just a little demo of the pittsburgh modular filter. really enjoying this filter - and i'm a SUCKER for filters, as you'll probably be aware! it's got some really cool and unique features, along with having perhaps the lushest, cleanest, most liquidy resonance (in "normal" filter mode)....especially in lowpass mode. that's not really what i've set out to show in this demo however, although it's in its most normal filter mode near the start.

initially it's in FILTER/ Q mode, (the Q cv input modulates the resonance). the sequence is all generated by the z8000: the slow notes are the actual osc from the AFG (pulse wave) playing a 4 step sequence clocked at one step per bar. i then tuned the cutoff of the filter to the same frequency as the AFG so i could use one of the 16 step outs to harmonise it (being randomly reset and changed in direction by the a149-2). so....essentially the filter plays the top part, and the AFG plays the bass notes.

initially i just use it as a normal filter, gradually increasing the resonance. then, at 00.55 i switch it over into OSC mode, which produces a nice growly self-oscillation. i have it set just on the cusp of self-oscillating (in this mode it completely cuts out if the Q is set below about 9'o'clock, making for some cool possibilities if you modulate the Q....it cuts in and out with a really crunchy sound. so i gradually start bringing in a bit of Q modulation from Maths - not ever really letting it cut out completely at first, but instead sweeping the Q drive up and down.

at 01:48 i switch it to Bandpass mode and play about some more with Q modulation, getting some nice growly effects.

at 02:40 i flick the 1/Q switch over to "1" - this turns the Q cv input/ attenuator into an inverted VCA. i didn't find this that useful at first, but i just discovered that when in OSC mode, you can fade between a growly distorted self-oscillation and a clean one (more like you get in FILTER mode).

at about 04.26 i start messing around, randomly changing the cutoff and letting Maths speed up and make the OSC mode cut in and out by modulating the Q cv. things go a bit awry, as i hadn't really thought what i was gonna do past this point, so i pause and regroup!

At 04:40 i come back in, this time with the Maths in env mode, triggered by some random gates from the a149-2. you can hear the effect of this modulating the Q - first in Q mode (cutting the sound in and out)...and then in "1" mode, where it is fading the self-oscillation from clean to dirty.

To be honest, it's not the best demo in the world, and i didn't really plan it out that well - but hopefully it demonstrates some of the odder aspects of this excellent filter. it sure is a lot of fun - especially when it's teetering on the brink of cutting in and out in OSC mode.

It certainly gets a thumbs up from me. and definitely among the best "squelchy" / "liquidy" lowpasses i've heard so far. In my opinion it beats the RS110, z2040, Borg2, SEM/20, a108, a105, a106-6, Cwejman S1 mk.2, Blue Lantern Diode Filter, Blue Lantern LM4250, Harvestman Polivoks and Toppobrillo Multifilter on that score. This isn't the demo to particularly demonstrate that though...maybe i'll do another focusing on it's squelchy/ liquidy side.

The only filter to please my ears EVEN more than this is the one found in the Vermona Retroverb Lancet, although that is obviously not as "modular", and has less CV options.