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Inertia block for Jaguar vibrato?

Posted: Tue Feb 11, 2020 11:45 pm
by Ceylon
Someone (can't remember who, sorry) commented on here a while back about crafting a brass "inertia block" to be attached onto the string plate of a JM/Jag vibrato. Apparently the result was a bit of an increase in sustain, but also in resonance, both behind the bridge and in the "normal" string section.

In theory this seems like it would be a way to get more of the JM/Jag tone. Since more mass is added to the bridge construction, which remains floating, it seems like you wouldn't really have more string vibrations going into the body, but rather remaining in the strings themselves, without changing the fundamental setup which produces the sound, overtones at all. Is it possible, then, that you could get more volume and sustain without losing attack and tone characteristics?

Has anyone tried this out enough to offer some feedback on how it works and how you would go about crafting one? Or does anyone know enough physics and string theory to tell me why it wouldn't work like this in practice at all? :fp:

Re: Inertia block for Jaguar vibrato?

Posted: Wed Feb 12, 2020 7:43 am
by ChrisDesign
Which part of the string plate are you attaching the weight to? I will assume the part hidden in the cavity, after the pivot.

Sustain is when the string’s plucked energy is retained between the bridge and the nut. Anything that absorbs energy reduces sustain. On a JM vibrato, the spring absorbs energy. So how would a weight affect sustain?

Increasing the post pivot weight will mean a tighter spring. A tighter spring is required to counter the force that rotates the string plate towards the bridge. A tighter spring means less energy is lost to the spring as it can move less.

That is the physics. Whether you can hear that difference is uncertain. You must build one to check. Given the high torque of the strings on the spring plate, I assume a very heavy weight is required; heavier than the vibrato’s cavity can hold.

Just tighten your spring.