Microphone problems

guy · Mar 25, 2010

I own a TB1 STUDIO PROJECT, a tube microphone, that broke down after i left it in an unheated studio while on tour.
I discovered that the tube wasn't heating anymore.As a result only a soft sound comes out with no bass.
I tried heated the tube artificially and it did revive it for about ten minutes. sound was fine.
I suspect a condenser breakdown or a gen resistance but i admit i hardly have any knowledge in this field.
a repairer tried fixing it without success.
If you know what might be the cause i would greatly appreciate your advice.

emrr · Mar 25, 2010

A tube heats because the filament lights and creates heat. If it's not heating, and the filament isn't glowing, then the tube filament has failed. Funny to me, given a recent thread on that topic. I have no idea what you mean by 'heating the tube artificially'. The only heat should come from the successful application of filament voltage. Any other heating method has nothing to do with it. Doubtful that cold storage would be a culprit either.

zebra50 · Mar 25, 2010

I'm guessing the original poster is heating the whole mic with a hot air gun or something.

Could it be a dry solder joint? Heating the mic makes something expand and make better contact.

Go round the mic with a magnifying glass, and then re-solder where necessary.

guy · Mar 25, 2010

Thanks for your replies.
to be more precise i heated the tube both with solder gun (from a safe distance) and also put the mic in the oven at low temperature for about 15mn.
Every time i tried it functioned normally for a while until the sound dropped as the mic or tube got colder.
Needless to mention the tube had been replaced because i thought that was the cause.

Best of all
Guy