Audio Switcher - more details below

[david.elsbury]

Hi all

Wanting feedback on the below please.

I would like to build an audio switcher to put into some portable racks I am building, that has the ability to take audio (over XLR) from an internal mixer, and an external XLR input from another mixer (think multi-room conference where the rooms split and combine)

 

It needs to have an "insert" point for a graphic EQ.

 

The options need to be as follows: 1) Audio from internal rack (via EQ). 2) Audio from external source (via EQ). 3) Audio from external source (bypass EQ).

 

Finally, it should default to the internal audio when first powered on. This precludes the use of a rotary switch or similar. (basically to idiot-proof the rack and to ensure consistent operation when powered on at the start of each day).

 

I had thought (and am happy to do so) that relays are probably the best option for the audio routing, and had considered an arduino or similar to handle the switching? I know there are audio routing IC's out there but not sure if they are the right tool for the job.

 

Hopefully it would be possible to have a front panel with a button for each routing option, and an LED or similar to indicate which option is selected.

 

Thanks for your help! :-)

 

Cheers

David

[Lamplighter]

David

I have used relays to build many audio switchers, for reliability I generally use BT47W spec devices such as these http://cpc.farnell.com/te-connectivity-axicom/v23105-a5476-a201/relay-dpco-12vdc/dp/SW02635

I have a 9 input /9 output unit in my workshop at home which has been used daily for around 20 years without a blip. It has various routing options such as eq/flat and a separate ,selectable monitor function. It also removes the selected input from that sources output , a hang over from the days of reel to reel recording. Simple to build and reliable.

Brian

[dbuckley]

The best answer is a DSP box, such as the soundweb (now the London Blue), Biamp, Symetrix etc. You get EQ and any other audio facility you need in there too.

 

If you've got no money the best answer is still a DSP box, just one bought on the second hand marketplace. The word is knee-deep in Gentner/Clearone boxes like the XAP800 and PSR1212, maybe as cheap as 50 bucks. Nothing like the flexibility of a soundweb, but matrix mixing, compression, eq, etc all in the box. And a clever mic mixer.

[david.elsbury]

Hmm good point. A basic DSP might be just the ticket. I am after 4 of these for 4 racks, as far as EQ goes it'll be different for different rooms (portable units) so I think a graphic is still the way to go.

 

David, can the Soundwebs default to a default state on power on, as per above?

 

Cheers :)

[david.elsbury]

Shure do a 2x2 that looks reasonable, has anyone used one and can answer some specific questions for me? :)

 

https://www.shure.com/americas/products/mixers-dsp/dfr22-audio-processor#downloads

[dbuckley]

David, can the Soundwebs default to a default state on power on, as per above?

Yep. I think they reload the programme as the thing starts up, but if not, you can do it in logic. Use a button to change the state through the GPIOs on the back.

[david.elsbury]

Thanks for that. The more I think about it, the more I think that a Shure DFR22 is the way to go, and I will forgo the requirement for a default state on power on. The Shure box has the preset selection on the front and this means I don't have to go to any trouble making, drilling and wiring 4 rack panels - and also makes it more repeatable when we want to get another couple of racks in a year or two. I may be able to get away with the automagic feedback reduction feature rather than a graphic as it's primarially corporate AV we're talking here. Lapels and lecturn mics.

 

Hoping I can get my hands on a demo unit :-)