CHD Elektroservis 7-701 User manual

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Module 7-701 v. 1.0
USER GUIDE
© 2014 CHD Elektroservis

Spectral Ring Modulator Module 7-701 v. 1.0
Copyright © 2014 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
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Content
page
1. Main features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Module functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Connection the module to the system . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Harmonic frequencies spectrum control . . . . . . . . . . . . . . . . . . . . . . . 6
6. Technical parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Warranty conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
This manual and other documentation are also available at : www.chd-el.cz
Manufacturer :
CHD Elektroservis
Nad kundratkou 27, 19000 Praha 9, Czech Republic
[e-mail]
www.chd-el.cz

Spectral Ring Modulator Module 7-701 v. 1.0
Copyright © 2014 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
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1. MAIN FEATURES
 Processing of both AC and DC input signals
 Spectrum control for feedback modulation
 Mixed output with “Dry / Wet” audio signal ratio control
 Carrier and Modulator input level controls
 Limiters on both Carrier and Modulator inputs
 Stainless steel front panel
 Pure analogue circuitry (no DSP technology used)
 Fully hand-made – each module tested and adjusted individually
OUR MISSION
Do things different
Always offer something unique and innovative not available on the market so far.
No compromises in the circuitry design
Don’t give up the sound quality for cost driven compromises.
Classic design and hi-end components
For long live and better serviceability of the devices.
Hand made in Europe
Each unit is hand made and individually adjusted for highest quality control.

Spectral Ring Modulator Module 7-701 v. 1.0
Copyright © 2014 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
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2. MODULE FUNCTIONS
Spectral Ring Modulator is module designed for Eurorack modular synthesizer systems. All controls,
signal inputs and outputs are located on the front panel (see Fig. 1). Inputs and outputs use standard
mono 3,5 mm (1/8”) mini-jack patch connectors.
Fig. 1 – Module front panel
[1] CARRIER – carrier signal input CARR-IN level control
[2] MODULATION – modulation signal input MOD-IN level control
[3] SPECTRUM – side frequency signal input level control
[4] MIX – ratio of direct signal from CARR-IN input and processed
signal from RING-OUT output at MIX-OUT output
[5] CARR-IN – audio or modulation signal input (Carrier)
[6] MOD-IN – audio or modulation signal input (Modulator)
[7] RING-OUT – ring modulator output
[8] MIX-OUT – mixed output
The Ring modulator module is usually used for metallic or bell-like sounds. Optimal result depends
on the module controls settings.
Spectral Ring Modulator is based on pure analogue signal multiplier. The scheme in Fig. 2 shows the
internal block structure of the module.
Fig. 2 – Block scheme

Spectral Ring Modulator Module 7-701 v. 1.0
Copyright © 2014 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
5
Spectral Ring Modulator function is fully four-quadrant multiplication of the analogue signals from
CARR-IN [5] (CARRIER – carrier signal input with f
CARR
frequency) and MOD-IN [6] (MODULATION –
modulation signal input with f
MOD
frequency). The result of this operation are two, so called, side
bands (new frequencies f
CARR
+ f
MOD
and f
CARR
- f
MOD
) and subsequent cancellation of the original
frequencies (f
CARR
and f
MOD
) – see Fig. 3.
Fig.3 – Examples of side bands creation
RING
W = X * Y
"Y"
"X"
"W"
VCO
SINE
130,81 Hz (c)
VCO
SINE
523,25 Hz (c'')
OUT
SINE
392,44 Hz (g' +2 cents)
+
SINE
654,06 Hz (e'' -13 cents)
RING
W = X * Y
"Y"
"X"
"W"
VCO
SINE
440 Hz (a')
LFO
SINE
25,43 Hz
OUT
SINE
414,57 Hz (g#' -3 cents)
+
SINE
465,43 Hz (a#' -3 cents)
3. CONNECTION THE MODULE TO THE SYSTEM
Fig. 4 – Bus board connection
To connect the module, plug carefully the supplied
ribbon cable into the bus socket of your modular
case. The colored marking of the ribbon cable
must be at the bottom of the bus connector!
Failure to check this may result in the module or
case PSU damage! (module is not protected against
permanent incorrect polarity).
The module uses ±12V of the system only (pins Nr.
1 to 10), GATE, CV and +5V signals are not used
(see Fig. 4).
4. OPERATION
Both CARR-IN [5] and MOD-IN [6] inputs can process signals in the frequency range of 0 to 20 kHz
(i.e. DC signals can be processed too). The input level of both signals is controllable by CARRIER [1]
(for CARR-IN [5] input) and MODULATION [2] (for MOD-IN [6] input). Minimal input level for optimal
signal processing is ±2,5 V
PP
(both pots are in the most right position – MAX in that case).
Both ring modulator inputs “X” and “Y” are equipped with limiter (see Fig. 2) – signals with input
levels higher than the multiplier can process are limited. In this case, certain distortion appears that
might be used for another special sound effects. When the signal is limited, the next new harmonic
frequencies are created.
Spectral Ring Modulator module is equipped with two audio signal outputs RING-OUT [7] and MIX-
OUT [8]. Both outputs provide signal with amplitude of max. ±5 V
PP
(accordingly to the front panel
controls settings).
RING-OUT [7] output provides direct output from analogue multiplier (see Fig. 2).
MIX-OUT [8] output provides the mixed signal of analogue multiplier and dry CARR-IN [5] input signal
(see Figr. 2). The “Dry/Wet” signals ratio can be set by MIX [7] potentiometer. In its most left
(CARR) position, MIX-OUT [8] output provides only the dry CARR-IN [5] input signal. In its most right
(RING) position, MIX-OUT [8] output provides only resulting multiplied signal.

