Fully agree that a lower voltage transformer will make it way more reliable.
Bipolars degrade a lot under higher voltages, a SOAR problem, somebody said "high voltage turns 250W tigers into 50W pussies"
It is not a dissipation problem per se, I often receive amps for servicing and owner says "I was not playing that loud, heatsinks were warm but not unduly hot, and yet .... "
You look inside and do not see fire and soot, nor exploded parts ... but power transistors are shorted. ☹️
Power MosFets are much stronger in that regard, heat and dissipation will kill them like anybody else, but SOAR "mystery deaths" disappear.
They also handle reactive loads (speakers) better.
Bipolars degrade a lot under higher voltages, a SOAR problem, somebody said "high voltage turns 250W tigers into 50W pussies"
It is not a dissipation problem per se, I often receive amps for servicing and owner says "I was not playing that loud, heatsinks were warm but not unduly hot, and yet .... "
You look inside and do not see fire and soot, nor exploded parts ... but power transistors are shorted. ☹️
Power MosFets are much stronger in that regard, heat and dissipation will kill them like anybody else, but SOAR "mystery deaths" disappear.
They also handle reactive loads (speakers) better.
Pulsed SOA at 70 V is falling fast on this type. Not suitable for these voltages at all. A real piece of junk as far as Sanken devices go. They offer types that will beat the pants off it. And the biggest OnSemi parts will eat those for breakfast.
And dont get fooled by the comment “no heatsink natural cooling” That only applies to the single pulse curves - where it literally only heats up the package by a few tens of degrees. The DC curve is into an infinite heat sink. The biggest clue how bad these devices are is how little the 100 ms pulse curve comes above the DC one. They converge way too fast above 50V. This type Is NOT as thermally stable as their LAPT versions. Even at +/-55V I’d use a better type - like the 2SC5200. And it was a horrible step back from the original 2SC3281.
And dont get fooled by the comment “no heatsink natural cooling” That only applies to the single pulse curves - where it literally only heats up the package by a few tens of degrees. The DC curve is into an infinite heat sink. The biggest clue how bad these devices are is how little the 100 ms pulse curve comes above the DC one. They converge way too fast above 50V. This type Is NOT as thermally stable as their LAPT versions. Even at +/-55V I’d use a better type - like the 2SC5200. And it was a horrible step back from the original 2SC3281.
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