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QSC 1450 RMX Fan kit?? (1 Viewer)

steve nn

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I have tried the search function and have fired a mail off to PE. Google has not been a help either and I know a kit exists "for the 1450" but I just cant find it. My objective is to reduce the noise of the fan. Any leads? I will mail QSC next I guess. Vexed
 

Eric Hargrove

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Nov 24, 2001
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Hi Steve,

I have emailed QSC tech support and they were absolutely no help. I have the RMX2450 and it has the exact same fan. The amp has plenty of power but the fan noise can be annoying at low volume. The QSC tech told me to just look at the back of the fan to see how much current it pulls. I do know it is a 80mm 24VDC fan QSC PN 8900-9050-1 and it is used in all RMX amps. I know nothing about its CFM rating or its rated loudness when it is spinning at its max airflow capacity. I am going to take a look at it today and see what I can find out. Tech support did say the fans on the PLX series are quieter. Who knows if they flow enough air or even fit. I will do a search on the net when I have some more info.
 

steve nn

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Jan 12, 2002
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Hey' thanks Eric. I will keep trying also. If I put my meter to within 6-8" of the intake or out, I register 55db. With all the technology we supposedly have now?> this is unacceptable imo. I wonder if I can go vertical on the QSC amp on the back of a sub? This would be a big improvement.:emoji_thumbsup:
 

Adam Butler

Auditioning
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Jan 25, 2002
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Check out the info here

I changed out the fan on my rmx-1450 with the panaflow that is recommended on the second page of the discussion. The difference in fan noise is amazing. The only way to hear the panaflow is to stick your ear right up to the front exhaust. The amp does get warmer if you run it hard for extended periods, but I live in a dorm room so I usually keep the volume at sane levels most of the time. Just keep in mind that changing the fan with another one will void the warranty. Overall, I am definitely glad I swapped out the fan, the difference was like night and day.
I bought a second panaflow from digikey when I ordered mine (they have a $25 minimum order), so if anyone is interested in buying it just shoot me an email.
 

Kyle Richardson

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I have a list of fans and the procedure to change them out if you would like to e-mail me. I'm not sure if QSC wants the information to be posted publically or else I would just paste it here.
 

Eric Hargrove

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Steve, I pulled this info off of the QSC forum. QSC engineer John Gordon advises against doing this however. He appears to be very knowledgeable on the subject. If I were to do this, I think I might try something like a 200 ohm 2watt resistor. Kyle appears to have some good info. You might want ot PM him. The fan noise in my RMX 1850HD is a bit loud. Are there any good ways to reduce the noise without risking overheating?
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Thanh Nguyen
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posted March 12, 2003 12:35 PM
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It requires opening the unit to modify the RMX fan circuit. YOU MUST BE A QUALIFIED TECHNICIAN TO WORK ON THIS AMPLIFIER. WARNING: DO NOT TOUCH THE FAN CIRCUIT WITH YOUR BARE HAND WHILE THE AMPLIFIER IS TURNING ON. YOU MAY GET AN ELECTRICAL SHOCK DUE TO HIGH AC VOLTAGE PRESENTS AT FAN CIRCUIT. Disconnect the amplifier from the AC and wait at least 10 minutes for internal voltages to bleed down before you work on the unit. The fan speed of the RMX amplifier can be set lower at idle to reduce the unwanted loud noise as changing the resistor R17 value from 120 ohm (standard) to 300 ohm maximum. R17 (120 ohm, 2 watt) is located on the AC PCB, behind the power transformer. If your amplifier will be used for speech program or home/church PA system, 300 ohm resistor is a good choice.

--------------------
 

steve nn

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Thanks Eric, Kyle, Jeff and Adam for your help. I think I will start out by seeing if I can go vertical behind my stack or buying a vented single rack enclosure to place it in. This issue can and will be overcome and you all have been a help. Thanks again!;) :star:
 

Martice

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John Gordon from another site:

One thing you can do, that is if your rack has a door or capable of installing a door, is to close a glass door in front of the rack. You need to leave about an inch of space between door and amp though. Which is easy to do because of the rack handles on the amps.
This is giving me an idea of possibly encasing the amp inside of a Plexiglas unit of sorts. The front of the case will be sealed (with an open and shut door built in to access the front controls when needed) with about 4 inches(max) between the front vents of the amp and the Plexiglas. The rear of the case will be open ended (no back wall) with vent holes on the top and sides of the case for ventilation.

