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  #1  
Old 11-19-2020, 10:13 AM
Robertj Robertj is offline
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Default Archtop following Benedetto design

With the lockdown in the U.K. in March I decided to build a few arch tops. Twenty yrs ago I started buying tone wood, I bought two Archtop sets of quilted maple from Canada, birds eye maple for two necks and two sets of Sitka spruce from the USA. I'm a hobby joiner or carpenter but decided to buy some locally sourced sapele or mahogany to practice the art of constructing an Archtop guitar following the Benedetto book. I overcame most of my mistakes on the prototype and the guitar sounds ok. I then built two Guitars with the quilted maple and Sitka spruce tops which worked out just fine and gave one to my brother.
I made a fourth Archtop from the mahogany and Sapele that was left over from the Prototype which again sounds fine, the tone and sound is probably the best. I understand that quarter sawn is less susceptible to splitting and the quality of the wood is paramount for stability and longevity.
My question is considering I have built four guitars from the same mould and dimensions why do the two mahogany Sapele guitars have a richer and fuller sound? I would like to post photos but the photo icon it asks for a url.
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Old 11-28-2020, 11:10 AM
PonchoFrancisco PonchoFrancisco is offline
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I'm surprised no one has commented. First, let me say that I haven't built an archtop, but I would guess the back and side materials are the main factor. My experience is, maple tends to be very transparent and does not 'color' the sound of the top. It can be sterile, so to speak. Mahogany tends to add a warm tone that gives very good fundamental without a lot of overtones. At least this has been my experience with flat tops.

Brent
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Old 11-28-2020, 06:52 PM
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Guitars44me Guitars44me is offline
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Smile This is the place

If folks here can't answer these questions I will be very surprised!!

Good luck with getting pics up. On my iPad safari will not work. I had to download the AGF app and use it to upload pics from my internal library.

Since I dont even have a computer I am no help there! Hahahaha

Looking forward to seeing your work!

Salud

Paul
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  #4  
Old 11-29-2020, 06:01 AM
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SprintBob SprintBob is offline
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Quote:
Originally Posted by Robertj View Post
With the lockdown in the U.K. in March I decided to build a few arch tops. Twenty yrs ago I started buying tone wood, I bought two Archtop sets of quilted maple from Canada, birds eye maple for two necks and two sets of Sitka spruce from the USA. I'm a hobby joiner or carpenter but decided to buy some locally sourced sapele or mahogany to practice the art of constructing an Archtop guitar following the Benedetto book. I overcame most of my mistakes on the prototype and the guitar sounds ok. I then built two Guitars with the quilted maple and Sitka spruce tops which worked out just fine and gave one to my brother.
I made a fourth Archtop from the mahogany and Sapele that was left over from the Prototype which again sounds fine, the tone and sound is probably the best. I understand that quarter sawn is less susceptible to splitting and the quality of the wood is paramount for stability and longevity.
My question is considering I have built four guitars from the same mould and dimensions why do the two mahogany Sapele guitars have a richer and fuller sound? I would like to post photos but the photo icon it asks for a url.
Here you go:

“How do you insert a picture into your posts? The picture must be held on a website: you may not post an image directly from your computer. There are a number of websites where you may upload pictures for free.

Locate the image (on the web) that you'd like to display in your post (the host must allow hot-linking/third-pary hosting for this to work), right-click on it and select the image properties/info from the menu. Copy the entire address (URL) of the image. In your post, click on the Insert Image icon (the yellow box with the mountains). A prompt will appear asking you for the URL of the image. Paste the link you copied, then click OK. This will insert the image into your post. (Note: You wont see the image until you preview or submit your post.)

The AGF mobile app provides an image attachment function and can be found here: Android | iOS

Charter Members and forum Sponsors can also upload images via the built-in attachment system per the instructions here.“

Go to the FAQ link at the top of this page to find this.
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  #5  
Old 11-29-2020, 07:43 AM
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Tim McKnight Tim McKnight is offline
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Quote:
Originally Posted by Robertj View Post
I understand that quarter sawn is less susceptible to splitting and the quality of the wood is paramount for stability and longevity.
My question is considering I have built four guitars from the same mould and dimensions why do the two mahogany Sapele guitars have a richer and fuller sound? I would like to post photos but the photo icon it asks for a url.
Quarter sawn cuts of wood are preferred by most builders of flat tops because this cut of wood is generally more stable to humidity swings because of the way the wood cells exchange moisture with the surrounding atmosphere. QS cuts of wood exchange moisture out of its end grain (IF) there is no run out present in the plates. The end grain should be sealed by the bindings and rosette which both work together with the finish to [slow] the moisture exchanges but never really stop it 100%.

Flat and rift sawn cuts of wood exchange moisture from the both faces of the board and are generally less stable and less resistant to moisture movement. T
As far as cracking and splitting go any wood can fail (IF) its subjected to extreme out of range exposure to the elements. Thin cuts of wood, commonly used to construct guitars, move more rapidly due to moiture exchanges. When wood moves, due to an expansion or contraction condition, something could fail which is either a glue joint or the wood itself. Wood is likely to move a greater amount during loss of moisture (dryness) than it is to move when swelling (from absorbing moisture). Maintaining an accurate 40%-55% Relative Humidity range, that your guitar is exposed to, will drastically reduce the risk of the wood ever moving beyond minimal amounts.

Although you are building guitars with arched (or carved) top and back plates so the explanation above doesn't exactly apply 100% because the exterior convex and interior concave carved surfaces expose a LOT of end grain and there is no way to effectively seal those surfaces from moisture exchange. Arch Top carved plates can remain relatively stable do the the higher radii used on the top and back plates. However, they are still susceptible to failures if the wood is exposed to extreme conditions outside the safety zone of 40%-55% RH.

The changes you hear in the tone are likely from three factors;
1) Variance in the thickness of both or either of the top and back arched plates
2) The mechanical properties of the wood itself i.e. its Modules Of Elasticity (MOE)
3) and the wood's density.
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  #6  
Old 11-30-2020, 08:12 PM
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morgankelsey morgankelsey is offline
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I took an archtop building class with Dale Unger a couple of years back. There were three of us in the class, and we all started with materials in the same state - most notably the front and back plates had CNC carved initial arches. The recurve around the perimeter was not carved though, we did that by hand in the class. All three sounded different in the end, and Dale's input was that the recurve is the biggest factor in the sound.
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Old 12-07-2020, 03:33 PM
redir redir is offline
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I cannot help you with the tone question. There is so much involved with that it might actually be impossible to answer really.

But I had bought Benedetto's book some 5 years ago and am finally gear up to build my first archtop. It's definitely a daunting feet for me and I've built 70 instruments to date.
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