303-centric rack with external sequencer

Hi!

The Stepper Acid sequencer is great, but I already have a tracker that I like to use for sequencing, and I think it requires external filters and oscillators. So I'm looking at the x0x heart module.

For doing acid basslines, the tricky part is the TB-303 note-assignable slide. I think there are MIDI messages for portamento that are relevant (e.g., MIDI CC 5 and 84), but I bet they're ignored by a lot of simple eurorack modules. Right now I'm thinking it would be better to use a gate triggered on another MIDI channel to control the slide CV in the x0x heart module of a rack like the one below.

This rack has some other stuff I'd be interested in using, too, but I'd start with the modules that drive the x0x heart.

Does anyone have any comments about this approach?

The key to the TB-303 sound is really the glide function as well as other aspects of the sequencer, and how these make most any typical single-VCO patch behave. The problem with the actual stock 303, IMHO, is that you have a very limited range of possible useable sounds, hence the various modded versions (such as the Devilfish) that popped up in the 1990s to alleviate some of this.

Frankly, I find that when I want a 303 "acid" sound, I turn to software. There are several software sequencers that more than adequately model the 303's sequencer behavior, and once that hurdle's been passed...well, I've found that a software knockoff of the Juno-60 works FAR better at sounding like a 303 than the oodles of "worshipful" 303 synth clones out there. Trying to make a modular synth emulate the TB-303 seems to me to be akin to buying a Lamborghini Countach simply to run errands around town.

Yeah, I guess the Neutron can be acid enough anyway. This track is me trying to use it to sound 303-ish. Close enough for me, I suppose.

EDITED Dec 29th 2018, 15:33

Not too bad...just be careful to use only one VCO in square wave (that was what the TB-303 had) and only the lowpass setting on the VCF. Granted, the Neutron's VCF is 2-pole, not Roland's weird 3-pole LPF, but in the right parts of the range and with perhaps a tad of overdriving the filter, you should be right in the ballpark. Again, the sequencer is the key here...that odd non-linear glide that the original 303 has is another great example of a "wrong" design doing something "right", sort of like Moog's CP3 mixer.

Not too bad...just be careful to use only one VCO in square wave (that was what the TB-303 had) and only the lowpass setting on the VCF. Granted, the Neutron's VCF is 2-pole, not Roland's weird 3-pole LPF, but in the right parts of the range and with perhaps a tad of overdriving the filter, you should be right in the ballpark. Again, the sequencer is the key here...that odd non-linear glide that the original 303 has is another great example of a "wrong" design doing something "right", sort of like Moog's CP3 mixer.
-- Lugia

Thanks!

Although I think I have a solution, I'm still interested to know how experienced patchers would activate the CV control for the glide of the x0x heart module. For me, with the DAW doing the sequencing via MIDI, I would reach for a second MIDI channel just for the glide control, switching the glide on and off via "note on" and "note off" messages from the DAW that produce a gate output from a MIDI-to-CV module. (Another MIDI channel and MIDI-to-CV would handle the real notes.)

But I intuit that my first idea probably isn't the best one.