The SBU Audio Switch is designed to compare different audio gear at various stages within an audio chain.
That means one is able to switch freely between: 3 Turntable (+2 additional Audio Sources), 2 Phono Preamplifier, 2 Audio Preamplifier, 2 Power Amplifier and 3 pairs of Speaker.
All signals are completely separated handled. Even the shielding for the audio signals is switched together with the audio signals. This extends up to the turntable groundings as well. The shieldings for the left and the right channels are also completely separated. Additionally is it possible to choose between three different switching modes.
The signals are switched by relays. To achieve the goal to keep everything separate 24 (Stereo) relays for the audio signals plus 32 (Mono) relays for the speakers are used. All in all 56 relays. All independently controlled by one micro controller and a few shift register.
The switching scheme for the SBU Audio Switch
Some schematics for the SBU Audio Switch. Well sort of...
An early test build on an improvised chassis
The almost finished SBU Audio Switch. Only a few things left to do. On the left the signal relays and on the right the speaker relays.