High power toroidal transformer for audio use. Input and output windings can be reversed or be configured differently i.e. Input windings series connected for 100V and output windings paralleled for 4 Ohm.
Primaries:
For 100V line use, connect in series, ie. join blue & yellow. Use grey & brown.
Secondaries:
For 16 Ohm use, connect in series, ie. join black & white. Use red & orange.
For 4 Ohm use, connect in parallel, ie. join orange & black and use white & red.
Secondary windings in series for 16 ohm loads
Secondary windings in parallel for 4 ohm loads