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matt82609 13th July 2010 01:26 AM

TubelabSE Overheating?
Been enjoying the great sound from my TubelabSE that I built about a month ago! Only problem so far, has been the amp shutting itself down, after about 1 to 2 hours of listening at moderately high volumes. The volume will decrease until its barely audible, which I attribute to the capacitors holding a charge, at which point I turn it off.

I am running 2A3C tubes at 275 volts and biased at about 60 ma. The heatsink on the filament regulator and rectifier were purchased from Radioshack. I bought two of them, being fairly small, that fit over each (regulator and rectifier).

Is this a case of overheating? There are a couple of extra holes in my case for added ventilation, do I need the addition of a fan?

Any help would be appreciated!

SGregory 13th July 2010 03:58 AM

Chances are that your filament regulator is over heating. Try putting a fan on it, the regulator heat sink, to see if it cures your problem. If it does then you will need a bigger heatsink.

Not seeing you case makes it difficult to guess but I would also makes sure air can flow underneath and into your chassis.

rknize 13th July 2010 04:31 PM

Next time it happens, walk over and look at the filaments. If they have gone out, you have your answer: the filament regulator went into thermal overload and shut down.

cgian 19th January 2011 12:08 PM

I have the same problem with tubelab se with 300B.
Matt did you find a solution.What part is overheating.By the way the filaments are ok when stops to play.
Thank you.

boywonder 21st January 2011 12:29 AM

Reading over the manual, George mentions that 2A3's pull more current (5A total) than 45's or 300b's, and this current is what heats up the filament regulator. So, the odds are high that you'll need a larger heat sink. Of course, as mentioned, if the filaments are still glowing it's something else.

Tubelab_com 22nd January 2011 02:21 AM

The only case of overheating related shutdown I have seen involved the filament regulator. If the regulator shuts down the output tubes will go dark. THe 5842's are not on the regulator and will remain lit.

Let the amp run until it shuts down and then direct a fan at the heat sink on the regulator and see if it starts back up. A hair dryer with the heat shut off works good.

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