Pioneer Electronic Corporation

Akira Kanagawa

Masayuki Kato

Shuichi Mori

Hisashi Kihara

Shinya Honjo

Atsushi Makino

Hiroshi Hattori

A digital graphic equalizer for obtaining a boost characteristic and an attenuation characteristic using band pass filters, each constituted by a digital filter, and an adder. For a boost characteristic, an input signal is supplied to first band pass filters and resultant filtered signals and the input signal are added by a first adder. For an attenuation characteristic, the output signal of a second adder is fed back to second band pass filters and resultant filtered signals and the input signal are added by a second adder.

Digital graphic equalizer

A variable frequency characteristic circuit to be used in compensating the frequency characteristics in an audio device in a vehicle. A single operational amplifier is used. Different resonance circuits of different frequencies are connected from ground to either the inverting or non-inverting inputs in order to provide local peaks and dips. Two variable resistors are connected in parallel between the inverting and non-inverting inputs. Different resonance circuits of different frequencies are connected from ground to center taps of the variable resistors to provide treble and base control.

Variable frequency characteristic circuit for a vehicular sound device

In a loudspeaker system having an adjustable balance between two speakers having different low frequency reproduction characteristics, the attenuation of low frequency signals applied to the loudspeaker with the better low frequency reproduction characteristics is selectively inhibited even when the balance is adjusted toward the other loudspeaker, so that an adequate low frequency sound will be produced at all times.

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Saitama, Japan

Akira Kanagawa