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Top Voicing
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Author:  absrec [ Fri Sep 27, 2013 7:32 pm ]
Post subject:  Top Voicing
Sorry if this has been discussed already. I found many posts referring to voicing the top but not a whole lot about how it's actually done. I found a YouTube video where a guy goes between shaving down the braces and then holding it up and tapping it to check his progress. That was helpful but I imagine there's more to it.

I've only built electrics so far so this is new for me. Anyone have advice on getting started? Any reference material you can recommend?

Thanks.
Author:  John Lewis [ Fri Sep 27, 2013 8:06 pm ]
Post subject:  Re: Top Voicing
Honestly, the best resource that I have come across are the two John Mayes DVD sets - Voicing 101 and Advanced Voicing. Buy 'em, watch them (and chuckle) a bunch of times and start carving braces. Enjoy!
Author:  meddlingfool [ Fri Sep 27, 2013 8:18 pm ]
Post subject:  Re: Top Voicing
The best resource is the Gore/Gilet books. Expensive but worth far more than the money....
Even if you just get book one....
Author:  Tom West [ Fri Sep 27, 2013 8:25 pm ]
Post subject:  Re: Top Voicing
Aaron: There are a number of reference data available to help. Kent Everett has put out a DVD specifically focused on voicing the top. Worth a look. Ervin Somogyi has a set of books where he discusses how he establishes a top thickness by deflection and how he voices after the braced top is attached to the sides. Trevor Gore also has a set of books on design and building in which he demonstrates measuring various modes of vibration in raw top blanks and via mathematics comes up with an ideal thickness. Both sets of books are excellent but I think Gore's is at the top of the heap and worth every penny if you are going to keep building acoustics. Aside from having some reference material or a local luthier to demonstrate it's a matter of doing and repeat until you guitars start to sound as you want them to. One has to keep certain things in mind. Stiff wood that is light in weight. Keep whatever you put on the top as light as you dare. Don't over brace. Watch getting things too stiff at the intersection of the top and sides. If your building dreads the stew mac plan is a good guide line. Do some more digging and reading in the archives. I'm sure other will offer other info. Have fun.
Tom
Author:  James Orr [ Sat Sep 28, 2013 2:07 am ]
Post subject:  Re: Top Voicing
I'll second John's recommendation of John Mayes' voicing DVD's.
Author:  Tai Fu [ Sat Sep 28, 2013 4:00 am ]
Post subject:  Re: Top Voicing
I don't know honestly, I haven't bought any reference materials because I am short on money and I hate math so even if I did buy the materials, none of it will really make sense to me.

I just keep building, and building the instrument as light as possible. I've found that the lower bout thickness is far more important than upper bout. Makes sense if you think about it, the upper bout does not vibrate much at all when the string is vibrating. That area should be built strongly because it handles most of the string pressure but the lower bout is what vibrates the most. Now I would take the top down to a set thickness such as .140 or .130 depending on the body shape, and then would overbrace them and shave the brace down as I go to get what I want. You're looking for increased sustain, bell like tone and reduced weight. If the top or the whole guitar feels heavy for its size, it's overbuilt. Honestly I do not know what tapping tells me at all because in reality what counts is when strings vibrate against the guitar. However I have noticed the good sounding guitars I have come across are light, and uses smaller bridges.

Some have said that the stiffness of spruce such as Engelmann is proportional to its density, so maybe it's better to find a tall, low density engelmann spruce brace and keep the brace tall in order to maximize stiffness to weight ratio... I heard some even use carbon fiber reinforced bracing, not sure what it does.
Author:  Fred Tellier [ Sat Sep 28, 2013 8:17 am ]
Post subject:  Re: Top Voicing
I started with the John Mayes' voicing DVD's and progressed from there, I watched a friends copy of the Kent Everett DVD and found it interesting but less useful than Mayes. The only book worth owning is Trevor Gore's but with internet searching and the Mayes videos I had plenty of details and success before reading the Gore books. The great thing with the Mayes video is you can hear what he is doing step by step so it is a great ear training.

No yet mentioned is Al Carruth's free plate voicing video about voicing using chladni patterns and a tone generator to voice a top.

