MIMF

Hi, I'm working from the Stew Mac triple o plan, but was wondering about switching it to nylon strings. I've braced the top and back as per the plan, but that is as far as I've gone. Any problem with converting it to a nylon string? I haven't started the neck, tail or bridge blocks yet so have options. Or, should I just look at building a classical next? That way I can brace it more traditionally for classical... I'm mostly playing fingerstyle and some simple classical stuff.

I think the answer is yes, maybe, and it's not the best idea in the world. One question is have you closed the box yet? You imply you have not. If the top is still off, you definitely have the option of changing the braces out, or modifying what you have. You won't be the first guy to plane off a set of braces and start over, maybe even thin the top down a little to make it more "classical". The big difference is probably the tension load of the strings - 170 lbs vs around 85 lbs for classical, so half the tension. That means the top is considerably over-built for classical strings and so will not respond well. So yes, of course you can DO it, maybe you can make it work out fine, and if you just do it, it probably won't be very good or make you happy. But what about making it a light tension - "silk and steel" or just light gauge .010 - .048 steel strings, with a classical width neck and bridge? Kind of a cross-over. I just finished an archtop with a classical width neck and bridge spacing, and steel strings.

Thanks Brian,
So far, I've just got the top and back to thickness, rosette and sound hole done, bracing almost all done. Sides aren't bent but thinned down ready for bending. Haven't started on the neck at all so that was another reason for giving the idea some thought.
I thought about removing the braces and starting over, but reading what you are saying, and knowing in my head it's what I should do, I'm just going to continue making the 000 the way it was intended and plan a classical for next time around. I can still fingerpick on the 000 (which was my intent in the first place). I've been picking up my classical (beginner's Yamaha) guitar a lot more lately so thought it might be an option. I like your idea about trying something with the lighter tension strings. But as you say as far as making a hybrid, I'd rather be happy with the build I'm doing than try to compromise.
I've got another back and side set that will be perfect for a classical build. Just need the top. And tuners. The tuners I have are for a steel string so will go on my current build.
Thanks,
Scott

The 12-fret 000 was Martin's last design for gut strings. Properly built it works fine. The OM was originally the 14 fret version of the same thing, so it should be OK too. As has been pointed out, you would need to reduce the top thickness and the size of the bracing. Assuming the top you have is the 'right' thickness for a steel string, you'd want to take it down about 20% for nylon. The bracing would be no more than 1/4" wide, and about 20% lower than the steel string version. If you're using a tieblock bridge you won't need a bridge plate. Martin used pin bridges, so the plate would be needed, but it can be a lot thinner and smaller. Try to keep the bridge weight down to around 20 grams or less, instead of the usual 25-35 gm of steel string bridges.

Thanks Alan.
Other than making a number of strum/picking sticks and a tenor uke, this is my first full sized acoustic. Since I followed the plan, my bracing is a little wider than the 1/4" you mentioned. Although I've read lots and have the Everett voicing DVD, being my first is a bit challenging. When I see people shave a bit more off braces hear and there for optimum tone and or flex, my experience just isn't there. Tapping I am not getting any thudding or dead zones, so I think I'm on the right track there. But optimum? I know that comes with building more instruments and observing the differences. I will make sure I take measurements and photos for down the road... There is also a local classical builder nearby that I am going to see if I can go buy an hour or so of his time to get some feedback and advise.

Scott Reid wrote:...I'm just going to continue making the 000 the way it was intended and plan a classical for next time around.

You made the right decision.

I've long been of the opinion that most guitars are too big for their own good. A guitar that is 390mm across the lower bout (000 size) is way too big for a classical guitar (which is why you will rarely see one).

My standard classical is ~360mm across the lower bout, as have been the guitars from most other makers, since around 1850. However, I get better volume and projection, whilst still retaining a good sound balance, from a smaller bodied classical.

The reason for this is that the sound radiated by a monopole source (the efficiently radiating modes of vibration of a guitar top) are proportional to a/m, where a is the effective radiating area of the mode and m is its effective mass. As guitars get larger, m tends to increase faster than a, as extra material has to be added to keep the top's deflections under control. But we all tend to use the same strings (same tension) to drive the top, irrespective of the size of the guitar; its not really possible to install a larger "engine". However, the sound radiated by a guitar is also proportional to the guitar top's acceleration, and the lower mass tops of small guitars accelerate better under the meager forces available from the strings and so can produce more sound. "Small is beautiful".

When you get around to building your classical, I'd encourage you to check out some of the narrower bodied models. This one's not bad.

Thanks Trevor,
What a great comparison. Made it understandable for me.
One of my customers from work was lucky enough to get a complete "kit" for a classical guitar (LMII mold, solera, plans, etc.) that he said I could borrow so I will probably go with that one. Not sure what model (for some reason, I'm thinking the Hauser) it is but I will be happy none the less I'm sure.
I really enjoyed that performance of Marc's. I am just watching some of his other videos now. Thanks for the link.
Scott

Trevor's correct, but there's a catch: increasing the span does reduce the A/m ratio, IF you don't alter the structure. Martin's adaptation of the X-brace does seems to be a bit more efficient structurally than the fan bracing that's standard on Classicals. The last 12-fret 000 I built for nylon strings has a top that is lighter in weight that I usually get on a standard Classical that is 2cm or more narrower in the lower bout. I will note, though, that the added cross grain stiffness of the X brace may change the timbre in ways that make it less attractive for the standard Classical repertoire. That last one does work well, but has a somewhat different tone than the usual Torres style instrument, and with somewhat lower mass and more area it's plenty powerful.

Thanks Alan,
I think I might have worded my original question a bit wrong. I was thinking of switching it to nylon as opposed to steel strings. Not to specifically make it into a classical guitar. It was just am idea since I have been seeing a number of Nylon string guitars out there.
But, after reading the suggestions that you folks have given, I think I will stick to the steel string triple 0, and then plan on building a classical down the road...And since I'm not really "buying" the guitars, but making them, my wife can't give me too much heck can she?