The only "goals" there were to have the A0 around C to give the open C some power on the first harmonic, and keep the B1+ above A to avoid excess power on the open A string.  These are "goals" in the experimental sense, to see how it works out, rather than a predetermination of what is factually desirable.

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Everything seems to be going according to plan for VSA,

 

Violin:  fitted the boxwood pegs (shafts treated with Clairol, as suggested by Jeffrey Holmes... worked well), and boxwood tailpiece.  The fingerboard projection had dropped about a mm, so I trimmed off the top of the bridge, as well as added scoop to the fingerboard (it was basically straight when I installed it).  With the new strings and lighter/lower bridge, I think there has been a beneficial balance shift to the high end.  My family complains that it's too loud, so that's a good thing.

 

It is an extreme lightweight:  364.4g without chinrest; 6g lighter than the Jackson Strad.  It wasn't really an attempt to go light, but the wood was so light and stiff it just came out that way.

 

The impact spectrum has evolved over time and with the changes.  The B1+ frequency is up to 550 Hz, and the "bridge hill" is more rounded hill-shaped, whereas before it was more of a plateau (this is something I have seen on almost all my violins in the first few months of life; I don't know why).  There is also something going on with the B1- frequency, where it looks like it is unevenly split by something.  I don't know what that is either; I'll look into it eventually.

post-25192-0-47255400-1409186452_thumb.jpg

 

15" Viola:  Almost done, except for fitting the pegs.  It's a viola, so there's not much I can say about it, other than it's interesting to play.  I notice that spectrally it's a non-violin... the resonance profile is shifted lower so that it has peaks where a violin has dips, and vice versa.  

 

I only have one viola to compare it with (my first one, 16"), and even that one I don't have any more.  The impact spectra show the A0 frequencies are almost identical, although the B modes are higher on the smaller instrument, as you would expect.  Interestingly, the amplitude of the smaller one is much higher, 3-6 dB over most of the lower range.  In bowed response and recording, that difference doesn't show up, perhaps due to the longer scale and higher tension of the strings on the bigger instrument.  The intent with this 15" viola was to see if I could get power and a big sound out of a small body, and at least there might be some signs that it's working that way.  The real test will be to see how it stacks up against other violas at VSA.

 

Here's a fiddler attempting to play a classical violin piece on a viola: Viola 17.mp3

 

I'll post photos after VSA.  It's a good contrast:  straight, new violin vs. heavily antiqued viola.

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