Being able to change the filter slope from the classic Moog 24dB per octave is a great feature retained from the Subsequent 37. You can now change this to 6dB, 12dB or 18dB via the hidden parameter settings.
Within the envelope section, there are four knobs on the front panel relating to the attack, decay, sustain and release. The additional delay and hold can be accessed using Shift mode plus the Attack and Decay controls respectively. Velocity to filter amount is available using Shift plus Sustain, and velocity to decay/release via Shift plus Release.
There would have been room on the front panel for Moog to print these Shift mode assignments, and I find myself wishing they had, as it would have helped with the high amount of hidden parameters.
Housed within the modulation section is the Subsequent 25’s single LFO. It can produce square, triangle, sawtooth, inverse sawtooth and Sample & Hold waveforms. The waveform selector offers settings for filter envelope, which allows the envelope to reach parameters that the LFO is meant for. The LFO range is around 0.1Hz to 100Hz, but it can be shifted to either a slower 0.01‐10 Hz or a faster 1‐1000 Hz via a hidden parameter. This means you can focus on a range that’s right for the patch at hand, and even do some basic audio‐rate frequency modulation with the faster setting. The range settings are saved per patch.
The modulation wheel solely acts as the modulation amount source. One nice touch is that the modulation wheel position is saved in a patch, so if you want a precise level of LFO in your patch whenever it is recalled, you can have it. This can be disabled if you prefer your mod wheel to be consistent.
The remaining front‐panel controls include the output section which provides two controls, one for headphone volume and one for master volume. Also located on the front panel is the headphone jack. The Pitch section offers a Fine Tune control, which affects all oscillators, and a Glide Rate control. You can change the Glide type between constant rate, constant time and exponential, as well as toggling legato via Shift functions. Also in the Pitch section are the Octave Up and Down buttons, which transpose the keyboard by ±2 octaves.
The final control to point out is the Activate Panel button. As well as being used, in combination with the Bank 4 button, to enable Shift, Activate Panel will relinquish digital control of the front panel and set all parameters to be exactly the values you see in front of you. Of course, when switching presets, it’s common to end up with knobs which don’t reflect the values you’re hearing. The Activate Panel button makes sure that you’re hearing exactly what you’re looking at. For any old school purists who don’t believe in presets, this is the mode for you.
Part III To Follow…