LX II Intermittent Popping-Hiss and Hum

Power Amps LXII
1

LX II purchased in May and had been glorious until last night. Cracking and popping sounds begun. I’m running in bridged mono into 16 Ohm cab with Ohms set to 8 Ohms, as noted for bridged mono. No cracking, hissing or popping in standby mode.

I’m getting some of the symptoms as in the post from “masterjj” on July 31… except nothing is smoking (yet).

The prolonged popping and hissing has subsided somewhat. Right now the issue is a quick pop and then a few seconds of hum and then quiet again.

At this time the problem is intermittent but I can’t take the unit to my gig tonight…

…some guidance would be truly appreciated.

Serial #LXID240679

2

I’m finally able to get back to troubleshooting the LX II.

I’ve swapped the tubes (top down view with the tubes on the right hand side).

( T1 T2 … T3 T4 ) Swapped = ( T3 T4 … T1 T2).

Popping and hissing disappears with Channel A enabled.

Popping and hissing evident with Channel B enabled.

3

Hi Rob,

So it sounds like you may have a tube issue. I would try a fresh set of tubes in the unit to see if that solves the issue. From the sounds of it, you may only need to change two of the power tubes out. I normally change all of them and the PI, but that is just me and there’s usually no need to change the PI out when I do. Totally up to you on how many you change out as the channels are separate.

Thank You,

Terry