PSA: Blow it out yer amps!

Greg Cameron

Greg Cameron

Senior
Jan 11, 2011
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This a friendly reminder to blow the dust out of your amps. I hadn't noticed the ol' Crest x001 amps in my amp closet where my rig is installed had been gradually running hotter and hotter. Last week one of my 8001 LF amps started to thermal. Thought is was another issue. Swapped it with a spare. Then realized it had twice the airflow out the front and it wasn't even getting warm whilst all the other amps were warm even at low levels. Then it occurred to me I hadn't blown them out in oh, 4 years! They're all running nice and cool now.

That is all...
 
Re: PSA: Blow it out yer amps!

Greg Cameron said:
This a friendly reminder to blow the dust out of your amps. I hadn't noticed the ol' Crest x001 amps in my amp closet where my rig is installed had been gradually running hotter and hotter. Last week one of my 8001 LF amps started to thermal. Thought is was another issue. Swapped it with a spare. Then realized it had twice the airflow out the front and it wasn't even getting warm whilst all the other amps were warm even at low levels. Then it occurred to me I hadn't blown them out in oh, 4 years! They're all running nice and cool now.

That is all...
Click to expand...
I have had amps in for repair in which the fans were so coated in dust they could not even turn!

No wonder the amp had a problem.

That is a problem that the old passive amps did not have. Does anybody even make a passive rack mount amp anymore?

But it is a good reminder- a little bit of simple maintenance can go a long way towards the life of any product-like changing the oil in your car-air filter in your house etc.
 
Re: PSA: Blow it out yer amps!

Ivan Beaver said:
I have had amps in for repair in which the fans were so coated in dust they could not even turn!

No wonder the amp had a problem.

That is a problem that the old passive amps did not have. Does anybody even make a passive rack mount amp anymore?

But it is a good reminder- a little bit of simple maintenance can go a long way towards the life of any product-like changing the oil in your car-air filter in your house etc.
Click to expand...

Passive cooling is still popular for install amps where fan reliability is a concern, not to mention that forced air cooling draws dirt and dust into the amp.

There are practical limits to how much power you can make without a fan, while the modern class D technology promises to increase that, while low power generally remains low tech.

This low power/low tech may be changing. I use a small class D amplifier SMD IC, about the size of a wood tick, who hasn't eaten lately. Great for low voltage battery operation. So rack mount amps without fans could happen. Studios and consumer markets would appreciate the lower noise.

JR
 
Re: PSA: Blow it out yer amps!

Greg Cameron said:
This a friendly reminder to blow the dust out of your amps. I hadn't noticed the ol' Crest x001 amps in my amp closet where my rig is installed had been gradually running hotter and hotter. Last week one of my 8001 LF amps started to thermal. Thought is was another issue. Swapped it with a spare. Then realized it had twice the airflow out the front and it wasn't even getting warm whilst all the other amps were warm even at low levels. Then it occurred to me I hadn't blown them out in oh, 4 years! They're all running nice and cool now.

That is all...
Click to expand...
Just to add another helpful hint-DO NOT just blow air through the amp to remove the dust. STOP the fan from turning-or you could damage the bearings-causing more damage.

Vacuuming out the majority of the dust is a better way to start. You also don't want to blow dust where it will act as a "blanket" on some parts-causing them to heat up more.

But simply blowing is faster.

You also don't want to damage any parts-or loosen them up with the air pressure so they break loose later on.
 
Re: PSA: Blow it out yer amps!

Ivan Beaver said:
Just to add another helpful hint-DO NOT just blow air through the amp to remove the dust. STOP the fan from turning-or you could damage the bearings-causing more damage.

Vacuuming out the majority of the dust is a better way to start. You also don't want to blow dust where it will act as a "blanket" on some parts-causing them to heat up more.

But simply blowing is faster.

You also don't want to damage any parts-or loosen them up with the air pressure so they break loose later on.
Click to expand...

I take a natural bristle paint brush and do the heat sinks and any other spots I can see dust accumulated, then blow gently and vacuum. It's a handy tool for the fan blades too, where the dust can cake on. Just picked up a used Yorkville A4.4 amplifier a week ago(for a song), and went through it and the one I've owned for over ten years. The foam on the new one was showing some clogging, which got me motivated to look under the hood of both and make sure they're nice and clean. It does make a difference, heat is the enemy.

