# Amp Cooling



## bcmatt (Aug 25, 2007)

So, I have a JCM800 2204 that I built a few years ago, and I love the cabinet that I had my dad build for me. A very classy feeling black vinyl covering with white piping and Purpleheart strip on the front valence. 








It's a nice compact cabinet, but that has it's drawbacks... well one drawback: The heat will build up in the cab too easily unless I keep that back off.








But, I like the look of the back and the idea that it will protect the glass, so it would be nice to engineer a good way to get some better ventilation in there. Here is a pic of the inside of the cab.








I have a couple 120VAC fans now, and you can see it resting on the left side of the chassis (unmounted).
I also have a single 12VDC computer fan currently installed in another amp that I could yank for this one (since I think I'll give it a bigger AC one). 

As you can see, things are quite tight in there, and there is no room anywhere remotely close to the power tubes for the AC Fan. I could probably squeeze the little DC fan between the Power tubes and OT, but it would be tight, and I would wonder if that would be too close to the power tubes...

Is it pointless to try and put a fan in there? Would I be better off trying to install a vent on top? I could cut a strip of this metal and spray it gold and mount it on the top of the amp towards the back:








But really, I'd worry about really getting it to look good. How would I even cut metal to look good in a top-mount type situation. I don't even know what you use to cut metal in nice straight finished lines. What sort of tool do I need a friend to have for that?

Any good suggestions? 
The AC fans seem VERY silent running. (much quieter than the 12VDC) but I wonder if it would cause noise being so near other amp components. Anyone mounted AC fans in amps?


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## Sneaky (Feb 14, 2006)

I'd try a top vent first. Even if you have to put a fan in it you'll want a top vent, so it just makes sense to try the vent first. There might be enough of a convection effect to keep it cool. One of my Boogies has a fan (I assume AC). I disconnected it because it was too noisey... not electronic noise through the speaker, but the fan itself.


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## greco (Jul 15, 2007)

I talked to Wild Bill about this recently. 
He highly recommended a fan to keep the tubes cooled, and for the amp in general.
We didn't get into specifics (unfortunately) re: 120 VAC causing noise if too close to the chassis, etc.

Personally, I would use the 120VAC fan and mount it on the inside of the head box/cab (mounted onto the centre of the right hand side "wall" of the cab, near the can/filter caps and transformers) as you have 120VAC in that area as it is (albeit, no motors) . I think if you were to mount it on some stand-offs you would get plenty of circulation and the fan outflow would be directed at the output tubes and transformers, where most of the heat is generated.

You could sneak the 120VAC cord out somehow, put the back of the head cab on and try it (re: noise problems, etc).
If it works fine, you could then wire it directly into the chassis with some type of disconnect that would allow you to unplug the fan for the removal of the chassis. 

The other nice thing is that 120VAC is easy to tap into, as compared to trying to find (i.e. create a circuit for) a nearby source of 12DC. 

Personally, I wouldn't try to cut open the top of the head cab for some type of metal grille/vent. The moving air resulting from the the fan will be much more efficient than relying on simply convection, IMHO

Just some thoughts.

Keep us updated...This is a great learning thread. Thanks for starting it.

We now await the thoughts (and/or preferably experiences) of others.

Cheers

Dave


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## GuitarsCanada (Dec 30, 2005)

I have a hot running Sovtek Mig 60. It has the grill vents in back and on top as well. I do not run it and super long intervals so not sure how hot she is getting inside, but it does get warm. Not sure how effective the top venting is.


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## greco (Jul 15, 2007)

Sneaky said:


> Even if you have to put a fan in it you'll want a top vent


With all due respect.....Why?

Cheers

Dave


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## WCGill (Mar 27, 2009)

greco said:


> With all due respect.....Why?
> 
> Cheers
> 
> Dave


Two vents should be in the amp for convective circulation, fan or not. Another option would be 2 vents on the underside of the cabinet on each side of the chassis. This would allow cool air in and the hot could exit through your existing vent on the back panel, the location of which makes it ideal, ie it's high enough. The back panel on any Fender amp is a good example of this: a space below and above the tubes, allowing air in and heat out.


