...Any ideas? Again: I have two identical units in the same space, and they both sound like this...
…But pretty much as Don's already said, all I can make out from your sample is what sounds like a handling "thump" at the head, with some harshness evident in the sibilant range when "the rockets' red glare" was being patriotically proclaimed in the true spirit of Thanksgiving.
The worst artefact to my mind was the bassy wind rumble from the lack of the urethane windshield that would be required for the poor whistling technique that started the sample.
(Experienced whistling performers know to aim their mic upwards and whistle "over and across the top" of their capsules, rather than directly into a mic's diaphragm.)
So all I can add to what's already been noted is that further attention to the pogo pins of your beta58 capsule (as Don's suggested and you've subsequently proven) may be all that's required for ongoing successful operation on your XD-V70 handhelds.
The fact that you could not get a Shure head to work on the V70 but that it did on a V30 is troubling. That makes me suspect mechanical coupling could be the problem. Line6 capsules do not work on Shure wireless so that's not an issue.
You could try putting ink from a sharpie pen on the traces of the V70 capsule and then screwing it back on. If the pogo pins are working correctly they will scrape off the ink in a nice even circle.
Dirt or oxidation on the pins of a Shure "head" could also easily be contributing to the issue at hand, so I'd try VERY CAREFULLY applying a few drops of something like this http://www.amazon.co..._pr_product_top to the base of those pogo pins.
My technique for doing that is to first spray the contact cleaner into its lid so as to create a tiny "puddle" of the stuff, from which I then pick up a droplet with the point of a pin in order to deposit it around the base of a given pogo pin.
Subsequent and repeated very gently depression of that pogo pin will then carry that minuscule amount of cleaning fluid in to where it can do its job.
Having done that, I then finish up by repeating the process with an equally tiny amount of a kerosene based moisture excluding lubricant, such as this http://www.amazon.co.../dp/B0083V8F7I/.
As for your RF dropouts, further support of this excellent checklist...
...If you cover the antenna you no longer have clear line of sight and you will cut your range.
How are your antennas hooked up? Do you have the terminators installed? Are your antennas splayed? How high above head height are they? What version of firmware are you running?
… is the fact that MY four XD-V70 handhelds (and one V75) all regularly operate at ranges of up to one hundred metres, (well over the stated maximum) ...but only when my antennae are deployed according to the guidelines stated here:
http://line6.com/dat...h ( Rev B ).pdf