Installing a fan

[MitchK]

I'm looking into installing a fan into my amp to keep things cool but I was wondering if anyone else has done this before?

What I don't know how to do is create a power supply for it? I was just going to use one of those 12v computer fans but the trick is that If possible I want to not run it off of the heater supply because I'm already sort of overusing that supply by running 4 kt88s in the amp instead of the 4 6l6s its made for.

Is there a way I can run it off of the secondary by putting a resistor in series with it?

[Ray Ivers]

Mitch,

I highly recommend Mouser P/N 670-OA60AP111WB. Compact, cheap, in stock, damn near silent - and 120VAC.

Ray

[SeanF]

I used the Mouser #433-3E-115B-20 recently with great success. 120VAC.

[geetarpicker]

If you really want to run a DC fan here is what I did for my '68 Marshall 100. I got a little transformerless AC-DC adapter from Radio Shack. They are a little pricey. However they don't emit any hum fields so you can mount them just about anywhere. Also I got one with selectable output voltages, so that I can tweak the fan speed. I have a tiny little DC fan pull tied to the inside of the back metal grill on my old Marshall. I like being able to find a setting that cools the amp, but doesn't over cool it. Sometimes if you really push too much air into a tube amp it doesn't quite sound right. Anyway, on my old Marshall I wired a short cut off extension cord to the on/off switch leaving the outlet side of the extension available to plug in the adapter, then I pull tied the adapter onto the chassis. I know it all seems way more complicated then an AC fan, but it works very nicely. I was able to do it without any permanent mods.

[MitchK]

so I'll probably get a 120v fan but for now I just have a little 12v 0.9a fan running off of the heaters, seems to be working fine but do you think this will stress the PT or anything like that?

[Rob Mercure]

Mitch, some amps tolerate lotsa extra current "pull" - pre-CBS Fenders fer example, while some, Laney's fer example, are marginal at best. So, what sorta amp do you have? And a few years ago there was some discussion about lowering the noise level by running these fans at 1/2 voltage. I'm not sure if your will do so but you can try it and I suspect that the decrease in current draw will be porportional.

Rob

[MitchK]

hey sorry I forgot to mention its a 5150. And I'm running the fan which is 12v off the heaters (6.3v) so it is running at about half the voltage right now.

[eruannu]

honestly my fave is 220 volt fan hooked to the 120 volt power source. a power switch is also a good idea for studio situations but not really needed as it does run very quiet and there is not the one and only sacred mic position especially if you are like me. (amp elavated. sm 57 pointed up from bottom as to keep away from fan and mechanical amp noise)

[timt]

adding fan: new fuse? positioning?

i was going to start a new thread but i figured it would be best to keep it all together, incase someone down the line wants to know any of this.


i want to mount a 120v switchable fan to my mesa chassis. i plan to run it from a tap right off the power cable, since the fan is low current draw i assume that should be fine. i do have a few concerns though.

1. should i connect it to the current fuse socket (currently 250V 2A slow blow), install a new fuse/socket, or not bother with a fuse at all?

assumptions:
- with no fuse, worst case the fan can blow from a power surge.
- on the current fuse socket, if current draw is an issue i can get a higher rated fuse but then if fan is off and something goes wrong what happens?
- with a new fuse socket... just more work/parts.

2. this is also a metal fan and rather heavy duty, will it cause any magnetic field or other issues which can affect tone?

assumptions:
- plastic fans still produce a field, the metal fan casing should theoretically cut this ones down though right?
- if it's not too close to a tranny or tube it shouldn't matter either way.

3. is a speed controller really necessary? how many people actually use variable controls on their amp fans?



maybe i'm over thinking it but i live by murphy's law. if anyone has any insight on the matter or has done this before, i'd love to hear their thoughts.


-tim

[SeanF]

I didn't use an extra fuse with the ones I did; I wouldn't really worry about it.

Mine were 120VAC, no circuit noise whatsoever; they're also mechanically silent. Maybe if you held the fan over the pre-amp section, you'd pick some up RF noise, but under the chassis they're pretty well shielded, plus their own metal housing provides some shielding as well.

[Enzo]

The purpose of a fuse in a fan circuit is not to protect the fan. it is to prevent the unit catching fire and burning down your house when the fan fails.

[timt]

heh, nice enzo. i now keep a fire extinguisher on each side of the rehearsal room because i had a boss foot pedal actually catch fire once. bad power adapter or a power surge, never figured it out.


in any case, i figured i'd go with just running it off the main fuse. if current draw blows the 2A fuse, i'll just move up a notch.

[olddawg]

heh, nice enzo. i now keep a fire extinguisher on each side of the rehearsal room because i had a boss foot pedal actually catch fire once. bad power adapter or a power surge, never figured it out.


in any case, i figured i'd go with just running it off the main fuse. if current draw blows the 2A fuse, i'll just move up a notch.

Just solder a pigtail fuse into the fan supply wire and insolate it with a small length of heat shrink or clear plastic tubing.

[pdf64]

You haven't got much more time left to get yourself compliant to ISO 9001:2008, I understood that all registrations had to be updated this year or be lost.