Author Topic: QSC buzz (Read 543 times)

David Houck · « **on:** April 23, 2004, 07:09:29 AM »

My QSC PLX has developed an exceedingly loud vibration. A loud buzz comes from the amp when I'm playing low notes; it seems especially bad around C on the E string. Any body have this problem before?

keavin · « **Reply #1 on:** April 23, 2004, 07:29:43 AM »

sounds like it could be possibly a loose screw,or somthing because low notes tend to vibrate things that arent tihgt or glued down, ,,,,,,but however it doesn't sound electrical to me,try gently shaking the unit wile its turned off and listen for somthing moving around inside,that might let you know if somthings kinda loose

David Houck · « **Reply #2 on:** April 23, 2004, 07:55:37 AM »

I agree, it's probably that something is loose. I have previously made sure all exterior screws were tight and there appear to be no rattles. I've got the cover off now and nothing jumps out at me except the sticker that says Danger.

keavin · « **Reply #3 on:** April 23, 2004, 08:11:51 AM »

yeah be careful, but also you can hit a low note with the cover off and look carefully inside to see what might be the source while hitting the note,but like i said over time bass stuff due to low frequencies will rattle loose,after 30yrs of bassplayin my wife always tells me i have another screw loose!,,,,musicians are like pick-ups, were not always wound tight!!!

David Houck · « **Reply #4 on:** April 23, 2004, 08:34:38 AM »

Well, with the cover off I put the amp on a padded stool, wired the rig back up and played some low notes. The amp did not buzz at all. I put the cover back on, put the amp back in the rack, put the amp rack on top of the rig and the buzz was back. I put the amp rack back on the padded stool; no buzz in the amp but buzz in the rig. I put the preamp rack on another padded stool; now just a little buzz from the speaker cab. Changed speaker cabs, still some buzz. Moved the cab a couple a feet, much less buzz.

I think what is going on is that the low notes are vibrating the house, and those vibrations are feeding back through the rig when it's all stacked up. I think I might look around the house to see if I can find some foam to put between each component of the stack; perhaps that might cut down on the feed back vibrations. It's certainly disconcerting to hear my QSC seemingly shaking itself apart.

811952 · « **Reply #5 on:** April 23, 2004, 08:47:53 AM »

I have that problem with my skb racks, so I try to either setup with my preamp/amp/stuff on the floor near my cabinets if possible. It's annoying and eventually components are going to vibrate loose if you don't get it taken care of. If you ask a QSC repair tech about it, I would bet he knows what parts are about to be liberated from the rest of the unit and would know of a solution for you (like maybe dabs of silicone adhesive around the offending part).

kevin_k · « **Reply #6 on:** April 23, 2004, 08:50:10 AM »

I have the same problem. I have two QSC amps that are in a SKB 8 mount rack. When the rack is placed directly on top of the cabs (4x10 & 1x18) it rattles/buzzes. I purchased a $25 platform to go on top of the cabs. The platform is basically carpeted ply wood with foam attached to the bottom. It dampens the vibrations before it gets to the SKB rack. I am sure you can make something similar.

Kevin

David Houck · « **Reply #7 on:** April 23, 2004, 09:18:11 AM »

Thanks guys. Yes, I'm using SKB's also; and I recently did switch the amp rack from a wood and carpet rack to the SKB, so SKB construction is probably contributing to the problem. I put my stack back together and separated the speaker cabs from the racks with an old blanket folded to size. That seems to have solved the problem. Looks a little funky, but it works. Life is much more pleasant now!

rraymond · « **Reply #8 on:** April 23, 2004, 11:53:56 AM »

I had the same problem - in reverse. I went from a SKB rack to a Road Ready rack and was treated to buzzing and rattling. Luckily, it was pretty easy to discover the source - the latches for the front and rear panels. The fix has been really low-tech; I wrap wide rubber bands or those little elastic pony-tail do-dads around the latches and that quiets them down right proper!

Reid

811952 · « **Reply #9 on:** April 23, 2004, 01:54:43 PM »

We are a scary bunch indeed...

John

David Houck · « **Reply #10 on:** April 23, 2004, 02:04:54 PM »

John; the solution may be to get a good speaker cab builder to design a house to practice in.

dannobasso · « **Reply #11 on:** April 23, 2004, 04:50:25 PM »

I always have to make sure the catches on my racks are seated firmly. Hardware rattles as do walls, furniture etc. I grew to detest SKB. Calzone, Anvil and Road Ready hold my gear. Discount Distributors in Holbrook NY have good prices.
Danno

811952 · « **Reply #12 on:** April 23, 2004, 07:45:51 PM »

Dave, Amen to the idea of designing a house for music. I somewhat did that with the house my wife and I have been building for the last 3 or so years. Extremely high ceiling, lots of pine, bamboo and precious little carpet or drywall. It's got a nice ambience for acoustic music. Ahh. I bet *everything* will rattle when I plug in a bass though..

I switched to the rattle-prone SKB racks because I'm just too old to carry all that plywood around anymore. I can see where maybe I'll switch back (after I buy a new hand truck), because the rattle can be demoralizing. I am one fickle old man..

John

rraymond · « **Reply #13 on:** April 23, 2004, 09:03:40 PM »

Demoralizing is the perfect word. I bought the Road Ready rack because I bought a QSC2402 amp and it wouldn't fit the SKB I had. The first time I fired it up - rattle and buzz. I was appropriately freaked - and demoralized - that the expensive, highly rated amp that I had just bought, had a serious problem. As I said above, a bit of investigation revealed the problem to be the latches. Whew!

Sounds like a nice house, especially for acoustic musicians, do you play upright? If not, rattle on! ;-)

Reid

bracheen · « **Reply #14 on:** April 24, 2004, 08:29:04 AM »

Why not get some type of stand for the rack to sit on beside the cabs rather than on them? Would that help? I've only played combos so far so I'm guessing.

Sam