Fan Mod on a QSC RMX850

Discussion in 'Speakers & Subwoofers' started by DavidVT, Jul 26, 2003.

  1. DavidVT

    DavidVT Stunt Coordinator

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    Has anybody heard about doing this?

    I bought this amp to drive my passive SVS and it does this just super, but does it too loud IMHO. When movies or music is played, I cannot really hear the fan of the QSC but at low volumes, it is present.

    Any assistance would be greatly appreciated!!!
     
  2. Ron_L

    Ron_L Second Unit

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    try moving the amp?

    you might be able to change out the fan, but you risk voiding the warrenty.
     
  3. steve nn

    steve nn Cinematographer

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    I understand your frustration David. I bought a QSC 1450 4-5 months ago and was quit surprised in the level of noise the fan made. I posted the same question as you on over in the DIY section and did get some good feedback. One was from John over at QSC. Just punch up my profile and then Threads started by me. It will be the sixth Thread down from the top. A vented Plexiglas/wood enclosure will also help along with placement. Just turning it a little if this is a option can help.

    After some time I have gotten used to it and have not dealt with it yet. I don't really notice it anymore but most likely still will address in time. I think I will go with the enclosure option. I run duel jumped SVS's and a AV15 off mine and have found the QSC very dependable. It's never even broken a sweat with three subs feeding off of it.
     
  4. DavidVT

    DavidVT Stunt Coordinator

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    Steve,

    Thanks so much for the reply. I know now what everybody has been saying about the SVS [​IMG] I put her through her paces today. Nothing but smiles. Even though it is an older CS model (25-31) tuned to 22hz, it fit in with my other sub, a Def Tech PF15tl+ seamlessly. I now will use the SVS for music and both for HT. I seriously thought my walls were going to fall down [​IMG]

    I am using the RMX850 in bridged mode and will eventually just use one channel for the SVS and the other for some bass shakers. During this evenings movie (thirteen ghosts) I couldnt hear the fan, but that was cause I was at reference levels.

    Will look into the info you provided via your post for acquiring a less noisy fan. I also bought an extension for the headphone jack so I can move it out of the built-in audio cabinet and into the equipment room.
     
  5. Steve Stogel

    Steve Stogel Supporting Actor

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    Whoa! That's an amp I was looking to perhaps get to power that DIY Tempest I just bought, and I believe it's 800+ watts when bridged into four ohms. I'd think that using just one side right from the get-go would be good (300w, methinks), but I've never pushed more than my 150w into the SVS. I'm pretty sure that much more than 350 or so could subject the SVS to bottoming out, BUT if you didn't bottom it out (I've heard that you'd know it if you did) while playing 13 Ghosts at reference, it may be that that will never be a problem (lucky you).

    Still, if you've got all the headroom you need with 300w, maybe that's the way to go...less THD and all (I think it's like 0.1% versus 1%). I know there's no way you can probably tell a difference, but just knowing that you've got one-tenth the distortion has to be worth some peace of mind [​IMG]. If you do a fan mod on the RMX, please do inform us of how you like it, as that's an amp I'd be interested in down the line. Talk to ya later.

    Steve
     
  6. Ben_E

    Ben_E Stunt Coordinator

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    Hey DavidVT, I have an RMX1450 from QSC and this thread over at AVS forum helped me when I did my fan mod.

    http://www.avsforum.com/avs-vb/showt...&highlight=QSC

    Overall its pretty easy, just a little soldering involved. I bought a 'quiet' fan and it was still too loud for my tastes. Good thing I ran accross that thread that explained to get a 15 turn 1Kohm cemet potentiometer to adjust it even further. I didn't get the popular panaflow only because I couldn't find it although I may still get it in the future and see if I can increase the fan speed with the same amount of noise as I have now. All I'm using is 1 channel of the RMX1450 to drive a 200watt sub right now so its not really getting a workout, I'll have to wait until I get my AV15 sub project done until I can see if I need to increase the speed of the fan. The 15 turn 1Kohm cemet potentiometer allows you to turn the screw decreasing the power to the fan hence slowing it down to your desired level. Let me know if you guys have any more questions about the fan mod(s).
     
  7. DavidVT

    DavidVT Stunt Coordinator

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    Hey fellas,

    Thanks for the replies. Steve, if you were cosidering this amp for your new sub, you should listen to it. It would definetly be considered loud. BTW, the invitation is still out if you ever get my way [​IMG]

    Ben,

    I'll give that a shot, maybe this weekend when I have some time to tinker with it... and thanks for the link on AVS.
     
  8. steve nn

    steve nn Cinematographer

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    Glad to here your getting things dialed in David. Something you might consider is calibrating each sub individually and then running both with a combined output at +? whatever you like for HT and then +- for music. You can make the adjustment for music on the pro if your PF15 is up to it??
     
  9. DavidVT

    DavidVT Stunt Coordinator

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    Steve nn,

    Just tried that last evening on the Eagles "Hell freezes over". DVD-A/DTS. Very, Very nice. Still figuring out the best settings for SACD, slowly but surley they are coming around!
     

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