ARP ODYSSEY MK 2
Then the Odyssey Mk II series came along, featuring 5 models (2810-2815) which were produced between 1975 to 78. Visually, they continued with the black and gold color-scheme seen on the late Mk I’s. But under the hood, the Mk II series had several improvements. The VCO design was improved for better tracking. The power supply was improved. The sample+hold memory was improved. The keyboard current source was improved allowing for CV and Gate control to be added. The rotary pitch bend knob was also replaced by ARP’s own PPC (Proportional Pitch Controller) – three pressure sensitive buttons, either by factory modification kit on earlier models, or from the factory on later models.
But the biggest change in the Mk II was in its filter. Early versions of the 2810 model still had the 2-pole model 4023 filter used in the Mk I but were soon replaced with a beefier 4-pole VCF (model 4035). This filter used a ladder design that was very similar to the Moog filter. While rumors persist that Moog sued ARP over this, no suit ever occurred. Arp and Moog came to an amicable agreement and a small licensing fee was paid by ARP for units previously manufactured. ARP soon after designed a new 4-pole, low pass filter – the model 4075 filter – which was used in all subsequent Odyssey models. Unfortunately, while the new model 4075 version of the filter was still beefy at low frequencies and very stable, it also had a well known bandwidth limit error around 12 to 14 kHz, resulting in a weak sound at high resonance or when driven into self-oscillation. This has made the rarer black and gold 2810 Odysseys with the model 4035 Moog-like ladder filter the more sought after and pricier models.