Changing loud fan in Amplifier, should I do it?

  • Thread starter Thread starter Dicus
  • Start date Start date
Dicus

Dicus

Enthusiastic Member
I have Peavey PV 1500 Amplifier. Which I use in my PA system, which happens to be my band room monitoring at the moment. I like the amplifier, works nice, lots of power and sounds good enough, but the fan inside it makes a lot of noice which is annoying while I'm recording.
I'm thinking of changing the fan inside, I have enough experience with moddling with pc's to know how those little fans work. My question is, does anyone know if I can change the fan (Superred CHA8024EBN-K) inside for a modern and silent pc fan of the same size (80x80x24). Anyone any ideas, suggestions?
 
If it is for monitoring, why do you need it on at all when tracking? You can't be using the speakers if you are tracking microphones.
 
That's right, most of the time it is off during tracking.
But it makes quite some noise, really annoying.

If it is possible to change the fan for a regular computer cooling fan, I would do it. Those things cost less then €10,-, these days.
 
I'm pretty sure this isn't the same as a pc fan, they are 12volts - this is more likely to be mains voltage and a lot more heavy duty. Why not grab a second hand NAD or equivalent of ebay?
 
I don't know if it is a mains fan or LV but I shall assume you know not to kill self or amplifier!.......

Buy a thermal switch The sort of thing you find in microwave ovens that protect the guts in the event of overtemperature.
Thing is, most of these devices are "normally closed" but you CAN get normally open types (or you can get clever with a relay!). Get one that closes at 50C. That temperature is too hot to bear a hand on for more than a few seconds and would indicate that the transistors are running near to 80C.

Best fitted by drilling and tapping the heatsink M3 add a smear of white thermal ***t. If such mechanical niceties are beyond you, use thermally conducting epoxy. Fit as close to the middle of the sink as possible.

Now, no fan! But if you drive the be-juices off the amp the fan will cut in.

Dave.
 
@ ecc83 Thanks a lot for the usefull reply.

There must be some sort of termal switch in my amp, because the fan has got a normal mode (loud), and a heavy duty mode (very loud).

The fan is now constantly on, but when I buy a thermal switch I'm afraid it will still be on all the time. Because it otherwise heats up to much.

Isn't there the possibility to replace the fan for a more silent one, so it will still use the internal thermal measuring device but then without making as much noice?

@bruiser, yeah you're right, didn't think of checking that. But of course pc fan is 12V and the one in my amp is 24, I need to find a 24V fan...
 
The fan that is now inside is:

Superred CHA8024EBN-K
DC 24V 0.24V 80MM
 
"But of course pc fan is 12V and the one in my amp is 24, I need to find a 24V fan..."

Just fit 2 12V jobs in series. You might be able to site them to drag air across the whole chassis/heatsink. One sucks, one blows.
I am suprised the amplifier gets so hot. Most class AB transistor amps get barely warm until you get to about 1/3 rated output. It could be that the quiessent current is wrongly set or just maybe it is some daft "audiophool" pure class A design?

Or: 514F - PAPST - FAN, 50MM 24VDC | CPC
many more but most of the 24V ones seem to be out of stock.
Dave.
 
Last edited:
ecc83 said:
Just fit 2 12V jobs in series. You might be able to site them to drag air across the whole chassis/heatsink. One sucks, one blows. I am suprised the amplifier gets so hot. Most class AB transistor amps get barely warm until you get to about 1/3 rated output. It could be that the quiessent current is wrongly set or just maybe it is some daft "audiophool" pure class A design
Click to expand...

That sounds like a cool idea, I'm not sure if I can fit two in, but I'll try.

But I guess I'd then have to find two 12V fans wich are also 0.24A to get the right Wattage, right? Or doesnt it matter how much Watts the fans are? (sorry, I know the right physics terms in dutch, not English)
 
Dicus said:
That sounds like a cool idea, I'm not sure if I can fit two in, but I'll try.

But I guess I'd then have to find two 12V fans wich are also 0.24A to get the right Wattage, right? Or doesnt it matter how much Watts the fans are? (sorry, I know the right physics terms in dutch, not English)
Click to expand...

Yes they need to have the same current rating but you would just order two identical fans.
You could probably get away with two smaller fans if their total air shift in ltrs/minute was the same or greater than the original. This should be stated in the specification but a good guide would probably be the power rating of the fan. The rating of the orignal is, as you say, volts times amp equals watts so two fans of equal total wattage should perform as well as one even if a bit smaller.

Dave
 
You must match the fan as close as you are able.
SUPERRED CHA8024EBN-K(E) made by Cheng Home Electronic, China
is not available on their website.

It is also used by QSC for their RMS850 amp.
8024 is a 80mm x 80mm x 25mm 24 volt. You do not "add" two 12v fans.

You must find a 24 volt fan.
Fans are also spec by how much air they move per minute. Unfortunately
can't find this fan on Cheng's website to tell you the CFM. (cubic feet per minute)
Contact the manufacturer of the amp for recommended fans.

As your amp works harder to produce a louder signal, the active components
usually mounted on a heatsink, will heat up. The fan will help reduce the temp by
moving air over the heatsink fins. So I would run a test with a thermometer, start
cold and measure the temp of the heatsink. Play some music loud for say 15 minutes.
Measure the temp of the heatsink. The difference is your target to match or better
yet reduce.

Replace your fan with a quieter fan.
Remeasure the heat rise. It should be the same difference or at least very close to
the original fan's heat rise. If it rises more with the quieter fan, it does not have enough CFM.
You can possibly damage the active components.
 
rcourtney said:
You must match the fan as close as you are able.
SUPERRED CHA8024EBN-K(E) made by Cheng Home Electronic, China
is not available on their website.

It is also used by QSC for their RMS850 amp.
8024 is a 80mm x 80mm x 25mm 24 volt. You do not "add" two 12v fans.

You must find a 24 volt fan.
Fans are also spec by how much air they move per minute. Unfortunately
can't find this fan on Cheng's website to tell you the CFM. (cubic feet per minute)
Contact the manufacturer of the amp for recommended fans.

As your amp works harder to produce a louder signal, the active components
usually mounted on a heatsink, will heat up. The fan will help reduce the temp by
moving air over the heatsink fins. So I would run a test with a thermometer, start
cold and measure the temp of the heatsink. Play some music loud for say 15 minutes.
Measure the temp of the heatsink. The difference is your target to match or better
yet reduce.

Replace your fan with a quieter fan.
Remeasure the heat rise. It should be the same difference or at least very close to
the original fan's heat rise. If it rises more with the quieter fan, it does not have enough CFM.
You can possibly damage the active components.
Click to expand...

Probably after 8 or 9 months, the guy has it figured out.

Welcome to the site.
 
True, but not that uncommon a question for future forum members.

Thanks. Nice to be welcome.
 
You must log in or register to reply here.
Back
Top