| 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:
|
Lowpass: diode ladder filter achieved with five stages, made by transistors with open collectors. Highpass: single stage Highpass with CA3080 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 |
Audioexample on youtube by Alex Ball |
| 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 |
iAudioexample on youtube by Alex Ball |
| 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 |
Audioexample on youtube by Alex Ball |
| System 500 |
No information available until now | Audioexample on youtube by Alex Ball |
|
| 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 Also there is a dropin replacement available from www.analoguerenaussance.com. See: http://www.analoguerenaissance.com/AR80017A/. |
|
| 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-10 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 ; there is a very technical, but nevertheless very interesting analysis of the 303 filter by Timothy Stinchcombe, which shows, that there is no "18db/Oct"-Filter, which was a long living myth. |