AMSynths AM8075SE Athena User manual

AMSynths
AM8075SE Athena Filter
User Manual
24dB/Octave Low Pass Filter
& 6db/Octave High Pass Filter
© AMSynths 2012
Rob Keeble, Owner & Designer
Contact: [e-mail]
Web Site: www.amsynths.co.uk

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Contents
1. Welcome
2. Front Panel
3. Connections & Controls
4. Module Description
5. Configuration
6. Warranty & Support
7. Specifications

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1Welcome
Thank you for purchasing an AMSynths product.
The AM8075SE analog filter module has been designed and
hand built in the UK to exacting quality standards. The
module uses high quality electronic components and
particular attention has been paid to the quality of the
audio signal path, stability of the control circuits and the
long term life of the product.
This user manual explains the basic functions of the
module, as well the historic background to its development,
how to install the module and the warranty and support.
AMSynths modules are produced in low volumes, with each
module having a unique holographic serial number and a
certificate of ownership. You own a rare and beautiful
analog synthesizer module that will provide many years of
amazing sounds and musical inspiration.
Rob Keeble
Owner & Designer
AMSynths
December 2010

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2Front Panel
AUDIO INPUTS:
InA, InB
CONTROL INPUTS:
CV1, CV2, CV3
AUDIO OUTPUTS:
Out
CONTROL POTS:
Signal A (white)
Signal B (white)
Signal C (white)
LP Frequency (blue)
LP Resonance (red)
HP Frequency (blue)
CV1 (grey)
CV2 (grey)
The serial number is on a small silver holographic sticker on
the inside of the front panel.

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3Module Description
The AM8075SE is a clone of the ARP 4075 4-pole 24dB low
pass filter in the ARP Odyssey Mark 3, Omni, Quadra and
Solus, and very similar to the ARP 4072 filter in later
models of the ARP 2600. The module also has a single pole
High Pass filter connected in series after the low pass filter.
This Special Edition (SE) uses high quality internal
components such as matched transistor arrays, low
distortion and low offset op amps and precision
Polypropylene capacitors, for a pristine sound quality. The
external design replicates the “look and feel” of the ARP
Odyssey Mk1 with slide potentiometers and coloured caps.
At the heart of this module is the LM3900 Norton Amplifier
chip which delivers the distinctive "smooth" 4-pole low pass
filter, with a clean low distortion output that will oscillate at
higher resonance settings. The filter response at high
resonance remains faithful to the original with a slight loss
of bass at higher resonance.
The high pass filter in the original ARP Odyssey is rather a
nasty affair based on a CA3080 OTA chip, so I have
replaced it with an improved design based on the higher
quality BA6110 OTA chip.
Athena is the Greek Goddess of inspiration and skill, and
we think this skillfully engineered filter will inspired your
music! The sound and look of the ARP Odyssey synthesizer,
and much more.

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Connections & Controls
The two uppermost jack sockets INA and INB are for
connecting audio signals into the input side of the filter,
these signals are mixed together. The level of each audio
signal can be varied from nil to maximum using the front
panel slide potentiometers SignalA and SignalB.
The middle jack sockets CV1, CV2 and CV3 are for
connecting modulation control voltages into the filter.
These signals vary the cut off frequency of the filter, with
the front panel slide potentiometers adjusting the amount
of modulation, except for CV3 which is directly connected
to the VCF.
The lowest jack socket marked Out is the audio signal
output of the filter and it is typically connected to a VCA.
The VCF Cutoff slide potentiometer varies the cut off
frequency of the low pass filter. At the minimum setting the
filter will cut off all frequencies with no audio output and at
the maximum setting the filter will pass all frequencies.
The VCF Resonance slide potentiometer adjusts the
resonant peak of the filter from a minimum setting of no
resonance, through subtle resonance enhancement to a
maximum setting when the filter will break into self
oscillation.
The HPF Cutoff slide potentiometer varies the cutoff
frequency of the high pass filter.

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4Configuration
The AM8075SE module occupies 16HP of EuroRack space
and is fully compatible with various Euro Rack cases,
especially Doepfer. The height of the panel is 128.5 mm
and there are four mounting holes at each corner of the
module. Four 3mm diameter mounting screws are included
to enable you to securely mount the module into your rack.
The module should be connected to the 12V Doepfer style
power bus within your case using the included AMSynths
multi-way power cable. Ensure the power is OFF before
connecting the module and BE VERY CAREFUL to ensure
that the power connector to the bus is connected with the
red stripe of the cable lined up with -12V (negative 12V).
This is standard Euro Rack power connection but be VERY
CAREFUL to get this right! Damaged modules will not be
replaced under warranty when the power has been
misconnected. The power socket on the AMSynths module
is keyed so that the cable can only be inserted the correct
way.

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5Warranty & Support
Repairs resulting from a defect of the module or its
construction process are covered by a one year warranty,
with the customer paying transit costs to AMSynths in the
UK.
Damage to the module resulting from incorrect power
supply voltages, backwards power cable connection,
abusive usage, fluid encroachment or out-of specification
voltage input are not covered by the warranty and normal
service rates apply.
AMSynths implies and accepts no responsibility for
undesirable harm to a person or apparatus caused through
operation of this device.
If you have questions regarding the use of this module or
you need technical support please contact AMSynths via
email at [e-mail].

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6Specifications
Power Supply:
+12V, GND and -12V standard Doepfer 10 pin connector
RED stripe on power cable is -12V (NEGATIVE 12V)
Current consumption:
TBD
Dimensions:
128.5mm (Height) x 70.8 mm (Width)
Euro Rack Size:
16HP/TE
Panel:
2mm machined aluminum with colour photographic print.
Frequency
20 Hz to 20 kHz
Resonance
0 to self oscillation
Output Impedance:
1k ohm
Input Impedance:
100k ohm