Κώστας Φ.
Truth hurts. Here's a teddy bear.
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Description:
Symasym5, is a "cute" power amplifier, designed with quality but still low price in mind. This resulted in a ClassAB BJT amplifier, using only TO92 transistors for input and VAS, with a reasonable part count. The topology used is well known and consist of a single diffamp for input, plus a 2nd diffamp with current mirror for VAS. This is followed by normal darlington EF outputstage using modern high beta devices. The circuit uses large amounts of feedback over the whole audioband and an unconventional feedback compensation scheme.
Right now symasym is designed to be driven directly from a CD/DVD-player, simply place a 22k poslog stereo pot between player and symasym. (as voltage divider)
Some specs:
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Symasym5, is a "cute" power amplifier, designed with quality but still low price in mind. This resulted in a ClassAB BJT amplifier, using only TO92 transistors for input and VAS, with a reasonable part count. The topology used is well known and consist of a single diffamp for input, plus a 2nd diffamp with current mirror for VAS. This is followed by normal darlington EF outputstage using modern high beta devices. The circuit uses large amounts of feedback over the whole audioband and an unconventional feedback compensation scheme.
Right now symasym is designed to be driven directly from a CD/DVD-player, simply place a 22k poslog stereo pot between player and symasym. (as voltage divider)
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
- Measurings: RMAA Symasym5 The measuring setup itself is far from perfect, but gives a good idea !
- Frequency response: 3.2hz to 145khz (-1db) using 4.7uf input cap
- Phaseshift at 10khz: <3°
- More will follow !
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