Armrest kills tone?

[HonketyHank]

I just finished making an armrest for my Theloar 700. Armrest is carved from walnut. Installed it and discovered that the mandolin no longer sings. The sound is almost like I am muting the strings with my hand on the bridge.

Photo shows the installation. Note the blue-black strip between the armrest and the mandolin body. It is leather; not permanently attached but I did plan to trim it and attach it prior to final installation.

So. My questions are:
Is the leather killing the vibrations of the soundboard? Would felt be better? Or something else? Or is there something wrong with the design? Or maybe I am tightening the barrel nuts too tight or not enough? Or do armrests just inherently kill the sound?

[MikeEdgerton]

I always used Siren String Works arm rests because they had a small foot print and they were a little higher. After a recent refret I realized it was damping the top. Removed it and it was fine. I never noticed it before and it was there for years.

[liestman]

Maybe its that the armrest encourages you to clamp the whole thing between your arm and torso morso?

[Doug Edwards]

That's interesting. I have hundreds of folks saying how the armrest increased volume on their instruments. The Siren is cantilevered like my armrests and only a 1/4" or less actually touches the edge, just like the bottom of the clamp. BTW, I notice cork on the bottom clamp in the photo. I'd change it to the leather. A few of my customers experienced interaction with the finish on their instruments with the cork. I don't think the cork or the leather cause any dampening but YMMV.

[MikeEdgerton]

That's interesting. I have hundreds of folks saying how the armrest increased volume on their instruments. The Siren is cantilevered like my armrests and only a 1/4" or less actually touches the edge, just like the bottom of the clamp. BTW, I notice cork on the bottom clamp in the photo. I'd change it to the leather. A few of my customers experienced interaction with the finish on their instruments with the cork. I don't think the cork or the leather cause any dampening but YMMV.

I would guess that if you lay your arm across the top it could be damped by your arm. The armrest then would probably remove that as an issue. With me I just noticed a difference and was surprised. I'd used the armrest for years.

[Doug Edwards]

So did you toss the armrest Mike? BTW, my first armrest was a Siren before I started making them.

[MikeEdgerton]

No, I still have two of them. I may decide I need it again some day

[HonketyHank]

That's interesting. I have hundreds of folks saying how the armrest increased volume on their instruments. The Siren is cantilevered like my armrests and only a 1/4" or less actually touches the edge, just like the bottom of the clamp. BTW, I notice cork on the bottom clamp in the photo. I'd change it to the leather. A few of my customers experienced interaction with the finish on their instruments with the cork. I don't think the cork or the leather cause any dampening but YMMV.

Interesting re interaction of cork and mando finish. I have a Morris which I bought from Sonny with a armrest installed when purchased. When I removed his armrest I noticed a) he used felt instead of leather, and b) the finish of the mandolin was crazed where the felt was in contact. I concluded that it must be an interaction between fumes from the contact cement used to attach the felt to the armrest. So I decided to use leather and to cement it with a water based cement like Elmer's plain old white stuff. But I hadn't gotten to the glue-up stage yet.

Sonny's armrest also has cork on the hardware, like mine, but I didn't see any sign of interaction of the finish with the cork. Maybe because it had been installed on the hardware long enough that any solvent based cement had long since outgassed before the bracket was installed on the mandolin.

[Doug Edwards]

Stick with the white glue for the armrest. I use a little super glue for the bottom of the clamp. The cork is hit and miss. I've seen instruments that had cork on the armrest three years and more and no mark at all. Then I had a regular customer have his new mandolin react in a very little time period. The mark did buff out and I've used leather top and bottom since without any problems.

[Dave LaBoone]

I've been very pleased with my McClung armrest!

[Boge Quinn]

I have Dudenbostel armrests on about eight mandolins. I love them. The damping footprint is very small, way smaller than my big ole arm.

[Ivan Kelsall]

There are at least 2 types of 'sheet' cork available to use. One is the 'natural' cork as it comes from the tree,& another is cork that's been made from cork granules bonded together with some type of adhesive. The natural cork should be pretty inert & non-reactive to almost all finishes used on mandolins. I'm pretty sure that it's the bonding adhesive in the 'fabricated' cork that's the culprit. Natural cork sheet is usually available in small pieces only,the fabricated stuff can be bought in 3ft square (& other sized) sheets.So be careful which you buy,
Ivan

[Big Joe]

If the arm rest itself touches the top of the mandolin anywhere except the rim it will dampen. It should not touch the top and you may want to check that. I've never seen a properly made and installed arm rest decrease volume, but always increase it.

[AlanN]

Arm Guard? nope
Pick Guard? nope
Tone Guard? nope
Right Guard? yep

My picker friends thank me for that

[Tobin]

In general, like Big Joe said, a properly fitted arm rest should reduce the dampening that you'd otherwise get from your arm being in contact with the mandolin.

