import type { IReset } from "@thi.ng/api";
import { AProc } from "./aproc.js";
/**
 * One-pole allpass filter.
 *
 * @param freq - normalized center freq
 */
export declare const allpass: (freq: number) => AllPass1;
export declare class AllPass1 extends AProc<number, number> implements IReset {
    protected _freq: number;
    protected _coeff: number;
    protected _z1: number;
    constructor(freq: number);
    reset(): this;
    next(x: number): number;
    low(x: number): number;
    high(x: number): number;
    freq(): number;
    setFreq(freq: number): void;
}
//# sourceMappingURL=allpass.d.ts.map