The Professional (Pro) Amplifier Owner's Thread

WaynePflughaupt

WaynePflughaupt

Audioholic Samurai
Just to confirm everett, that’s not your rack? Is it one of our other Audioholics member's?


Regards,
Wayne A. Pflughaupt
 
everettT

everettT

Audioholic Spartan
Just to confirm everett, that’s not your rack? Is it one of our other Audioholics member's?


Regards,
Wayne A. Pflughaupt
I'm not sure who's rack it is just pulled a random image. I used to use Middle Atlantic in my last house.
 
WaynePflughaupt

WaynePflughaupt

Audioholic Samurai
That’s good. Because that guy has great taste in racks, but has no clue how to use an equalizer!

Regards,
Wayne A. Pflughaupt
 
panteragstk

panteragstk

Audioholic Warlord
That’s good. Because that guy has great taste in racks, but has no clue how to use an equalizer!

Regards,
Wayne A. Pflughaupt
Maybe that's for the subs or something...

I have a middle atlantic rack in my office closet for all my servers and such. Very nice, VERY heavy. I put some large casters on it so I can pull it out of the closet when I need to. I've yet to build a rack for the theater, but sound from the amps or any of that isn't a concern for me since the rack isn't in the theater. If only I could quiet the projector...
 
KEW

KEW

Audioholic Overlord
I was curious about the specs on that fan. According to info provided on the Mouser Canada website, that fan works with a fixed DC voltage of 24 volts. But the RMX fan circuit supplies a varied voltage to the cooling fan depending on the heat generated within the chassis. With the published fan specs, I suspect that the fan which you installed may not be appropriate for the RMX850. If the voltage provided by the amp's circuit is far lower than the required 24 volts, that could damage or even burn the fan motor. I would suggest that you verify the situation to avoid problems.
There were a couple of forums where people substituted this specific fan for the stock one as a means to quiet things to a lower level (you can still hear the fan, but it is not as "in your face"). This fan does not afford the air flow of the stock fan, but I will always use it in an air-conditioned room.
This is the same fan PENG chose so I feel pretty good about the electrical end of things.
To that end, the spec sheet indicates an operating range of 12 to 27.6 Volts, so this fan can be operated as variable speed.
My understanding is if it were powered under 12 Volts, the fan may not spin; however, the fan starts whenever I turn on the amp (which would generally be the lowest temperature situation resulting in the lowest voltage).
Also, there were reports on a couple of forums where this fan was used with good result.

Interestingly, I have never noticed the original or replacement fan speed changing!
 
Verdinut

Verdinut

Audioholic Spartan
There were a couple of forums where people substituted this specific fan for the stock one as a means to quiet things to a lower level (you can still hear the fan, but it is not as "in your face"). This fan does not afford the air flow of the stock fan, but I will always use it in an air-conditioned room.
This is the same fan PENG chose so I feel pretty good about the electrical end of things.
To that end, the spec sheet indicates an operating range of 12 to 27.6 Volts, so this fan can be operated as variable speed.
My understanding is if it were powered under 12 Volts, the fan may not spin; however, the fan starts whenever I turn on the amp (which would generally be the lowest temperature situation resulting in the lowest voltage).
Also, there were reports on a couple of forums where this fan was used with good result.

Interestingly, I have never noticed the original or replacement fan speed changing!
So there is an error in the specs on the Mouser website. I have no reason now to question the spec sheet that came with your fan. From the info which you provided, that fan is an appropriate replacement for the one that came with the amp.
It is quite possible that the speed of the fan won't change because the amplifier is not driven to moderate or higher output levels which would generate more heat.
It's always good to be on the safe side. :)

Cheers,
André
 
KEW

KEW

Audioholic Overlord
Did you find it a little bit complicated to switch the fans? I heard or read somewhere that it was not as easy as on some other amps.

Cheers,
André
Not that I remember.

