Sound Posts

[Slack_Key]

As always, a great thank you to the café for your time and expertise. As a musical idiot, I appreciate the help and insight.

I just got a Rover RM-35s (second hand store). It has a solid top. On the right "f" sound hole, there is a bit of a depression, best described as a fender dent. I saw the post for the Gibson with the sinking top, but did not think it was appropriate to interject my question about a Rover into a Gibson conversation.

https://www.mandolincafe.com/forum/t...-9-sinking-top


The RM-35 is a definite improvement over the RM-25S. It is light and vibrates in a way the 25 does not. It also sounds like a mandolin to me in standard tuning, where the 25 sounds wrong (heavy and dull) to me unless it is moved up to ADAD tuning, perhaps a problem with intonation. My question though is given the fender dent in the RM-35, should I try to fix it? It seems structurally stable and solid. My luthier has suggested either steaming it and allowing it to return to its normal curve and then allowing it to dry out in that position or to put a sound post under the dent to push it up. Although not a high end or collectable, I do like this one better than the 25. Should I try a sound post or because it is currently stable, should I just leave it "as is".

Also, if the intonation and set up on the RM-25 is correct, is there a way to change the tone (heavy/Dull) with different strings?

As always, thank you for your thoughts.

[EdHanrahan]

... given the fender dent in the RM-35, should I try to fix it? It seems structurally stable and solid. My luthier has suggested either steaming it and allowing it to return to its normal curve ...

Somewhat similar situation with, yes, an RM-35s, probably 10-12 years ago. A local violin shop had one with an asymmetrically sunken top, due, I suspected, to the badly out-of-place bridge; it would have been untuneable even if not sunken. But rather than hassle with their supplier, they simply put a rock-bottom price on it. Being semi-sure that the braces were okay, I went for it.

Summertime is warm & humid in northern NJ, so I took a shot at re-humidifying. In short, I took off the strings & bridge, sealed it in a plastic garbage bag with a slightly damp sponge, and hung it in the (non-A/C) garage for 2-3 weeks. Pretty constant warm temperature, staying above 80 even on cool nights (w/ garage door closed), and well over 90 in heavy sun. It worked! The top lost 97% of its waviness, and some slight bridge sanding gave me something that looks, feels, and sounds pretty much like, ya know, a mandolin! It's currently my "lay around the house/backyard" instrument.

But thinking a bit further: Your isolated "depression" is most likely due to a defect in the wood -or- from bad storage in its prior life. My best guess is that flattening it -at least anything beyond what I did- will have zero effect on the sound & feel, and not much effect on the looks. It is, after all, an economy instrument from a 2nd-hand store. I'd be tempted to leave well-enough alone.

As to tone: Different instruments respond differently (some cheaper ones hardly at all), so others' experience probably won't apply to you. The good part is that strings are cheap, so feel free to experiment. For example, my '17 Gibson A-1, some of them fairly boomy, responded nicely to a lighter G course.

Bonus: In the end, you'll be pretty good at setting the bridge location / intonation. That alone is worth whatever the expense!

-Jazz guitar setup is similar to your mandolin, both being archtops w/ floating bridge. Go to the bottom for bridge placement:
http://www.frets.com/FretsPages/Musi...tstring02.html

Disclaimer: I'm simply a tinkering amateur. There are true professionals, some of the best around, that often chime in here.

[Slack_Key]

Thank you Ed! This was exactly the insight I was hoping for. I think the problem with the RM-25S is that it is built like a tank, probably also the reason it looks pristine. When some of the café dwellers mentioned concerns about tuning strings higher and placing more pressure on the top, I thought to myself, "why these mandolins look really sturdy". Now I see the better instruments have thinner tops and vibrate more. And sound better.... I guess this is how MAS starts.

As I understand the Café rules regarding MAS and MIF, if I sell the RM-25S, all proceeds must go towards the purchase of the next mandolin. As I also understand, since the RM-35S is my second mandolin, I should skip the third Mandolin and go straight for the KM-150. Or skip the RM-150 and go for the Eastman. Sadly, I still suck at tremolo and cross-picking.

[HoGo]

I've seen soundpost in a mandolin with sagging top once and it was pretty poor sounding one, but the owner said it sounded "better than before" just like Dawg, but I guess the "before" was just as awful as after. Since the pressure of bridge is much higher on mandolin, the soundpost showed through the plate as a bump.
If you want to know how a mandolin with soundpost will sound, try plucking violin. that will at least give you a hint - very likely low volume and short decay.
Fitting soundpost in violin without damaging the top is not straightforward and requires some expertise.

[Richard500]

Well, that strange, almost mandolin I’ve shown here recently had a half-inch diameter dowel resting on a square pad on the staves of the bowl, and pressing on the otherwise totally unbraced top, somewhere near the treble side of the bridge. It got removed, the top given two transverse braces, etc. The data point is that it sounded pretty much the same, before and after. The bowl seems extremely thick, and therefore immobile, and this weird thing actually has good sustain, although not loud, so no definite conclusions.
Anyway, I’ve long had this little sculpture, of the graceful ancient tool variety, pictured here. It’s a set of soundpost installers, pointy ends stuck in a cork, floral hooks up. It really works too.

[DavidKOS]

Bowed string instruments have had soundposts for hundreds of years.

Plucked stringed instruments have not.

There's a reason!

[JeffD]

Bowed string instruments have had soundposts for hundreds of years.

Plucked stringed instruments have not.

There's a reason!

Yes. A mandolin does not make sounds the same way a violin does. If you are referring to the sound post as it is in a violin, a mandolin doesn't have one and doesn't need one. If you are referring to another aspect of the bracing, it should not be called a sound post.

[Dave Hanson]

Many years ago I fitted a soundpost to an old Harmony plywood mandolin with a sinking top, it didn't alter the sound at all, and it surely stopped the top sinking.

Dave H

[DavidKOS]

Yes. A mandolin does not make sounds the same way a violin does. If you are referring to the sound post as it is in a violin, a mandolin doesn't have one and doesn't need one. If you are referring to another aspect of the bracing, it should not be called a sound post.

Bracing is one thing. I was referring to a real stuck-between-the-back-and-top soundpost.

[Richard500]

While we’re on the terminology, the same applies to the ‘tone bar’ which, whatever its acoustic or structural-function, is a longitudinal stick, but is a ‘brace’ at other angles. With this degree of semantic liberty, it may be forgivable to call a top-to-bottom connection a sound post whatever its primary function.
And if anyone knows what a Virzi should be called….

[DavidKOS]

And if anyone knows what a Virzi should be called….

It should be called "expensive"....or "not needed musically".