Both the ARP 2600 and the Neutron comes without any sequencer or arpeggiator, Beside CV-note/gate they both accept MIDI via a DIN5 or USB, but even if you plan to play it over MIDI it can be convenient to have a sequencer feeding it CV-data (note and gate) while setting up the patch, in stead of bending backwards reaching for a MIDI keyboard. Likewise there will be situations where you want to play these directly from a sequencer, in stead of having to setup your sequence in your DAW (in my case Ableton Live). So I went shopping for a sequencer. First I decided on the KORG SQ-1 (right). The KORG SQ-1 is an old-school analog CV-sequencer, and while it offers the ability to quantize the note CV-signals it's great for dialing in sounds by ear, but less attractive when you want to dial in specific notes (I don't have perfect pitch by any chance). But it's still a very nice sequencer with either 8 steps for 2 different outputs (A and B), or the two rows can be combined for sequences with 16 steps for a single device. As it generates CV-output (it can actually also output to MIDI) it can naturally be used to generate CV-signals for other purpose than note/gate signals.
As written above, dialing in specific notes with the KORG SQ-1 is less easy when you don't have perfect pitch. So I went looking for another way to sequence. The choice was the Behringer CRAVE (left). The CRAVE is a full-blown semi-modular analog synthesizer on its own (very similar to a Moog Mother-32, but about one 4th of its price), and it have a feature rich patch-section in the top (with 18 input- and 15 output- patch-points). So even though it appear simple (1 oscillator, noise-generator, low/high-pass filter, a single ADSD/AD envelope and a single LFO) it can do some weird things thanks to its patch-section. At the bottom of the device you find all the controls that lets you interact with its Arpeggiator and Sequencer (32 steps/64 memory slots) and "keyboard-buttons" for a single octave (up/down buttons lets you switch octave). The portability of the CRAVE also makes it perfect to take out on its own. It would have been nice if it could have been battery-powered and had a build in speaker. So beside the CRAVE you also need to bring its power-plug and a pair of headphones. But armed with an extension cord and headphones, you can be sitting in in the sofa while setting up sequences and dialing in patches before you bring it back into your studio and connect it with other equipment.