BYO Moustaches and Pickguard damping sound?

Peter Davies

Hello forum members, I wonder if I can pick your brains on an issue that I can't explain regarding my attempts as a very amateur guitar maker? I've been trying to build Selmer Maccaferri guitars as a hobby over the years and recently finished the third one (all 12 fret to the body, D holes). The sound of this latest one is louder, well balanced from bass to treble, resonant and responsive compared to previous attempts. I think I've hit the jackpot, sound wise.
However, when I temporarily attached the thin rosewood moustache pieces, with tiny spots of adhesive putty, the sound seemed distinctly damped or muted on the treble strings. After removing them the sparkle returned. So I've left them off for the time being.
Now I've moved on to reworking one of the previous D hole guitars to see if I could reproduce the sound of my latest effort. After removing the neck, increasing the neck angle, thinning the top and reducing the bracing under the bridge, the sound has really opened up. Don't ask me how, I surprised myself.
No moustaches on, but I have tried attaching a clear pick guard that clings on purely by static. Guess what? - strumming a chord, there's a distinct reduction in the sound of the treble notes. Playing a few notes of melody on the first two strings seemed muted.
Removing the pickguard brought back the sparkle to the treble notes again.
My question is -
Has anyone else had this experience?
Am I doing something wrong? I haven't seen many Selmacs without the moustache pieces.
Could it be more noticeable on the 12 fret to the body guitars, with less string tension to drive the soundboard?
Sorry for rambling on but any thoughts at all would be gratefully appreciated.
Wishing you all a Merry Christmas,
Peter Davies

Jazzaferri

What strings are you using and what is the scale length.

Peter Davies

I'm using Argentine 10s and the scale length is 640mm.
I've been using plans from F. Charle which specify the braces just behind and in front of the bridge to be 17 -20mm in height. I went for 17mm on the third Mac and reduced the reworked 2nd guitar down from 20mm to 17mm.
The soundboard thickness is 2mm for both with heat bent arch (pliage) under the bridge area.
Hope some of this helps.
Pete

Craig Bumgarner

Moustaches and the pickguard add mass to the top assembly. Most moustache pieces weigh at least a couple grams apiece, sometimes two-three times that and are right where mass, or the lack of it, matters most. A five gram difference can be clearly heard as you have found. If anyone wants a demonstration, just stick a lump of modeling clay about 17mm in diameter (~5gr) anywhere in the immediate bridge area and listen to the difference. The added mass will noticeably reduce the volume, response and attack.

Pickguards typically weigh 4-5 grams or more depending and while not centered at the bridge area, are still within the most sound producing part of the top. Try sticking the clay in the center of the pickguard area to see what you get.

Much of getting the most response and volume out of the top is about optimizing the stiffness to weight ratio of the top assembly (top plate, braces, bridge and attachments like moustaches and pickguards).

I recently did some neck work on a nice petite bouche that sounded over built. It sounded like the top was too stiff, but when checked, it was not. The stiffness was pretty much where it might be expected for a good PB and the top and braces all looked about right in their dimensions. Found the 20mm tall ebony bridge was close to 20 grams (yikes!). Made a new bridge out of walnut and got the weight down below 11 gram. Made a very significant difference in the response and volume. So, the stiffness was good, but the top assembly was overweight in the bridge area where mass is most critical.

It is a bit of game to tease out adequate stiffness in the top assembly while reducing mass, but moustaches, bridges and pickguards can be easy targets for reduction of mass with no loss of stiffness (well up to a point, a 5 gram bridge may not have adequate stiffness for the structure). Of course, this is what the doming of the top with arch and pliage is all about, stiffness from the arch effect with no added mass. As close to something for nothing as it gets.

As Peter says, moustaches are very commonly used and are an iconic part of these guitars. There are heavy ones and light ones. A 1 gram moustache is not out of the question. Rosewood is 2/3 the weight of ebony and walnut is half. Most any wood can be dyed black to look like ebony. Balsa moustaches anyone?

Jazzaferri

I would think that 10's would be light for that scale length. You might do well to try 11's or depending on the top and bracing possibly even 12s but my experience with shorter scale length GJguitars is they work better with 11's than 10's unless they are phenomenally lightly built.

Peter Davies

Thank you Craig for your thoughtful and informative response. I hadn't considered Walnut for the moustaches. A lighter weight wood is well worth trying in order to get the full Maccaferri look. I'll also trim the pick-guard so it doesn't cover too much of the soundboard. I'm relieved to find that perhaps it's not just my hearing that's to blame.
Thank you too Jazzaferri. I'll try Argentine 11s in a while, when the guitars have had time to settle a bit. I don't want to risk putting too much stress on them so soon, but I'll get a of set of 11s ready.
I really don't know whether I've built the guitars lightly or not. I double checked the Charle plans and there's no specified height for the braces running parallel to the bridge. A height of 17 - 20mm is only specified for the braces running near the neck and sound-hole. No soundboard thickness either.
However, 12 fret D-hole plans I got from Roy Courtnall specify 15mm height for the bridge area bracing. So I hope I've kept within tolerances and it doesn't all implode.
Perhaps the 14 fret, 670mm scale length guitars aren't so sensitive to such small alterations? Sounds like a future project to look forward to.
Thanks again,
Pete

Jazzaferri

Normally going up in size de emphasizes the highs a bit. But if the top isn't quite working right all manner of strange things can happen.

You could try tuning up a semitone and that will tell you something in the short term.

Bones

What Craig said. That's how a violin mute works. Adds mass to the bridge. My Gallatos (very loud) came without the moustaches attached and I never bothered to put them on. Not necessary functionally but it does look a bit weird without them. I do have a very thin (removable) pick guard though to protect the spruce. A concession to functionality.

Jazzaferri

Btw @Peter Davies .....what is on the plans just gets you close. Grain density, straightness, and orientation, wood species and aging process all Impact strength, rigidity. Lutherie is an art and a craft. Every one you build will have its own personality and challenges to bring out the best. Experimentation leads to discovery and learning. Enjoy your ride and best of luck with it.