Amp: How long have you worked with Mesa/Boogie?

Chumley: I started in the woodshop in 1990. From there I went to speaker cabinet assembly for a few years. After cab assembly, the natural progression is assembling combos, which led to my current role.

Amp: Can you explain the process of how an amp comes together?

Chumley: Final assembly starts in the woodshop, where the cab parts are cut, glued, assembled and finish sanded. After that, the cabs are painted and wrapped with the appropriate covering. Next, the cabs are fitted with all hardware (I.E. corners, handles, castors, jackplates etc.), and finally loaded with the speakers and/or chassis the cabinet was built for. After that, they are moved into the appropriate testing area for final playtest and quality control inspection.

Amp: What is your role in the chassis assembly?

Chumley: The chassis is a separate entity from what I do. I  coordinate the rest of the parts needed to complete an amp according to what chassis are being finished. The people in Mechanical(assembly of pots, knobs, transformers etc. to finish coated metal chassis), PC( circuit board inspection and assembly), and Wiring( finish wiring and final inspection before Tech), all have their own systems of checks and balances to make sure every process along the way has been done properly.

Amp: And you deal with quite a bit of the Quality Control inspection as well?

Chumley: Myself and/or Vice President Jim Aschow are responsible for all of the visual and "feel/function" final inspection of every product before it is packaged.

Amp: Explain the process of Final Quality control inspection.

Chumley: We start one side at a time, looking for any blemishes or inconsistencies in the vinyl covering. Even the slightest nick ,cut or scratch puts the amp or cab into the blem stock area. If the covering makes the cut, we then make sure grilles and logos are squared and straight, corners and handles are fitted securely, and backs screwed down tightly. All chassis' are thoroughly inspected in the Mechanical department for scratches or inconsistencies in the coating/silkscreeen process, and will be checked again after the amp has been assembled. Every  switch is flipped and every knob is rotated for the right "feel". Any pot or switch that doesn't feel right will be removed, replaced, and the amp retested before it is packaged. Tubes are checked to be firmly seated in their sockets, and finally, making sure the right footswitch, slipcover(if applicable), and Owner's Manual packet is included before the box is closed.

Amp: So no stone (knob) goes unturned before the amp goes into a box?

Chumley: Absolutely not!!!!

Amp: Being at the last stage of assembly in the birthing of an amp, what are some of the most important aspects of that process?

Chumley: Combo construction in particular requires proper tension of chassis mounting screws and the tension screw on the underside of the chassis, as well as external components being well secured to the cab and/or chassis. Making sure that all of the screws and adjoining points in the amp are solid is the most crucial point of combo assembly.  All of our assemblers have a good "feel" for tensioning screws properly according to the amps specific needs.

Amp: Sounds like a lot of responsibility rests on your shoulders being the last guy to build, see and touch an amp before an excited customer cracks the box....

Chumley:  It's up to me to make sure the amp is visually and mechanically perfect before it's ready to ship.  While playtest is the final hurdle for the amps tonal response and overall function, final QC is definitely the make or break point for an amp aestetically.

Amp: Being such a big part of the assembly and quality control, do you get involved with the playtest process much?

Chumley: I have been a playtester at various times, although that is not my main responsibility lately. When I look at it from the assembly standpoint, my play testing experience has been helpful in understanding what it takes to make a really solid amp. My main goal now is to make sure amps flow smoothly through the assembly, playtest and packaging process.

Amp: What are some of the more difficult aspects of the assembly/playtest process?

Chumley: Troubleshooting rattles and buzzes is tricky. There are only so many parts that can make noise, but at the same time it's not the easiest thing to narrow down when your head is near a blaring speaker. Most vibrational noises emanate from the tubes, usually power tubes, but sometimes preamp tubes as well. A microphonic preamp tube may not identify itself by the obvious squealing or howling that people attribute to microphonics, but they can be the cause of vibration in the amp being amplified through the rest of the circuit, making finding the rattle a bit more difficult. You may think you've isolated the rattle to the tubes, only to find after changing all of the preamp tubes you were dealing with a physical vibration being amplified.

Amp: What are the "tricks" to making that distinction easier?

Chumley: Holding the tubes with a towel while someone plays the offending note or chord will sometimes identify the culprit tube. If the noise or problem is altered or goes away by handling a certain tube, that's the first place we'll start. Some physical noise from the tubes is normal, especially in higher wattage amps with a high output potential. There is sometimes too much sound pressure in an amp like a Mark IV or a Trem-O-Verb combo for their not to be some amount of rattle from the tubes.

Amp: What about other parts in the amp?

Chumley: If the tubes aren't the cause of the noise, we then move on to the external components in the amp... Transformers, tubeshields, handles, underside chassis parts in general. Even if handling a suspect part does not eliminate the noise, if it alters it, it gives us a direction to look into. If chassis parts don't seem  to be the problem, we grab the back, put pressure on the front grille, hold the handle etc. Basically, we'll handle every part of the amp while it's being played through until we isolate the problem. It's a process of elimination.

Amp: What do you like about your job most?