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-   -   Do I want a fan? (http://www.diyaudio.com/forums/tubes-valves/65774-do-i-want-fan.html)

buliwyf 11th October 2005 06:43 AM

do i want a fan?
 
The amp is a Laney VC30 (guitar amp, combo). Class A, 4xEL84 Sovtek's at the power section, 3xECC83 in pre-amp (sovtek too i believe. they got covers).

The valves are "hanging" at the bottom of the amp and are exposed.

Now, I always run my amp at full blast (volume at 10), with overdrive for at least an hour straight when playing on shows.

It gets pretty hot... Would it help (valve life or something that I dont know) if I put fan behind the amp? Should it be "blowing to" the EL84's or just acting as an exhaust/air circulator?

I noticed that when the amp is hot, the treble response decreases. Now I like this sound :cool: but i was wondering if this is bad for the amp?

Robski666 11th October 2005 07:53 AM

Hi buliwyf

I see your in the Philippines so your local wx is hot and humid yes?

more cooling is always a good thing this usually was not a major design concern ( a lot of equipment was/is designed for cooler climates) but additional cooling could extend the life of the components in your amp. The problem is how practical is providing the extra cooling? Without knowing the details of your amp I have used fairly low velocity fans to move air over the out put tubes and then to the outside of the enclosure. What this does is slightly cool the glass envelope of the tube which in turn removes heat from the internals of the tubes.

hth
Robert

AJT 11th October 2005 08:39 AM

hi,
can you post pictures? a fan or fans is not a bad idea at all! your amps will be happy that you did put in fans!

buliwyf 11th October 2005 10:13 AM

here it is, without the metal grill
http://xs50.xs.to/pics/05412/vc30back.jpg

with the metal grill (will mount a fan to the grill perhaps)
http://xs50.xs.to/pics/05412/vc30back-cover.jpg

top vents
http://xs50.xs.to/pics/05412/vc30top.jpg

Trout 11th October 2005 01:10 PM

Hi, Though Not the most popular amp, Seymour Duncan had an easy approach to a fan to its 100W convertable,
Heres a picture from The DIY guitarist website Fan

The DIYGUITARIST Site.

I own that exact Duncan amp, The Fan does effectivly provide some additional cooling, Any airflow around the tubes is a good thing :D

It could easily be installed in your amp with minimal tools. Just read The Saftey section on this board while preforming such mods!!!
Gene

SHiFTY 11th October 2005 09:13 PM

Do it. Preferably blow air over all the tubes and transformers. Even a standard computer fan would be fine...

Johan Potgieter 12th October 2005 10:45 PM

An almost unnecessary reply since we all agree, but just to support:

YES, DO ADD THAT FAN!!

If note is taken that e.g. in an 6L6GC the maximum plate dissipation rating goes up from 25W to 30W (some make it 35W) by the almost unnoticable increase in G1-fin size and mounting rods thickness (i.e. improved radiation/conduction to the socket), the importance of extra heat removal is evident.

One must further keep in mind that heat is also a definite enemy of components, particularly capacitors. With your mounting, the tubes will certainly generate a substantially higher temperature in that department. I would go so far as to say that that could easily be your greater danger.

With the moderate cost of efficient fans these days, I would even consider 2 of them in a blow-in blow-out kind of fashion. (Some of us do prefer push-pull, don't we?!)

buliwyf 13th October 2005 06:25 AM

okay i put fans :D

2 80mm 12v fans (4,000rpm@12v). I also put an on/off switch and an outlet for an AC adapter for convenience.

I used a selectable voltage adapter, so I can choose from 1.5v to 12v :cool: currently im running them at 7.5v since anything above that is waay to noisy.

btw, they're getting air outside then blow to the tubes

http://xs50.xs.to/pics/05414/fanned.jpg

Optical 13th October 2005 06:41 AM

Interesting, i have often wondered about this as my valve amps get damn hot..

time for some fans!

Nordic 13th October 2005 06:54 AM

Just blow the air over the hot parts, Blowing air provides lots of fresh cool air molucules which come in contact with the heatsink and carries off the heat... when you reduce the density of airmolucules (sucking), you starve the heatsink of air to cool down with efficiently...

In enclosed containers like PC cases its acceptable to have exhaust fans, but the should not be where they interfere with airflow to the heatsink...

The noise is mainly because you screwed the fans directly to the grill... you get these rubber grommets you can mount the fans with cheaply... dont know what to drill holes in to mount it on in a grill though... anyhow, alot of the noise is formed by the fans vibration... a 120mm fan spins slower to move the same amount of air, and should be much quiter..

P.S. Johan do you think the transistors will heat up more even if you don't turn the volume higher than before?


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