The 903 Effects Doppler V2 is a pedal that combines two effects in one box: a vibrato and a reverb. It was announced in February 2023 as a new version of one of the first circuits built by the maker, a small builder based in Tyler, Texas. At the time of the announcement it was listed as "Coming Soon"1.
The reverb side is based on the BTDR-2H chip, which produces room and hall type ambience, and the vibrato is integrated with it. A toggle switch in the center of the pedal lets you switch the order of the two effects, which the maker's press coverage describes as radically changing the final results1. If you are comparing pedals of this kind, the Doppler V2 sits between a straight reverb pedal and a vibrato pedal, with the ordering switch as its distinguishing feature.
What the maker says
The Doppler's product page describes it as having "knob-for-knob functionality with two onboard stereo effects that can also process external audio"2. In other words, the two effects are stereo and can take audio from outside the instrument, not only the guitar plugged into the front.
The manual goes further on what the Doppler platform is: "The Doppler is a polyphonic, 2-operator FM synthesizer with a unique approach to sculpting, tweakability, and has 8-note"3. That describes the underlying design the effects are built on, which is worth knowing if you are weighing the Doppler against conventional reverb or synth pedals.
The Doppler is not a conventional reverb circuit under the hood: the manual describes it as a polyphonic, 2-operator FM synthesizer, with the reverb and vibrato built on that platform3.
Features at a glance
- Vibrato and reverb in one box, integrated with each other1
- Reverb based on the BTDR-2H chip for room and hall type ambience1
- Center toggle switch that swaps the order of the two effects1
- Two onboard stereo effects that can also process external audio2
- Built on a polyphonic, 2-operator FM synthesizer platform3
How it sounds
Delicious Audio's Paolo De Gregorio described the Doppler V2 as "producing useful and tasteful effects throughout the knobs' sweep without using into extreme or weird sonic territory"1. That positions it as a pedal whose controls stay in practical territory across their range rather than pushing into extreme sounds at the extremes.
Sources (3)
- Upcoming Pedal: 903 Effects Doppler V2 Reverb + Vibrato, Delicious Audio, 2023-02-10
- The Doppler, Hungry Robot
- DOPPLER MANUAL, Hungry Robot Pedals