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Old 23rd January 2012, 06:13 PM   #1
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Join Date: Apr 2011
Default JCM Build - Hum and Crackle

Hey,

I've had my JCM 800 2204 build up and running for a while now! - However, The Amp has a low frequency hum which you can really hear when you turn up the volume! - But more annoyingly, every now and then it crackles... It also crackles when I tap (Not particularly hard but not soft) on the top of the amp! :S

The Hum could be because I haven't grounded the C.T of the heater windings... I wasn't too sure about grounding them as I'm using the C.T of the heaters to make up 6.3VAC across the valve (One tap is 6.3, so I had to use the C.T otherwise I would have 12.6VAC to the valve heater pins!).
Will grounding the C.T have any affect on anything other than getting rid of the hum? Click the image to open in full size.

I have no idea of what could cause the crackle so any ideas on that would be great! Click the image to open in full size.

Many Thanks in advance! Click the image to open in full size.
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