Microphonic JC Emerald

[burkhart87]

I've got a JC Emerald that has become "microphonic", for lack of a better term. Tapping on the enclosure or the knobs creates a thump from the amp, almost like playing a drum. I've tried replacing the JC Emerald tubes (both or single) with new tubes or tubes from working, non-microphonic sushi box pedals (DIY bassdude or particle accelerator). Conversely, the tubes from the JC Emerald do not make the other pedals "microphonic" when swapped. So, I don't think the problem is the tubes. Any advice? Thanks!

 

[vigilante398]

Well that's a weird one. It's not very common, but I have seen one or two instances of a capacitor going microphonic. It's certainly more common for tubes to go microphonic though.

If it's causing problems that make it difficult to use, shoot me a message here or an email through the Sushi Box website and I'll get you taken care of.

 

[Creach]

I've got a JC Emerald that has become "microphonic", for lack of a better term. Tapping on the enclosure or the knobs creates a thump from the amp, almost like playing a drum. I've tried replacing the JC Emerald tubes (both or single) with new tubes or tubes from working, non-microphonic sushi box pedals (DIY bassdude or particle accelerator). Conversely, the tubes from the JC Emerald do not make the other pedals "microphonic" when swapped. So, I don't think the problem is the tubes. Any advice? Thanks!

Hello burkhart87,

You could chopstick it, open the back cover, turn it on (connected as usual) and use a chopstick to gently tap on every components to locate the faulty components, or faulty solder.

Only the chopstick can touch the electrical area, watch out for your safety.

 

[burkhart87]

You could chopstick it, open the back cover, turn it on (connected as usual) and use a chopstick to gently tap on every components to locate the faulty components, or faulty solder.

How about one of these?

 

[burkhart87]

Seriously though, it's an SMD board and (to me) difficult to tap on anything specific other than the green cap, tubes and daughter boards, footswitch board. Anyway, I can say the sound comes from the left-hand side of the board and is perhaps more pronounced tapping on the tube and tube socket. So I think I'll take the PCB out and have a closer look.

 

[Creach]

Seriously though, it's an SMD board and (to me) difficult to tap on anything specific other than the green cap, tubes and daughter boards, footswitch board. Anyway, I can say the sound comes from the left-hand side of the board and is perhaps more pronounced tapping on the tube and tube socket. So I think I'll take the PCB out and have a closer look.

Yes the spoon can do the job, on the handling side.

If you feel that the sound is strong when you tap near one of the the 12ax7, try swap the 12ax7 left and right. To see if the trouble followe thw swap.

 

[burkhart87]

Yes the spoon can do the job, on the handling side.

If you feel that the sound is strong when you tap near one of the the 12ax7, try swap the 12ax7 left and right. To see if the trouble followe thw swap.

I'm pretty sure it's not the tubes themselves, see the OP above.