Rycote/Rode Invision Shockmounts - do they work as well if inverted?

[Mike Stranks]

Here's something that's had me pondering for some time: do 'Invision' shockmounts work as well if upside-down?

The basic principle is that of the lyre - a U within a U if you will. In their normal plane they work by compression - a load on the inner U is born and cushioned as the force is transmitted to the external U.

But are they less effective if placed upside down and the load is now applying tension rather than compression?

I have several different versions of these effective devices, two of which I sometimes use on a boom arm with the shockmount inverted.

Of course, I know they won't work as designed if operated in a vertical mode - ie with the load being applied as a shearing force. This typically happens if a third-party twin mic holder - eg to get ORTF spacing - is placed into an Invision.

Jus' wonderin'....

[Hugh Robjohns]

Just for clarity, which InVisions are you talking about the LDC (Studio) version:



Or the SDC version:

And by upside down do you mean with the mounting bar/ring horizontal above, or vertical?

H

[Mike Stranks]

Well both really!

But with the LDC version - when I had one - I just inverted the mic so the shockmount was as in your pic, but the capsule was below it.

For SDCs I have three of various sizes and configs, but when (not at the moment) using an SDC on the angelpoise I mount it like this:



Obviously it still works, but I'm wondering if it's losing some of its effectiveness?

Hardly a key and fundamental question, just idle curiosity.

[Hugh Robjohns]

Ah yes... I don't think mounting that way up affects the isolation performance to any significant degree. It's the acute angles in the sections joining the two 'U's that provide most of the compliance and I believe that doesn't change between pulling and pushing.

However, that's just my own theory... I've emailed the original designer to ask for his take on it, and will post his response when received.

[ef37a]

I bet there is some G'awful mathematics involved invoking Young's whatsit!

Dave.

[Mike Stranks]

Ah yes... I don't think mounting that way up affects the isolation performance to any significant degree. It's the acute angles in the sections joining the two 'U's that provide most of the compliance and I believe that doesn't change between pulling and pushing.

However, that's just my own theory... I've emailed the original designer to ask for his take on it, and will post his response when received.

I thenk yew...

[Hugh Robjohns]

Words from the guru:

Turning a lyre sideways or upside down has very little effect on its
operation. From the beginning of the lyre concept I assumed that mics would have any orientation with regards to gravity. After all, I was at various times a sound recordist myself and knew that you pointed the things up, down or sideways, so any mount needed to be able to work properly irrespective of orientation.

That applies equally to the "crown" (Studio) version for side-address mics - I presumed that many would be used in a horizontal plane or fully inverted. Hence the use of 4 lyres on the Rycote mounts to hold horizontal mics reliably, irrespective of rotation.

There are, if you like, two elements to the design. The one is to provide a high compliance along the axis of the mic's diaphragm - that's what keeps it well isolated from vibration - and secondly to provide physical support. The latter is important because if the mic can slew around, sideways forces that would normally only have a slight effect on the diaphragm become translated into axial ones that have a much worse effect.

Provided that the support for a mic - particularly a heavy one - is roughly around its centre of gravity (or cantilevered firmly in the case of a rifle mic), and the mic doesn't have a tendency to wobble sideways, roll, pitch or yaw, then the lyres will work fine no matter which way up they are.

With the ORTF arrangement - yes, I think I understand what you are describing - two linear lyres, but with the mic heads pointing at an angle. Not ideal.

So... it doesn't matter which way up you use them. But placing two mics in a coupler (ORTF, XY, etc) on a single lyre is non-ideal because the maximum lyre compliance is no longer along the axis of either mic.

HTH

[Mike Stranks]

Thanks Hugh - and please pass on my thanks to Chris.

I'd suspected that something from Rycote would be versatile, but just wanted confirmation.

And practical experience (once!) of using a coupling/spacing mount in a vertical Invision SDC mount showed that it was far from ideal. Apart from everything else, the shearing force - even with two CM3s - was significant.

Thanks again!

[Hugh Robjohns]

Thanks Hugh - and please pass on my thanks to Chris.

Will do!

And practical experience (once!) of using a coupling/spacing mount in a vertical Invision SDC mount showed that it was far from ideal.

Indeed... Chris came back with more specifically related to this:

The trouble with in-line lyres used for ORTF or XY is that you ~only~ get a 50% (ish) reduction in handling noise - there's a vector at 55° or 45° that still helps to some extent. I used that technique for the Cyclone stereo XY mount - no chance of fitting individual lyres to the CCMs etc used for that - and the results are not bad. That's mainly
because the lyre is so good that a 50% reduction is still acceptable.

The more critical error is when the supporting lyres are close together and give too short a "wheel base", with the mics stuck far out. The leverage on the lyres increases and the likelihood of wobble, with all the translation of forces that that brings about, reduces isolation massively.

...exactly as you experienced!