The release of MC-505 took place in 1998. Groovebox is based on the same core as the JV series instruments are, and shares a lot with the JV/XP synthesizer lines. MC-505 is designed for aggressive genres of music, like techno, and for this purpose the drums from drum machines TR-808 and 909, as well as acid TB-303 textures were added to the library. It combines an intuitive interface and a huge set of sounds, as well as its distinctive feature - mixer.

MC-505 has advanced capabilities in individual elements settings: the filter, in addition to low-pass (LPF), got new types introduced: high-pass (HPF) and band-pass (BPF). Slightly below there are mini-faders with attack, decay, sustain and release adjustment, as well as an LFO section with a selection of 8 waveforms.

In addition, a section with effects has been upgraded: delay and reverb can change the time settings and "dry/wet" range. The built-in sequencer has 714 presets among the patterns, 200 user, and 50 songs.

Compared to the predecessor MC-303, MC-505 has its own mixer. It is located in the center, it includes 8 faders and 2 rows of buttons that are responsible for all the instruments and rhythm parts.

All the main drums pass through the master (R), and other samples are individually put through another channel – they can be muted or edited independently. As for the library of samples, it includes the sounds of pianos, violins, organs from JV-XP.