Griffith A5 design details............

[Max Girouard]

Hi All,

I'm in the stages of desinging a mandolin based off of the famous Griffith A5 serial number 74003. Here is a link to the mandolin archive of the mandolin itself:
http://www.mandolinarchive.com/gibson/serial/74003

There was a recent thread on this particular instrument where Daryl Wolfe from the F5 Journel posted several pictures of the Griffith A5 along side with a gibson oval hole. Thanks Daryl!

Here is a picture that Daryl posted in a previous thread aobut the Griffith A5. The thread can be found here: http://www.mandolincafe.com/forum/sh...r-A-5-drawings

[Max Girouard]

Here is a copy of the photo that Daryl posted in that thread.

[Max Girouard]

After study of the photo my eye see's a depressed area around the bridge that may be due to camera angle or actual depression of the wood due to stress from the bridge. I decided to draw it up in my CAD program with a Bezier curve to see if this was true. From the edited photo it is clear to see that the top seems deformed due to string pressure. However; these are just assumptions that are to be made looking at a photo and tracing some lines in my CAD program.

[Max Girouard]

I recently worked on a mandolin that was built by a friend. The top was carved too thin and it exhibited some of the same traits that I think I'm seeing in the Griffith A5. The area before the bridge is dipping down and the area near the tailpiece is bulging up. My friends mandolin is still playable, but has very similar characteristics of the Griffith A5.

[Max Girouard]

Here is a tracing I did from Adrian (HOGO) plans comparing the Griffith A5 to a Gibson F5:

[Max Girouard]

I'm expecting a few thousandths of error due to paper stretch and scanning, but if the drawings are correct, it shows the same issue I saw in my friends build. The front of the arch being driven down, and the rear of the arch bulging towards the tailpiece. It is slight but it is there.

[Max Girouard]

Here is a tracing of the Siminoff A5, Siminoff A1 plan against Adrain's F5 arch profiles for the longitudinal arch on the instruments. Some very interesting data shows up.

[Max Girouard]

From looking at these tracings, I'd say that the Griffith A5 was carved the same way as a period F5, and not as an A model unless the drawings are very off. The Siminoff drawing shows the arch of an A1 or F4 as having an arch of 19mm, where as the F5's and Griffith A5 have and arch measuring around 16.5mm.

[sunburst]

I think at least part of what you are seeing in the photo is a reflection of the strings crossing the bridge. The upward angle of the strings over the bridge is reflected as a downward angle, and the curvature of the top curves the reflected lines so that it looks like a sunken top. I've seen the same thing in other mandolins; the reflected strings causing an optical illusion.
That's not to say that there is no sinking of the top because I don't know. I've never held the mandolin. I'm just pointing out something to consider.

As for the bulge behind and the depression ahead of the bridge, I've seen that in many mandolins with the top carved too thin for the mechanical properties of the top wood, but also consider this: There was no design for an A-5. There was a design for an A, and there was a design for an F5, and basically, the two were combined into the A-5. If the normal arch for an A was modified for the elevated fingerboard extender but not for the different bridge placement (what I think may well have happened), that places the bridge toward the neck from the apex of the arch. That, in itself, results in more arch behind the bridge and less arch in front of the bridge. If there is any distortion of the top, it already had a head start, so to speak.

[Max Girouard]

To further complicate maters here is the drawings with the Scot Antes version of the A1 plans....................

[Spruce]

[MikeEdgerton]

I need to get me one of those.

[Mike Black]

One other thing you need to take into consideration is that Darryl specifically said "Snakehead". Neither the Siminoff or Scot Antes are drawings of a snakehead. They are paddleheads. Snakeheads are carved differently than the paddleheads.

[randygwatkins]

One other thing you need to take into consideration is that Darryl specifically said "Snakehead". Neither the Siminoff or Scot Antes are drawings of a snakehead. They are paddleheads. Snakeheads are carved differently than the paddleheads.

Hmmm...that's the first time I've heard that...
Mike, does this account for the perceived differences in tone?

[Michael Lewis]

In regard to deformation of instruments, Graham Caldersmith wrote an article in the GAL magazine several years ago, though it was focused on violins. The concepts still hold for mandolins and as Mr. Hamlett said, he has seen such distortion in some mandolins, as has anyone that has been paying attention to mandolins for several years.

The arching used by Gibson before the F5 is the "typical" arching used by many if not most makers for a lot of years. It rises quickly from the edges and tables off in the center of the plate, like the old Stainer violins. This type of arching gives an easy warm response but succumbs to string tension eventually. I watched some of my early instruments go through this distortion, and developed a different approach to arching and graduation to prevent it from happening.

[pfox14]

I like the popcorn holder

[Mandoborg]

I Love threads like this where the 'science' of the craft is discussed because i've never really thought it out that much !!! My first few mandolins i carved with a thinner top trying to get volume and depth out of it. Those, while still alive, are all deformed and like waves on a beach !! A wise man told me to carve much thicker, some as much as 1/4 in the center and you just have to wait a while to get the tone but it will last a lot longer. Just a differant string gauge would make the above archings do differant things i would imagine? Acoustic guys take the pull of the top into consideration when setting necks as well...theres go up, ours sink down ! Never really had a desire to 'copy' an instrument to the smallest deatil, but love when people do, and i love where your going with this Max !! Good Luck !!

[Jim Hilburn]

Grisman's Loar also has that hump behind the bridge. That's what makes them sound so good!

