Upside down view of the awesome JBL L-65 home stereo speaker enclosure. I tried rotating it upright but the picture becomes very disorienting so oh well. I got a pair of these old JBLs in for repair and seems like they’re kind of coveted — a pair still sells these days for around $1000-2000. Unfortunately both of the 12″ woofers were blown as well as a tweeter.
It has a 3-way crossover with low frequency woofer, midrange speaker, and a crystal tweeter for the highs. I listened to a good recording on the cab that still had the working crystal tweeter and it sounded like the snare and the high hat were in the room with me.
The two control knobs you see in the bottom right are for the presence (mids) and brilliance (highs) volume controls. The woofer just is. Crossover is on the right.
The cab with the fried crystal tweeter also actually had it’s volume control literally burnt to a crisp, like the Carcass song. I could not take the knob off and put it on the new L-pad I installed because it was melted to the shaft. I wondered why in this application it is called an L-pad attenuator and how this was different from a regular old volume or tone pot in an amp, but by looking it up it makes sense.
“In its most basic form, the L-pad Attenuator is nothing more than a very simple voltage divider circuit used in many electrical and electronic circuits to generate a lower voltage while maintaining a constant impedance.”
“A pot (potentiometer) is a single, variable resistive element. An L-pad is two resistive elements; one in parallel with the load and the other in series with it (forming the shape of an L). Two fixed resistors are often used to “pad down” (attenuate), e.g., the output of a tweeter without altering its frequency response.”
JBL L65 Jubal technical manual