OAM Time Machine Expander

Build guide

Designed by Timo Rozendal, this is an expander for the OAM Time Machine multi tap delay module which adds filtering and stereo effects.

Please note this module does nothing on its own, you must have an OAM Time Machine module for this to work.

It's an easy build but you will have to update the firmware on your Time Machine module for this to work.

Please see instructions in the build guide linked above.

OAM Time Machine kits available here

The active expander adds:

• 4 knobs and cv inputs that are summed and control various things
• stereo offset mode A: odd inputs are panned left, even inputs are panned right
• stereo offset mode B: right delayline has an offset (also works with clocked mode)
• filters per delay tap, you can choose lowpass, highpass, bandpass and a second bandpass based on the 4MS SMR resonator code. You can set the frequency for the first tap and the last tap and it interpolates in between. You can also change the resonance, this is shared for all taps.

Notes:

• short press on the button changes from lpf, hpf, bandpass (both filter leds on), filters off
• when filters are on the delaybuffer becomes mono (needed to save mcu cycles), but the processing and output is still stereo.
• this also means that stereo mode B is not possible when filters are on.
• with filters off: button long press selects stereo mode B (mode led turns on)
• with bandpass selected: button long press selects the 4ms SMR bandpass mode (mode led turns on)
• cv input range is 0..5V, but it is summed with the knob that also goes from 0..5V. So if the knob is max (5V) you need a negative voltage 0..-5V to cover the whole range

About Feedback and Resonance:

• resonance is basically the feedback of a filter
• the way feedback works with the time machine currently means that the echo that feedbacks is added at the same tap
• this means that increasing the feedback of the time machine with filters with some resonance will increase the resonance even more
• conclusion: be very careful with the feedback when you are using filters with resonance