KAT ‘ASF Sequential Splitter/Combiner’

Just recently, a customer asked if we could design him a multi-functional unit that could be used to split one input into two outputs such that the input could be switched to either output A or output B, or, both by way of three sequential foot switches.

The unit had to be fully transformer balanced, mains operated and enclosed in as small a case as possible as it would be residing on the stage and not in a rack unit!

The unit we designed weighed in at less than 220mm wide, was fully transformer balanced, mains operated, with a fully buffered low noise/high headroom hi-impedance input stage.

We also managed to design-in an additional feature such that pressing button A would route the signal only to output A (whilst output B was fully muted). Pressing button B would route the signal to output B (Whilst output A was fully muted) and pressing button C would route the signal to both outputs A and B without ANY level loss. Additionally, pressing any active button again activates the mute function.

Each footswitch button has its own Led, as does the two output jacks, so visual feedback is provided even when all other senses are focussed on the performance. 

Inside the ASF Splitter/Combiner (It only ‘just’ all fitted in!)

Performance wise, the ASF Splitter/Combiner has exceptionally low noise and very high headroom (the internal power supply has a 30V swing). Both outputs are transformer balanced with output A provided with an ‘Earth Lift’ switch feature.

I have to say, we are very pleased with the resulting unit! It is totally transparent when inserted into the signal chain and exhibits no noise or hum, which is something to be proud of when the power-supply is integral to the unit! No wall-warts here!

Just as an add-on, and to explain how we did this, we designed it around a full-time distribution system with mutes, so instead of switching signals to the outputs we wanted them to go to (leaving the unwanted outputs floating), we actually sent the signal to ALL the outputs ALL of the time, then simply ‘Muted’ the outputs we didn’t want to hear! That way, ‘inactive’ outputs are prevented from throwing unwanted noise out to amplifiers when they are not being used because they are physically muted!

Footswitch ‘A’ Pressed - Output ‘A’ active, output ‘B’ muted.

Footswitch ‘B’ Pressed – Output ‘B’ active, output ‘A’ muted.

Footswitch ‘C’ Pressed – Both Outputs active, all mutes lifted.

Another happy customer! ……………..We love those! (and a thoroughly enjoyable project with possibly the most ‘laid back’ yet ‘focussed’ customer we’ve ever had!) …… Thank you Antony!

All the best,



Knight Audio Technologies Ltd © 2019