[pfox14]

Here's an A-5 replica on eBay

http://www.ebay.com/itm/Mark-Taylor-...item3386e54e71

[bernabe]

Many of these instruments took a while to get that way....this is what I believe contributes to change in tone/volume after a newly strung up mando has had a certain amount of time as such. Changes may be subtle on most well built instruments, but changes none the less.

[Max Girouard]

I think at least part of what you are seeing in the photo is a reflection of the strings crossing the bridge. The upward angle of the strings over the bridge is reflected as a downward angle, and the curvature of the top curves the reflected lines so that it looks like a sunken top. I've seen the same thing in other mandolins; the reflected strings causing an optical illusion.
That's not to say that there is no sinking of the top because I don't know. I've never held the mandolin. I'm just pointing out something to consider.

As for the bulge behind and the depression ahead of the bridge, I've seen that in many mandolins with the top carved too thin for the mechanical properties of the top wood, but also consider this: There was no design for an A-5. There was a design for an A, and there was a design for an F5, and basically, the two were combined into the A-5. If the normal arch for an A was modified for the elevated fingerboard extender but not for the different bridge placement (what I think may well have happened), that places the bridge toward the neck from the apex of the arch. That, in itself, results in more arch behind the bridge and less arch in front of the bridge. If there is any distortion of the top, it already had a head start, so to speak.

Thanks for the input John. I know what you are saying about the optical illusion that the reflection of the strings can have on the top. Unfortunately I've not ever seen the instrument in person, so going off just photo's is a little difficult.

As I understand it, Gibson had a pantograph that was used to carve the plates. It would make sense that they used the pattern for the newly designed F5 in the carving of this particular plate. I'm trying to determine if I should make the replica with the standard F5 plate arching, or skip a couple of decades of time and design the deformation that I believe I'm seeing into the plate from the start.

One other thing you need to take into consideration is that Darryl specifically said "Snakehead". Neither the Siminoff or Scot Antes are drawings of a snakehead. They are paddleheads. Snakeheads are carved differently than the paddleheads.

Hi Mike, you are correct I missed the part where he mentioned it was a snakehead. I've always read that the snakeheads were carved differently, but I always assumed it was in the graduations rather than the plate shapes, so thanks for pointing out the fact that they are different arch profiles. This leads me to several questions, where the F styled oval holes of that period also changed or did they follow the old arch profiles of the teens instruments? Did Gibson use different arch heights on the teens Gibson which would result in the two different arch heights shown in the Antes and Siminoff plans?

[HoGo]

I won't speak of other drawings than mine which were taken from CT of nice example of Loar F-5.
My personal guess without holding the mandolin would be that the top shows severe bulging under tailpiece and some sinking under bridge as well. I think the mandolin started its life with arching and grads very similar to F-5 (especially recurve shaping and more or less parabolic curve in the center). Since this shape of arch is relatively symmetric about bridge position on F-5 (actually the highest point is somewhere 1/4 to 1/2" behind bridge position) and less curved at the thinner areas around perimeter it holds remarkably well under pressure. But once you move the bridge so far forward you have long curved area behind bridge left with so much pressure of strings trying to fold it. The top will deform in the way that we see on he first photo. It will find the weakest spot and it will bulge and the bridge will necessarily go down as top wood won't stretch.
From what I heard about tone of that mandolin and from the few recordings I suppose the top is perhaps tiny bit thinner than would be healthy (in long term). I've seen several mandolins with these symptoms and they all had really impressive sound - easy to play and responsive with great chop and throaty mids and highs but several of them already had to have failing top joint repaired under tailpiece and in one case the top started buzzing against tailpiece in humid weather.
If I were making a copy I would start with probable original arching derived from F-5. If required I would try to emulate the sound of original by thinnig the top while strung up in the white and I'd bet the minimal amount of bulging would be already there... In next 90 years it can be where the Loar A-5 is today.

[Willie Poole]

I have read that Bob Givens copied the Gibson A 5 when he was building his A model mandolins, I owned a Givens A model and it did not have as high of an arch as my Gibson F model...I`m sure there are some Givens drawings around somewhere and if they could be compared with the F models I believe you would see less of an arch in the top....That probably doesn`t answer the question about the top sagging with age but I don`t think it was very high to start with...Just my 2 cents...

Willie

[Gail Hester]

The Loar A5 is an incredible sounding mandolin and it has been the way it is for a very long time. Think A4 more than F5.

[Dobe]

I tried my hand at a Griffith copy a year or so back. Pictures from threads here, blown up to size; basically Siminoff / Stew-mac road maps for the plates. I just couldn't bring myself to absolutely copy the Griffith; the F-hole and bridge placement just looked too 'wrong' for me, so a little 'cowboying' went into my design. After a week or so of anguished staring at it, I fudged a little on the fingerboard; the neck joint crosspiece is more like 14 1/2th fret; Took the F-holes back just a bit closer to the tail, as such the bridge is a bit forward of the F-hole notch. All in all I was happy with the layout. Sounded pretty good out of the gate, not stellar but very good as I recall, but I didn't have it as long as I typically do before it sold (maybe a couple months?) Listening to the video again today it sounded pretty good. Hopefully a few years of loving spanking has opened her up. Lost my pics but if you pause this vid at 3:36 you can get a pretty good look at the bridge/F-hole orientation. It was very close to the Griffith. Good luck ! :