Most of what you see in this post works well. However, a crossover network inside the speaker cabinet doesn’t work at all. Could the Unbrokenstring Crew sort out a solution that would put this cabinet back to work?
Here is some file old hardware from the 1980s. This cabinet has an eighteen inch subwoofer underneath two ten inch loudspeakers.
Behind this panel is found a crossover network that routes the input signal to the proper destinations. The crossover automatically routes the really low frequency stuff to the 18 inch loudspeaker and the rest is routed to the ten inch loudspeakers. Or, you can specify which signal goes to which driver using the BI-AMP jacks.
The sheet metal screws hold this circuit board in place. An inductor plugs into the pins in the center of the picture.
The input jacks are seen in this view. The capacitor is part of the crossover network, and has been replaced. As this is in a high powered audio network, the electrolytic capacitor is a non-polarized variety.
We can examine the circuit side of the printed circuit board to figure out the schematic for this assembly.
This inductor is cooked. Unfortunately, this part is no longer available.
An examination of the inductor may give us some clues that we could possibly use to fix it and use it again.
This component can take the place of three different inductors, thus the three wires. Any two wires yield a different inductance. Unfortunately, the insulation is thoroughly cooked. No salvaging this guy.
The functions of each ‘net’ on this circuit board is labelled with a felt tip marker.
For this particular model of crossover, the inductor wires we need to use are indicated by this inductor symbol.
This is an inexpensive crossover kit, with similar specifications. We can harvest this inductor for use in the crossover.
Here are a few details, listed on the end of the box.
This inductor is has a laminated bar core.
We can remove this inductor from the circuit board and use it in the Peavey circuit.
The back side of the donor network is covered with some self-adhesive foam rubber.
The foam sticks really well! But now we have access to the solder joints that need to be unsoldered.
The mechanical mounting scheme is VERY robust for this heavy part. We can use all of this in the Peavey circuit.
These white plastic caps are handy to hold the mounting nut and to insulate the exposed iron core.
We will use the original circuit board as a template for finding and marking places to drill new mounting holes in the Peavey circuit board. We can search around for a practical mounting location.
The mounting holes are marked. Away We Go!
One end of the inductor is electrically wired here.
The other end of the inductor is wired here.
We will make lock the threads of the mounting screws with this stuff.
The thread locking compound is thin enough to seep into the threaded fasteners and lock them.
Now, we can reassemble the crossover network assembly.
The original inductor was mounted in the foreground. This doesn’t look to tacky, does it?
One last look before it disappears into the enclosure.
The panel is ready for reassembly into the enclosure.
No. Wait. We need a new gasket between the I/O panel and the cabinet enclosure. This self-adhesive foam strip material is just the ticket for this application. Note the mitered corners. Because I’m OCD like that.
Holes for the mounting screws are cleared with the Exacto knife.
OK, NOW is one last look at this assembly. The wire pairs go to the loudspeakers in the cabinet.
This system is pretty awesome. Everything tests out at full power. Life Is Good!
Thanks for reading all the way to the end!
CONTACT – David Latchaw EE