534 Chapter 19 No of bands: Type Mid/HF crossover frequency: LF/Mid crossover frequency: HF path time delay compensation Mid path time delay compensation Three Linkwitz­Riley fourth order 3 kHz 400 Hz 80 usec, tolerance +/-5% (path length 27 mm) 400 usec, tolerance +/-5% (path length 137 mm) Gain: 0dBu in for 1 Vrms out The crossover has balanced inputs, but in its basic form the outputs are unbalanced, the assumption being that if a balanced interconnection is required, this will be provided at the power amplifier inputs. The possibility of adding balanced output stages is examined at the end of the chapter. If the overall audio system can be satisfactorily designed with balanced crossover inputs but unbalanced crossover outputs, as opposed to unbalanced crossover inputs but balanced crossover outputs, then the former is clearly more economical as for a stereo crossover it requires two balanced input stages rather than six balanced output stages. Low-impedance design is used throughout; the circuit impedances are designed to be as low as possible without causing extra distortion by overloading opamp outputs. This reduces the effect of opamp current noise and resistor Johnson noise but has no effect on opamp voltage noise.