Ampeg PF-500 fan noise. What can I do?

markorbit · #1 09-09-2011, 10:39 PM

Wonderful amp but I need to get the fan noise down. Yes, I know it's not an issue with everybody but for noodling around the house (and for acoustic sessions I do) it's too loud.

There are two contributors - 1) the pitched whirr of the fan itself and 2) the airflow noise of a very fast fan.

I'm no expert but I bet the fan doesn't always need to be at full RPM for low volume noodling.

Ideally, I think the solution would be to replace it with one that is temperature controlled so that for low volume noodling it's barely needed.

Can anybody point me in the right direction here? Is that even an option?

Nice amp all the same.

okcrum · #2 09-10-2011, 02:54 PM

It's probably not an option, at least under warranty. The fixed speed fan is a low cost alternative to temperature controlling it, which needs more circuitry. You could replace the fan with a slower, quieter one at your own risk.

JimmyM · #3 09-10-2011, 05:28 PM

Not a good idea to replace fans in SS heads unless you replace it with one with the same cooling specs or better. And it does void your warranty. I don't know why folks get so wound up about fans...I can't ever hear them. And these fans today are a million times quieter than the fans of the 70's, so at least you have that going for you.

lowendgenerator · #4 09-10-2011, 05:37 PM

Finally, a chink in the PF-500's armor. I swear I was about to buy a PF for around the house. I guess I'll stick with my Crate Powerblock into a 15.

timsmcm · #5 09-10-2011, 06:20 PM

Play louder

ButtUglyJeff · #6 09-10-2011, 06:22 PM

Quote:

Originally Posted by timsmcm

Play louder

This...

beans-on-toast · #7 09-10-2011, 06:40 PM

If you could, I would check out another PF-500 in a store. Maybe something is wrong with your fan. It could be loose or mounted incorrectly causing the airflow to be deviated in some way which would add extra noise.

If everything checks out, call Loud customer service and ask if they can recommend anything. Maybe some of the installed fans have issues. Maybe it can be lubricated by a tech. It depends on the fan.

If all else fails, consider replacing the fan. Look up the specs of the currently installed unit and try to find a replacement. The fan in there meets Loud's requirements but there are often higher cost alternatives out there that offer better performance. For instance, ebm-papst sells some very quiet, high CFM fans. They are available from electronic outlets such as mouser, newark, and digikey. Just keep the old fan.

markorbit · #8 09-10-2011, 07:00 PM

What got me thinking was I recently just bought a quiet fan for my media PC. It cost £4 and comes with a temperature gauge wire and then spins accordingly. Alternatively, a fan with small Hi | Lo speed switches would be fine. The amp doesn't appear to get warm at all at home so I'm sure it'll be fine. For gigs I'll just switch it back up.

The other thing for me is the 'B15' is really a studio amp... and this is affecting that vibe. The original B15 was tube driven, got really hot, didn't have a fan and for recording you could keep the head sat on top of the cab which was mic'd up.

I don't understand why a modern, efficient class D design should need this amount of cooling and at the back of my mind I think of the affordability of the PF-500 and surely there must be a quieter option. I owned a Markbass F1 and the fan was fairly inconspicous bar a soft whirr. IIRC it was the same for the RH450 and Streamliner and the latter has warm tubes.

Just wondered if anybody had already done the homework and found an alternative. I'm not too fussed about voiding the warranty if I end up with a quieter PF-500.

Having also owned a Micro VR stack I feel the fan noise is the achilles heel of the new lower priced Ampegs. I just want to investigate improvements on this very nice amp.

EDIT: Yeah, thanks Beans-On-Toast. I did visit Mouser yesterday but got a little confused by what I would actually need. I found the PF-500 fan specs but there were other things to take into consideration beyond the basic specs. Maybe as you say I should see what Loud can recommend.

Windreaper · #9 09-10-2011, 07:12 PM

You could also get a variable resistor (such as Zalman Fan Mate) to control the fan speed (install it inside the case and either set and forget or drill a small hole for the pot shaft). Or just get a premade low volt adapter for a few bucks (or solder in the resistor yourself if you want to do it ghetto style).

However, as with everything else, there is no free lunch. Some bearing types are a little quieter (such as Sony FDB and similar) and some fans have a more pleasant noise profile but you pretty much need RPM to get CFM and that is going to make some noise. Manufacturer dB/CFM specs are about as reliable as frequency response and sensitivity specs for bass cabs...

