 Less frequently an optional set of bass pedals could be attached.Soundwise, combo organs are very similar to each other, although there are definite discernible tonal characteristics that differ between models that might be considered "default" for each model.For instance, the Vox Continental tends toward having somewhat of a Hammond-like, or "sine wave"-like sound (only thinner); while the Farfisa Combo Compact has an aggressive, raspy quality to some of its boosted tones, and the Gibson G-101 has a cleaner, contoured, more "sawtooth wave"-like tone, with harpsichord-like, percussive sound capabilities and a slight "after-jingle", with Sustain selected, on some voice settings.