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Help:
It's too late to back track now. I have a plan I drew up. I put the sound hole on the plan but didn't draw in the rosette. I planned the rosette on another sheet of paper, installed it and leveled it flat. I went to cut out the sound hole and didn't have room for a 4 inch hole. I cut a 3 3/8 inch hole with 1/4 inch between the rosette edge and sound hole. I braced the back with the sound hole braces closer to the sound hole.
I now have second thoughts on finishing the guitar with this top.
How bad is this?
Can a sound port in the upper bout compensate for the smaller hole?

I'd like to delete this post.

are you sure dude? i think you have a great question. i dont think you are the first guy to do something like that and certainly not the last. do you want to make a new top. time and money, right? someone who knows much more than i will have to advise you on how to fix the situation, but im pretty sure you can do just that.

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Hi Bill,
I'm not sure about the effects of sound hole size and soundports on the final sound of an instrument. Have you checked out Matt Mustapick's rosette/sonudhole design?

http://mustapickguitars.com/aurora/2/pages/2.htm

It sounds like if you go with a design like this, you could end up with a 3 7/8" soundhole. Don't know whether this would fit with your rosette design...

Just a thought I had while reading your post

Christian

A picture would help...

So it looks like you cut the sound hole too big and the rosette wouldn't fit? I normally cut out the rosette channel first, then the 2 ring on either side of the rosette then 1/8" from the inner ring would be the soundhole cutout. I am not sure about having a soundhole that is too big but perhaps you can custom make your own rosette to fit your new soundhole, using purfling strips or pieces of wood binding, and save your pre-made rosette for another project?

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No, it looks the rosette is too big and the hole doesn't fit in.

I suspect you can't enlarge the hole more because of the back braces? If the box is closed, you could cut a bit on the braces (and use HHG or CA to attach additional braces behind the original ones if you think they become too weak). If the top is not attached to the box yet, simply move the braces.

Otherwise I do not see any problem with having a smaller gap between rosette and hole edge. On classical guitars the space if often less than 1/10" and I often saw guitars that have the rosette right up the edge.

I don't agree with throwing away perfectly good wood for errors such as this, if they can be corrected reasonably.

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Build log

Making the soundhole smaller than planned will increase the bass response of the closed box (it lowers the Helmholtz frequency).
If I were you, I'd run with it as is, and see how she sounds!

Good luck!

Dave F.

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The main problem is that a 3 3/8 hole would look rather odd on a big guitar. He planed for a 4" hole so it has to be a big guitar.

I use 3 3/8 for my Torres style classical which is exactly the Martin 0 size (save for the upper bout which is wider than Martin's)

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Build log

http://farm4.static.flickr.com/3605/347 ... ce93_m.jpg
I had originally posted from work and my memory was off on two measurements. There's only about 3/16 from the sound hole to the rosette. and the sound hole measured out to 3 9/16, Which is a whole lot different than what I posted last night (I tried to delete the post but had logged out and back on.)
You can see from the pictures that the hole will probally look OK proportionally. I looked at pictures of the first guitar and a 4" inch hole can look huge if the rosette is wide.
I'm going to put in some kind of backing for a future sound port, just in case .

Ok I have only done one rosette so this is more of a question than a solution for what you are doing.

If this was me, and I hadn’t installed the braces on the other side, I might just flip the top and do a new one on the other side. Depending on the structure I might add a sound hole patch (thin layer of soundboard material) over the one you have in there now for a bit more support. I have seen the sound hole patch on some ukes and I think some classical guitars use it. It is on the back side so you wouldn't see it. I might bind the sound hole if the wood from the old rosette was unsightly after the new hole was cut. Or if your sound hole patch was right up to the sound hole it might give a layered look to the sound hole which might look cool.

Again, I’ve never done this so these are thoughts based on no experience at all and may not work.

Sooooo from the people that know, Would that work? Becase I can see myself having to pull something like that off in a couple of months.

Good luck,

John

If it were mine, I would run with it th e size it is......might sound great. You have a great backup plan which is to add a sound port if you need more volume or want to change the sound. It will be a nice experiment and a learning experience for you.

By the way, I've heard some folks claim that a non-round shape seems to do better as a sound port than a round shape.......for what it's worth. They claimed an oval or triangle produced a better sound. I mention it incase you want to allow for an odd shape now while the box is open.

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Dude, the rosette looks ok, but you've got brick and concrete inside your guitar, it's going to be heavy!

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Bill,

I may have an answer to the question of a sound port. Mike Chock at Hana Lima 'Ia teaches a method of creating a tuned sound hole on Ukuleles that may apply here. The biggest deviation here is that the ukuleles are strung up before finishing. Mike uses a decibel meter outside the sound port hole. The sound port is started and then the sound port volume is checked. You slowly increase the size of the sound hole and watch the meter. Once the meter shows the sound level decreasing then you stop and bind the sound hole. This method would allow you substitute a pair of sound/air exits for the single sound hole without worrying that you have gone too far with the openings.


Philip

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