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 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





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

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

