Introduced late 2022. This PCB is designed for Crimson OEM use.
The PWR14 had some stray thermal coupling which cause a slightly higher than expected offset due to differential heating in the input stage current mirrors. This is resolved by making the dissipation lower increasing the foil area (heatsink) and increasing the physical separation of the parts.
Extra limiting diodes have been added the input stage to ensure that clipping is very clean.
The separation of the two grounds (power and signal)causes an increase in DC offset voltage due to bias currents flowing via a low value linking resistor(10R). A compensating resistor has been added to eliminate this source of DC offset error. Typical DC offset voltages are now a few mV rather than few tens of mV.
The optional thermal, switch a TO220 type fitted in U9 (70C Normally Open), is retained. This is held on by a common screw with Q5.
This PCB is intended for dual 60V rails. This will give up to 200W into 8 ohms. The protection load line is for 2.7R plus any value of series reactance. A quick acting latch disables the PCB if the protection circuits operate.
The indicator diode is also a clip indicator. This PCB requires an external bicolour LED whereas previous PCBs used tricolour. This reduces the number of wires by one.
The PWR15 can be produced with a single output pair for twin 35V rails.
The design has been optimised to produce low off/on transients. The on transient is +7 volts over 0.2 seconds. The off transient is 1V over 0.4 seconds. This is very acceptable subjectively and eliminates the distortion and complexity that would be incurred with a relay solution.