Fred
Author:  Pat Foster [ Sat Sep 28, 2013 9:08 am ]
Post subject:  Re: Top Voicing
I started with the John Mayes DVDs, then Kent Everett's, then Alan Carruth's, Ervin Somogyi's, then the Gore/Gilet books. The ones I got the most from for voicing were Mayes's, Carruth's and Gore/Gilet. Somogyi's was good for the philosophical aspects.

Pat
Author:  meddlingfool [ Sat Sep 28, 2013 10:04 am ]
Post subject:  Re: Top Voicing
Tai,

.140 and .130 will almost certainly be thicker than necessary. IIRC, Martin's standard thickness is .110, and they will certainly have been erring on the side of caution, though it will still make a fine guitar. The books may seem expensive and full of hard math, but you will certainly burn through their price in materials long before you get anywhere near gaining the brains they contain. I don't do math well either, but even the chapter summaries were enough to advance my work hugely, almost overnight.
Author:  Tai Fu [ Sat Sep 28, 2013 10:11 am ]
Post subject:  Re: Top Voicing
I'm talking about a jumbo (j-200) type guitar here.. .110 is a good starting point for dreadnaughts. I mean there's always space to reduce the thickness from the outside if it's too thick.
Author:  Terence Kennedy [ Sat Sep 28, 2013 11:44 am ]
Post subject:  Re: Top Voicing
Don't forget Dana's articles. I re-read them on a regular basis. I suspect a lot of John Mayes' expertise came from him.

http://www.pantheonguitars.com/stillvoi ... eaming.htm
Author:  EddieLee [ Sat Sep 28, 2013 1:02 pm ]
Post subject:  Re: Top Voicing
I can not add much. I think all the above are a must. I found Everett's explanation of what he wants to hear when he is tapping very useful. Gore's stuff make a lot of since to me and helped me integrate the info in Alan's video.
Author:  Alan Carruth [ Sat Sep 28, 2013 5:40 pm ]
Post subject:  Re: Top Voicing
Tai Fu wrote:
"Some have said that the stiffness of spruce such as Engelmann is proportional to its density, so maybe it's better to find a tall, low density engelmann spruce brace and keep the brace tall in order to maximize stiffness to weight ratio..."

The Young's modulus (E) along the grain of softwoods in general tends to track the density pretty well. In the tops I've measured about 60% fall within 10% of the predicted E value based on density. In the range we work with (between about 300 and 500 kg/m^3) the plot is pretty well linear.

Young's modulus is a measure of the force it takes to stretch or compress something. It's related to stiffness, in that two pieces with the same E value with have the same stiffness at the same dimensions. However, the stiffness of a beam is proportional to the cube of the height, assuming the width remains the same. The way it all sorts out when you have differences in both density and E values, is that the differences in mass are less than you might think: the denser tops have higher E values and can be left a bit thinner, so they don't gain weight as fast.

Also, of course, we're working with a natural material, so there's quite a lot of scatter in the data. The upshot is that the least dense top in my stash, which is Western Red cedar at 336 kg/m^3, would probably make a heavier top that one of the Engelmann sets that is a little more dense , at 348 kg/m^3. I actually have a Sitka top with a density of 466 kg/m^3 that could end up making a lighter top that that cedar, simply because that Sitka has a killer E value. It's all about the relationship between density and E value, and how that sorts out from one piece to the next.

I think more about the density of the top itself, since that's where most of the weight is. Usually all of the bracing together amounts to about 30-35% of the total weight of the top, and it's possible to make a bridge that outweighs the bracing. If the bracing is 35% of the total, and you save 10% of the weight by choosing the lightest stock for it, that's 3.5% of the total weight of the top. If saving weight is the goal, there are better ways to do it.
Author:  absrec [ Sat Sep 28, 2013 7:44 pm ]
Post subject:  Re: Top Voicing
Thanks to everyone for the info. I'm working on a dreadnought. It's what I've seen/owned for the most part so I figure it's smart to go with a familiar sound and vibe for a first (acoustic) build. My top is around .125" - .130". Sides are bent, lined & glued up. Once I figure out how to make the rosette look like something other than crap, it's time to brace and voice.

I watched a video where Robert O'Brien said something about achieving a "sheet metal" type sound while voicing. From what I gather, the top starts out sounding like a wood block when you tap it and by the time you are done, it has more of a open resonance. He also talked about an important node that exists in the outer 3 inches of the guitar where the scalloped portion of the braces start.

