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Learning to love the SEM filter ... [eurorack content]

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Learning to love the SEM filter ... [eurorack content]

Postby Ben Asaro » Fri Apr 20, 2018 6:16 pm

I am very much an 'East Coast' philosophy guy when it comes to synthesis -- in particular, the Moog sound. I guess it was just ingrained into my brain from all that prog rock I grew up with. When I got my Studio Electronics VCO, as it was based on the SEM, I figured, heck -- I may as well go with a SEM filter so I can have two very different sound!

And then I connected them together ... and, man, did I not like the way it sounded! It had a very harsh (to my ears) tilt to it and the choices seemed to be between All or Nothing as far as the sizzle was concerned.

It took a very long time (about a year, in fact) before I started to understand, appreciate, like, and finally love the SEM filter. I know what the differences are between a 12dB and 24dB filter (or at least I thought I did) but the actual sonic reality of it didn't hit home until I had actually started to make patches with it.

So, here's what I have gained from my Life And Times with the SEM:

First In a word, this thing is TOUCHY. I was so accustomed to the Moog, which rewards grandiose sweeps with a pleasant rolloff and a generous 'fudge factor'. Not so with the SEM filter -- a 1/16th of a turn can make a vast difference in the final sound.

Second, this filter loves having multiple waveforms thrown at it. A single waveform is nice and all but when you double or triple down you get a a sort of phase blending to that nasal harshness that makes it more euphonic and rich.

Third, the bandpass output is AMAZING. You can, theoretically, triple track with the SEM at low pass, high pass, and band pass and blend them to taste and have a very large, complex sound at the end of the day.

I doubt any of this is going to be revolutionary for those of you who already know about this sort of stuff but for me it's been a fun, educational journey thus far. :)
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Re: Learning to love the SEM filter ... [eurorack content]

Postby Dave B » Fri Apr 20, 2018 9:09 pm

It's interesting that we've had people rave about the Moog ladder filter for years, and yet most of the synth heads I know all have a real soft spot for the Oberheim sound. I'm terrible : given the choice, I'd go Obie all the time - even over the classic Moog filter. I'm such a heretic that I use Obie synths in favour of Moog for bass pedals!

And it's worth bearing in mind that when all this stuff was new, things like the SEM were seen as an addition to a system so that you had options. It's great that we are back to that way of thinking. There is so much great kit around at the moment.

Out of interest, who's SEM filter did you go for? Alan's AJH Gemini is stunning and has that whole SEM-thing in spades - if I wanted that sound, I'd be looking at that.
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Re: Learning to love the SEM filter ... [eurorack content]

Postby Ben Asaro » Fri Apr 20, 2018 9:14 pm

The Doepfer SEM filter; cosmetically it looks like the WASP, but sounds very different.
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Re: Learning to love the SEM filter ... [eurorack content]

Postby Martin Walker » Sat Apr 21, 2018 4:00 pm

Dave B wrote:It's interesting that we've had people rave about the Moog ladder filter for years, and yet most of the synth heads I know all have a real soft spot for the Oberheim sound. I'm terrible : given the choice, I'd go Obie all the time - even over the classic Moog filter.

I've often thought that the secret of the Moog filter is that its resonance greatly reduces as you go down the octaves, so you can get plenty of squelch at the top end without sacrificing your big bottom once the sweep has dropped significantly in frequency ;)


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Re: Learning to love the SEM filter ... [eurorack content]

Postby pilot-wave » Sat Apr 21, 2018 11:48 pm

After decades of seeing a wide variety of synths come and go there's been one blind spot for me and that's the SEM filter which I too have only come to appreciate within the last year. Like you say, that 'sizzle' area, at first, seems to be excessively wide until you get into finer interactions within and into the filter.

I notice that people often tweak wildly away on YouTube filter/synth demos completely overshooting the hidden areas and interactions that their gear can most excel at... like you've discovered, a careful, small, amount of pot travel can often yield surprisingly large shifts in tone when other conditions such as resonance are at certain settings.

Enjoying it first in the DSI OB6 desktop and now in the SE Boomstar SEM which, unlike the OB6, allows for external signal treatment.

Another classic for me that is distinct from the Moog ladder filter has been the Korg traveller type HP/LP yielding BP combo (dating back to the Mini Korg 700) which has been approximated in Eurorack. The VCF-74 Mk2 by Vintage Synth Lab is worth investigating for this, building on the original with a boost option and slightly different behaviours here and there which seem to add to its reach.
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Re: Learning to love the SEM filter ... [eurorack content]

Postby Ben Asaro » Sun Apr 22, 2018 11:30 am

Thanks for the tip, I will check it out. The Jove filter is probably next on my Hit List.
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