Stereo DC Control Amplifier (1980-87)
The SU-A4 is a state-of-the-art control amp. It follows on the tradition of the SU-A2 introduced two years ago. just as the SE-A3 power amp follows the well respected SE-A1.
Besides this unit's impeccable credentials as a phono EQ preamp, it handles control functions in an audio system. To prevent switching and crossover distortion, all amplifier stages are class A. ICL circuitry includes the MM and MC inputs employing FETs And the only coupling capacitors are one for downstream MC and another for MM, making this amp capable of straight DC amplification from AUX inputs to output.
Thanks to a special buffer amp, output impedance is so low that you can put your power amp as close to a speaker system as possible, yet have the SU-A4 convenient to your listening position without affecting waveform fidelity.
In addition to the usual tone controls, Super-Bass and Super-Treble controls let you effectively deal with typical audio equalization problems
Thanks to class A amplifier circuitry from input to output, the reproduced waveform is completely free from switching and crossover distortion. Open loop performance is so good that little NFB is required.
All high-level inputs (tuner, tape, aux) encounter no capacitors in the signal path. FETs are employed to eliminate the need for input capacitors. When used with a DC power amp such as the SE-A3, this means that DC amplification extends all the way to the speaker terminals, the advantage of which can be seen in the excellent 3DA profile obtained for this control amplifier.
Frequency response: 20Hz to 20kHz
Total harmonic distortion: 0.001%
Input sensitivity: 0.1mV (MC), 2.5mV (MM), 150mV (line)
Signal to noise ratio: 73dB (MC), 79dB (MM), 98dB (line)
Channel separation: 55dB (line)
Output: 150mV (line), 1V (Pre out), 15V (Pre out Max)
Dimensions: 430 x 97 x 360mm
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