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Using a fan on a tube amp??


LA-Ü-RA

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I always have a fan close up behind my amp facing away from it. This allows the fan to drag the heat created by the tubes directly out of the back which in turn creates an influx of cool air from the front and top vent :love:

 

I'm teh smart boy :love:

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I use 2 80mm computer fans on the back plate of my DSL100; one draws air in, and the other draws it out. I usually let the amp heat up for about 15 minutes before turning them on, and I have noticed that it really helps keep the tubes in a good temp zone. I think that it helped prolong the life of my tubes too, as even with gigging and practicing at volume, my first set of tubes lasted almost 5 years. Some folks will say that you need to have a certain amount of heat to keep the amp happy, but by moving the air around you can keep the temps from getting too high.

 

I've talked to my Marshall authorized tech about it, and he said it will do no harm, and may actually help.

 

-mr moon

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The only part of a tube that needs to be hot is the cathode. That is the only thing you want to keep "cooking" in a tube. (That of course excluding the filament that has a sole purpose of heating the cathode). The more one can cool the other parts the better. A conventional tube has a vacuum inside it so convectional cooling of the plate is pretty much impossible, however a tube can still dissipate the heat by both radiating (the anode is typically black to enforce this) and by convectional cooling of the envelope that is typically bonded to the anode

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ahhhhhh, I wouldn't think so unless its a DSL401


that just keeps other parts cooler since it can dissipate heat from EL84's

 

 

I installed a fan on my DSL401 and it did little, if anything, to actually cure the problem. The problem with the earlier DSL401's is the the amp is COMPLETELY ENCLOSED by wood and has NO ventilation. Why Marshall didn't put a vent on the top of that amp is beyond me. I ordered a 'Small Plastic Vent' for a Marshall MG50 amp and installed it the DSL and problem is totally solved. Cost: 15.00 for the vent and easy to install. (Trace the inner part of the vent onto top of amp or make a template/cut out wood with jigsaw and the vent 'snaps' right into place)(Ahhh, make sure you remove the amp from the cab before you do this!) I routinely run it 4-5 hours and it doesn't get any hotter than any other amp out there. Before the vent, you could run it for 2 hours and fry eggs on the backplate.

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My Yamaha T100C combo has a huge fan on the bottom that blows cool air up to keep the tubes cool. I thought it was a pretty good idea and probably won't hurt anything.

 

 

Don't get me wrong, I'm not opposed to fans. Before I figured out exactly what the problem was, I installed a small fan with a 'thermostat' on it that I bought from a guy on Ebay to pull heat away from the tubes on my DSL. The hotter they get, the faster it goes. Permanently installed it and wired it right to the amp power switch. It's probably overkill in my case but I see no reason to remove it. My point was specifically regarding the DSL401. A fan on this particular amp is a band aid but NOT the cure.

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I run a modified 100 watt stack and my power tranny after an hour could fry

eggwhites couldn't touch it less than one second,got an old 12volt computer fan soldered a variable a/c $5 dollar wall wart to it.cut a hole in the front grill,

now it pulls in fresh air, blows across the PT, across the power tubes and out the back grill,i could leave it on overnite and still hold onto my PT fine [not that i would].I E-mailed Bruce Egnater and told him of the problems i was having, he told me the fan was a smart move and will probably extend the life of the tranformers and tubes,Bruce thats all a needed:thu: to hear.

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Don't get me wrong, I'm not opposed to fans. Before I figured out exactly what the problem was, I installed a small fan with a 'thermostat' on it that I bought from a guy on Ebay to pull heat away from the tubes on my DSL. The hotter they get, the faster it goes. Permanently installed it and wired it right to the amp power switch. It's probably overkill in my case but I see no reason to remove it. My point was specifically regarding the DSL401. A fan on this particular amp is a band aid but NOT the cure.

 

 

I agree with you entirely. It really depends on the design of the amp. The Yamaha is a semi open back, so there is already a nice supply of air flow. On the other hand, look at the DSL series or the B-52 AT series...those things are pretty much space heaters with a tone circuit.

 

If a small vent took care of all of your problems, then that's great.

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On my DSL401, I added a heat sink to the bridge rectifier, which was the main bit that used to fail in the older versions. Also two fans mounted on the rear grill. One blows in, the other sucks out. They are mains powered, but wired in series so each only gets half the voltage. Hence they run gently and super quiet. The front panel used to get too hot to touch, now it just gets a bit warm.

 

By removing the main source of heat (from the tubes), the chassis is cooler and the insides are cooler too.

 

Its all neatly internal, with fans wired to the main switch The amp has been very reliable for three years.

