Sonic LAB: Boomstar Modular SEM Filter

US Eurorack format classic Oberheim sound with drive 17/08/15

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We're looking at the Studio Electronics Boomstar Modular SEM filter. A version of the SEM Boomstar Desktop synth for Eurorack.

This is a recreation of the classic Oberheim SEM filter, a voltage controlled state variable filter, which combines multi-mode 2-Pole filter (not self resonant) with the extra features Boomstar brings.

Primarily this allows you to again drive the filter via a dedicated input level. CV control is provided for Cutoff and resonance, as well as a 1/Oct CV for keyboard tracking. The filter can is variable between LP and HP mode, with a separate output for Bandpass too. This variable filter state parameter is unfortunately not controllable via CV - this is the one thing I would dearly love to see as it sound great when modulated. Perhaps this would have made sense instead of the resonance CV control, if space was an issue.

The filter itself can be switched between HP/LP mode and Bandpass mode, which does give significantly different flavour to it.

I do love a 2-pole filter and this indeed does sound great, though it would have been nice to add a touch of self oscillation in there - perhaps this would have compromised the sound though.

As with the 4075 filter, CV inputs are plus/minus type, though with no centre marker or stop, its a little tricky to get to zero and the scaling is quite sensitive around the 0 point.

Another reason to get a bigger case if you are into Eurorack - god help you!

Available now, priced at £229/$269 MSRP

Size - 12hp
Depth - 39.7mm with ribbon cable attached
Power Usage - 23mA, 30mA (+12 / -12)

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