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## bcmatt (Aug 25, 2007)

Wow! Actually a great discussion so far guys! Last time I checked, there were no replies, just a few looks.

I should say that my cabinet is actually even smaller than it looks. Seeing typical small-box Marshalls will deceive the eye into thinking this is as big as them when in fact it has much less clearance. It is actually exactly 1 inch between both the top of the power tubes and the ceiling of the cab as well as between the top of the back vent and that same ceiling. It's tight.

I like the idea of mounting a fan by the back on the right, but that AC fan does not fit in that space with those filter caps.









I was thinking about the possibility of a jack to disconnect the fan from the Chassis if it was mounted to the cab instead, but most places in this cab would put the fan in the way of chassis removal anyways.

As much as I'd like to avoid the extra work of creating a top vent, I'm thinking this amp could really benefit from one. I feel that last inch above the top of the back vent is a real efficient heat-pooling system in this cab.

I'm still unsure which would be more effective between a top-vent and a well placed fan. To me, installing a fan would be much easier, since I actually have the parts.

So, if I was to try the effectiveness of just a fan installation first, where should I place one? The AC fan could really only fit on the wrong end of the chassis, so where would y'all recommend trying a smaller DC fan? Any point in trying to wedge it between the Power Tubes and OT?


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## dtsaudio (Apr 15, 2009)

While I realize you already have the 120V fan, a better solution would be to install two fans, one on either side of the amp, possibly one blowing in, and one sucking out. 
You might also want to try something like this Heyco® Vent Plugs
One over each power tube may be easier (and neater to install)


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## greco (Jul 15, 2007)

*dtsaudio.*...The Heyco Vent Plugs are a very cool (pun is intended !!) concept. The data sheet indicates that the maximum panel thickness for installing the plugs is 0.25 inches. Need to get a bit "creative" to install these into the top of the cab. Still...the more choice of ideas, the better.

Cheers

Dave


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## dtsaudio (Apr 15, 2009)

The panel thickness refers to the way they snap in. I've used similar products in thicker panels by gluing them in.


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## greco (Jul 15, 2007)

bcmatt said:


> I like the idea of mounting a fan by the back on the right, but that AC fan does not fit in that space with those filter caps.
> 
> 
> 
> ...


If you turned the AC fan in the pic by 90 degrees, can it be mounted on the end panel of the cab with standoffs of about 1/2 inch or so?

I was also thinking that a DC fan run off of 9V battery might be an option. It will run slower...but not by much. 
I'm also not sure how long it would run on one battery. *You would certainly want to test how long the fan would run on a battery before going this route. * However, keeping an eye on the need for new batteries would be a pain. Some way of installing a switch (to the outside of the cab) for the circuit would be essential, possibly in the metal screen/venting grille. Another power supply option would be to find a DC source inside the chassis and put in a 9V voltage regulator in this circuit with an 1/8 inch jack in the chassis to accept a plug from the fan. You would likely want to talk to an amp tech first about doing this. 

A 9VDC wallwart supply (instead of batteries) could be used and easy to sort out as far as just having a jack installed on the back panel of the amp, again, possibly in the metal screen/venting grille. However, this creates the new pain of having to have some way of plugging it in to a 120VAC source fairly close to the amp.

I will be anxious to see *WCGill's *comments on the above (re: the electronics of everything).
I am preparing for the worst....LOL (however, can't blame a guy for trying) 

Just thinking "out loud here". I am on my second cup of coffee...is it showing?...LOL 

This thread could help many others in the future, I'm sure.

Cheers

Dave


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## greco (Jul 15, 2007)

dtsaudio said:


> The panel thickness refers to the way they snap in. I've used similar products in thicker panels by gluing them in.


Good to know. Thanks.

Cheers

Dave


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## greco (Jul 15, 2007)

WCGill said:


> Two vents should be in the amp for convective circulation, fan or not. *Another option would be 2 vents on the underside of the cabinet on each side of the chassis*. This would allow cool air in and the hot could exit through your existing vent on the back panel, the location of which makes it ideal, ie it's high enough. The back panel on any Fender amp is a good example of this: a space below and above the tubes, allowing air in and heat out.