Best regards,

John
 
Re: PSA: Blow it out yer amps!

Ivan Beaver said:
Just to add another helpful hint-DO NOT just blow air through the amp to remove the dust. STOP the fan from turning-or you could damage the bearings-causing more damage.

Vacuuming out the majority of the dust is a better way to start. You also don't want to blow dust where it will act as a "blanket" on some parts-causing them to heat up more.

But simply blowing is faster.

You also don't want to damage any parts-or loosen them up with the air pressure so they break loose later on.
Click to expand...

While everything you've written is good advice I'm sure, is a little air through the fans really an issue? Can anyone document actual fain bearing failures due to a few seconds of air? From my experience it hasn't been that difficult to remove dust from an amp - even with one of those cans of air, and I find it implausible that there is a big issue here. From reading the rest of this thread, it seems like any attempt at cleaning the amp out will almost certainly ruin it - apparently we should throw the dirty amp away and replace it with a new one.
 
Re: PSA: Blow it out yer amps!

TJ Cornish said:
While everything you've written is good advice I'm sure, is a little air through the fans really an issue? Can anyone document actual fain bearing failures due to a few seconds of air? From my experience it hasn't been that difficult to remove dust from an amp - even with one of those cans of air, and I find it implausible that there is a big issue here. From reading the rest of this thread, it seems like any attempt at cleaning the amp out will almost certainly ruin it - apparently we should throw the dirty amp away and replace it with a new one.
Click to expand...

There is a popular stupid human trick to take a high pressure air hose and spin up a fan to way higher than it's design speed to hear it scream like a siren. I have never done this myself but have heard anecdotes about fans being damaged, and it sounds plausible.

JR
 
Re: PSA: Blow it out yer amps!

While you are at it, exercise your input gain knobs.

I had a show in a new bar/club last Friday, and I didn't get all the way through line check before I had some really ugly noises coming through the system (mostly the subs). I spent a couple of minutes unconnecting and then reconnecting the speaker cables at the boxes, as well as a couple of turns of each knob at the extremely dirty amp rack. It cleared up at least for the moment and we got through the show ( I won't mention having to repatch three of the fourteen xlr cables the club actually seemed to own with my own while the band was playing). I am sure that other people are going to get the "Its never happened before" speech I got before anything is fixed.
 
Re: PSA: Blow it out yer amps!

John Roberts said:
There is a popular stupid human trick to take a high pressure air hose and spin up a fan to way higher than it's design speed to hear it scream like a siren. I have never done this myself but have heard anecdotes about fans being damaged, and it sounds plausible.

JR
Click to expand...
Although I have heard many fans in amps "scream like a siren" when hit with 100 psi with no bearing damage, I have started to stop the fans after hearing of some fan speed control circuits that may be damaged by the voltage produced by the fans at very high speeds, as the fan acts like a generator.
Also, a spinning fan blocks more air than a stopped fan, more effective compressed air (and dirt) transfer with it stopped.

And TJ, if you think that a can of air is enough to remove the crud that builds up in an amp, you must be too young to remember the buildup of tar and nicotine sludge mixed with dust from smoking barroom use amps that would require a spatula to scrape off, 100 psi of compressed air would hardly do anything.

The house amps at First Avenue used to be so gross that the sludge was like printer's ink with dirt mixed in, smelled like ashtrays from hell..
 
Re: PSA: Blow it out yer amps!

TJ Cornish said:
While everything you've written is good advice I'm sure, is a little air through the fans really an issue? Can anyone document actual fain bearing failures due to a few seconds of air? From my experience it hasn't been that difficult to remove dust from an amp - even with one of those cans of air, and I find it implausible that there is a big issue here. From reading the rest of this thread, it seems like any attempt at cleaning the amp out will almost certainly ruin it - apparently we should throw the dirty amp away and replace it with a new one.
Click to expand...

There are idiots that will find a way to damage anything that they take the screws out of. No, cleaning out an amp is not rocket science. Take it apart, clean it without breaking it, and reassemble. There are common things that can damage systems. Spinning fans with air is a fun thing to do. Yeah, I've done it. However, a couple things can happen. One, the high speed of the fan can indeed cause bearing damage. Not likely with a couple seconds of spinning, but you'll shorten the life of the fan if you do it regularly. A bigger problem though, is on some fans, spinning the blades can turn the fan into a generator, sending voltage back out into the driver circuit. When the fan spins at ridiculous speeds, the back voltage can be quite high.

