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...or maybe not. I've got a pretty good older stash of tone woods and really like going through them once and a while to tap and listen and ooh, ahh, or groan, depending on what I hear, pretending to know what to listen for in a 'good' top.

I have some redwood, cedar, Englemann, German spruce, some Port Orford Cedar, some plain old spruce and something I'm sure I'm forgetting.

As I'm tapping my way through my stash I'll get some nice ringing of various pitch and tones and some especially great ringing tones from a couple redwood and cedar tops but there's this one gorgeous piece of red wood that just goes 'thud', and that is giving 'thud' more credit than it deserves.

So my question is, will that thuddy redwood top ever make a good sounding guitar? It's pretty stiff by feel and if I thin it will it wake up? Does the current thud mean it will never amount to anything good on a guitar top? Or is it a matter of dialing it in with thickness and bracing to make it behave as a great sounding guitar top? Or should it simply be reserved for a test guitar of some sort?

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In general its very subjective. It has a lot to do with overall thickness of the top and how the bracing effect the tap tone as well. Sometimes some of the worst tap tones that sound like wet cardboard make the best tops.

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been building for over 20 yrs now and many that were mentors of mine didn't hold anything to that other than to know it wasn't cracked. The top will have braces that makes the difference , to know hoe to brace a top and voice it later to get out of it what your looking for.
One of the best guitars I ever made , the top sounded like wet cardboard. Once built and voiced it sold very fast.

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John Hall
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Thanks so much for replies. It seems a bit counter intuitive to choose a wet cardboard top wood and knowing it can make a great sounding guitar but that's mostly inexperience muddying the waters.

Again, thanks for the time and replies...

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It depends in part on why it sounds that way. This is one of those places where using Chladni patterns, so that you actually see the mode shapes, helps. I've had tops that had a couple of modes that came in a nearly the same pitch. The patterns will be confused and so is the tap tone. Often a small change in the size of the piece, trimming it a little narrower, say, will shift the mode pitches so that they don't overlap and more, and the sound clears right up.

On the other hand, I got some 'salvaged' redwood tops a few years ago that really did tap like cardboard. They were relatively high in density ad low in stiffness along the grain, too. I suspect the wood came from the center of the tree near the base, where the weight of the tree and the built-in stress were high enough to cause crushing on a microscopic scale. Sometimes the grain of such wood will also look like crushed velvet, with a sort of random curl/quilt look that's hard to describe but easy to recognize once you've seen it. I did not surface any of those pieces to check but just sent them back. They were not doing what I get redwood to do.

If there is not any such damage to the wood structure, and the modes are not mixed up, it may just have high damping. We tend to feel that's a bad thing, but, in fact, I don't know of any studies that definitively show it to be detrimental within reason. It's distressingly easy to start with low damping wood and make a structure that has high damping. The wood sets a limit on how good the guitar can be, maybe, but it's up to you to realize that potential. A good maker can make a better guitar out of mediocre material than a bad maker can make out of the best stock.

Probably wouldn't be the best choice for a classical, but steel strings can be counterintuitive. Super low damping seems to cause a sort of hollow nasal tone, as the higher harmonics overpower the fundamental.

Build it and see what happens. Maybe pair with Indian rosewood or other low damping back/side wood.

Well, redwood has the most disparity in qualities of all potential top woods. I'd suggest that if your redwood top taps like thud, to move on to something else. My barrier of acceptance is quite wide, I wouldn't pay for redwood again unless I was able to personally select the piece. I've pissed off quite a few redwood dealers by returning product. If you don't have a quantitative means for selecting top material I would suggest putting redwood at the bottom of you list. Way down.

I do not have an answer to the question as such but something to think about. It is on thinning out tops. One method is to thin out the top and 'wobble' it, hold it by the edges and shake it back and forth. If the tone goes away the top is thin enough. I thought of this and what is happening. I think the stiffness of the top along with the weight goes down as you thin it to the point where the air load on the top dampens the mass-stiffness resonance.

Now, how does that translate to a thudy top? If the weight of the top is low enough it might behave the same way resulting in a thud. I am guessing the mass and stiffness line up to cause a resonance too low to give a good tone when tapped. This is just a guess, maybe it will give someone else an idea. So while I am still tapping tops trying to figure out what it means I only know for sure that it tells you if a top is cracked.

Thank you again. I have a very limited amount of experience that may tell me what a 'good' top should sound like both before and after voicing but the first thing I do is pretend I know and listen for some musical indication while tapping. There is a spot when held just right that this thuddy top will give signs of a nice tap tone so it might be a matter of sizing thinning and bracing.

I'm a huge fan of redwood so it should be worth the effort.

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That is SO interesting to me John. Thanks for sharing that story...

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It depends on how thick the boards are too. If you are tapping 3/16th in boards you might get a good ring but when you thin it out to guitar making dimensions it starts to sound dull. Add the braces and it brings the ring right back up. I have also built a good sounding guitar with top wood that tapped like a wet noodle. So I always take tapping with a grain of salt.

Thank you again for all the great feedback. I'm feeling much more comfortable with a future guitar from this piece of redwood.

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Maybe this is obvious, but John hurried past an important point he takes for granted. If you've tapped as many sets as John has, you know the sound of a cracked piece of wood. But depending on how it's cracked, and where you hold it and tap it, a crack can sound a lot like a "dead" piece of wood. Redwood (especially the nicest, most resonant old growth) is prone to cracking. Do both halves of the book-matched pair have the same dull sound no matter how they're held or tapped? If not, have a closer look.

Will double check and thanks for the info...

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One of the reasons I like to have a large stash. Far bigger than I can ever use. I love to start with a happy ring! Who wouldn't! A great guitar starts with great wood.

Every piece of Redwood and Cedar I've tapped had a great Ring.

I witnessed another Builder build with a set of Sitka that sounded kind of like a dud, and sure enough the guitar sounded kind of like a dud! (Experienced builder tho) On the other hand, I was handling my first set of European spruce, and to me it did not sound Lively at all. My mentor told me that that's just how European is. Have not built with it yet, but I am probably going to give it a try.

New username, same ole Pat Macaluso!

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Pat