The DocDerr ELRX-H from Empirical Labs is a horizontal multi-purpose tone enhancement module that houses six different sections of digitally controlled analog processing and designed for any API 500- Series enclosure. The DocDerr features a low-noise preamp capable of working with line level or instrument level signals, followed by four sections of EQ combining a two-position, high-pass filter with three parametric bands, each with its own set of carefully tuned frequency presets. An internal jumper can turn the DocDerr into an unparalleled instrument preamp with 16 dB of gain, great for acoustic guitar, bass, synths, exotic plucked instruments, and more.
The EQ is followed by a dynamics section which offers compression and a musical tape emulation circuit that softens and tames high frequencies and transient spikes. The DocDerr features the Mix knob, which allows the user to blend the uncompressed EQ's signal with the compressed and saturated signal. The DocDerr is great for tracking, fine-tuning tracks during mixing, and studio quality tone control.