Hi,
this amp is seriously overloaded trying to push 750W into 2ohm.
It can drive 750W into 2r0, but, only as long as the device temperatures are kept at or below 60degC. This test load confirms that the amp COULD be suitable for 4ohm speakers.
Bridging exacerbates the problem. Each half of the bridge thinks it is driving an impedance equal half the real load.
Hang a 4ohm (reactive load) on a bridged amp and each half sees a 2ohm reactive load. It cannot even cope with a resistive 2r0 load continuously. A reactive load is about three times worse.
Four pair of MJ21194 (very robust To3 and good for +-80Vdc) can drive about 500W into 4ohm at 54degree phase angle as long as the Tc remains below 40degC (a very large heatsink running at about 35degC). This suggests this amp should never be used with speaker loads below 4ohm.
If you feel you must bridge it then the MINIMUM speaker load is 8ohm.
But, just run each channel into each 8ohm driver and you still get 320W + 320W into the speaker and the amplifier will just cruise giving a total output of 640W and last forever, if you keep the heatsink cool.
A transformer coupled quasi output is unusual today but may have been more common 30 or 40 years ago for a PA amplifier.
this amp is seriously overloaded trying to push 750W into 2ohm.
It can drive 750W into 2r0, but, only as long as the device temperatures are kept at or below 60degC. This test load confirms that the amp COULD be suitable for 4ohm speakers.
Bridging exacerbates the problem. Each half of the bridge thinks it is driving an impedance equal half the real load.
Hang a 4ohm (reactive load) on a bridged amp and each half sees a 2ohm reactive load. It cannot even cope with a resistive 2r0 load continuously. A reactive load is about three times worse.
Four pair of MJ21194 (very robust To3 and good for +-80Vdc) can drive about 500W into 4ohm at 54degree phase angle as long as the Tc remains below 40degC (a very large heatsink running at about 35degC). This suggests this amp should never be used with speaker loads below 4ohm.
If you feel you must bridge it then the MINIMUM speaker load is 8ohm.
But, just run each channel into each 8ohm driver and you still get 320W + 320W into the speaker and the amplifier will just cruise giving a total output of 640W and last forever, if you keep the heatsink cool.
A transformer coupled quasi output is unusual today but may have been more common 30 or 40 years ago for a PA amplifier.
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