Frequency Central State 700 Manual

Frequency central
Build documentation for:
State 700
Based on the Roland System 700 state variable filter module. Rev.1 Jan 2016
100K Lin 100K Lin Dual 50K Log 100K Lin 100K Log 100K Log
Key to PCB screen print:
n: This signifies NPN BC547 transistors. Note the correct pinout as shown by the half circles.
p: This signifies PNP BC557 transistors. Note the correct pinout as shown by the half circles.
The PCB shows the correct orientation for BC547/BC557. Other transistor types can be used (eg
2N3904/2N3906), but please observe the correct pinout.
Please observe the correct polarity of the electrolytic
capacitors.
Gnd: ground connection between PCB and all sockets
In 1: wire to Audio1 socket
In 2: wire to Audio2 socket
HP:wire to HP output socket
BP: wire to BP output socket
LP: wire to LP output socket
CV1: wire to CV1 socket
CV2: wire to CV2 socket
Tip #1 -don’t mix up the 47R and 47K
Tip #2 - don’t mix up the 100R and 100K
A big part of the sound of the State 700 is the way in
which resonance is reduced as the audio inputs are
driven harder. It won’t self oscillate with a hot audio
input, throttle back a little and you’ll get squelchy ear
bleeding resonances!

Bill of Materials
47R x 1
100R x 3
1K x 3
1K5 x 2
1K8 x 1
4K7 x 1
5K6 x 1
10K x 3
15K x 3
22K x 2
47K x 1
56K x 1
68K x 1
100K x 7
150K x 1
270K x 1
1M x 1
All resistors ¼ watt
470pF x 2
1uF BP x 3
10uF x 1
22uF x 2
47uF x 2
LF351 x 1
(Please use TL071 instead)*
TL072 x 2
LM13700 x 1
BC547 x 1
BC557 x 1
1n4148 x 2
A50K Dual x 1
A100K x 3
B100K x 2
10K trimmer
100K trimmer
Power header
*Reports of some duff LF351 making the rounds, TL071 will work equally well.
Calibration
1. Scale trimmer: turn Res all the way to self oscillation. Patch a 1V/oct source into CV input 1,
with the attenuator fully clockwise. Play octaves and adjust the Scale trimmer until they are
spot on.
2. Freq trimmer: you want to tweak this so that the filter is fully open when the Cutoff pot is
fully clockwise.

Underside of the PCB showing:
Ground bus between sockets and PCB
Connections between inputs/output and PCB
I use solid core for all of the above.
This is how I ground all the sockets to the PCB, The wire far left goes through the PCB ground pad:
RDH 06/02/16
http://www.frequencycentral.co.uk/