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Titan 2000 Protection Circuit

HiFi, LoFi, Tubes, Transistors, ICs, Commercial, DIY

Titan 2000 Protection Circuit

Postby shadders » Wed Jan 16, 2019 3:28 pm

I was examining the Titan 2000 protection design, and more specifically the DC offset detection.

I used LTSpice to simulate, with LT1028 opamps and LT1011 open collector comparators. I set the two signals to simulate the amplifier input signal and amplifier output signal, then adjusted the relevant resistances (potentiometers) to reduce the signal difference to a minimum for IC1b output.

The text states that an offset of +/-5volts will create an error condition.

In simulation at 20Hz, 0.9volts offset causes no DC offset detection, yet 1.0volts does cause an offset detection.

For 1kHz, 5.8volts offset causes no DC detection, but 5.9volts does cause offset error detection.

Therefore, was the specification for the offset detection value based on a 1kHz input signal, where the offset detection value is distinctly lower for a lower test frequency ???

If one were building a 3 way active speaker, then i would assume that the DC offset thresholds for each amplifier (low, mid, high) would need to be designed according to the frequency range used ???

At 20Hz, the initial conditions of the circuit, the transient response and no offset causes an error condition for 4 cycles of 20Hz. At 30Hz there is one cycle that causes an error condition.

Can one assume that these error conditions for a small number of cycles do not occur in real life ?

Thanks and regards,
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