heat from crack

[nub]

How much heat builds up inside of the wood chasis?

[Laudanum]

My top plate gets pretty good and warm but not uncomfortably hot to the touch.   That should be a pretty good indication of the air temp within the wood chassis.  Or did you need a more specific answer?
Keep in mind, the heat will vary depending on tubes used as well as other factors like room temp and air circulation and probably several other things Im not thinking about.

[nub]

My top plate gets pretty good and warm but not uncomfortably hot to the touch.   That should be a pretty good indication of the air temp within the wood chassis.  Or did you need a more specific answer?
Keep in mind, the heat will vary depending on tubes used as well as other factors like room temp and air circulation and probably several other things Im not thinking about.

Hey thanks for the feedback.  I just ordered a crack kit and am trying to plan out my build.  I was thinking about modifying the wooden base and installing a fan if there would be any benfit from keeping it cooler in there.  If I do this,  I will have to ask for help figuring out where to wire it up to.  (if this happens, it will be a 12v dc 120mm computer fan)

[Laudanum]

It really doesnt get that hot.  The most heat generated is probably from the tubes which are obviously up top.  There are two 10 watt cathode resistors that sit right under the slit vents in the top plate in the stock build.  They also generate some heat and maybe a little bit from a couple wirewounds in the power supply.  The two 10 watt resistors are removed when/if the Speedball upgrade is installed.  Either way, stock or with speedball upgrade, a fan really isnt necessary at all.   In the least, I would suggest that you build it without any mods for a fan and check for yourself.  If you feel that you need a fan, then go ahead and mod the base.  But again, I dont think you will find it necessary. 

[Doc B.]

Adding a fan will not make it run any faster. ;^)>

[defenestration]

actively cooling the chassis could result in fairly reduced tube temps though, which might give a longer tube lifespan?

[Doc B.]

The heat in the tubes is in the glass envelope, so the fan would have to be playing on the tube envelopes themselves to cool them enough to make a difference. It's a little difficult to say whether cooling the 6080 and 12AU7 would extend their lifespan, as the other factor determining tube lifespan is of course how fast the cathode uses up its emissive material and that is pretty much determined by how much current runs through it. Another issue is the idea that tubes sound better once they are warmed up, and this creates a question of exactly how cool does one want them to be?

IME the situations where I have seen fans used or used them myself was when a tube was in a confined space like inside a cabinet or when the tube was something with a really high current draw like a big transmitting tube. I the case of transmitting tubes a chimney is often used to direct the airflow around the tube.

I listen primarily with open back cans and I would not want to hear the fan. But it probably wouldn't hurt anything to install one, unless it puts electronic noise into the amp circuit.

[Paul Joppa]

With Speedball, the current source dissipates the same heat as the cathode resistors which it replaces.

When and if the high-current Crack mod comes to pass, it will double the heat dissipated under the hood. Doc may have a better idea about this after RMAF, where he'll be running it all day ...  :^)

[nub]

I had been thinking about general longevity of the components inside the chassis.  It sounds like the amount of heat generated is not enough to affect their lifespan.  So my idea of a fan mod for the Crack is probably not a very good one. :/

[Laudanum]

Yep, forgot about that.  The heat-sinks do their jobs and get a bit toasty in the process.  But again, overall, it's just not that hot under the hood.

[HF9]

When and if the high-current Crack mod comes to pass, it will double the heat dissipated under the hood.

You've got my attention Paul

[Doc B.]

No data on longevity yet as I had to pack the modded Crack up to ship to Denver last week. But I can say that whereas I found the Crack marginal with some 62 ohm AKG K701s before the mod, with the lowered output impedance of the modded Crack they now sound quite good. After the show we will inspect the PC board for heat damage and determine if we need to make any changes for the sake of reliability.

[Natural Sound]

I HATE FANS! Especially those nasty little ones that spin at really high RPM's to compensate for their small size. I would never add a fan to a piece of audio equipment. If you want to increase the airflow in your Craic* simply raise it up on some higher feet or isolation pods. You might also consider boring some large holes in the rear panel. I'd avoid using a fan at all costs.


*"Craic" or "crack" is an Irish term for fun, entertainment, and enjoyable conversation.
http://en.wikipedia.org/wiki/Craic

[nub]

I am not fond of fan noise either, however depending on the size of fan used and more specifically the type of fan used, they are not all very loud.  I have not received my crack kit yet so i am not sure exactly what would fit, but I had been thinking of using a low speed 120mm fan at the back as an exhaust.