Mass Support Block - Positioning

[Mitch Lees]

I make my guitars with modified side splints to house magnets which mate with similar magnets on a knee support. The support I use is a modified Ergo Play (magnets instead of suckers): it has 3 attachment points and hence 3 magnets - 2 on the upper bout and 1 on the lower bout. For the first time I am modifying my building process to use several of the ideas in the 'Books' - in this case mass loading the sides if required. It would be very convenient if I could use the mass support blocks as magnet housings. However, this would mean that the 2 mass support blocks would both be on the treble side; also the mass attachment nut on the lower bout block could not be central because the magnet needs to be in the middle.

So my question is: does it matter if the additional weights applied to the sides are both on the same side of the guitar, and does it matter if one of them is not in the middle of the side but nearer the top (or back)?

Grateful for your views
Mitch

[Trevor Gore]

does it matter if the additional weights applied to the sides are both on the same side of the guitar...

I frequently use added mass only on one side, usually the treble side, so no problem there.

...and does it matter if one of them is not in the middle of the side but nearer the top (or back)?

The advantage of a central fixing is that masses drilled through the centre can spin without hitting either the top or the back. (The masses can twist (spin) on the bolt when you torque them up). If fitted eccentrically, you lose that benefit and a loose mass could rotate and hit the back or much more dangerously, the top.

Anecdote: A customer who flies a lot internationally had his side masses "inspected" by TSA agents. The masses were replaced but the screws were only done up finger tight. No damage, because provided the screws stayed in (which they did), the masses couldn't hit anything when they rotated.

Otherwise, there doesn't seem to be an acoustical downside provided the masses are very firmly attached and can't act as an independent spring/mass system.

[Mitch Lees]

Trevor,

Thank you, I will get on and design my blocks now.

Mitch

[kiwigeo]

Anecdote: A customer who flies a lot internationally had his side masses "inspected" by TSA agents. The masses were replaced but the screws were only done up finger tight. No damage, because provided the screws stayed in (which they did), the masses couldn't hit anything when they rotated.

You'd have to fill the guitar with coke to get the same weight as a couple of metal side weights

[Trevor Gore]

You'd have to fill the guitar with coke to get the same weight as a couple of metal side weights

I guess the side masses will look a bit weird on the Xrays...

2nd anecdote: I was traveling with a guitar through LHR. Picked up the guitar at the baggage carousel and found a neat round hole punched in the side at the head end of the case. Took me a while to figure out what would cause a hole like that in a Hiscox case.


It had been core sampled.