In the Forum of www.sequencer.de arose the question which analogue Roland synth used which filter. So I made a tour through all my schematics and created this list. This list still is missing the data for some synths, especially if you have the schematics of the Alpha Juno Series I would be interested in detailed information.
^M ^M ^M ^M
Synth
Filtertype(s)
Technology
Comment
SH1
24 dB Lowpass
four OTA-stages with CA3080 with FET transistors as Buffers (no hint for selection of OTAs)
schematic
audio related changes in direct filter circuit beginning with SerialNo 711149
SH2
24 dB Lowpass
four OTA-stages with selected BA662 with FET transistors as Buffers
schematic
No filter changes in the history of the SH2
SH3
24 dB Lowpass
diode based ladder filter with five stages
schematic

SH3a
24 dB Lowpass
Ladder Filter with four transistor stages(very moogish)
schematic
there were three revisions of the SH3a filterboard, but none of them affected the filter circuit itself.
There are constant rumours that the change from SH3 to SH3a should have be caused by an infringement of Robert Moogs patent on the transistor cascading filter. But appearently this is not true, because the newer(!) SH3a uses the moog filter, where the older SH3 uses a diode ladder filter. Assumingly the true infringement happend with the SH2000 (see below).
SH5
VCF switchable to:
  • 24 dB Lowpass
  • 6dB Highpass (see comment)
  • Bandpass (see comment)
Static parametric Bandpass 6dB
Lowpass: diode ladder filter achieved with five stages, made by transistors with open collectors.
Highpass: single stage Highpass with CA3060
Bandpass: serial switching of Highpass and Lowpass.
schematic
No filter changes in the history of the SH5.
Technically the highpass filter is a 6dB/Octave, but this signal is mixed inverted to the Lowpass. The resonance only is caused by the lowpass part. So assumingly the "real" highpass function is done by the phase cancellation caused by the mixing the lowpass with the inverted signal.
The Bandpass is in fact the 6dB highpass and 24 dB Lowpass in series.
SH7
24 dB Lowpass
four OTA-stages with CA3080 with FET transistors as Buffers (no hint for selection of OTAs)
schematic
No filter changes in the history of the SH7
SH09
24 dB Lowpass four OTA-stages with selected BA662A with FET transistors and the BA662's bufferstages as buffers.
schematic
No filter changes in the history of the SH09
SH101
24dB Lowpass
four OTA-stages integrated in Roland IR3109
schematic

MC202
24dB Lowpass four OTA-stages integrated in Roland IR3109
SH1000
24db Lowpass
diode based ladder filter with five stages
schematic
No filter changes in the history of the SH1000
SH2000
24db Lowpass
Moog transistor cascade
schematic
comment on the schematics: the switch S26 loops to a resonance potentiometer (50kOhms A) on another board. Originally there was no real cutoff frequency potentiometer. The on ewhich is labeled as "cutoff" was a envelope amount in fact.
The SH2000 is the only Roland synth which used a quite complete clone of the moog cascade filter. According to several people on Analogue Heaven maillist the SH2000 was the instrument that caused the true infringment of Robert Moogs patent.
System 100
24dB Lowpass
(both: Model 101 and Model 102)
diode ladder filter achieved with transistors with open collectors.
schematic

System 700
Module 703a,b,c: 12dB LP  / BP / HP / Notch

Module 703e,d,f:
24dB Lowpass
Module 703a,b,c: State variable filter with CA3080 as OTA and CA3140 as Buffer
schematic

Module 703e,f,g: four OTA-Stages with CA3080 and CA3140 as Buffer
schematic

System 100m
24 dB Lowpass
(both: Module 110  and Module 115!)
four OTA-stages with BA662A with FET transistors as Buffers (no hint for selection of OTAs)
schematic_Module 110
schematic_Module 121

Jupiter4 / Promars
24dB Lowpass up to Serialnumber 800800: four OTA-stages with selected BA662 with FET transistors as Buffers

Serialnumber higher than 800800:
four OTA-stages integrated in a Roland IR3109
schematic old version
schematic new version
There is also a slight change in the I-control of the resonance, above S.No. 790799 but this should not affect the sound
The change to IR3109 might be a remarkable change in sound.
Jupiter6
24 dB Lowpass
24 dB Highpass
12 dB Bandpass
four OTA-stages integrated in Roland IR3109 configured as two 12dB State-Variable-Filters. Those two filters are switchable into the three types of filters (see comment)
schematic
from the Service manual of the JP 6 (typos and japenglish are original):
"VCF is comprised of two seriese connected filters o fbasically the some configuration. Each can function as either LPF or HPF of 12dB/oct slope when its output is suitable selected.
Moreover the VCF will serve as a BPF by configuring one filter into LPF and the other HPF. In the JP-6 the 1st becomes HPF and the 2nd  LPF when VCF Mode selectors are in BPF. Slight difference between two stages in circuitdiagram illustrates compensation means for level and prevention against peak clips."

Unfortunately it is not possible to disable one of the two filters. This would end in a 12 dB/oct filter, which would be very nice.
Jupiter8
12dB/24dB Lowpass
four OTA-stages integrated in a Roland IR3109; the 12dB filter is achieved by simply picking the signal after the second OTA-stage
schematic
No filter changes in the history of the JP8
Juno 6
Juno 60
24dB Lowpass four OTA-stages integrated in a Roland IR3109
No filter changes in the history of the Juno 6 / 60
Juno 106

four OTA-stages integrated in a 80017a chip (A10H800170) (similar to IR3109)
schematic
The 80017a is a collection of SMD-chips coated with resin. They are is known to fail after some ten years: Since some time there is a recommendable procedure how to remove this coating and so revive the chips again. See http://www.youtube.com/watch?v=W4lF0xSVQlg
JX3P
24dB Lowpass four OTA-stages integrated in a Roland IR3109
schematic
No filter changes in the history of the JX3P
MKS30
24dB Lowpass four OTA-stages integrated in a 80017a chip (A10H800170) (similar to IR3109)
schematic
See comment to Juno 106
MKS7
24dB Lowpass
see comment
The MKS 7 has seven 80017a filters chips. Six of them CPU-controlled in the same fashion as Juno106 (Chord and lead section), and the seventh one ENV-controlled from an IR3R09 envelope generator (bass section).
(Thanks to Henrik from Sweden for this information)
JX-8P
24dB lowpass
IR-3R05
No changes in the history of the JX-8P to my knowledge
JX-10
24dB lowpass
IR-3R05
No changes in the history of the JX-8P to my knowledge
MKS80
24dB Lowpass
IR-3109 / IR3R05
IR-3109 until Revision 4, IR-3R05 in Revision 5
MKS-50, Alpha Juno 1, Alpha Juno 2
24dB Lowpass
IR-3R05
As far as I know no changes in the history of the alpha juno series
TB-303
24dB Lowpass four stage diode ladder filter achieved with transistors with collectors connected to base.
schematic
No filter changes in the history of the TB303