Thanks for explaining. This is a reasonably simple, but effective approach.

If the vents were installed, would you still go the route of adding a fan?

Cheers

Dave


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## WCGill (Mar 27, 2009)

greco said:


> If the vents were installed, would you still go the route of adding a fan?


Probably not Dave.


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## greco (Jul 15, 2007)

greco said:


> If the vents were installed, would you still go the route of adding a fan?


*IF* you did add a fan...how would you approach it? 

Please also comment of some of my thinking in post #11 ...to help others in the future.

Many thanks !!

Cheers

Dave


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## bcmatt (Aug 25, 2007)

dtsaudio said:


> While I realize you already have the 120V fan, a better solution would be to install two fans, one on either side of the amp, possibly one blowing in, and one sucking out.
> You might also want to try something like this Heyco® Vent Plugs
> One over each power tube may be easier (and neater to install)


These are neat. I like vent ideas that don't involve complex re-tolexing.
This might be another good product to use in combination with a cabinet mounted DC fan sucking air outt hese vents in the top. I wonder how hard it would be to find some of these... I wonder if there are everyday hardware store items that look as good...





greco said:


> If you turned the AC fan in the pic by 90 degrees, can it be mounted on the end panel of the cab with standoffs of about 1/2 inch or so?
> 
> I was also thinking that a DC fan run off of 9V battery might be an option. It will run slower...but not by much.
> I'm also not sure how long it would run on one battery. *You would certainly want to test how long the fan would run on a battery before going this route. * However, keeping an eye on the need for new batteries would be a pain. Some way of installing a switch (to the outside of the cab) for the circuit would be essential, possibly in the metal screen/venting grille. Another power supply option would be to find a DC source inside the chassis and put in a 9V voltage regulator in this circuit with an 1/8 inch jack in the chassis to accept a plug from the fan. You would likely want to talk to an amp tech first about doing this.
> ...


 
The DC fan solution is a very applicable one to most people. I did do it in my old Traynor without a fan, and that is the one I may replace with the bigger ac fan in order to use the DC fan in this application.
No need for a battery.
You can tap off the heater supply and convert to DC with a diode and a cap. It works great:
Guitar Amp Talk: Amp Cooling Fan

You are thanking along the same lines as me regarding an 1/8" jack if the fan is mounted to the cab.

I see what you are saying regarding standoffs and mounting parallel to the side wall. That would be out of the way I think. I think I may try that and see if it moves the air enough... So you mean like this?:








I could plug the AC fan right into the wall socket and see if it is effective before wiring it in to the amp.
Whether it gets hot air out of the can wis the big question. I imagine air would be drawn around the fan and pushed out over the PT, but who knows if much would end up exiting the vent in the back...


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## greco (Jul 15, 2007)

bcmatt said:


> These are neat. I like vent ideas that don't involve complex re-tolexing.
> This might be another good product to use in combination with a cabinet mounted DC fan sucking air outt hese vents in the top. I wonder how hard it would be to find some of these... I wonder if there are everyday hardware store items that look as good...
> 
> The DC fan solution is a very applicable one to most people. I did do it in my old Traynor without a fan, and that is the one I may replace with the bigger ac fan in order to use the DC fan in this application.
> ...


The way you have the fan mounted in the pic looks good. It is not the exact way I was thinking of mounting it, as I did not think of mounting it to the 1" x 1" piece of wood, as you have shown in the pic. I was thinking of mounting it about 2 inches lower and on standoffs. Your way looks like less work/easier.

I like the DC fan concept the most...thanks for the link...very informative. 
The DC fan did not cause any noise in the Traynor...I assume.

Cheers

Dave


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## bcmatt (Aug 25, 2007)

greco said:


> The way you have the fan mounted in the pic looks good. It is not the exact way I was thinking of mounting it, as I did not think of mounting it to the 1" x 1" piece of wood, as you have shown in the pic. I was thinking of mounting it about 2 inches lower and on standoffs. Your way looks like less work/easier.
> 
> I like the DC fan concept the most...thanks for the link...very informative.
> The DC fan did not cause any noise in the Traynor...I assume.
> ...