Again, this is what I've been able to decipher so fat from the limited info on the net. The question in my mind is when do I stop? And I know this may seem like a strange question but what am I shaving down? Is it the tops of the braces? The scalloped ends? Am I reducing the height? The width? That's the confusing part for me. Plus... there is the X brace, the finger braces, tone bars, etc. not sure if I'm shaving down all of them or if there some that are typically just "standard" dimensions.
Author:  EddieLee [ Sat Sep 28, 2013 9:56 pm ]
Post subject:  Re: Top Voicing
The sheet metal sound Robbie talks about is for thicknessing the top. The video here shows the process. https://www.youtube.com/watch?v=JHs7s1_pbAg#t=80. Other really good videos can be found here http://www.obrienguitars.com/videos/.

In the top thicknessing video Robbie starts at 125 mil and takes some of the tops to 105 mil. Is suggest watching this and thickness your top before moving on to bracing. However the rosette must be in first.

I also Highly suggest you sign up for Robbie's online course if this is your first acoustic.

Happy Building,
Author:  meddlingfool [ Sat Sep 28, 2013 10:17 pm ]
Post subject:  Re: Top Voicing
The sheet met thing seems iffy to me. It only reflects gross grain stiffness, not long grain.
FWIW, my dreads with lutz in that range are usually between .105-.110...
Author:  DennisK [ Sat Sep 28, 2013 10:55 pm ]
Post subject:  Re: Top Voicing
absrec wrote:
The question in my mind is when do I stop? And I know this may seem like a strange question but what am I shaving down? Is it the tops of the braces? The scalloped ends? Am I reducing the height? The width?

You stop when you like the sound and feel of it :) The trick is discovering what you like.

It would be quite an educational experience if a bunch of builders got together with voiced tops and passed them around to tap and flex. I bet they'd all be different, but all good, and very valuable information for newbies, building some mental database of the stiffness range we work in.

Actually, that's a great idea for the next St. Louis gathering in May... I'll make sure I have a voiced plate to bring and pass around, and send out an email to the group to see if anyone else wants to join in. Would be a long drive from Atlanta, but we'd love to have you there [:Y:]

As for the "what am I shaving down?", the height is what really matters. Stiffness varies linearly with width, and cubically with height. Carve to triangular or parabolic profile first (better stiffness to weight ratio than rectangular), then do your tuning by removing height.

You can maintain the triangular profile while reducing height if you want (I do), but the weight savings is pretty insignificant.
Author:  absrec [ Sun Sep 29, 2013 7:21 am ]
Post subject:  Re: Top Voicing
I'm an audio engineer. It sounds like the difference between a drum head before and after it's tensioned on the shell. Or maybe more appropriate would be to compare it to a panel absorber which is a panel of a certain thickness mounted on a frame where nothing touches the inner 99% of it. It resonates at a frequency and insulation inside the box absorbs that frequency making it audible in the room. I understand the basics of the whole membrane/resonant chamber concept. For acoustical design there are calculations and guidelines. For a drum, there are tension rods. With a guitar, there is pretty much intuition. I'm not asking anyone for specifics, more just a way to think of it or some general guidelines to keep in mind as I venture into the unknown. There are a lot of things that can go wrong. When you're voicing a top, I imagine these things will manifest in a way that's different from if it were coupled to a resonant chamber. Once the thing is together and you can finally hear what it sounds like, there is not a whole lot you can do about it if it happens to be a sound you don't want.
Author:  Ken Jones [ Sun Sep 29, 2013 9:00 am ]
Post subject: 
Quote:
Finally - stick close to an established plan which is not grossly over-built if you do not have at least a part time mentor or the ability to directly translate written methodology into actionable decisions. Avoid plans which are problematic (e.g., anything Antes, the OLF SJ, and MJ), and stick to those with detailed materials info and bracing plan/profile (e.g., the Collins J-45, the McRostie 000 and herringbone dread, and the GAL Size 1) - Martin and Gibson were responsible for the guitars which set the standard for what most players want in an instrument, and sticking close to their practice will result in nothing worse than an above average instrument until you start gaining the ability to move beyond the 'cookbook' approach.


Great advice, Todd. I'm curious what you feel is problematic about the OLF SJ plans.



