I've picked up the power amp module of a pioneer multichannel receiver (appears a handful of models used this power amp module) and it's using these rather unusual output devices.
They appear to be power mosfets of some description.
Has anyone experience with these? I found a circuit diagram, and I do have the entire module (looks like one channel was dead as those outputs are missing) .. might these be worth pressing into use for a diy 2 channel amp? The specs on the receivers seem not bad (110wpc @ 0.09% 8Ω) but could surely be improved upon... TIA
They appear to be power mosfets of some description.
Has anyone experience with these? I found a circuit diagram, and I do have the entire module (looks like one channel was dead as those outputs are missing) .. might these be worth pressing into use for a diy 2 channel amp? The specs on the receivers seem not bad (110wpc @ 0.09% 8Ω) but could surely be improved upon... TIA
The MOSFETs look to be made by Sanken and re-badged for Pioneer. The Sanken original parts are SAPM01N and SAPM01P - a kind of 'ThermalTrak' FET with temperature compensation built-in.
Thanks, that's very helpful! So it seems they are essentially normal power mosfets but with a baked in idle current biasing
The amp architecture needs various improvements to get better performance, its probably needing a current mirror load for the differential pair (there is already a current mirror that seems to do nothing but drive another current mirror, perhaps it can be repurposed). Such a mirror load will increase gain, thus increase feedback (but need compensation cap changes). It will also eliminate even-order distortion from the differential pair.
The VAS is a single transistor, that's usually improvable by either cascoding or adding an emitter-follower stage to buffer the input stage from the VAS.