Power Tube Resonance???

[Telefied]

Hey Dudes

OK so I have a MOD50 (I have had this amp for 6 months now wow record for me haha). I love this thing. But... I have had this issue that has been buggin me but never enough to ask until now.

Does anyone else have an issue in which you can hear a power tube "ring, hum or rattle" when you play certain low notes for example a B or C on the 2nd/3rd fret respectively on the 5th string. This happens to me only with this head. I have tried brand new sets of 6L6GC Winged C, Tung Sol 5881 and JJ 6L6 tubes with the same result. This does not happen however with 6V6 JJ's or EL34s of any type.

Note the effect is less obvious with the Bass knob on a module is turned down, Bass boost switches off or Density nob at 0. But.. it is still there regarldess even at lower volumes. The worst offenders are the Tung Sol 5881's.

Oh and before you ask yes I have tried these tubes in other amps and have not had the same issue and yes I have tried sitting other heads on the same cab with out this issue. And yes I have switched the tubes from right to left and result is the same.

Seems to b the power tube furthest from the transformer (if looking at the amp from the back the one to your right).

Jeff you use these 5881's and love them right? I love the tone from the Tung's the best but the noise is ridiculous. Anyone else have this issue or a solution??? I am posting this on the gear page too.

Thanks
Ross

 

[Telefied]

Ahhhh Egnater MOD50 a blessing and a curse hahaha. OK so here is the deal now this is odd but... bought a used B'Man module off eBay. One of the Tubes (the v1) was bad and Microphonic.

Odd part is stick my head in the amp and the power tube I called out is rattling. Tap the power tube lightly and the same pitch and tone of the rattle noise is on the power tube in that socket.

Toy'd with the switch on the B'Man module and noticed the same rattle coming from a power tube. Switched out to every other module I have and whatta know no rattle even with the Bass knobs dime Bass boosts at full and Density max'd. Switched out the v1 tube in the B'Man and perfecto rattle gone hahahaha. So strange guess the microphonic ring of the pre tube caused a chain reaction and the power tube rang in it's own right. Odd but fixed no fancy ass silcone rings needed.

Sooo many moduloes sooo many tubes love you and hate you Egnater. Just kidding this is a great problem to have haha

 

[EWSEthan]

Man thats a new one. Never heard anything like that. Some good detective work you did here!

 

[stephen sawall]

I saw this once a long time ago. My dad fixed amps on the side when I was a kid in the Moter City. I can't be sure, it seems to me it was a Twin.