iAMP200 - stereo OPS with two pairs of output transistors per channel. Each IPS board have separate PSU with capacitance multiplier circuit.
Main board consists:
- BJT tripple emiter follower output stage / MOSFET source follower output stage (depend on the schematic)
- Thermal protection
- DC protection
- Fast speakres OFF feature
- Delayed speakers ON feature - reduces speakers ''thumb'' at amplifier turning ON phase
- Short circuit and overload protection
- Separate capacitance multiplier for each IPS board
- LED diagnostics
Recommended transformer --> 2x 40Vac 500VA
Output power --> 2x 140W @ 8R load
THD @ 1kHz, 8R load, full power --> 0,002% (IPS depended)
Transformer size and output voltage should be matched to the output load. The reasonable compromise is 2x 40Vac / 500VA, at 4R load PSU rail voltage will drop and reduce output power to approx 200W per channel.
Speakers protection is using SSR mosfet relays so the mechanical components are eliminated (improved reliability, no arcing at switching), lower ON resistance than classic relays (not affecting so much the damping factor of the amplifier), extremly fast switching. SSR relays are fitted at the GND return, so the amplifier output goes dirrectly to the speakers.
The short circuit protection is using opto triac as a current sensing element so it doesn't affect the sound coming from the output terminals at all !! (as the VI limiter does).