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.
|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.