updated - 2/9/2018



CMS/DISCRETE SYNTHESIZERS has faithfully reproduced the world famous ARP 1047 multimode filter from the ARP 2500 system in a high quality version of the euro-rack format.

CMS has extensive knowledge and experience building and repairing these classic sounding, highly resonant filters. We have taken this expertise and applied it to the euro-rack world. A world somewhat lacking in high fidelity (in our, and some of our customers opinions). We are on a mission to change all that.

Don't let the compact size of the 1047E fool you. This unit is an audio monster. The low end response is remarkable even on the band-pass and high-pass functions. The sonic clarity, high end response and resonant sizzle, sets this filter apart from all the other filters made today. The high-pass response actually has the ability to resonate bass and sub bass audio signals significantly, producing some monster bass sounds for the dance floor, especially when used in series with a 24db low-pass filter.

The 1047 multimode filter is the module that gives the ARP 2500 it's distinctive sound more than any other 2500 module by far. The CMS 1047E is a "dead ringer" as far as audio performance and sound, compared to the original. Actually our version has lower noise specs due to better design, quality components, and no matrix switches.

Using the 1047 high-pass response in series with the 1006 low pass function really captures the classic ARP 2500 sound. You can now realize this sound in your studio with the 1047E and 1006E from CMS.

If you want to reproduce the sound of the ARP 2500 exactly, check out our other 1000 series modules that will soon be available from CMS. They are all based on the ARP 2500 and 2600 systems.


This unique and complex circuit utilizes 3 discrete ARP / Wilson current mirror VCAs to produce it's distinctive and highly resonant sound.

High quality construction and top shelf components, Switchcraft jacks, Alps attenuators.

CMS engineering used in many professional recording studios across the USA and Europe.

Main frequency control pot features an extra large geometry "virtual infinite resolution" potentiometer for accurate control of frequency.

3 control voltage inputs. 1 fixed at 1v per octave and 2 more with attenuators.

1 Voltage controlled resonance input with attenuator.

Easy to understand flowchart front panel graphics facilitate operation, even under "influential conditions".


ARP Module 1047 is a functional circuit package designed for use in the ARP Series 2000 electronic music synthesizers. The unit consists of a highly resonant filter with voltage controlled frequency and resonance, and provides high pass, band pass, low-pass, and notch outputs. The filter is capable of providing a wide variety of formant shaping and tonal modulation. The band pass response is that of a natural acoustic resonator, and is most useful in synthesizing instrumental timbres. In addition, the high degree of stable resonance and frequency tracking accuracy attainable enables the filter to perform precise, narrowband spectrum analysis of audio signals.

The center frequency of the band pass output is the cutoff frequency of the high pass and low pass outputs, and is referred to as "Fc". Fc may be set by the frequency knob over the range of 16 Hz to 16 KHz. Control signals applied to any Fc input will change the center frequency from the knob setting by 1 octave per volt when the knob above the control input is at maximum. Control signals from the individual inputs are summed with the Fc knob controls, and may be positive, negative, or audio.

With the RESONANCE (Q) knob at minimum and the RESONANCE switch set to "NORM", the band-pass output has a gain of 0.5 at Fc and attenuates 6 db per octave above and below Fc. The high pass output has unity gain from Fc to 20 KHz and attenuates 12 db per octave below Fc. The low pass output has unity gain from DC to Fc and attenuates 12 db per octave above Fc. The notch output has flat response everywhere except for a deep (40 db) notch at a frequency determined by the NOTCH FREQ knob with this knob set to 1, the notch occurs at Fc. NOTE: The notch output is effective only at low Q.

As the RESONANCE (Q) knob is turned up, a resonant peak occurs at Fc in all four outputs, except in the notch output when the notch frequency is at Fc. The gain at this peak is numerically equal to the "Q",and the 3 db bandwidth of this peak is equal to Fc/Q. Thus, as Q is varied from V2 to 512, the bandwidth varies from 2 Fc (2 octaves) to Fc/512 (1/32 of a semitone). When using high resonance, the audio input control may have to be turned down to prevent overload. The Q may be controlled by external signals. The Q control characteristic is exponential; that is, each volt applied to a "Q" input doubles the Q when the input knob is at maximum.

Some things not included in the 1047E compared to the original 1047:

The keyboard percussion - can be easily reproduced on the 1047E by feeding a pulse such as an ADSR (with all controls set to zero) into the audio input to "ping" the filter. The highly resonant circuit generates a sine wave that decays at the rate determined by the Q setting.

The final Q - is almost always used along with the keyboard percussion. It's function can also be easily realized on the 1047E by modulating the voltage controlled resonance input by a keyboard gate or an ADSR. When the key is released the resonance drops to the "final Q". There was really no critical need to have any of this, if you know how to patch the module correctly. These 2 features are in reality, just patching conveniences.

The limited resonance - is a weak sounding version of the normal resonance, same sound, just at really low volumes, sounds quite bad, so we intentionally left that out.

We really wanted to have the overload light, but there was no freaking room left!



CENTER FREQUENCY (Fc): 16 Hz to 16 KHz, voltage controlled.
BANDPASS RESPONSE: Single pole resonator, 6 db per octave.
RESONANCE (Q):1/2 to 512 (0 to 54 db peaking at Fc), voltage controlled.
BANDWIDTH (3 db): 2 octaves to 1/32 semitone.
HIGHPASS AND LOWPASS RESPONSE: 12 db per octave cutoff at Fc, with same resonant peak at Fc as in Band pass Response.
NOTCH RESPONSE: Resonant peak at Fc as in Band pass Response, plus notch at frequency determined by NOTCH FREQ/Fc control.
With this control at 12 o'clock, response is flat except for notch at Fc.
NOTCH DEPTH: > 40 db.
NOTCH WIDTH (3 db): 2 octaves to 1 semitone.
CONTROL INPUT RANGE: ± 10v maximum.
INPUT IMPEDANCE: 50 K ohm minimum.
Fc CONTROL CHARACTERISTIC: 1 octave per volt; at OV, Fc is equal to the frequency knob setting.
Q CONTROL CHARACTERISTIC: 1 volt doubles Q; at OV, Q is equal to resonance (Q) knob setting.
AUDIO INPUT RANGE: ± 10 v maximum.
POWER REQUIREMENTS: ± 12 volts @ 50 mA, regulated to+0.1%.


MODULE DEPTH: 1.75 inches






PRICE - $529.00 USD. Georgia residents must add 7% sales tax.

Shipping and insurance:

Shipping and handling USPS priority mail:

Continental US - $15.00 USD uninsured, $22.00 USD fully insured.

European customers: $66.00 USD uninsured, $72.00 USD fully insured.

Canadian customers: $46.00 USD uninsured, $52.00 USD fully insured.

Overseas customers are responsible for all taxes and duties. Orders will be shipped within 48 hours.


Send a paypal payment to filter@discretesynthesizers.com to order. We will send you a PDF Invoice. You can also request a Paypal Invoice by clicking on the email link below.

You can also send a check to CMS/Discrete Synthesizers. Email us at filter@discretesynthesizers.com for the mailing address and more info. We will send you a PDF invoice reflecting your payment.


e-mail: filter@discretesynthesizers.com

Phone: 912-727-2195

©2017 Phil Cirocco