Something I've noticed at several live shows (especially blues and jazz) is these short plexiglass walls placed in front of the guitar amplifiers. Why would they do that? What are they for?
Why is plexiglas(perspex) sometimes placed in front of guitar amplifiers at live shows?
They are used to manage the on-stage volume levels while still allowing the amplifiers to be cranked up for tone. These shields limit the amount of sound directly hitting the on-stage performers. You will also see them around drummers.
This type of shielding will also reduce cross-talk, e.g. preventing the drum sounds getting captured by the guitar microphones, but I haven't heard of this being the primary driver for on live shows; but they have been used in studio situations to reduce bleed.
1You can also see sound shields on stage in orchestra. Usually to protect the players that are in front of the trombones.– ÉdouardMay 16, 2014 at 14:59
@Édouard accurate. Source: am trombonist :-) May 17, 2014 at 7:49