Multiple radios and one pair of headphones/speakers

[bob-the-scanner-man]

I know this topic has been discussed a few times in the past but I'm still a little unclear on how to achieve this.

I have a CB radio, an Alinco DR-135, and a Radioshack Pro-2050 that I'd like to hook up to the same speaker or pair of headphones.

I also have a Radioshack SSM-1200 mixer board. Can I hook all of the radios to this particular mixer board and use it to output them all to a single speaker or pair of headphones?

I understand that I can "physically" connect them to the mixer board with the right adapters, but are there any hurdles I'll have to clear on the technical side of things?

Here are the specs for my mixer board.

 

[zz0468]

...are there any hurdles I'll have to clear on the technical side of things?

Yes, but nothing seriously complicated. Your mixer has high impedance inputs, and require low levels of audio. Your radios are probably 8 ohms impedance with roughly around a watt of audio. The two problems you'll have are a severe impedance mismatch, and grossly over driving the mixer.

You'll need an 8 ohm load for the radio speaker output, and maybe a 10K pot to trim the audio level down to where it doesn't overload the mixer. Transformer couple it if hum is a problem.

 

[dsalomon]

If you can get your hands on one of these used (they're not made anyone), it makes receiving multiple sounds streams simultaneously very nice. If can put the soundstream from 5 different radios in 5 "virtual" places in your head using headphones,

NCS 3230 Receive Console, New Communications Solutions NCS-3230 Multi-RX

 

[bob-the-scanner-man]

Yes, but nothing seriously complicated. Your mixer has high impedance inputs, and require low levels of audio. Your radios are probably 8 ohms impedance with roughly around a watt of audio. The two problems you'll have are a severe impedance mismatch, and grossly over driving the mixer.

You'll need an 8 ohm load for the radio speaker output, and maybe a 10K pot to trim the audio level down to where it doesn't overload the mixer. Transformer couple it if hum is a problem.

Thanks for the info, but I'm unsure of what I need to do here. How would I go about creating an 8 ohm load for the speaker output?

Although I'd prefer not to, is there anything cheap that I can buy that will do what I want out of the box?

 

[737mech]

First determine if the headphone output or ext spkr will be used? Headphone output is controlled by volume control right? The ext spkr output has no level control correct? Use the headphone output set the volume to lower levels at first. Don't overblast the mixer. Check the mixer options, line in vs' phone in. Is there a switch for each input? I believe it can all be tried without damage to any unit but just start low. There may be a need for ground loop because sometimes you'll get hum and buzz. Good luck give it a try let us know.

 

[looknlisten]

I also have a Radioshack SSM-1200 mixer board. Can I hook all of the radios to this particular mixer board and use it to output them all to a single speaker or pair of headphones?

I used to have one of those.(I liked that it was rack-mountable)
Just route the outputs from your radios (headphone jack works fine) to the individual line-level inputs on the back and select the 'line' input from the switch at the top of the sliders. ( You could also use the 'CD' input if you wanted to).
You may want to use y-cables to get the signals to both left/right channels.
Otherwise put two radios on the right channels and the other on the left.
The only issue I recall with it was the isolation between inputs was poor and there was some leakage between them. Not a big problem in your situation though.

 

[bob-the-scanner-man]

I used to have one of those.(I liked that it was rack-mountable)
Just route the outputs from your radios (headphone jack works fine) to the individual line-level inputs on the back and select the 'line' input from the switch at the top of the sliders. ( You could also use the 'CD' input if you wanted to).
You may want to use y-cables to get the signals to both left/right channels.
Otherwise put two radios on the right channels and the other on the left.
The only issue I recall with it was the isolation between inputs was poor and there was some leakage between them. Not a big problem in your situation though.

What's the best way to hook a pair of headphones to this board? It has a 1/4 phone plug for headphones on the face of the board, and RCA outputs on the back marked AMP and REC.

The reason I ask is when I hooked two scanners up the way you mentioned I could only hear them when I monitored them individually. When I turned the dial over to MASTER I could barely make them out. So I'm wondering if I need to pull the output audio from the rear jacks instead of the monitor jack.

Will I need to worry about impedance mismatch in this case?

 

[looknlisten]

Now that I think of it...I actually may have used the mic inputs (RCA to 1/4 phono plug adapters http://www.kenable.co.uk/images/6.5mm_jack_to_phono_1.jpg on each line)...just adjust the radio outputs accordingly.
Keep your crossfaders (located at the bottom) at the mid position and you should here the two radios (per stereo channel)...one in each ear. You have 4 stereo inputs and two faders that will allow you to select which radio you want to listen to. Of course, it is only stereo, so you have to choose the priorities of which radio is on which side, left or right. Hope this isn't too confusing...it will work...I did it.

(PS: I'm actually using a much smaller version with 4 scanners using those adapters...it works fine http://thumbs1.picclick.com/d/l400/...Four-Channel-Stereo-Microphone-Mixer-With.jpg)

 

[cavmedic]

Feed the scanners to the inputs of the mixer board , you might have to toy with the volume controls on the units and the input controls on each channel of the mixer until you get them where the audio sounds best and use amplified computer speakers on the output .....

 

[bob-the-scanner-man]

Now that I think of it...I actually may have used the mic inputs (RCA to 1/4 phono plug adapters http://www.kenable.co.uk/images/6.5mm_jack_to_phono_1.jpg on each line)...just adjust the radio outputs accordingly.
Keep your crossfaders (located at the bottom) at the mid position and you should here the two radios (per stereo channel)...one in each ear. You have 4 stereo inputs and two faders that will allow you to select which radio you want to listen to. Of course, it is only stereo, so you have to choose the priorities of which radio is on which side, left or right. Hope this isn't too confusing...it will work...I did it.

(PS: I'm actually using a much smaller version with 4 scanners using those adapters...it works fine http://thumbs1.picclick.com/d/l400/...Four-Channel-Stereo-Microphone-Mixer-With.jpg)

I figured it out. The problem is that I wasn't using a stereo cable for one of the radios. I already had one Y splitter and the radio hooked up using that cable could be heard fine. I bought another one and now I can hear both of them just fine, even with regular headphones.

If I ever come across something smaller then I may get it, but this board will work for now. It was $10 at a local thrift store so the price was right.

Thanks for the help everyone!

 

[phillmobile]

why not just have 3 seperate speakers, that way you know whats signal is coming from which speaker

 

[RFI-EMI-GUY]

Too bad those are no longer made. I doubt most appreciated the SPATIAL mode feature. Maybe someone will develop something like that for general purpose use.

You can line up 5 (6?) radios left to right and determine which one the audio is emanating from by the phasing in the headphones. For folks who have to use headphones all the time, this is pretty nice.

I don't know if any public safety consoles are doing this, but it would be a nice feature in that environment as well. It would reduce fatigue.

If you can get your hands on one of these used (they're not made anyone), it makes receiving multiple sounds streams simultaneously very nice. If can put the soundstream from 5 different radios in 5 "virtual" places in your head using headphones,

NCS 3230 Receive Console, New Communications Solutions NCS-3230 Multi-RX