AD60VT hum/surge at Startup

[marcovox]

Hi - apologies if this has already been covered elsewhere - if so, I couldn't find it

When my son turns the amp on there is a loud hum which builds for a short while then suddenly stops. The amp works OK after that, but it happens every time it's switched on and does not sound healthy.

Any pointers would be much appreciated

Cheers

[Voxman]

I wouldn't call it a loud hum, but its perfectly normal. Lower the power selector when you first switch on to quieten the hum.

[marcovox]

"I wouldn't call it a loud hum"

Huh? How could you know? I know you're good Rich, but really...

It is a loud hum, really. And the amp didn't always do this, which is another reason I'm treating it as a fault. It's as if some component or other is just not handling the initial surge of voltage on power up

Retro Bob - do you have any insights please?

[retrobob]

Does it hum at start up with no guitar or effects plugged into it (including nothing in the loop)? This will tell us it is in the amp and not any outside sources.

Remove the tube from the amp, does it hum at start up without the tube? This will tell us if it is in the pre amp/tube or power amp section.

If the hum is gone with the tube out, try another tube installed in the amp. Sometimes a weak tube will do this.

If the tube makes no difference, you'll need to take the amp to a tech.

[Voxman]

"I wouldn't call it a loud hum"

Huh? How could you know? I know you're good Rich, but really...

Sorry Marco, I typed that too quickly - I meant to say that I hear a hum too at start up which is normal, but that its not loud on my amp!