Spectral Ring Modulator Module 7-701 v. 1.0
Copyright © 2014 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
6
5. HARMONIC FREQUENCIES SPECTRUM CONTROL
Spectral Ring Modulator module is equipped with special feedback function with level controlled by
SPECTRUM [3] potentiometer. This feature can create additional harmonic frequencies. In its most
left position (NARROW) the ring modulator creates only basic side frequencies (f
CARR
+ f
MOD
and f
CARR
-
f
MOD
), while in its most right position (WIDE) the maximum possible spectrum of harmonic
frequencies is created. The following charts on Fig. 5 depict the signal spectrum at RING-OUT output
for frequencies 2 kHz (CARR-IN) and 400 Hz (MOD-IN).
Fig. 5 –SPECTRUM regulator settings results

Spectral Ring Modulator Module 7-701 v. 1.0
Copyright © 2014 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
7
6. TECHNICAL PARAMETERS
Mechanical dimensions
Module width : 8 HU (40,3 mm)
Module height : 3 U (128,5 mm)
Module site depth : 35 mm (without power supply cable)
Power supply
Supply voltage : ±12 V from the system bus
Current requirement : max +15 mA / +12 V
max -15 mA / -12 V
Inputs / outputs
Inputs : CARRIER  min ±2,5 V
PP
for full driving / Z
IN
= 10 kΩ
MODULATION  min ±2,5 V
PP
for full driving / Z
IN
= 10 kΩ
Outputs : RING  max ±5 V
PP
/ Z
OUT
= 200 Ω
MIX  max ±5 V
PP
/ Z
OUT
= 200 Ω
Accessory
Ribbon power supply cable with 10 / 16 pin connectors, length ca 200 mm
7. WARRANTY CONDITIONS
The equipment is provided with thirty-month warranty starting from the date of the equipment
take-over by the customer. This date must be specified on warranty list together with dealer's
confirmation. During this period of time, all defects of equipment or its accessories, caused by
defective material or faulty manufacturing, will be removed free of charge. Warranty repair is
asserted by the customer against the dealer. Warranty period is to be extended for the time period,
during which the product was under the warranty repair. The relevant legal regulations take effect
in case of cancellation of purchase contract.
The customer will lose the right for free warranty repair, if he will not be able to submit properly
filled out warranty list or if the defects of the product had been caused by:
• unavoidable event (natural disaster),
• connecting the device to the incorrect supply voltage,
• inputs or outputs overloading by connecting the signals source or load source with not-
corresponding characteristics etc.,
• faulty equipment operation, which is at variance with the instructions referred-to in the operating
manual,
• mechanical damage caused by consumer during transportation or usage of equipment,
• unprofessional interference with the equipment or by equipment modification without
manufacturer’s approval.

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