Using compressed air can cause damage in a couple ways. First, if you just use a regular air compressor, the compressed air will have a high humidity content, to the point of spitting moisture out of the hose. You can see the obvious problem with that. Secondly, compressed air can force dirt and debris into areas that you can't get it out. eg, air getting forced into the pots will cause dirt to get inside, and static sound results. Also using too high of pressure can cause component damage from the force.

Using a vacuum works, but is often less effective than compressed air. Using a vacuum doesn't cause any more static than compressed air does. The difference is that a typical vacuum hose is plastic, which doesn't dissipate the static energy anywhere. Using an anti-static hose on the vac will eliminate that problem. You could mod your own simply by wrapping some tinfoil around the hose opening and grounding it. Obviously make sure the amp is powered down when using it so you don't short anything out.

If you use a brush with compressed air, or the vac, make certain that the brush is an anti static brush. Older amps aren't going to be as sensitive to ESD as new ones with DSPs built in, but it's good practice to be ESD safe any time you're inside your gear.
 
Re: PSA: Blow it out yer amps!

Art Welter said:
Although I have heard many fans in amps "scream like a siren" when hit with 100 psi with no bearing damage, I have started to stop the fans after hearing of some fan speed control circuits that may be damaged by the voltage produced by the fans at very high speeds, as the fan acts like a generator.
Also, a spinning fan blocks more air than a stopped fan, more effective compressed air (and dirt) transfer with it stopped.

And TJ, if you think that a can of air is enough to remove the crud that builds up in an amp, you must be too young to remember the buildup of tar and nicotine sludge mixed with dust from smoking barroom use amps that would require a spatula to scrape off, 100 psi of compressed air would hardly do anything.

The house amps at First Avenue used to be so gross that the sludge was like printer's ink with dirt mixed in, smelled like ashtrays from hell..
Click to expand...

I am indeed too young to remember that, and make a point to stay out of the few such places that still exist. I would offer that any amp in such a condition - either from smoke/haze/fog/smaze/fryer oil/whatever will likely have bigger problems than bearings slightly worn from a few seconds of spinning with compressed air.
 
Re: PSA: Blow it out yer amps!

TJ Cornish said:
I am indeed too young to remember that, and make a point to stay out of the few such places that still exist. I would offer that any amp in such a condition - either from smoke/haze/fog/smaze/fryer oil/whatever will likely have bigger problems than bearings slightly worn from a few seconds of spinning with compressed air.
Click to expand...
The gummed up amps only had thermal problems, which went away when the sludge was removed, and would come back again as the sludge built back up, made me glad my lungs were not in the same environment regularly.
None of the fan bearings on the old Peavey CS 800 and Crest amps used in the install ever failed when being blown out even though we didn't bother stopping the fans back then, though it is a good idea to stop fans from turning for the two reasons mentioned in post 12 and 13.

I recently traded a boat anchor Crown PSA 2 for a (somewhat) lighter six channel Rane MA 6 that had been thermalling off on hot, busy nights in the nightclub it was in.
I knew the amp had never been cleaned and previously had been in a smoking bar, sure enough several ounces of goo and dust bunnies needed to be cleaned out, now it covers four monitor mixes (biamped drum fill with two channels bridged, and 3 channels normal) nicely for small gigs.

Those amps are older than many of the readers here..
 
Re: PSA: Blow it out yer amps!

Art Welter said:
The gummed up amps only had thermal problems, which went away when the sludge was removed, and would come back again as the sludge built back up, made me glad my lungs were not in the same environment regularly.
Click to expand...

For the Crest amps, I do give them a blast of air down the "cooling tunnel" for a quick general dust out. When i have them apart for service, I'll wash the heat sinks with quick dry electronics cleaner which does a great job removing the goo. Since we do a fair number of reggae shows, the goo issues aren't do to haze so much as another type of resin ;)
 
Re: PSA: Blow it out yer amps!

Brian jojade said:
There are idiots that will find a way to damage anything that they take the screws out of. No, cleaning out an amp is not rocket science. Take it apart, clean it without breaking it, and reassemble. There are common things that can damage systems. Spinning fans with air is a fun thing to do. Yeah, I've done it. However, a couple things can happen. One, the high speed of the fan can indeed cause bearing damage. Not likely with a couple seconds of spinning, but you'll shorten the life of the fan if you do it regularly. A bigger problem though, is on some fans, spinning the blades can turn the fan into a generator, sending voltage back out into the driver circuit. When the fan spins at ridiculous speeds, the back voltage can be quite high.