But, it does seem to make sense that even a well-fitted arm rest would have some small dampening effect when compared to playing the mandolin without any arm contact. Even though it may not be dampening the vibration of the top plate or back plate in relation to the rim, it still adds mass to the instrument. And adding mass will "soak up" more of the energy that you add when you pick the strings, reducing overall vibration of the instrument as a unit.

I wouldn't know whether the additional mass and its dampening effect on the entire instrument would even be discernible, but maybe it would explain what you're experiencing? Especially if your armrest is thick and heavy. As an experiment, you might try carving out all unnecessary wood from the underside and thinning it to the minimum you need for strength.

[HonketyHank]

Thanks to all for thought provoking replies. I think I have found my answer. My armrest does have relief on the underside to allow for the arch of the top. The problem is that it is not enough. I replaced the thin leather padding (that blue-black piece above) with a thicker leather piece (quite thick, like what you might use to make a horse saddle) cut to shape and only 1/4" wide. This raised the armrest considerably. Reinstalled the armrest and now the mandolin sings like before.

I plan now to carve out more relief so I can go back to the thinner leather pad.

Thanks again. MC is a great place, right? I already got the hat, maybe I should spring for a tee shirt.

[CeeCee_C]

I have Doug's McClung armrests on all my modern acoustic instruments.

I paid particular attention to the sound before and after installation. There didn't appear to be a significant difference in tone or volume with and without the McClung on any of them.

I've been very pleased with these armrests.

[Paul Hird]

Sorry if this has been mentioned earlier. Are there any issues with the case closing properly with an armrest installed?

[sblock]

I am very dubious about the possibility that the armrest itself is doing anything to muffle the tone of your mandolin. Armrests do not kill tone. As others have pointed out, changes in your own arm and body position in the presence of the armrest are likely to be responsible for any changes you hear. Does any part of your arm touch the mandolin? How far is it from your torso?

[Bertram Henze]

Are there any issues with the case closing properly with an armrest installed?

I guess this depends on the case. The classic flat-topped case should have problems only if the armrest rides up higher than the bridge.

[Polecat]

I ordered a McClung armrest a while back and found that it definitely improved both volume and tone by reducing the damping effect of my arm on the soundboard whilst playing. There may be a minimal damping effect involved in clamping it on the instrument, but as far as I am concerned, the advantages vastly outweigh the disadvantages, and I am sufficiently impressed to have ordered a second one.

[HonketyHank]

Well, I am having second thoughts. Yes I do think it possible that I did not provide enough clearance for the arch of the top under the armrest and that has been corrected. But the dead tone persists, most notably in the D strings but also in the G course. I have two theories at this point.

Not long before I made and installed the armrest I also did some work on the bridge. The action was somewhat high even though the saddle was lowered all the way down. So I sanded about 0.10" off the top of the saddle and reslotted. The slots are shallow so that the strings are still sitting on top of the saddle (ie, not down into a deep slot). But maybe this affected the tone.

Or, maybe, my ability to detect the difference between a somewhat dead tone and a nice ringing tone has improved and I am just now noticing a difference that has always been there. Not impossible since I am a beginner on mandolin.

[Steve VandeWater]

Hank, on the armrest you made, does it only touch the top right along the rim (not more than about 1/4" from the edge? That's how it should fit. If it touched the top of the mandolin further out from the rim, I could see how it could deaden the tone.

[Polecat]

Not long before I made and installed the armrest I also did some work on the bridge. The action was somewhat high even though the saddle was lowered all the way down. So I sanded about 0.10" off the top of the saddle and reslotted. The slots are shallow so that the strings are still sitting on top of the saddle (ie, not down into a deep slot). But maybe this affected the tone.

Or, maybe, my ability to detect the difference between a somewhat dead tone and a nice ringing tone has improved and I am just now noticing a difference that has always been there. Not impossible since I am a beginner on mandolin.

I find it easier, if it is necessary to lower the action beyond what the bridge allows, to sand wood away at the bottom of the saddle, where it sits on the thumb screws rather than on the top, where one will also alter the compensation - if the top of the saddle is now wider than before, that could easily also damp the vibration of the strings.
It is easy to become obsessed with ones tone - I recently tried replacing the adjustable bridge on my 1908 A3 with a one-piece bridge following Red Henry's advice, and made two bridges, one of maple and one ebony. Both were louder than the adjustable bridge, but didn't sound as balanced to my ears, so I reverted to the bridge that was on when I bought it. When I have time, I may continue to experiment, but for the moment I have decided that playing the instrument is more important to me than playing with it.

[HonketyHank]

Hank, on the armrest you made, does it only touch the top right along the rim (not more than about 1/4" from the edge? ...

Yeah, that's how it is now. And there is now little, if any, improvement when I take the armrest off. Previously (before adding extra relief to the under side of the armrest), there was a significant improvement when I removed the armrest.