The DC fan made a bit of noise just from the moving parts (probably being old and dusty), but nothing coming through the speaker. Nothing bothersome at all.

OK, here's the new plan...
I swapped one of my two new ac fans into the Traynor, and stole the little DC guy. I am about to mount the DC fan into the inside of the back grill right next to the power tubes and it will suck air out right there. We'll see how it goes.


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## greco (Jul 15, 2007)

I look forward to hearing about the results. 

Are you trying it with a 9V battery first?...just to see if the results impress you enough to continue.

Good luck with it !

Cheers

Dave


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## bcmatt (Aug 25, 2007)

greco said:


> I look forward to hearing about the results.
> 
> Are you trying it with a 9V battery first?...just to see if the results impress you enough to continue.
> 
> ...


Probably a good idea, especially seeing as I'm having trouble finding a a suitable plug/jack system laying around for me to scrounge. A 1/4" jack seems excessive. Thought I could use an rca jack from an old stereo, but they don't really mount easy (probably end up with even more drilling).


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## greco (Jul 15, 2007)

I hear you !
In my experience, 1/8 inch jacks are not always that easy to find. 
1/8 inch plugs...no problem.

I am fortunate to have 2 fairly decent electronics components stores nearby.

If you can't find anything locally to you.....let me know and I'll get what you need out to you for only Canada Post + component(s) costs.
No extreme shipping and handling costs that the large suppliers charge.

I have learned from your thread...making this offer is the least I could do.

Cheers

Dave


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## bcmatt (Aug 25, 2007)

Thanks Dave,
That is very nice of you. 
But, I really doubt I have the patience for that. I know a shop in Calgary, and if I want something really specific, I could pick it up in a couple weeks when I go through. However if I make a final decision, I will most likely be avoiding waiting at all costs.

I tried it with a battery, and it did seem to pull some heat out slightly more than without it on. It is rather hard to tell. I think I need to be playing it hard and not just letting it sit with the volumes cranked. Unfortunately, I don't have any guitars at home with me today. So, I am not producing any significant heat with this thing.
The ac fans definitely blow a lot more air. I tried the AC fan on the right where we talked about, and while it caused a lot of air movement inside, I couldn't feel anything coming out the vent. It's really all about heat though.
I need to try some experiments while riffing on it with a thermometer inside.
Heheh, this would have been a good elementary school science experiment...

I do feel a little silly just slapping a tiny fan in the middle of big rear vent. I feel like I should be more proactively directing the air where to flow. One thought would be to block a couple inches around the fan so that air is coming into the cab from a wider draw and then out right there next to the tubes.


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## WCGill (Mar 27, 2009)

You're going to need another vent for airflow in or the fan will just be recirculating the air around itself. It's easy to make a dc supply with a diode and cap that will give enough voltage to run a 12vdc fan. Tap off your filament supply, one side is ground to your fan and the other goes to a diode (1N4007 is common) hooked to a 100 or 200uf e-cap (16-20v), positive to the diode, negative to your fan ground. Connect the fan positive to the junction of the diode and cap.


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## bcmatt (Aug 25, 2007)

WCGill said:


> You're going to need another vent for airflow in or the fan will just be recirculating the air around itself. It's easy to make a dc supply with a diode and cap that will give enough voltage to run a 12vdc fan. Tap off your filament supply, one side is ground to your fan and the other goes to a diode (1N4007 is common) hooked to a 100 or 200uf e-cap (16-20v), positive to the diode, negative to your fan ground. Connect the fan positive to the junction of the diode and cap.


So, I went ahead and wired up the 12VDC fan just like you said (and how I had previously in a different amp):
I used a 1/4" jack with the diode, cap and heater wires:








Connected the wires to the pilot lamp heater connection:








And then connected the fan to a 1/4"plug that could plug into the jack on the side of the chassis:








Got it all put together and then booted her up...


