For quite some time now, I've been wondering why the Fullerton and the Rogue acoustics I own do not have a vertical back reinforcing center strip on the inside. Anything information on the net as to why some guitars have it and some don't is either very vague or based on incorrect assumptions. Several people state that only guitars with a one piece back without a purfling strip running down the outside or guitars that have a 'plywood' back are missing this strip simply because they do not require the extra strengthening it seems to provide.
Well, the Rogue's back is laminated (or 'plywood', if you must insist... ) so, I can understand why it's missing, in that case. My Fullerton, however, has a solid, two piece rosewood back and does not have the strip. Some Martins do not have the strip as well - a few high-end models and their all-mahogany acoustics, all of which are solid wood guitars and some have two piece backs. I've had the pleasure of trying a few of these guitars built without the reinforcing strip and I can say with near certainty that they're all solid woods. I think I've even found this unusual feature on some other top name-brand all wood acoustics as well so, the "it's either a one piece back or it's plywood" reasoning has got to be wrong. I've been unable to find any other explanations for this feature anywhere else.
Has anyone got a practical reason or theory for this reinforcing strip not being needed on certain acoustics?
My understanding of the strip's purpose on a guitars with the purfling strip down the back is that the routing done to inlay the strip may weaken the strength of the wood at that point along the guitar's back (especially on guitars with a two piece back) so the feature adds reinforcement along that "weak" spot. What is confusing to me is that one person's statement seem to infer that any guitar with a two piece back must have this strip for strengthening because the glue (hide or any of the modern glues used today) used to join the halves is not going to be strong enough to hold it all together without the added reinforcing strip. This would mean that the guitars such as my Fullerton (solid, two piece back) and, for example, Martin's D-15M or DRS1 model acoustics (both solid, two piece backs) all should have the vertical reinforcement strip down the inside of the guitar's back or they would literally split apart at that point under string tension - and none of them have it. I've had the Fullerton for about 8 years now and it's fine, no evidence of any kind of crack or anything starting in that area at all. Martin (and I think I'm stating the obvious) would never build or sell an instrument with such a supposedly critical feature missing. That would be unthinkable, given their long history, experience and reputation as a major guitar company. So, it's a mystery as to why this is missing on those examples and on other guitars I've encountered. Are companies using some type of super-strong glue that precludes the use of the reinforcing strip (or brace)? Maybe they've developed some sort of special joint for two piece backs that, when glued together, are strong enough as is, no reinforcement needed? I can offer some practical guesses but I rather know the truth.
I emailed the Martin Guitar Co. about this issue a while ago and got a reply yesterday:
The center strip on the back does reinforce the glue joint but it is not needed. We offer different styles and, in some cases, omit the back strip.
C.F. Martin & Co., Inc
(888) 433-9177 X2205
So, I'm assuming that unless there is some sort of purfling stripe down the back of the guitar that requires routing along the glue joint, then the center strip is cosmetic, to give the guitar a more traditional look. I can rest easy now, knowing my guitars aren't going to "self-destruct" anytime in the foreseeable future!
My solid wood Martin (w/ no purfling) and my solid wood Seagull (with purfling) both have the internal back strip. My laminate Seagulls (bookmatched backs/no purfling) do not have it. I think it is just an extra reinforcement that adds a step of labor in manufacturing that you may or may not see used on less expensive guitars. It has no impact on the sound of the guitar in my humble opinion.