Spice Simulation – Ecler PAM 1400

Spice – Ecler PAM 1400

Founded in 1965, Ecler is a well known manufacturer of premium, professional products located in Barcelona, Spain. In 1997, they received an award for their Switching Power Mosfets (SPM) technology. The PAM 1400 was one such product as she uses industrial switching power mosfets IRFP240/9240 for her power stage.

Fig 1 – DC Analysis

Fig 1 is a stripped down version of the PAM 1400 (Click here for Original schematic). Her circuit is quite innovative in that the thermal controllers ae not located at the VAS but instead are at the first set of transistors. Notice the two transistors at the bases of the 2N5551/5401. They reduce the bias when the heatsink heats up, thus preventing thermal runaway.

After the first stage is the VAS. This stage performs double duty. Apart from amplifying the voltage, the transistors BD139/140 also drive the power mosfets. Note the mosfet sources are connected to the rails and their drains to the output. This is like collector out in BJT.

Fig 2 – Transient Analysis

Fig 2 is the Transient analysis of the Ecler PAM 1400. She has no problem swinging to the rails with an 8Ω load.

Summary

I heard this amplifier sometime in the 90s. I didn’t have a chance to really evaluate it though. When time permits, I will prototype this circuit. I’m curious to hear how she sounds like with the mosfets drain output.