Modular FM Bell

Classic DX7 tubular bells created with a Buchla inspired dual oscillator...

The story

I’ve recently finished building a Buchla inspired dual oscillator (a Stroh 258J, in MU format of course) and decided after a lot of energy being focussed on FM synths at the moment to try some real, raw, analogue and unsanatised linear Frequency Modulation with my modest modular set up (not all this digital stuff that pretends to be Frequency Modulation whilst it’s actually Phase Modulation).

The patch I ended up recreating was the classic DX7 tubular bells, but limited to 4 operators by the amount of envelopes and VCAs in my system (thus the FM Algorithm I went for were two dual operator pairs at ratios of approximately 1:3.5 which due to all operators being slightly detuned gives it this nice organic chorusing).

After having some fun playing some sequences on that patch I just wanted to play it polyphonically, so decided to quickly sample it. This was done in major thirds with 4 round robins over 4 octaves, which required retuning of the modulators as those exponential converters are sadly not as good as the ones in the Buchla clone. Sadly this is where a slight accident occured when I was readjusting the modulators and inadvertently changed the FM ratio to 1:4 for the top two octaves.

There are two instrument patches which includes a stereo one that layers 2 round robins for some extra width and chorusing.
Also I should mention that this sound is slightly out of tune; in my opinion just by about as much as one can get away with to call it chorusing rather than being detuned, but you may have to adjust some notes if you get annoyed by imperfect pitch.

Signal chain was balanced out from the final VCA, into the Mic Pre on a Studer Console, through the busses and sum into a Babyface and recorded & edited in Cubase.


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