Ex Polk Audio RT25i's
Polk Audio (USA)
Circa early 2000's
Part number: RE0528-1
20W ~ 100W RMS Power rating (Polk Audio specs for the RT25I's)
8 Ohm nominal impedance input (from the amplifier)
Filters/splits into the 25i two way speaker system, a woofer/driver (MW5532) and the tweeter (SL6510).
Design crossover frequency is 3Khz, with a second order filter.
Possibly useful for other custom 2 way loudspeaker systems but keep in mind the LC network was designed to work with the specific characteristics of the original woofer/driver and tweeter.
Each board (single sided) measures: 70mm x 70mm
Quite heavy (due to the 2x inductors) @ 200g per board
Spade terminals used for the speaker connections (+ terminal is larger to facilitate correct polarity connection)
Central mounting hole, original screw is supplied
COSMETIC CONDITION:
One board is excellent
The other board has been repaired and is now fully functioning (tested)
What happened? While taking a look inside the cabinet of the loudspeaker, I dropped heavy pliers onto the cross-over board! This board is the old phenolic material and it flexed but when flexing, 3 hairline cracks were created in the copper tracks underneath. No topside components suffered any damage at all.
I have cleaned back the PCB coating and soldered a solid bridge across these 3 tracks (only one crack actually measured open circuit but to be sure, I bridged the other two as well - see the underside photograph) The PCB board is now physically and electronically stable and tested with a woofer/tweeter combination - all is good NOW.
For all the talk of Polk Audio design excellence, this single screw (sitting in mid-air) securing system of the crossover network PCB does seem pretty flimsy and of not a good design, although Polk Audio probably didn't expect anyone would drop heavy pliers on top of the board!
TESTING:
Both crossover boards were tested after removal from the bookshelf enclosures, no problems at all with the filter operation and outputs to the woofer/mid range driver and the tweeter.
Packaged as in the photograph and sealed in plastic
