Drop fabric that is visibly opaque but acoustically transparent

We're doing a production of "Ragtime" in which we're putting the orchestra upstage of the scenery so we can leave the pit covered and bring the singers/dancers cloesr to the audience. I need to hang a drop downstage of the orchestra (upstage of the set) that I can front-project onto, as well as hitting it with some cyc lights. Does anyone have a recommendation for a fabric to use that is visually opaque (projections won't bleed through onto the orchestra and orchestra lights won't visibly show through the drop to the audience) but acoustically transparent. I don't have the equipment or rental budget to fully mic the orchestra, so I need the live feed in the house.

Thanks!

Such a puzzle.

I would say some sort of scrim Or 2 scrims double up.

Even though it's not completely acoustically transparent, any loose woven, plain weave or stretch fabric won't have significant absorption or diffusion of the sound of your orchestra, and should be more physically resilient than scrim or cyc material.
And assuming your orchestra is good at self balancing, a couple of overhead mics would be sufficient at making up the presence lost by the 40ish feet they're further away from the audience. You will have some time alignment issues, however.

There are microperforated projection screen/surfaces, I know Gerrits makes them. My assumption however is that the cost of a microperf drop is going to be about the same price as the cost of renting enough mics to amplify the orchestra.

macsound said:

Even though it's not completely acoustically transparent, any loose woven, plain weave or stretch fabric won't have significant absorption or diffusion of the sound of your orchestra, and should be more physically resilient than scrim or cyc material.
And assuming your orchestra is good at self balancing, a couple of overhead mics would be sufficient at making up the presence lost by the 40ish feet they're further away from the audience. You will have some time alignment issues, however.

Click to expand...

This is probably the best solution. If in doubt, shove a monitor speaker where the orchestra would be and test it out. You shouldn't need a lot of level from the overhead mic's but you will have some mid/high-frequency you'll want to compensate for that'll get lost in the fabric.

Most digital sound consoles have delay built into them. In this case, you would want to send all the pit orchestra mic's to a mix buss, drop an effects module in on that mix buss to add 20-60ms of delay until the acoustic sound of the drum kit is matched up with the amplified sound coming out of the PA.

Please be mindful: Many consoles also have "Input Delay", where you can delay individual channels as soon as they arrive in the console. At first glance it may seem like this solves your problem but if you are putting drums or anything percussive into foldback monitors for the pit orchestra or the singers you will discover everyone losing their rhythm when their stage monitors are delayed +40ms from the instrumentalist 10' away from them. Input delay affects the signal anywhere/everywhere that channel goes. You only want to delay the pit orchestra in the feed that goes to the mains -- not in any stage monitors.

30 denier or heavier Tricot. If it's not stretched too tightly it's translucent without being transparent. It is damn-near acoustically invisible.

Both Rose Brand and Dazians offer the "Janus" line of IFR rated polyester scenic fabrics. They are acoustically transparent. We have had our acoustic engineer measure this fabric and it works very well in our applications. It comes in several colors including a few grays that work well for video projection. It is not 100% opaque.

I'm a little late to this party...

I haven't done any scientific testing in terms of accurately measuring acoustically transparency, but to my ears and in my experience -- I would recommend a product called chameleon scrim. It's cheaper than conventional scrims, takes paint pretty well, and is a decent projection surface. It does have a texture weave to it. It kind of looks like spun fiberglass, or the fabric you use on the bottom of bed box springs. Anyway, here's a link to it:
http://www.studio-productions-inc.com