Fan Cooling System for a Guitar Tube Amplifier

Picture of Fan Cooling System for a Guitar Tube Amplifier
This Instructable will show you how to make a
fan cooling system for your guitar/bass tube amplifier.
*This instructable requires electrical/electronics/woodworking tools and knowledge.*


If you can't or don't want to make one for your self,
I soon will have them available at...

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Step 1: Fan Cooling System (pics of on/off temperatures)

Picture of Fan Cooling System (pics of on/off temperatures)
This is a Fan Cooling System for a guitar/bass tube amplifier.
The Idea behind this instructable is that  tube amplifiers get very HOT!
I understand that Hot tubes=Great tone!!
Although heat can kill an amplifier.
If your power transformer gets to hot, it will cost about $100 to replace,
heat will kill your capacitors in the amplifier killing your tone, and be costly to repair,
If the temp gets to hot inside the cabinet you speaker could blow, it will cost $50 or more!
So this system can keep your amp cool and save you money!!!

I have ran many tests with this system on many different amplifiers,
on average a power transformer gets to 120deg. or more,
with My fan cooling system the temp drops to about 70deg.

Step 2: Tools and Materials required

Picture of Tools and Materials required
tape measure, pencil
drill, small drill bit, 2" hole saw
table saw or circular saw?
clamps, wood file, sand paper
razor knife, and paint brush
24" x 24" x 1/4" thick plywood
computer fan, electronic on/off switch, 9v battery, clip, and connector
2- 8-32 screws with washers and lock nuts,
electrical tape, U/L list metal duct tape, black paint

Step 3: Measure the back panle

Picture of Measure the back panle
To make the back panel for this fan cooling system,
you need to measure the inside of your amplifier cabinet
edge to edge, and about 1/2" down past the tubes

or you could use the existing panel cover
that came with your amplifier this also makes
a great template for the tube vent hole that has to be cut out.

lemonie4 years ago
That's a really nice job, two questions:
Could you fit the fan on the inside?
Are these things then badly designed in the first place, or just "cheap"?

ampRiser (author)  lemonie4 years ago
I would NOT install the fan inside the chassis,
there is way to much power in there to mess around!
To say amps are badly designed? I say Yes and No,
Tube amp circuits get Hot it is a fact,
amp manufactures suggest placing a fan on your amp to keep it cool?
I have had power trans, caps, and other parts burn up because of heat.
With the fan cooling the trans, and circulating air in the cabinet,
I have Not had a problem in years!
Fitting the fan inside was a space consideration, I don't quite get the "there is way to much power in there to mess around!".
Do tube-amps sometimes come with fans, is yours one that just didn't?

ampRiser (author)  lemonie4 years ago
The Fan Only extends about a 1/2",
for this instructable and liability reasons I kept it low voltage, and
isolated from the chassis and High Voltage circuitry.
The fan is cooling the power trans. (120v) that feeds 450v caps.
There is No tube combo amplifier with a built in fan?
Rack power amps have them built in like a computer does.
Nothing like this is available.

Patent Pend.

thanks again!
nownvr ampRiser4 years ago
peavey classic 50 is on the inside just to say
ampRiser (author)  nownvr4 years ago
Yes you are correct, the peavey classic 50 has a cooling fan built in,
this was designed for the application and is UL tested and listed.

Thanks I knew if something like this was already out there the experts
here at instructables would find it and let me know?
could you not put the electronics of the fan in a plastic case inside the cab, thus allowing you to store the fan inside
Right, that makes things clearer, thanks.

XOIIO4 years ago
Umm, I doubt anyone can completely know about electricity and guitar tube amplification, I think a basic understanding would be good enough.
ampRiser (author)  XOIIO4 years ago
I did Not mean completely, my point is if you don't understand electricity
within a tube amplifier, DON"T attempt to make this instructable!

I see a lot of crazy people on here when it comes to electricity?

Just a basic understanding of electricity is what gets people killed!!
XOIIO ampRiser4 years ago
True, True LOL

I'm just a stickler sometimes.
gmoon4 years ago
Great! Top marks here.

I'm rebuilding an old Kalamazoo Bass 30, and using it a lot for guitar. But it's very poorly ventilated. So I've been planing on adding the fan.

My only concern is something you don't mention--noise. How did you choose the fan, and did you test different fans? Were there any noise issues after the installation?
gmoon gmoon4 years ago
Ah, now I notice it's battery operated, so at least it's electrically isolated. Still, RPMs would cycle in the audible range, I should think.

No problems, though?

I'd want something that would run off the same mains connection.
ampRiser (author)  gmoon4 years ago
I  have never wired one into the mains,
I know it can be done though, filter caps might block noise?
My personal amplifier I hard wire the amp to an outlet plug,
installed inside the cabinet for pedal power packs,
and have Not had any issues with noise?
gmoon ampRiser4 years ago
Cool, thanks!
ampRiser (author)  gmoon4 years ago
Thank you very much!
Because it is Battery operated there is NO Noise?
I have made a few with different types of fans, there all about the same?
The only time there was any noise is when you use a poor quality
wall transformer to power the fan.