RelVol1 and RelVol3  

64-step relay attenuator kits  


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  RelVol1 and RelVol1C are are stereo attenuator boards made using relays and precision resistors. The RelVol3 board is a balanced version of RelVol1. The "C" version includes a control section with a rotary encoder and remote control receiver. The standard versions can be used with the different "Control" and "VolControl" boards.

The attenuator is normally setup with 64 1dB steps, but other step sizes like 1.5dB are also possible. The attenuator has a constant input impedance, and any impedance value can be delivered at no extra cost. Standard values are 1k, 5k, 10k, 20k, 50k and 100k.

The kits are available as complete kits and PCBs only (both come with manuals/part lists). Resistor kits with MRS25 or Dale RN55 1% resistors are also available - two kits are needed for a RelVol3 board.

The boards need a +5V supply. The non-C versions can be supplied by the input selector board (if one is used). The board sizes are 75*83mm (RelVol1), 75*93mm (RelVol1C) and 89*75mm (RelVol3).

I designed the RelVol1/3 circuit in the winter of '03/'04. But I was not the first to design this circuit. Alex Nikitin of A.N.T. Audio designed the same circuit more than two years before me (which I didn't know until recently). He describes the circuit here. When looking through that thread, it looks like others have "invented" the circuit also :)

RelVol1 schematic (GIF 38kB)

Qty: Order code: Description: Price (ex. VAT):
RelVol1 Relay attenuator board without resistors 30,00 €
RelVol1C Attenuator board with control section (no resistors) 42,00 €
RelVol3 Balanced relay attenuator board without resistors 47,00 €
RelVol1RM RelVol1/3 MRS25 1% res. kit. Value: 3,00 €
RelVol1RD RelVol1/3 Dale 1% resistor kit. Value: 5,00 €
RelVol1PCB RelVol1 attenuator - PCB only 10,00 €
RelVol3PCB RelVol3 attenuator - PCB only 14,00 €
Delivery time: 3-4 days