| 摘要 |
1515904 Gain control ORANGE MUSICAL INDUSTRIES Ltd 3 Dec 1976 [11 Sept 1975] 37480/75 Heading H4R [Also in Division G5] An instrument amplifier has an amplifying section whose characteristic can be selected digitally and a programming and memory section into which can be set a plurality of different digital values corresponding to different characteristics and any one of which can be selected to control the amplifying section. In its simplest form (fig. I) a binary signal abcd selects by means of switching transistors T1-T4 various values of feedback R4, R5 and input resistors R1-R3 to select the gain of the amplifier A. The resistors can be replaced by capacitors, inductors, diodes &c. The controllable amplifier A may form the active element in tone control circuits 15; a distortion (fuzz) circuit 60; a reverberation circuit including a spring line 39; a compression (sustain) circuit 36; or other effects circuits whereby controlling the gain selects these various effects. A keyboard 68a, 68b is provided which may be used both to select and set individual registers in each memory S1-S7 and to select in use which register controls each amplifier A.
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