My RMX 850 is about 15 inches deep so the case could be about 20 inches deep so hopefully that may help with lowering the sound of the fan in the rear of the unit. The RMX 850 is about 3 inches high so if the case was about 6 inches high the amp could be raised about 1 1/2 inches on the inside of the case to help with air flow on the bottom of the unit. I'm still undecided about about putting some type of sound deadening material on the ceiling of the inside of the case because of heat issues.

One thing that seems a little interesting is the possibility of putting some type of filter foam on the rear of the cabinet that will still allow proper air intake but also will keep the unit kind of quiet fan wise.

Things that concern me about this idea is:

1. Heat issues and if the overall design (top and side vents included) will allow good enough air flow to keep the amp cool enough.

2. If the choice of materials (Plexiglas) is a bad choice and if the unit will start to sweat on the inside.

Any ideas or is this flawed from the beginning?
 

steve nn

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Martice your thought process has been exactly what I have been thinking of. I was thinking wood possibly though and I was thinking no bottom. It would be sort of like a square cake lid or what ever you call it? If I could cut the sound in 1/2 I would be one happy camper. I think I would hide it behind the couch and pull it out when called for. My amp sits on my sub-subs. A guy could line it with sound deadener sheets to. It might not look all that great with the sheets using the Plexiglas but "we do what we do when we have to and for good reason".;) How's that for grammar??;)
 

Martice

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Sounds good to me. How about tinted plexiglas? That would be sweet. I have a link below that does custom jobs but I'm sure that we could find it cheaper if not, do it ourselves (YIKES!!).

Custom Fab Acrylics
 

steve nn

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Tinted sounds great! I think that could possibly move me on over to the Plexiglas camp? I will be sure to check the link out. Another piece of fine furniture for my wife to admire.
 

Darren_T

Second Unit
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Oct 1, 2001
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I suggested this to Martice, I haven't seen the inside of these amps but couldn't you just snip the fan leads and put spade connectors on them and the new quiet fan and connect them up that way? No need to solder and you can swap fans at any time after that if you felt the need to experiment with more selections.

Darren
 

steve nn

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After actually running the QSC for the past week now I thought it best to reiterate just a little.
>
Although the fan is a little noisy during viewing it is not noticeable except with the real quiet scenes and this can be overcome with the prior suggestions.
>
This thing is built like a Sherman tank and doesn't break a sweat. Nothing but cold air coming out of that thing and cold to the touch. The performance and cast-iron feel of it's enclosure ads to my confidence in this unit.
>
Setup was a breeze. Simple, straight and forward and my new rig sounds great coupled with the 1450 QSC.;)
 

John A. Gordon

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Hello all,

Cooling fans, you have to love ‘em or hate ‘em. In either case, airflow is essential for the RMX amplifiers. The question seems to be can a quiet fan be installed in a RMX. What I can tell you is that some people have installed quiet fans with great success for home use.
As for the plexiglas option mentioned in above thread, it may work. My best guess would be the RMX is not going to even get close to getting hot enough to melt the plexiglas. The air floor coming out the front of the RMX can get warm, but for most home use the airflow is cool to warm at best. For confidence sake, why not try putting a scrap piece of plexiglas in front of the RMX, keeping some clearance of course, to see how it works out. One thing to remember, the airflow is from rear to front.
Hope this helps.
 

steve nn

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Thanks John. Thus far I think I could use it as a air-conditioner. I am only running one sub off of it now but when my other arrives it might give it a little more of a workout? I am using my old sub as a table for it running another sub and my new sub on the way will be 28" H so I will notice the fan noise more I would think? I think I will just house it in something
 

John A. Gordon

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Steve nn,
You are correct when you say your amp will have a "little more of a workout," but keep in mind the "little" portion of your statement. You might be quite surprised when you add a second sub and you do not notice much of a thermal change.
 

steve nn

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Yes I do believe that John. I have noticed no thermal change what so-ever. I am waiting on confirmation from Brian Bunge of (Rutledge Audio) that my other new sub has shipped and then I'll see what I can do. Like I said, after running the QSC amp I could see it had a Sherman tank quality to it and do not expect one iota of thermal change. I still think possibly QSC could address the fan issue for us in-home users though, but it is worth the cost and it can be overcome with a little ingenuity.
 

Seth_L

Screenwriter
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Apr 5, 2002
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Richard,

You're right, but the price might scare people away. Especially when compared to the PLX line up.

Seth
 

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