Ken Jones
Mountain Song Guitars
Author:  Tom West [ Sun Sep 29, 2013 9:45 am ]
Post subject:  Re: Top Voicing
Todd Stock wrote:

Finally - stick close to an established plan which is not grossly over-built if you do not have at least a part time mentor or the ability to directly translate written methodology into actionable decisions. Avoid plans which are problematic (e.g., anything Antes, the OLF SJ, and MJ), and stick to those with detailed materials info and bracing plan/profile (e.g., the Collins J-45, the McRostie 000 and herringbone dread, and the GAL Size 1) - Martin and Gibson were responsible for the guitars which set the standard for what most players want in an instrument, and sticking close to their practice will result in nothing worse than an above average instrument until you start gaining the ability to move beyond the 'cookbook' approach.

For anyone doing their first few guitars I think this is the absolute best and easiest route to take. There is a vast amount of info available and if one gets too deep into the weeds of it all at once things can go astray especially if it is all mixed together.
Tom
Author:  DannyV [ Sun Sep 29, 2013 11:07 am ]
Post subject:  Re: Top Voicing
I'm curious how many builders take playing style into account when when building a top. Do you think that a lightly built, extremely responsive top can be over driven by a player with a heavy attack? All the guitars that I have felt I have over built I felt still sounded good when played a little more aggressively. I suppose starting out with good materials is a factor. What about string gauge? Do you factor that in when top voicing? Maybe I should just buy the book(s).
Author:  Tai Fu [ Sun Sep 29, 2013 11:49 am ]
Post subject:  Re: Top Voicing
Yes, I don't think every players will play Joe Satriani light on their guitar, if the player is like that by all means go with 9-42 electric (nickel steel) strings and build the guitar VERY lightly. However if the player has a heavy hand then it makes better sense to build it heavier. Many acoustic players in fact (the strumming kind that is) tends to slam on the guitar, not to mention use the guitar like a drum, in that case a heavier build may be favored.
Author:  James Orr [ Sun Sep 29, 2013 1:31 pm ]
Post subject:  Re: Top Voicing
DannyV wrote:
I'm curious how many builders take playing style into account when when building a top. Do you think that a lightly built, extremely responsive top can be over driven by a player with a heavy attack?


Yes, definitely. John Mayes' "Advanced Voicing" is specifically geared towards this.

The lighter the touch, the less energy there is driving it, and visa versa. An ideal instrument for fingerstyle could sound incredibly muddy strummed.


Sent from my iPhone using Tapatalk - now Free
Author:  James Orr [ Sun Sep 29, 2013 1:46 pm ]
Post subject:  Re: Top Voicing
Todd Stock wrote:
I'd be interested to know where other builders experienced the jump from rote compliance to intuited changes, but with my limited sample set, it looks to be in that window of the first 10 projects.


After some reflection, I don't know that I ever followed a plan. I ordered a seconded top from Martin for the layout, spoke with a number of luthiers I admire, and followed John's DVD as far as the tap tone went. The first one sounded pretty good, but not quite what I was looking for; it has a very traditional sound, but I wanted something with more bleed and "wetness" between notes. So the second saw a few changes (.5" tall X v. .6", and tapered braces, kept the top around .105"). Got closer. Third was still a bit different. Started coming to my top thickness using the warble test in Kent Everett's DVD.

Now I'm looking for more bass. This one I'll be spraying next week has a thinner top, around .095. From here on out I'll be testing deflection, and I'd like to explore Trevor Gore's equation for deriving target thickness as well---see how similar the resulting thicknesses might be. I'll also be trying a lattice in the lower bout rather than traditional long tone bars.


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Author:  meddlingfool [ Sun Sep 29, 2013 4:30 pm ]
Post subject:  Re: Top Voicing
Just get the Gore/Gilet books. Just do it. Get them. If you want to build any guitars, you need them. You do. The intuitive approach will get you there eventually, the books will get you there tomorrow. Instead of having to go through years of experimentation. Call it cookbook if you will, but the recipe is sound. You can still add your own garnishes, but it will prevent you from putting peanut butter and ketchup in the same sandwich. If you are an audio engineer, and can do the math needed to design panels to tune a room, you're laughing at the head of the pack. It really is just like tuning a drum. You'll still need to learn the craftsmanship, and you will still need to learn the unteachable aspect of putting your art into it, but the books will get you right away to the point of understanding how to do what you want to do. They will give you the brains you need to create your own recipes.
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