Spica TC-50 Crossover Schematics

Two versions of the TC-50 exist, the TC-50 and the TC-50i. Spica started shipping the revised TC-50i (improved) units in January of 1988 (around Serial number 7500). The change was brought on when the supplier for the woofer surrounds out went out of business and Audax (FR) / Polydax (US) had to find a new supplier. In order to match the efficiency gain of the new woofer, Spica had to incorporate a new tweeter, modify the crossover, alter the felt padding geometry (rectangle became a square), and they doubled the doping coating on the woofers. (SLUG post). You could also send your speakers back to Spica for a $200 upgrade, so some early serial numbered TC50s also have the factory upgrade.

The TC-50 crossover is described as a high-pass slope, approximately first-order, 6dB/octave; low-pass slope, fourth-order, 24dB/octave, Bessel; both drivers connected with the same polarity.

The TC-50/TC-50i crossover is not complicated, but you need to understand about service codes. Spica carefully tested and graded each woofer. Then based on those parameters a service code was assigned and paired with a matching crossover. For this reason, it is unlikely that your components will match these exactly.

Spica TC-50
Spica TC-50i
TC-50   TC-50i
TC-50 Crossover   TC-50i Crossover
TC-50 Schematic   TC-50i Schematic
Type Qty TC-50 Schematic Qty TC-50i Schematic
Elect. Cap. 50V C1 4.7 ufd C1 same
Elect. Cap. 50V C2 4.7 ufd C2 same
Elect. Cap. 50V C8 4.7 ufd C8 same
Mylar 50V C3 0.22 ufd C3 0.1 ufd
Elect. Cap. 50V C4 33 ufd C4 40 ufd
Mylar 50V C5 0.33 ufd C5 0.22 ufd
Mylar 50V C6 0.33 ufd C6 0.22 ufd
Elect. Cap. 50V C7 3.1 ufd C7 same
Mylar 50V C9 0.1 ufd C9 0.22 ufd
Metal Film 1/2 watt R1 1 Ohm R1 2 Ohm
Metal Film 1/2 watt R2 1 Ohm R2 4.1 Ohm
Metal Film 1/2 watt R3 1 Ohm R3 2.7 Ohm
Inductor L1  1.02 mH  0.23 Ohm L1 same
Inductor L2  0.778 mH 0.23 Ohm L2 same
Inductor L3  0.353 mH 0.11 Ohm L3 same

Thes are sample values, they will likely not match your values. Crossover values were determined by the service codes of the woofer.