| Author | Message | ||
| davehouck
Senior Member Username: davehouck Post Number: 484 Registered: 5-2002 |
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
Advanced Member Username: keavin Post Number: 305 Registered: 12-2002 |
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 | ||
| davehouck
Senior Member Username: davehouck Post Number: 485 Registered: 5-2002 |
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
Advanced Member Username: keavin Post Number: 306 Registered: 12-2002 |
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!!! | ||
| davehouck
Senior Member Username: davehouck Post Number: 486 Registered: 5-2002 |
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
Intermediate Member Username: 811952 Post Number: 155 Registered: 10-2003 |
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
Junior Username: kevin_k Post Number: 45 Registered: 4-2003 |
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 | ||
| davehouck
Senior Member Username: davehouck Post Number: 487 Registered: 5-2002 |
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
Member Username: rraymond Post Number: 56 Registered: 6-2002 |
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
Intermediate Member Username: 811952 Post Number: 158 Registered: 10-2003 |
We are a scary bunch indeed... ;) John | ||
| davehouck
Senior Member Username: davehouck Post Number: 488 Registered: 5-2002 |
John; the solution may be to get a good speaker cab builder to design a house to practice in. <g> | ||
| dannobasso
Junior Username: dannobasso Post Number: 17 Registered: 3-2004 |
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
Intermediate Member Username: 811952 Post Number: 159 Registered: 10-2003 |
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
Member Username: rraymond Post Number: 57 Registered: 6-2002 |
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
Senior Member Username: bracheen Post Number: 407 Registered: 11-2003 |
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 | ||
| dannobasso
Junior Username: dannobasso Post Number: 18 Registered: 3-2004 |
I used to use a 10sp case in case rack for my rig when I was using midi bass pedals and 2 modules, wireless etc. It was just too much to bring to NYC gigs. I've since dropped the pedals I've gone to 2 6 sp road ready, calzone racks. One for stage, one as a spare rig. If the club has chairs, you just saved on a stand for your head! Danno | ||
| 811952
Intermediate Member Username: 811952 Post Number: 160 Registered: 10-2003 |
Danno, I used to use a Calzone case-in-case, which was tall enough to stand by itself next to my speakers. That was a great setup, but totally unmanageable for me to lug around these days. I used Taurus pedals those days. Oh how the floor would shake...  Sam, I try to use chairs or empty cases if I can. I might build something a little more elegant. Reid, I play just enough upright to be really average. I envision acoustic jazz to be more a part of my life as I age and am surrounded by serious jazzhead friends and family (which I already am). Until then, though, I will be rattling... John | ||
| rraymond
Member Username: rraymond Post Number: 59 Registered: 6-2002 |
Hey John, Sounds like you and I are in the same ballpark regarding the upright. I really dig playing it, but right now it's more of a specialty thing. I don't actually have a doghouse bass, I use a Zeta Crossover, it's pretty cool and it gets the job done well-enough! I never used the Taurus pedals, but I've still got an old Moog Rogue sitting around, definitely a floor-shaker! I read elsewhere on the boards about the floor-shaking capability of the SF-2, now I want one! It never ends, does it? | ||
| rraymond
Member Username: rraymond Post Number: 60 Registered: 6-2002 |
Yoiks, I almost forgot! Hey Sam, your question about setting the amp on a stand is absolutely valid, but the manufacturer of my cabs recommends placing the amp on top of the cab to help it couple to the floor. They are Acmes and they really shake floor! :-0 I'm trying to imagine the goodness an SF-2 would add... Take it easy, Reid | ||
| dnburgess
Advanced Member Username: dnburgess Post Number: 247 Registered: 1-2003 |
Acme recommends placing the amp on top of the cab from the point of view that weight on the cab will further reduce cabinet vibration that might otherwise muddy your sound. I find that, in practice, the rattles and shakes in my rack outweigh the benefit and I always place my rack on the floor near to my Acmes. David B. | ||
| davehouck
Senior Member Username: davehouck Post Number: 490 Registered: 5-2002 |
Speaking of floors. I rehearsed Friday night at a house with a deep carpet that seemed to really eat up my speaker output. I'm wondering if getting my speakers off the floor would have helped significantly. Any one have any suggestions? How far off the floor would make a significant difference? | ||
| son_of_magni
Junior Username: son_of_magni Post Number: 31 Registered: 1-2004 |
I had a cab that developed a buzz and I spent many hours trying to get rid of it. If I pushed my knee hard against the back it wouldn't buzz so I threw out all the old screws and replaced them with longer screws and added a bunch more. Still buzzed. The cab sat for years unused because of this problem. It was at the house where I grew up. I had kept it there because we still have jams there a few times a year. Finally I brought it home to try to fix it. Turns out it doesn't buzz now. Must have been something else in the room all along. | ||
| rraymond
Member Username: rraymond Post Number: 61 Registered: 6-2002 |
Hi David B., Thanks for the clarification re:amp placement on the Acmes. I went back to the manual and realized that I had remembered the first sentence of the paragraph detailing amp placement, the "where", but I had forgotten the "why." Out of curiosity, do you stack yours end-to-end as a column, or on their sides? I've got a B2 that I use on small/mid-sized gigs, and a B4 for bigger gigs and I have never had the need to pair them up. They sure are great cabinets! Reid | ||
| dnburgess
Advanced Member Username: dnburgess Post Number: 248 Registered: 1-2003 |
I have used the B2 horizontally on top of the B4 - with the Spyder. Now thats a nice sounding set up. I am just playing in a B2W which I look forward to using with the B2 in horizontal vs vertical configurations. A very busy Sydney player just bought a B2 and will probably add a B2 or B2W - so soon I'll have plenty of horizontal vs vertical experience to report. |