Ideally, the new fan might have had a matching connector, but I just snipped off the existing connector and either wrapped the leads together and used electrical tape or used a couple of crimp on connectors. I don't remember which, but I was too lazy to pull out the soldiering iron.

Aside from that, just removing the cover of the amp and 4 screws for the fan.

There is a shroud that is in front of the fan that the screws also had to engage, but I don't remember any complications!
 
P

PENG

Audioholic Slumlord
There were a couple of forums where people substituted this specific fan for the stock one as a means to quiet things to a lower level (you can still hear the fan, but it is not as "in your face"). This fan does not afford the air flow of the stock fan, but I will always use it in an air-conditioned room.
This is the same fan PENG chose so I feel pretty good about the electrical end of things.
To that end, the spec sheet indicates an operating range of 12 to 27.6 Volts, so this fan can be operated as variable speed.
My understanding is if it were powered under 12 Volts, the fan may not spin; however, the fan starts whenever I turn on the amp (which would generally be the lowest temperature situation resulting in the lowest voltage).
Also, there were reports on a couple of forums where this fan was used with good result.

Interestingly, I have never noticed the original or replacement fan speed changing!
My brand new RMX 850a's stock fan also starts as soon as the amp is turned on. The speed always seems to be at maximum and never changes. I email QSC about it because they advertised it as variable speed. No response from them to date. It may be an honest mistake, probably by copy/paste from the specs of their higher end units, otherwise it is false advertisement.

The replacement fan I told you about is indeed the one other user forums recommended. As you mentioned, the specs says 12-27.6 VDC. I installed a pot for manual speed control and found that it would spin at a little >10 V iirc. I left it at about 12 V for acceptable noise from about 10 ft and the temperature rise appeared to be about the same as with the stock fan running full blast, only about 1-2 degrees C higher, but I don't listen loud.
 
KEW

KEW

Audioholic Overlord
My brand new RMX 850a's stock fan also starts as soon as the amp is turned on. The speed always seems to be at maximum and never changes.
That is what I was thinking!
If that was low, I can't imagine how loud the fan might be on high!
I guess the thing that stands out to me about the fan noise was there seemed to be a dominant whir from the motor in addition to the sound of the air blowing.
 
P

PENG

Audioholic Slumlord
That is what I was thinking!
If that was low, I can't imagine how loud the fan might be on high!
I guess the thing that stands out to me about the fan noise was there seemed to be a dominant whir from the motor in addition to the sound of the air blowing.
I can assure you it is not temperature speed controlled because the supply voltage is fixed at around 25-27V (don't remember exactly but it was constant). As you know mine is the 850a but I think the 850 is likely the same. In case I forgot to send you the photo, here it is, of my speed control pot.
 

Attachments

KEW

KEW

Audioholic Overlord
In case I forgot to send you the photo, here it is, of my speed control pot.
You never told me you were thinking about sending it, so I never missed it!
However, it looks like you did forget to put it in your post!:)
 
P

PENG

Audioholic Slumlord
You never told me you were thinking about sending it, so I never missed it!
However, it looks like you did forget to put it in your post!:)
I didn't forget but file size too big. Trying to figure out how to shrink it down.
 
P

PENG

Audioholic Slumlord
Kurt, using a speed control pot you can fine tone the voltage to further reduce the fan noise. If you apply the full 25 VDC that the 850 provides, even with the replacement fan, you are going to hear the fan from 10 ft in a quiet room. For normal home use, the stock fan is probably 3X over kill.
 
Verdinut

Verdinut

Audioholic Spartan
I didn't forget but file size too big. Trying to figure out how to shrink it down.
If you had Photoshop, it would be rather easy to shrink it down, but it looks that you have finally succeeded.

Kurt, using a speed control pot you can fine tone the voltage to further reduce the fan noise. If you apply the full 25 VDC that the 850 provides, even with the replacement fan, you are going to hear the fan from 10 ft in a quiet room. For normal home use, the stock fan is probably 3X over kill.
It was definitely designed for public performances. :)
 
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