I've since received an email from Spendor. Spendor provided the original Spendor 20 product brochure. Also, according to Spendor: "Historically, S20 is the forerunner of the Spendor SP3/1 loudspeaker (which started life as a sealed cabinet loudspeaker)."
Here are the S20 Specs.
Size (HxWxD mm): 380x220x260
Weight: 9.5kg
HF Unit: SCANSPEAK D2010 19mm soft dome
LF Unit: SPENDOR 160mm Homopolymer Polypropylene cone
Normal Impedance: 8 ohms
Frequency Response: +/- 3dB 70Hz to 20Hz
Pair Matching: 1dB
Power Handling: 70 watts
Sensitivity: 84dB/1 watt/1 metre
Maximum SPL: 100dBA at 1 metre
Input Connections: 4mm terminals/bi-wired option
Crossover Point: 4kHz
Here are the S20 Specs.
Size (HxWxD mm): 380x220x260
Weight: 9.5kg
HF Unit: SCANSPEAK D2010 19mm soft dome
LF Unit: SPENDOR 160mm Homopolymer Polypropylene cone
Normal Impedance: 8 ohms
Frequency Response: +/- 3dB 70Hz to 20Hz
Pair Matching: 1dB
Power Handling: 70 watts
Sensitivity: 84dB/1 watt/1 metre
Maximum SPL: 100dBA at 1 metre
Input Connections: 4mm terminals/bi-wired option
Crossover Point: 4kHz