Using compressed air can cause damage in a couple ways. First, if you just use a regular air compressor, the compressed air will have a high humidity content, to the point of spitting moisture out of the hose. You can see the obvious problem with that. Secondly, compressed air can force dirt and debris into areas that you can't get it out. eg, air getting forced into the pots will cause dirt to get inside, and static sound results. Also using too high of pressure can cause component damage from the force.

Using a vacuum works, but is often less effective than compressed air. Using a vacuum doesn't cause any more static than compressed air does. The difference is that a typical vacuum hose is plastic, which doesn't dissipate the static energy anywhere. Using an anti-static hose on the vac will eliminate that problem. You could mod your own simply by wrapping some tinfoil around the hose opening and grounding it. Obviously make sure the amp is powered down when using it so you don't short anything out.

If you use a brush with compressed air, or the vac, make certain that the brush is an anti static brush. Older amps aren't going to be as sensitive to ESD as new ones with DSPs built in, but it's good practice to be ESD safe any time you're inside your gear.
Click to expand...

I actually have some experience in all the areas mentioned - electronics, anti-static suction through my woodworking hobby, and fan bearing issues through my day job as an IT guy. For amps such as what Art mentioned, vacumming won't make any difference. For more normal amps, a can of compressed air will do at least as good of a job of "dirt relocation" as any vacuum, and avoid the moisture and oil issues of compressed air.

I very much doubt that a few seconds of air is a big problem for the fan bearings, but as has been said - back voltage might be.

I posted because I thought it was a little funny that it sounded like everything was bad.
 
Re: PSA: Blow it out yer amps!

Art Welter said:
And TJ, if you think that a can of air is enough to remove the crud that builds up in an amp, you must be too young to remember the buildup of tar and nicotine sludge mixed with dust from smoking barroom use amps that would require a spatula to scrape off, 100 psi of compressed air would hardly do anything.

.
Click to expand...
I remember that "gunk" well. It has a "unique" smell.

When I was in DC-I did gigs that the secret service would have to "sweep" the room with dogs before people were let in.

Everytime the dogs would focus in on my amp racks. I would have to go through and prove that each amp was working and show them the wiring etc.

My guess is that the "smell" from the bars was a smell that the dogs did not recognize and they didn't know what to do.

YEAH-it would clog up amps pretty quick. My MA2400's could only do 1 or 2 gigs before I would have to clean the filters.

And a little bit of dust when mixed with the "gunk" would be like cotton balls dipped in oil and rolled around on the floor.

Those were the days.
 
Re: PSA: Blow it out yer amps!

TJ Cornish said:
While everything you've written is good advice I'm sure, is a little air through the fans really an issue? Can anyone document actual fain bearing failures due to a few seconds of air?
Click to expand...

Heck yes. It's widely understood/experienced in the computer tech circles (google is your friend).

Take half a second to stick something in the fan (coffee stirrers work great, dry ones even better) to keep it from freewheeling. The bearing in these things are pretty delicate. And while it may not fail right off the bat, or look visibly damaged, I guarantee you it's life will be severally shortened. Even more fun - it will probably decide to die on you when being stressed. Say from a really heavy and jamming set when the amp has it pumped up to max revs. Is an amp cutting out due to thermal overload during the heaviest part of the show considered bad form? I just realized my crown amps have one fan only on the rear at least. If they do have a front fan is it enough to carry the amp under load? I now will be opening them to blow them out and also explore their redundancy too.

Then again I'm some faceless nobody on the Internet. Why spend half a second exercising due diligence and logic when nothing will probably happen anyway because anecdotally it hasn't happened to anyone you know, right?
 
Re: PSA: Blow it out yer amps!

Incredibly naive question: How effective, useful, PITA, or damaging can fitting some furnace-filter type-material over the fan (back to front forced air ala QSC) or over intake grilles (for front-to back drawn air cooking - ala Crown). Yeah, airflow would be reduced and need attention much more often than blowing out the unit (especially a fan filter).

Thank God I'm in a non-smoking situation. I know that gunk.
 
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