Steiner Parker filters compared

Steiner-Parker filters first arrived with the Synthacon in 1975. It's a
"sallen-key" filter, with an interesting characteristic: it uses positive feedback
so that as you increase resonance you don't lose volume the way you
do in a Moog-style ladder filter.

Here I'm comparing the four that I happen to have (there are more
available in eurorack format than just these). Three are analog, and
one, the Vult, is digital.

The source audio is a Doepfer A-111-3 VCO. Envelope courtesy of
Zadar, sequence courtesy of TINRS Tuesday.

00:00 Intro
00:20 Sweep - Vult Freak
00:52 Sweep - Manhattan Analog
1:44 Sweep - EAR Model 41
2:18 Sweep - Frequensteiner
2:56 LFO - Freak
4:36 LFO - Manhattan
5:59 LFO - Model 41
7:27 LFO - Frequensteiner
8:51 Fast LFO - Freak
10:08 Fast LFO - Manhattan
11:34 Fast LFO - Model 41
13:08 Fast LFO - Frequensteiner
14:40 Sequence - Vult Freak
16:14 Sequence - Manhattan
18:12 Sequence - EAR Model 41
19:58 Sequence - Frequensteiner