R-2R / SHUNT VOLUME CONTROLLER with 4 selectable sources
Product available in our webshop.
Vicol-Audio volume controller offer important sonic advantages over
common potentiometers due of discrete resistors and
method of signal attenuation: resistor
Discrete resistors offer better low noise and characteristics than the
carbon or cermet resistor elements used in potentiometers. Vicol-Audio
volume controller make use of low tolerance, noninductive, professional
MELF resistors for R-2R/Shunt attenuation network.
MELF is the acronym for Metal Electrode
Leadless Face - a leadless cylindrical component that is metallized on
It is designed majorly as a SMD (Surface Mounting Device) component.
Since manufacturing process of MELF resistor is more complex than
MELF resistor has its own advantages over flat-chip type.
Compared with regular flat-chip
type SMD resistors, MELF offer low
TCR (typical lower than ±5ppm/°C), greater surge handling,
low noise and ultra low distorsion, ensuring
high stability through time and over temperature variations.
The total measured resistance for each position of our
volume-controller remains constant throughout years of use. This is
because the wearing (rubbing) parts in Vicol-Audio volume controller
are low resistance switching relays, not resistive elements with wipers
sliding on them as in potentiometers. Potentiometers can add clicks,
pops, and noise to wear.
Stereo potentiometers used as volume controls often produce different
volume levels for each channel, and the amount of mismatch can
vary as the potentiometer is turned up or down. The channel-to-channel
tracking specification for stereo potentiometers, even very expensive
ones, is typically 5% to 20%. With Vicol-Audio volume controller you
can easily achieve stereo signal levels matched up to 0.1%.
Outstanding S/N ratio and excellent THD of the amplifier is
not compromised in any way, and the same superb sound quality will be
obtained at any volume setting. Signal level has been
for each step, so front panel display can represent actual signal
PCB board may support
LCD or LED display up to the Atmel software.
– low tolerance 0.1% R-2R network with melf resistors
– attenuation in 64 steps - each step 1dB
– Input resistance ranges from 20k to 1M for a Rload of 1M.
– Output resistance ranges from 9.75k to 10.5k.
– 4 selectable inputs with option to edit input name
– one direct input
– Infrared RC5 autolearning (can be used with any RC5 compatible
– display light programmable On/Off - if Off timeout 10s
– tube menu for delaying plate voltage
– two open collector outputs for power On/Off and tube plate delay (see
schematic J7 connector)
– AC power consumption, Max. 6W
ladder network or shunt operation can be selected by
using only one board jumper.
The boards are balanced or multichannel ready. That means you can
control up to 8 relay boards with only one controller. A connector will
allow you to easily cascade one board in top of other.
In order to decrease output impedance, an optional buffer with LME49600
can be plugged into relay board.
You can switch between 4 selectable sources and one direct input with
no relay in signal path.
Standard input impedance is 20KOhm and can be adjusted by changing R-2R
ladder network values up to your needs.
We are alble to provide this his product in following formats:
- only PCB - for those who want to build the volume-controller from
scratch, firmware and bill of materials are available below
- PCB with ATMEGA ready soldered and programmed with our latest firmware
- DIY KIT with all components included and ATMEGA
microcontroller ready soldered and programmed with our latest firmware
- ready mounted and tested stereo version
- ready mounted and tested stereo balanced version
- ready monted and tested 6 or 8 channel version.
For OEM firmware please contact us. We are able to
provide any custom version you are looking for.
Schematic - click on below
image to download
LED Atmel software (Please note that this firmware is no longer supported. Use as it is or migrate to LCD display.)
LCD Atmega16 firmware ver. 3.10 (latest version)
- this will address a very short display flikering, with this new version is completely gone.
LCD Atmega16 firmware ver 3.8
- correct a problem with menu edit text
LCD Atmega16 firmware ver 3.5
- reduce substantially clicking noise due r-2r relay operation
LCD Atmega16 firmware ver 1.0
to program and update your Volume-Controller firmware.
to set-up infrared remote controll for your Volume-Controller
PCB GERBER files &
BOM list - Bill Of Materials
Logarithmic R-2R ladder network
calculator (under construction).
Build your own Vicol-Audio R-2R/Shunt Volume-Controller (under construction).
LCD display dataseet.
Description on how to connect the
board to trafo and IN/OUT RCA and XLR connectors.
For stereo RCA´s use below setup
In case you are using a balanced
volume-controller please refer to below setup. Each XLR use different
relay boards for IN+ and IN-. A better setup is presented in below
Balanced  picture
Second and the best setup for balanced and multichannel is using each board for a balanced chanel.
If you are mounting Vicol-Audio
volume controller in a pre/amplifier with a sigle ground star point,
connect 0ohm resistors R41L and R42R.
PCB board version1-left and version2-right.
Studio 12 channels Volume-Controller
For more information please use contact
page, or visit our webshop.