Tim Berg, Justin Peters, Mark Eichenberger wah wah tubes
Evan Chapman, audio & video
Recorded on Jan. 30, 2017 in Blue Parallax Studio, Brooklyn, NY
Can be played as a duet, trio, quartet or quintet. I have only heard the duet and trio versions. As far as I know, no group has tried it with five tubes.
Meinl Percussion makes two pitches; they are substantially larger with warm tones. The instruments shown in the video are from Schlagwerk. They are much more toy-like than Meinl ones. You can easily find them in the US.
The performers choose pitch combinations.