auto switching Audio A/B switch Question.

[vontar]

Just wondering if anyone knows if they made something like this. I am going to try to describe what I am trying to find for a friend and heck if I can find one I might want it too.

Lets say I have 2 Sources, both have stereo output 1/8 inch.

Lets say I have Source A and Source B.

One of the sources is going to be plugged into an EMS/Fire Department radio that is only going have traffic/voice very intermittent.

The other source will have music 100 percent of the time.

The Goal is

EMS/Fire Department on Source A

Music on Source B

The plan is for music to be able to play as long as there is nothing on source A, however when Source A becomes Active is takes over with the switch and gets priority. (the switch goes automatically from B to A)

When they finish talking the switch should go back to B.

(I am fine with using adapters to get what I want in the end.)

If we end up with mono out for both that is even fine.

We don't want to break the bank, and it can't be a large device, it can't be a computer setup or anything like that. Kinda hoping something small portable.

Right now we have a Y cable so both play though at the same time which can get confusing if when the Radio talks over the music.

[Guest Lester Weevils]

Vontar possibly you could find something like that not too expensive from a stocking supplier of lots of broadcast/commercial sound gear. Possibly Markertek would be a good place to look. Such devices are useful in wiring such as conference room built-in sound systems, so the boss can interrupt anybody else if he desires, or whatever.

Markertek - Audio and Video Equipment - Professional Broadcast Studio Equipment

Markertek has lots of obscure goodies, though few of them are price bargains.

However if you can find a cheap used or new audio dynamics compressor-- One with a side-chain input--

A compressor/limiter keeps a signal from getting too loud. There are knobs to adjust the effect. The ones with side-chain input normally have the audio input connected to both the variable gain amplifier and also the level detector (which controls the volume of the variable gain amp to level the audio, according to the audio amplitude hitting the level detector).

The input connection to the level detector is normalled to a back panel jack, so if you plug in a second audio source into the back panel jack it disconnects the input signal from the level detector. When you have a second audio source plugged to the side chain input, the second source will control the volume of the main input signal.

This configuration is commonly known as "ducking" and is often used to control the volume of background music so that it is not too loud for narration. The narrator's microphone is connected to the side chain, and every time the narrator speaks the background music feeding the input of the compressor gets quieter so it doesn't overpower the voice. The compressor knobs adjust how much ducking you get, from modest to extreme.

Without some kind of small inexpensive mixer, you would still need to use one or possibly two Y cords.

Sometimes compressors are real expensive new, though there are many inexpensive new compressors nowadays. Around music areas, sometimes really nice previously-expensive compressors can be found really cheap when people get out of the biz or they go from analog to digital operations.

Just saying, that method would be "overkill" compared to finding the exact perfect dedicated ducking box. But it would be a generic solution and the compressor would be good for many other tasks in the future.

Edited February 22, 2011 by Lester Weevils

[vontar]

To give you a bit more of an idea how we plan to use it.

At work, we are on the phone all Day. Headset normally on our right ear.

We are allowed to listen to radio/music over an ear bud in in our other ear.

So I plan to combine them both to one ear bud, so I have music and the EMS/Fire turns out the music when needed.

Myself, I am quit good at dealing with my Tech support job while listening to music in my other ear and recently I have started using the Y connector to listen to the EMS/Fire Radio along with my Music. (A co worker is trying to get me into a First Responder class this spring.)

[Guest Lester Weevils]

Hi Vontar

I briefly looked over the Markertek inventory, and don't see the kind of small device I recall that was used for conference room auto-microphone selection installs. I don't recall the devices being especially cheap anyway. Last I looked, there were some conference room mic mixers that had the auto-ducking built-in, but dunno if those are made anymore either. It is "niche gear" and I never worked in that sound install niche.

It sounds like you need a gadget pretty compact, so a side-chain compressor might be too bulky.

One gadget I had in mind that will do it might be too big but it isn't especially expensive. Alesis 3630 compressor/limiter. These gadgets have been made a long time. It is easy to find snobs who think these boxes suck, but I recall a time when compressors costing hundreds of dollars were no way as good as the 3630, and that was far enough back that a few hundred dollars back then would be a couple of thousand dollars in today's dollars.

They sell for $99 nowadays (used to cost a little more) and if you happened to find one used it might be less than half that price.

http://www.alesis.com/stuff/contentmgr/files/0/3cc655bd8252b3248e88913d155a2bbd/file/3630_manual.pdf (see page 10 in the manual)

Alesis 3630 Dual-Channel Compressor/Limiter with Gate and more Compressors & Limiters at GuitarCenter.com.

The gadget is a viable inexpensive "off the shelf" solution if the gadget is not just too big to mount in your cubicle. It ain't huge but it is 19" wide.

It is a two channel gadget. The side-chain connections are tip-ring jacks. Channel audio input is buffered and output on the ring, and side-chain input is on the tip.

So you could feed the music into Channel 1 input. Feed the scanner into Channel 2 input. Make or buy a 1/4" cable that connects Tip on one end to Ring on the other. Insert the ring-side of the cable into the Scanner Channel 2 side-chain, and insert the tip-side of the cable into the music Channel 1 side-chain.

Connect the outputs of channel 1 and 2 thru a Y cord into whatever amp is driving your headphone.

Adjust the Channel 2 compressor knobs for minimal compression and a scanner output level you like. Adjust the Channel 1 compressor knobs so that the music is attenuated or even keyed-off to your taste when the radio makes noise, otherwise the Channel 1 music runs at the level you like (mixed against the level of the radio using the Channel 1 and Channel 2 output master gain knobs).

If you build analog electronic projects, it wouldn't take many parts to build a specialized device that does exactly what you need in a much smaller box than a 1-space rackmount. However, considering a cost of the 3630 in the $40 to $100 range, it would be difficult to build a specialized box without your parts cost exceeding the cost of a 3630.

Edited February 23, 2011 by Lester Weevils

[mikegideon]

ST-ACR1M Microphone Level Audio Controlled Relay - 0.5 to 5 s delay

This is exactly what you need. 100 bucks or so. You will have to add pigtails so you can plug things in. You may also have to add a 24V wall wart power supply. Not sure if it comes with one. If you decide to do it, let me know and I'll make a drawing for you.

Edited February 23, 2011 by mikegideon