 

John

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On my DSL401, I added a heat sink to the bridge rectifier, which was the main bit that used to fail in the older versions. Also two fans mounted on the rear grill. One blows in, the other sucks out. They are mains powered, but wired in series so each only gets half the voltage. Hence they run gently and super quiet. The front panel used to get too hot to touch, now it just gets a bit warm.


By removing the main source of heat (the tubes), the chassis is cooler and the insides are cooler too.


Its all neatly internal, with fans wired to the main switch The amp has been very reliable for three years.


John

How do yuo paly wiht no t00bz?

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Depends on the amp. Tubes operate on heat (thermonic emission),

so they're going to get hot no matter what you do.

If the amp has adaquate ventilation, a fan isn't going to do

anything extra to prolong tube life.

I've never worried about cooling fans myself,

modern tubes are going to wear out quick anyways.

What will benefit the most from a fan is all the capacitors

and resistors provided the fan is reducing chassis heat build up.

That's the main reason for cooling my map.Also it's probably just me, but when my map is hotter, it sounds warmer :idea:

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On my DSL401, I added a heat sink to the bridge rectifier, which was the main bit that used to fail in the older versions. John

 

 

John,

 

I had John Phillips help me with this when I was having trouble. The MAIN heat issue with the older DSL 401's is that bridge rectifier AND the fact that the amp itself has NO VENTILATION. The amp is surrounded by all that wood and there are no vent holes of any sort. That bridge rectifier generates ALOT of heat and it has no where to go. If you click that thumbnail and look at the larger picture, I purposely placed that vent in front of the handle because now the vent sits right over that bridge recitifier. Yes, you can reduce the overall heat somewhat by putting fans on the tubes but if you really want it to run cool and actually cure the problem, get some ventilation to the amp itself. With that $15.00 vent I installed on mine, I can run without fans for hours on end and the amp stays cool.

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  • 8 years later...
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I recently installed some "hotter" preamp tubes in my Bugera Infinium v22 amp, pulling out the OEM 12AX7s and installing TAD 7025WAs. The new tubes gave me just the tone I was looking for and I was thrilled with the new sound! But...I noticed the amp was much hotter to the touch, especially the front of the chassis, where the knobs are.

I wracked my brain for a solution. And just yesterday, I found (at Target) the Vornado Flippi. Brought it home, put it in the corner of the amp below the preamp tubes, and turned it on. That fixed it!

The neat thing about the Flippi is that it's tiny enough to just put it in the back of the amp...and forget it's there.

What I found, to my delight, is that I can play for hours and the fan keeps the amp at an acceptable heat level (not hot...but not cold, either). And it does that at the lower fan speed. It's very quiet, too.

I'm more than satisified with this as a permanent solution to my problem. I was afraid the excessive head might begin "cooking" other elements in the amp, but I don't worry about that anymore.

No, I don't own stock in Vornado and I don't get any $ for posting this. I just was lucky enough to find a solution and thought I'd share it with you guys.

Cheers!

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The heaters inside the tubes receive the same voltage/current no matter what tubes you use. Some may run a little warmer or cooler depending on the design of the filaments. but none are going to make drastic differences and using a fan isn't going to prolong the life of the amp in any way.

Tube temps are well below anything else in the amp. Caps have ratings up to 400 degrees Fahrenheit. If your amp is a hybrid containing solid state chips and tubes, heat can be a concern because those components normally operate with lower voltages and lower temps and may fail due to high temps, but a standard amp 100W or less isn't going to have issues.

 

Especially in your case with a combo, you have convection currents which should be more then ample for cooling the chassis. You just don't want to block the amp placing it flat against a wall and you'll be fine, otherwise, cooling the tubes does zero besides make you feel good. The tubes have to get hot to make electrons flow. Its the radiation given off by heaters that make the tubes conduct. Weather you cool the outside of the tubes or not doesn't make any difference at all. Tube amps will work on the north pole exposed to the coldest temps or in deserts where the temp outside is scorching.

 

The exception with cooling comes down to some of the plastics in the amp. In the old days you'd have wires cloth and even asbestos wrapped. Today most of your wires are Teflon coated. Like Teflon pans, that can take allot of heat and never melt. Plastic knobs can deteriorate over time depending on what they're made of. Fans are normally used in cabs that don't have good convection or there's so many power tubes convection isn't sufficient. Having the chassis hot to the touch is normal however. All may guitar amps have chassis that get hot to the touch. Considering the one 50W amp was made in 1968 and the other 65W amp made in 1976 and never had a heat related issue is a testament to how durable components in amps actually are.

 

Again, with a small Bugera like you're It may make you feel good to cool it, but its pretty much a waste of time and effort. The only thing that can actually burn in there is the wood cab and the tubes wont get anywhere near 451 degrees Fahrenheit The entire chassis would need to be glowing red to get to that temp.

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