Please note: the following post mentions a product produced by a company that closed 22 years ago, all relevant patents have expired.

Looking for a circuit designer to design and prototype a digital audio delay circuit. The idea would be to recreate the character of early 80s delay units similar to Deltalab Effectron units. These units utilized a delta-modulation circuit rather than the now ubiquitous pcm type delay circuits. They had a several desirable qualities over pcm type delays. Most notably the ability to change delay times on the fly which would create very interesting and musical sounds, limited bandwith "low-fi" sounds, and a modulator circuit to further modify the character of the delay. The primary limitations of the design were high noise and lack of a "tap tempo". A tap tempo allows the user to set the delay time in tempo with the song.  

The circuit design ideally should:

resemble the sound and function of the Deltalab Effectron  ADM1024 or similar unit

incorporate a tap tempo feature if feasible (but also retain the delay time knob)

Be designed physically to be incorporated into both a guitar effects pedal type package, and also a API 500 series rack module (VPR Alliance standards)

include input and output approriate for both guitar (unbalaced high impedance) 1\4 inch connectors. And pro level balanced +4dbu in and output conforming to the API VPR Alliance standards.

If a single VPR slot is not sufficient space for the circuit, the design could be made stereo and utilize two slots

Preferably utilize traditional circuit components rather than than SMD style circuit board.

incorporate a high pass and low pass eq circuit to modify the incoming signal (HP adjustable from off up to  300Hz, and LP adjustable from off down to 800Hz

incoporate high quality components, switches, knobs, and connectors suitable for use in a professional audio setting