I doubt you could hear a moisture packet rattling at that volume. Probably something else.
Here is someone else experiencing the same buzz.
From a
sweetwater review:
Compact thunder
January 30, 2014
some guy in lbc, Los Angeles, CA
Music Background: bass player - unsigned indie scene - LA
The point of this cab is walking into the gig with everything you need in one trip. A giant rig is a blast to play, but, it's giant. How's that spine treating you? This cab can be a viable alternative for some.
I'll start with the most negative thing I've noticed: it's simply not that power efficient. It handles power, but it also *needs* power pumped into it. Compared to the GK 212 Neo cabs that I also own, the SP212 is dramatically quieter at the same settings on the head. Like, different class of volume. And it's probably a valuable comparison, as both cabs are 2x12 and similarly priced.
I'm not saying this cab doesn't get sort of loud, it's just not nearly as loud as some of your other options.
I'm using this with a P bass with a slightly overdriven rock tone, which is actually probably what this cab most wants to do. As such, I'm not missing the tweeter horn this cab doesn't have, nor am I missing the seismic lows that this cab doesn't deliver either.
If your standard tone is a warm, mid-heavy thing, this cab might work well for you.
I played a smaller room with it where the kick drum was mic'd but my bass was not in the mains. The musicians in the crowd commented later that they were surprised that all of the bass came from just that cab. So, it can fill a small room with a 500W class-D head driving it.
If your band is genuinely loud, and your instrument amps have to carry the room, this is probably not a candidate for your main rig.
However, if you're playing a venue that has massive house sound, this may be fine, since the mains are where the work will get done.
Style-wise, the Orange gets respect, so if you want to waltz in to the venue with this little box while the other bass players are dragging around their "small" Ampeg 410HLF boat anchors, you'll suddenly have a bunch of new friends because people want to check out the tiny thunder box. The 410 will still ultimately spank the SP212, but again, if you're not actually using all that headroom, the joke is on you for dragging that thing around. I would know. I have a 410HLF too, and I have bring my truck when I use it. I can just whip the SP212 in the trunk of my car.
When I first unboxed and plugged in the SP212, there was a terrible buzzing sound, and I thought I had a bad unit. Thankfully it turned out to be a silica gel pack that was hidden way back in the port. After rolling the cab over a few times, it fell out, and everything has been fine since then.
So, there's a ton of blab on the SP212. It's a good little box, if you ask the right things from it.