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 voltage dividers. 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 two ends. It is designed majorly as a SMD (Surface Mounting Device) component. Since manufacturing process of MELF resistor is more complex than flat-chip resistor, 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 pre-determined for each step, so front panel display can represent actual signal levels.

Ready mounted LCD R-2R volume-controller

Specifications:
– 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 universal remote)
– 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

PCB board may support LCD or LED display up to the Atmel software.
R-2R resistor 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.

LCD volume controller

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.

Balanced volume controller

Documentation and firmware

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

How to program and update your Volume-Controller firmware.

How to set-up infrared remote controll for your Volume-Controller

PCB GERBER files & PCB PDF 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).

PCB dimensions.

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

wiring instructions

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 [2] picture