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## bcmatt (Aug 25, 2007)

*Disaster!!!!*

turned on the power (standby still off), and the fan seemed to be awful slow at getting up to speed.
After about 10 seconds I was noticing smoke.
I turned off the power, pulled the power chord, raced to get the back off, then raced to unmount the chassis. 
Smoke was still coming out of it, and finally looked inside to see this:









The heater wires coming out of the PT and melted off the wires!
I'm not sure what happened, but it was terrifying. I still haven't recovered. Trying to get a great amp looking nice and working efficiently, and next thing I know, I may have fried the most expensive component in the amp!
Was I somehow just drawing more current than this PT could handle? I thought a little fan was almost negligible?
Would something else cause this?

interestingly, it is just that first run of heater wire from the PT to the first Power tube that melted. That's where heaters split off from to go to both the rest of the tubes as well as over to the pilot light and fan.

I'll have to mount a terminal strip right next to the PT to reroute new heater wires...
I sure hope I don't need a new PT. I really can't afford that!!!
I really wish I hadn't started all this fan nonsense. I could have just continued to take the back off when I play it.


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## greco (Jul 15, 2007)

bcmatt said:


> I really wish I hadn't started all this fan nonsense. I could have just continued to take the back off when I play it.


*OH SHYTE, SHYTE, SHYTE !! *

*I just read your last post.*

Now I am feeling very guilty that I was so enthusiastic about this whole fan thing.

I am praying for your PT (and everything else) to be OK

All the best, given the circumstances. 

Recover soon (seriously).

Dave


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## bcmatt (Aug 25, 2007)

greco said:


> *OH SHYTE, SHYTE, SHYTE !! *
> 
> *I just read your last post.*
> 
> ...


Haha. No, you shouldn't feel guilty at all. If anything you almost convinced me to slow down and wait before just getting impatient and doing the 1/4" jack thing (and drilling a hole with lots of precautions to avoid metal filing getting in the amp). I wonder if wiring to this jack caused some issue and something somehow grounded to the chassis. I don't feel like it did because I thought I was quite careful.
Anyways, I am starting to feel better.

Although, I am praying for the PT too. Sadly, these amps are the closest thing I have to a family... Feels like my child got hit by a car because I threw a ball into the street.
I'm not going to do any more electronics today. In the next couple days I'll redo the heater wiring and test things out.
I'm quite scared of DC fans now until someone teaches me about how possible it is to go over the heater current ratings with such a device... not every amp has transformers like a Traynor.


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## WCGill (Mar 27, 2009)

If wired properly, there should be next to no current draw from your filament supply, let alone what seems to be almost a dead short in your case. Looking at the pictures, it seems like your work is fine. I've used this many times without incident but I've never used a jack and plug, just hard-wired. As you said you've done this before without any problems, please recheck your wiring as well as the fan. Nothing in this circuit should touch ground and this is what happened I'd say. Chances are the PT will be ok.


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## bcmatt (Aug 25, 2007)

Ya, I guess something got grounded out... I bet the 1/4" plug touched something because it was a right angle one.

Anyways, I replaced the melted heater wires and the amp works great again. I played it today with the back on (and no fan), and I don't feel like it was getting to warm.
I think for now I will just continue to take the back off for any louder or extended jams; but with the PPIMV I don't need to get the amp cooking as much as I used to...

Tragedy Averted!!!


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## WCGill (Mar 27, 2009)

Great news.


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## greco (Jul 15, 2007)

bcmatt said:


> Tragedy Averted!!!


Fantastic news !!

What a sigh of relief.

Cheers

Dave


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## mhammer (Nov 30, 2007)

I was chatting with forum member Nonreverb/Richard over the weekend. he had commented that while working at Bluesfest, he was rather disappointed in the performance and reliability of amps coming straight out of the box and plastic, and that heat was increasingly becoming an issue (global warming affects tube guitar amps?).

In chatting, I started wondering if any company had ever made a sort of clip-on aftermarket fan for amps, to keep the heat at a modest level. When I mentioned Mesa amps, Richard noted that they rarely come in for repair in his experience, and of course many (though not all) of them have fans built in.

Naturally, mounting a fan on an amp so that it can suck away heat from the tubes requires having some kind of predictable form factor that lets the mounting arrangement works. And given the array of cabinet form factors, a simple squeeze clip with a fan on a gooseneck might not work for everything or even most things.

But it's worth thinking about.


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