Studio Night

Modding KBilly’s amp

KBilly has a 25 watt Fender Frontman amp.  It’s a little combo that is great for practice, and has a surprisingly biting tone, especially when it’s cranked up.  We’ve recorded it on a few upcoming songs with great results.  KB also has a 4×12 speaker cabinet of unknown origin, which he recently liberated from storage.  The mission: add a make/break 1/4″ speaker output to the Frontman.

What that means is that we wanted to add a speaker output to the amp that would disable the amp’s speaker if an external speaker (like the 4×12 for instance) was connected.  Otherwise, the amp would work normally.

It was a pretty simple job.  We dismantled the amp, which consisted of removing four screws from the cabinet that hold the actual amplification electronics in place, and disconnecting the speaker.  The speaker was connected using simple crimp-on connectors, so we just had to pull them off the metal tabs at the base of the speaker.

KB brought the appropriate output jack hardware: a ‘closed-circuit’ 1/4″ jack.  This would allow us to insert it into the circuit and preserve the ‘default’ connection, but on inserting a cord into the jack, the ‘default’ connection would break and the signal would be routed to whatever the cord is plugged into.

We did a dry run, wiring up the output jack between the circuit board and the speaker, and everything worked perfectly.  We clipped the crimp-on connectors off of the speaker leads and soldered the wires to the output.  We also soldered the new speaker connection wires onto the jack’s connectors.

KBilly daringly drilled a hole into the metal panel on the back of his amp.  Impressively, he didn’t do any additional damage.  Yay for you KB!

We mounted the output jack in the newly created hole, threaded the speaker wires down to the combo’s speaker and made connections, and then we tested it out.

Bam!  An 8-ohm speaker out from the practice amp.  We had to disable three of the speakers in the 4×12 cabinet, since it wasn’t wired correctly for 8-ohms, but KB will rectify that in his own workshop.  Allegedly.