**B-string** · #10 09-10-2011, 07:21 PM

I don't understand? G-K has had temp driven variable speed fans for decades. What's up with LOUD Ampeg?

JimmyM · #11 09-10-2011, 07:22 PM

Nothing's up with LOUD/Ampeg. I think people are insane with these fans. I don't think they're loud at all.

okcrum · #12 09-10-2011, 07:26 PM

Amazing how the internet brings out the mountains from molehills crowd. Especially the ones who need 500w for noodling around.

This is like saying a shovel is no good because you can't slice a ham with it.

Windreaper · #13 09-10-2011, 07:29 PM

Quote:

Originally Posted by B-string

I don't understand? G-K has had temp driven variable speed fans for decades. What's up with LOUD Ampeg?

Would need to use a few more components (running a fan full-tilt is as easy as tapping a 12V rail). Not good for bottom line.

EDIT: Class D designs are wonderfully efficient (and thus don't need that much airflow over the heat sink) so it would seem weird to overspec the fan to a point where it is disturbingly loud. I don't know if it is a sleeve or ball bearing type, but BB fans can exhibit noticeable bearing noise (even when new, fans usually get louder as they age), especially if mishandled at some point.

markorbit · #14 09-11-2011, 05:25 AM

'Mountains from molehills'... I reckon you should join us in 2011.

Some of my other stuff doesn't even have fans and is wonderfully silent.

The PF-500 fan is dual ball bearing if I remember correctly. The issue is probably speed more than type. It ain't far from a hairdryer.

Frankjohnson · #15 09-11-2011, 05:39 AM

If it is a bad fan - get it replaced under warranty......take it to an authorized shop - or call whoever you got it through.

If it isn't, try sitting further away from it?

beans-on-toast · #16 09-11-2011, 09:05 AM

Quote:

Originally Posted by markorbit

I found the PF-500 fan specs but there were other things to take into consideration beyond the basic specs.

What is the make and model number of the PF-500's fan?

markorbit · #17 09-11-2011, 09:50 AM

It's this one:
fan - Detailed info for fan,electric fan,fan,YM1206PTB1 on Alibaba.com

I don't believe the fan is faulty as my Micro VR was kinda similar. I just think it is running flat out even though IMHO it doesn't always need to.

beans-on-toast · #18 09-11-2011, 07:37 PM

Quote:

Originally Posted by markorbit

I don't believe the fan is faulty as my Micro VR was kinda similar. I just think it is running flat out even though IMHO it doesn't always need to.

It is more cost effective to just let the fan run full tilt. I guess that's why they do it. When you are playing loud, the fan noise isn't an issue. Same thing with the SVT-VR, the fan roars making it hard to use in a quiet room at low volume.

I found some specs for your fan. At a noise level of 37 dBA, it will make some noise and there is room for improvement. If you found a better fan with a noise level of around 30 dBA, it would be very quiet in a small room.

As you said, slowing your fan down would make a big difference. It would have been nice if they included something like a PWM circuit in the amp's design to control the fan. More expense and more things to fix if they break I suppose.

Handyman · #19 09-11-2011, 07:52 PM

Quote:

Originally Posted by okcrum

Amazing how the internet brings out the mountains from molehills crowd. Especially the ones who need 500w for noodling around.

This is like saying a shovel is no good because you can't slice a ham with it.

I use my 500W LMII for everything, including noodling around the house. That's what volume knobs are for. I've never found the fan noise to be a problem, though.

For the $400 it costs to buy a PF500, I'd be perfectly happy to have a fixed speed fan. These things are crazy inexpensive.

vin*tone · #20 09-11-2011, 08:10 PM

Quote:

Originally Posted by beans-on-toast

It is more cost effective to just let the fan run full tilt. I guess that's why they do it. When you are playing loud, the fan noise isn't an issue. Same thing with the SVT-VR, the fan roars making it hard to use in a quiet room at low volume.

I found some specs for your fan. At a noise level of 37 dBA, it will make some noise and there is room for improvement. If you found a better fan with a noise level of around 30 dBA, it would be very quiet in a small room.

As you said, slowing your fan down would make a big difference. It would have been nice if they included something like a PWM circuit in the amp's design to control the fan. More expense and more things to fix if they break I suppose.

37db?? Wow. That's a freakin hair dryer! The replacement fan I put in my Walkabout was between 7-17dB! (Noctua NF-R8 Quiet Computer Fan 80mm)

Fan noise is important for some people - I found the WA fan unacceptably loud for home practice so swapped it out. A replacement fan needs to match the pressure/airflow figure.