laolu

A thermal problem, maybe. Something gets warm / hot inside the receiver. To confirm this, I would open up the revceiver and when the crackling appears, blow cool air inside. If it stops crackling, go into details with a freezer spray. Systematically circle in on the heat sensitive components. Caps are among the usual suspects. Good luck.

When I started reading your post, I remember the headaches I had in 20+ years of theatre work. And my job was with university students! It is quite a futile endeavor to amplify a shy whisper so that a booming voice comes from the PA. No no no. So your >head of drama< has only two options: train the kids to speak up. (They can be noisy in other situations!) Or pre-record everything and let them lip sync. Whether children can do that, I don't know. BTW, I used 2 shotguns hanging from the ceiling and 3 on the floor, and fed the signal to speakers at the rear wall. Audience in the front could hear sound from the stage, audience in the back sound from the speakers. Those in the middle a little bit of both. And it worked - sort of.

I put everything under a UV light over night. I am hopeful, but not 100% sure, if that works. For peace of mind - yes.

As jivemaster seems to suggest, add a power sequencer, if you think turning and and off amps is the problem. We have one on our theater PA, with just one button for turning the system on and a different button to turn it off. Never had a problem from that point of view. If your HF drivers blow regularly, then the PA-users (= students, teachers) are responsible. Maybe invest in something like a dbx driverack, even if you only use its limiters. My 2 cents

Often, when they ask for "echo", they mean "reverb". If that's the case, presets 1-10 would be worth experimenting with. If really it is "echo" they want, preset 14. But this unit has no tap tempo, so it may be troublesome to find the right tempo. Aside from that - I'd use an AUX out (to send signal to the FX2000) and a line in (to get the effect signal back) rather than insert. You'd have better control over the amount of effect you want to add. Hope that helps Norbert

Mipro Taiwan. Which used to produce the kit for Beyer back in the nineties, is quite established in the professional audio market. I'm using their products for more than 10 years. They offer what you need in a range of 480 to 960 MHz: there should be something for you to choose from. Just don't know whether they have a dealer in the UK. ( https://www.mipro.co...p5.html?gid=424 ) P.S. Made in Taiwan is NOT Made in China! :D