TFPRO P4 Serious Mic Amps

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    Ted Fletcher

    Some products sell well, other just don’t…. and one of those was the little ‘dual Mic Amp’, the P4….. this was a 2-channel mic amp designed for radio commercial recording. It was not particularly successful, partly because people didn’t believe it could be any good at the price, (this often happens!) and partly because we had a ‘gritty crosstalk’ problem with some of them; under some conditions you could hear a harshness on channel 2 caused by speech on channel 1, But recently I was able to spend some time investigating…. and fixed the problem completely, and improved the performance as well! They really are very good indeed, with a clever asymmetric limiter/compressor.
    They are on the ‘shop’ page because we don’t make them any more; these are the last few.
    The spec is…….
    MICROPHONE INPUTS XLR Balanced, designed FOR 200Ohm source impedance. 48V phantom power switchable.
    Maximum system gain 70dB
    LINE INPUTS 20Kohm Balanced floating (1/4 inch jack). Maximum system gain 50dB.
    OUTPUTS Nominal +4dBu from balanced ¼ inch jack
    Nominal -10dBu from Phono socket (RCA jack)
    Amplitude frequency response; microphone, +0 -1dB 8Hz to 15KHz. HF response reduces at approx 3dB per octave to 25KHz.
    Line; +0 -1dB 8Hz to 22KHz; HF response reduces at approx 3dB per octave to 40KHz.
    Harmonic distortion; less than 0.01% 3rd harmonic, less than 0.03% 2nd harmonic. At all gains and levels up to +18dBu output.
    Distortion increases as limiter operates.
    Noise. Equivalent to 127dB below input for mic gains above 50dB. (Current mode microphone input, noise reduces with increased input impedance).
    Power consumption 4 watts.
    Size, 1/2 rack
    Weight, 1Kg.

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