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Symasym 5.3 amplifier

All resistors are standard metal film 250mW except: R1/3/4/7, these are 2W metal film, and the 0.22ohm beeing 5W.

Around R7 is wounded a 0.6mm isolated (enamelled) copper wire forming the output coil. (~12 windings)

For c19 i used 470uf/16v, all other electrolytics 63v. The 10/100/330pF should be mica-caps.

The 100nf and 47nf is recommended to be Wima MKS2 (or better), also for C1 i suggest Wima MKS2, 4.7uf is enough.

For Trimpot i use a Piher. The MPSA18 can be substituted by BC550C, for all other parts i do not recommend changes, especially the feedback network (r29/30) should be kept unchanged, feedback compensation is very delicate for this circuit !

Some specs:

        THD: ~0.005% (measured) sim'd: 0.002%

        Power into 8ohm: 60 watts

        Power into 4ohm: 100 watts

        Gain: 32dB (~1:40)  full output at 0.7v input (0.5v rms)

        Feedback: 57dB

        GainBandWidth: ~400Mhz

        Slewrate: ~20v/us (symetrical)

        Supply voltage: +/- 36v

        Biasing: 55ma, ~12mv across a single 0.22 ohm

        Freq. response: 3.2hz to 145khz (-1db) using 4.7uf input cap

        Phaseshift at 10khz: <3°


 The bias is adjusted via the trimpot (R22). Recommended bias is 55ma, resulting in 12mv across a single 0.22ohms or 24mv across both 0.22ohms. Connect a DMM to the upper wires of these resistors and adjust trimpot until DMM reads wanted voltage.