Diezel Herbert Mkii question

[Dabzilla13]

Diezel Herbert mkii owners- i recently bought a used herbert mkii, and sometimes when i am playing and put the amp in standby, a loud POP happens no matter how low the volume is....is this normal for a herbert mkii or should i be concerned? thanks in advance

 

[hopkinWFG]

Diezel Herbert mkii owners- i recently bought a used herbert mkii, and sometimes when i am playing and put the amp in standby, a loud POP happens no matter how low the volume is....is this normal for a herbert mkii or should i be concerned? thanks in advance

You may need to change or resolder that pop cap that wired parallel across ya standby switch..... or try change output tubes?