So I buy a PLX2402 from a talkbass brother. Near perfect condition. Obviously never been in a bar environment. I throw it in the rack for tonights gig, wire it up and turn it on, no problem. Plug my Sadowsky into it to make sure some sound comes out and what I get is the most unbelievable buzz from parts vibration I've even heard. This is at a conversational volume set up in my friggan' kitchen! Thus begins two hours of tapping and vibration hunting. The plastic air ducts are vibrating against the fiber ducts, both of which are vibrating against circuit boards. The circuit board that takes the ribbon cables is vibrating on all four mounting posts. Nothing is shock mounted that I can see and it would appear that no attempt was made what-so-ever at the factory to address vibration issues. Mr. QSC I would respectfully suggest that you take the entire PLX series back to the drawing board and invest in a little rubber or clearly state that these things are totally inappropriate for use in a rack mount bass amplification system. It does however, seem to sound pretty good once you put foam under the corners of the circuit boards and tape all the air duct seams.
Hmmm ... my new PLX 3402 has none of these problems. It's kind of dumb to assess the entirety of one of the best amplifier lines available on the basis of one used example. Wonder why the guy was selling it. Maybe he dropped it just that one time?
You can blast an entire line based on your experience with one used unit (freedom of speech at work), but don't expect a lot of "me too" replies. If you did a poll on PLX owners, I bet you would find around 90% plus who really believe that they are vrey good investments. My experience with the PLX1602 that I've owned for about 6 months, is all complimentary and no criticism.
their customer service is absolutely incredible! try talking to them first and then ranting if they are unreasonable... which i am fairly certain they won't be. and if it was working before it shipped your beef may be more with UPS or fed-ex rather than QSC.
I have 5 PLX units; none of them buzz noticably, though I have other branded amps that do. One of the 5, which I bought Reconditioned, went bad and QSC fixed it for free and shipped it back very quickly. QSC Rocks! Aloha, Jonathan
The only reason I blasted the entire line is because I looked inside and saw that, to me, the problem was obvious. You could see it comming down the street with a brass band leading the way. You can't put lose fitting plastic parts in a power amp and expect anything else. You can't friction fit circuit boards to steel posts and expect them not to losen sooner or later. To me it just seems like thoughtless design. It's not an issue in a comercial install and it's not an issue in a sound company's amp rack but sitting on a bass players cabinet it is. If your's doesn't make noise that's great. Sooner or later it will. I don't see any way it can't. Look inside your's and you'll see what I'm talking about. Let me reiterate, the one I got is spotless inside and out. No evidence of any use at all. No dust, no smoke, no nuthin' certainly no dropage. I mean come on, give me a break. They ain't cheap. I could strap my Crown to the side of a jack hammer and not worry about it. The unit sounds good. It seems to be made of top quality components. It's just very frustrating that they seem to have chosen to take all that hard work and just snap it together rather then mechanically connecting the pieces. Like I said, look inside yours. The issue is there.
I had a buzz in my 2402 (brand new) when it was sitting on my Berg 322. I bought a Auralex Gramma and that totally stop it. Shame one would have to do that though. Anyway I found lots of uses for the Auralex Pad. Since I've sold the 322 and now the rig sits a top my BergNV610 with only a 1" piece of foam insulation under it. I use that anyway because the SKB case slides on the cab. NO buzzes that I can hear. Your problem sounds a lot more severe. My buzz was only slight and most when I hit a lower E-F-F#-G. A real nice "Brother Talkbasser", sent me some Stays (little plastic board clips) but I never installed them. QSC is a great product, I have one PLX and two MXA's. Good luck.
I also heard some loud vibrations when the rack holding my 2402 and Kern sits atop either of my cabs. A solution for me was to place a couple of mouse pads between the rack and the cab. No more vibration noise... you may also want to try other vibration-dampening materials.
Hmmmm....I got a Crown that sits in a rack atop an Eden 410, and sometimes a 215. I have NEVER heard a buzz, a rattle, or a squeak. What I do hear is some killer tone! -Mike
WOW! Gosh! I own two PLX'and have nothing but praise. I'd have 2-3 more if I could justify a use for them. So sorry to hear that you had that problem. Please write to QSC customer service about the issues that you found. They are at the top of the list for customer service.
That is the "keyhole mounting" thing I mentioned in the "resonance" thread. The QSC is designed to be used for PA, meaning somewhere it isn't going to get shook up like a combo bass unit. Frankly, that's how they are made affordable. But, QSC is an absolutely killer line of amps, I wouldn't jump them for that. I have had them REPLACE AN AMP for me when we were doing a sound gig at the NAMM show. We had a dead one and went to their show booth to see if we could get a loaner. Dude, they BROUGHT a new one over, wrote the paperwork on the spot, and took away the bad one. DONE. if that ain't cool, I don't know what is. A class act. And I would suggest just what everyone in the "resonance" thread said....don't put it on the speaker, and don't worry.
dude.....what are you all excited and YELLING about?? you had a dead amp, and they REPLACED it for you? on the SPOT? they even BROUGHT it over to you? instead of what? replace it the next day? you BRINGING it OVER to them? what else were they supposed to do at a show to showcase their gear? flip you off and walk away? you like QSC alot, as i can see....that's cool....but your experience is not something any other company wouldn't have done in the same situation. -Mike
FWIW, I use a PLX3002 in my bass rig, sits in an SKB rack directly on top of 8 10" speakers, loud as hell, plenty of lows, and I have NO problems at all.
My new PLX3002 has no issues of any kind and sits directly on top of 4 Acme Low-B2s. Tops on the customer satisfaction scale here. At some point I will probably invest in a gramma pad to protect the PLX and my DB680. Your suggestions about adding foam and rubber shock mounting are sensible and based on experience I am certain QSC will consider the ideas, if they haven't done something to address this already. They really pay attention to customer satisfaction.
i have a 3402 that i used on top of a bergie 210 and 322... never a problem. nothing but smooth, clear tone.
I picked up a new 3002 this week and noticed a HORRIBLE (yes, HORRIBLE) internal buzzzzzing while in an SKB sitting on top of my Aggie 112's. To get through our gig last night I put a couple of pieces of white packing foam under the corners of the case and the buzz was eliminated. This is totally unacceptable from a $800 power amp and its going back to GC this week. BTW, Notanaggie, according to the user's manual these QSC amps are designed for instruments, not just PA applications.
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