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Hey all,
I'm in process of building a '37 Hauser-like instrument. Having a bunch of nice Engleman on hand, I'm wondering how much I should take into consideration the general differences in stiffness between the materials used in the original and the Engleman.

How much thicker (if any) should the top and braces be left as I move forward?

Thanks for any advice you can lend,

Dave Livermore

Unfortunately it really depends on the individual top piece. The 37 Hauser top is let's say an average thickness of 2.8mm. If we consider the important lower bout area to be about 800cm2, and consider that excellent quality and stiffness Euro spruce can range from say 370 to 430 Kg/m3, we get a weight from 82.8 to 96.3 grams. The difference is 13.5 grams which is quite a lot. Since we can't tell what density Hauser's spruce was without destroying the guitar, it really depends on your building experience to tell what works and what not. Hopefully someone experienced in building successful Hauser copies will chime in and say more. I have a gut feeling Hauser might have been selecting very light tops, so a fine piece of Engelmann or Italian spruce should work very well. Using the heavier type of spruce feels very much like cutting against the grain of an apparently inefficient design (low doming, very thick top, very light braces)

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Build log

exactly what I was thinking.
We have no idea what density or stiffness that guitar top had.
This being my first classical of a Hauser design, I'm at a loss as what to expect from the top I'm using and the idea of using a thicker top and lighter braces doesn't exactly jive with the way I build steel strings.
I did build a torres like instrument a few years ago and it turned out pretty good. 2mm top with 4-6mm fans.
This is just a little different and before I put the hide glue in the heating pot, I thought I'd gather some info.

Dave

Yes Hauser's design is a different animal, even if a quick look at the plans makes them look almost identical. My Torres style tops are thinner too, a bit over 2 in the center and less than 2 towards the edges, with the braces at 7x3mm, and a heavy app. 15' arch. I don't try to compensate the density and stiffness differences from top thickness alone, as there is room with the fan brace material too. It varies too in weight and stiffness, and the profile can range from a heavier half circle to a sharp and light triangle. So when I choose material and "voice" I try to make some guesses... Of course these are still mostly arrows in the dark after only completing 5 guitars, but in the near future I hope to learn some more patterns.

The Hauser being so different, if someone would ask me to build one I would try to pick a very low weight Euro top, perfectly quartersawn, since the bracing is not that helpful across the grain, being so tiny. Thin it to an even 2.9mm or whatever is a little over the plan average and then when it is done, just before gluing the bridge, measure the top resonance, and if needed thin it a bit all over or according to the patterns from the plan, until it falls somewhere between A and A#. After the bridge, it should fall down about a tone, depending on bridge weight and stiffnes. Here it also depends on what you want to achieve, more warmth/bass, or more clarity, etc. I feel it is rather dangerous to force the resonance much down with a new guitar by over-thinning, would be better if it goes lower as it ages and its played in.

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Build log

Alexandru has given you great advise!

Follow it and you'll be fine.

Mike

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Mike Collins

good stuff.

Thanks

I was going to suggest or ask about deflection data, but the resonance is at least something to go on.


Much appreciated.

Dave

I've read in an American Lutherie that Brune told Hill that Hauser's soundboards are dense euro and over 3mm. The only Hauser I've held has a top that looks very, very dense.

I wonder how Brune reached this conclusion without ripping a piece from the soundboard and measuring the density? I strongly believe "looks" is a poor criteria in guessing spruce qualities, but I also don't have a vast experience.
But again, here are 2 pics with the famous "Augustine" Hauser played by Julian Bream, and the (not yet famous) guitar I am currently building. The spruce looks quite similar I think, I mean really similar , but my piece weights from 360Kg/m3 for the outer part and 390Kg in the sapwood. I also have extremely similar pieces weighting from 400 to 435 Kg/m3, and also pieces with obvious tighter hard-to-count grain that again weight 420 Kg. All this is cut in Austria.

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Build log

Well, the top I mentioned has wider latewood than most spruce I've seen. Of course density can't be measured by eyes but that top doesn't seem to be a piece of lightest european spruce. It's no doubt a stiff guitar. Perhaps Hausers have stiffer and looser models and most Hausers in the US are the stiffer?

I recommend that anyone who wants to build a Hauser style guitar make the top 3mm thick regardless of it being spruce or cedar. Many of the Hauser I, II and III guitars that I have played, owned and examined have tops at 3mm. I wouldn't go thinner than 2.8mm. To approach the Hauser sound you need to replicate the many other definitive construction details. The top is only one of many key features. Don't be afraid to use the thick top. You will be surprised at the beautiful sonority and volume it will provide.

If you are new to building classical guitars don't worry about resonances and voicing. Focus on good joints and control of your wood. You can make outstanding guitars no matter where the resonances are. So don't get hung up on that stuff. I've meet many world-reknown builders and they don't do any voicing or resonance testing. There is no secret resonance. I'm not saying that resonance testing isn't important. It is good to know about that stuff. Think of it as another tool.

In my fan braced guitars I don't do any resonance testing. I only do that with my lattice guitars. On my lattice guitars I sometimes string them up with the back off and voice them. You would be surprised how loud a guitar is without the back! The tone isn't that much different. I also thin the top to adjust the feel or playability of the instrument. If it feels too stiff I thin the top near the edges and the feel becomes softer. It usually takes the removal of at least 0.004"/0.1mm before you hear and or feel any slight difference. When voicing a guitar you can only bring out the sound to the best that the instruments has. You can't polish a terd. Don't think of voicing as a way to make an ok guitar a world class instrument. It doesn't work that way. Each top has an optimal thickness or sweet spot. Experience is the only way you will find it.

Lots of good advice so far.

I, too, wonder how you can tell 'dense' spruce just by looking at it. I measure that stuff, and there doesn't seem to be any correlation I can see between appearance and density.

There is, however, a strong correlation between density and stiffness along the grain. If you assume that long-grain stiffness is the most important factor in keeping your guitar from folding up, then measuring the density is a good way to find it to a reasonable approximation.

Engelmann averages somewhat less dense than Euro, from the samples I've measured, but it's not a huge difference. If you consider the spread of the data, it really is true that you need to look at the piece rather than the species.

If I were making a Hauser copy, I think I'd pull out one of the less dense tops and leave it at 3.0mm, but that's only my opinion.

Thanks all for the response and the advice.

The top is right now around 3.2 at the center and 2.5 around the edges. It isn't braced yet, that's just where it came out after the first and only pass through the thickness sander. (I was trying to be efficient and was thinning down the back and sides at the same time, flipping and rotating and swaping out before changing the thickness on the sander. When they were just under the thickness of the top, I threw that on the sled. what I didn't realize was that the hardwood sands much differently than softwood. Lesson learned, and I won't do that again.)

I'll keep the bracing the same and see what happens.

No matter what, this is going to be one fine LOOKING instrument.

d

Loudness is relatively easier to measured than tone quality. That Hauser III I've held is not loud at all ,and the trebles are clean and focused but not considered full of rich harmonics. It is a lovely sounding guitar, tho. I don't think Hausers were always looking for maximum efficientcy of a guitar, at least not this one. So it's probably okay for a Hauser copier to use a top that is not light.