HAM/CB shared external speaker

[hidesertwheelin]

Is it possible to share a external speaker between a CB radio and a HAM radio? I'm planning on installing a Cobra 75 CB and eventually a HAM radio. I'd really only like to install 1 external speaker for both to use. Is there a speaker that will work for this?

 

[opg4759]

You would need a audio mixer of some sort or you could wire a switch inline to have one audio source at a time.

I am planning on using this for my radio setup so I output multiple sources to a external amp and speaker.
http://www.amazon.com/Behringer-MX400-BEHRINGER-MICROMIX/dp/B000KGYAYQ/ref=sr_1_3?ie=UTF8&qid=1449522528&sr=8-3&keywords=12+volt+audio+mixer

 

[Comanche Scott]

I think they make a patch device that is auto sensing / auto switching.

Fwiw; I have some hearing damage, and found I don't need an external speaker with the Cobra 75wxst. Even with the top down.
Might try the cb as is first, then get a speaker if needed.

 

[4x4junkie]

If you get an amplified extension speaker of some sort, it wouldn't be difficult to run both radios through a resistive combiner of some sort (say two 10-ohm resistors, one inline with the speaker lead from each radio to the ext. speaker's input). The speaker's built-in amplifier should recover the volume that would otherwise be lost in the resistors to an unpowered speaker (and then some). This would allow hearing both radios simultaneously on the same speaker if needed.


And FWIW, I strongly recommend you reconsider that Cobra 75 purchase... That's about the worst radio you can buy when it comes to sound quality, both transmitting and receiving. A FAR better unit (no exaggeration) is Uniden's PRO-510XL (or 520XL). If you absolutely have to have a handheld or all-in-one type unit, then consider the Midland 75-822. Those Cobra 75s are a big contributor to why so many people in the 4x4 community complain about "crappy" CBs. Yeah they're 4 watts like everything else, but 4 watts of muffled boxy-sounding audio as if you got 15 wool socks pulled over your mic isn't going to get you out very far regardless of how good your antenna is.


Edit:
Here's a speaker that would work for this. The description isn't real clear, but it looks like maybe it might be able to accept two input sources as it comes:
http://www.amazon.com/Uniden-BC23A-Communications-Speaker/dp/B009TNAGDA

I also found this...
http://www.amazon.com/RoadPro-RP-160-Visor-Extension-Speaker/dp/B001JT5MCC
Again it's not clear if it has two separate inputs, but if not, it shouldn't be difficult to internally rewire the two speakers separate and add a 2nd wire going to it.

 

[1Louder]

Is it possible to share a external speaker between a CB radio and a HAM radio? I'm planning on installing a Cobra 75 CB and eventually a HAM radio. I'd really only like to install 1 external speaker for both to use. Is there a speaker that will work for this?

Just get a cable where two inputs can go to one input. So they would all be female connectors. Radio Shack, Amazon, Monoprice.com, wherever have those. Heck Target and Walmart might. Then plug the CB in one, the Ham in the other and the speaker cable into the single end.

Something like this but the other end would have to be female or maybe an adapter to join the two male plugs.
http://www.monoprice.com/product?c_id=102&cp_id=10218&cs_id=1021813&p_id=5615&seq=1&format=2

http://www.monoprice.com/product?p_id=7230

 

[4x4junkie]

^^
That could potentially cause the sound to become distorted (if not also cause the radio's audio output amp to overheat). Reason being the output from one radio will not only be going to the speaker, but will also be back-feeding into the output circuit of the other radio (and is reason for having the resistors I mentioned in my above example).

 

[opg4759]

Just get a cable where two inputs can go to one input. So they would all be female connectors. Radio Shack, Amazon, Monoprice.com, wherever have those. Heck Target and Walmart might. Then plug the CB in one, the Ham in the other and the speaker cable into the single end.

Something like this but the other end would have to be female or maybe an adapter to join the two male plugs.
http://www.monoprice.com/product?c_id=102&cp_id=10218&cs_id=1021813&p_id=5615&seq=1&format=2

http://www.monoprice.com/product?p_id=7230

Without doing a resistor bridge you will potentially damage each radio by sending voltage into the speaker output.
what 4x4Junkie mentioned "If you get an amplified extension speaker of some sort, it wouldn't be difficult to run both radios through a resistive combiner of some sort (say two 10-ohm resistors, one inline with the speaker lead from each radio to the ext. speaker's input). The speaker's built-in amplifier should recover the volume that would otherwise be lost in the resistors to an unpowered speaker (and then some). This would allow hearing both radios simultaneously on the same speaker if needed." would be quick and simple and the bare minimum that you should do trying to do this.

 

[hidesertwheelin]

Thanks for the info everyone. I ended up buying a Midland 75-822 from the scratch and dent section of Amazon. All this technical talk made me realize have I have no business trying to install some fancy wiring since most of the advice here sounded like Chinese to me. I'll just get a single speaker when I eventually get my HAM licences.

 

[4x4junkie]

Thanks for the info everyone. I ended up buying a Midland 75-822 from the scratch and dent section of Amazon.

Good deal.

Apologies for getting technical, I just know there's little available to effectively (and safely) combine two speaker circuits into one (meaning you would need to build something). My suggestion would be to find two separate speakers that are maybe a little smaller than average, and just put them side-by-side if you can't find separate spots for them (if you can find separate spots though, this will actually make it easier to tell which radio the sound is coming from).

 

[hidesertwheelin]

Good deal.

Apologies for getting technical, I just know there's little available to effectively (and safely) combine two speaker circuits into one (meaning you would need to build something). My suggestion would be to find two separate speakers that are maybe a little smaller than average, and just put them side-by-side if you can't find separate spots for them (if you can find separate spots though, this will actually make it easier to tell which radio the sound is coming from).

No apology needed. Wiring and electrical tech is not my thing. This thread just re-enforced it.:sombrero:

 

[Utah KJ]

It's actually really simple:

http://www.amazon.com/JL-Audio-CL-SES-2010-BLOWOUT/dp/B0036NFR7E

signal sensing or use supplied switch. I was part of the R&D team 10 years ago. It was disco'd this year, but they're still out there.

 

[geo.greg]

Do you need to be fully listening / using them both at the same time? If not a simple a/b switch should work.

 

[gary in ohio]

A mixer is the way to go, but for low grade radio audio try http://electronics.stackexchange.co...vely-mixing-two-or-perhaps-more-audio-signals

 

[rayra]

^^
That could potentially cause the sound to become distorted (if not also cause the radio's audio output amp to overheat). Reason being the output from one radio will not only be going to the speaker, but will also be back-feeding into the output circuit of the other radio (and is reason for having the resistors I mentioned in my above example).

You could do something like it by installing diodes on the feed wires from each radio to the speaker. The diodes act as one-way gates to electrical current, thus would isolate the devices from each other while still allowing both to feed a shared speaker. in-line diodes are available from many electrical suppliers.

 

[4x4junkie]

^^
That won't work because the audio signals going to the speaker are AC, all diodes would do is rectify (break up) one half of the audio waveform causing extreme distortion.

The only good way to do this (short of someone offering a device specifically made for this purpose) is to use two 8-10 ohm resistors (one inline with the + speaker lead coming from each radio) going into an amplified speaker. If somewhat reduced volume can be tolerated, then you probably could forgo the amplifier part and just use a regular speaker.

A couple things that have to be watched out for is if one or both radios have a speaker output where both speaker leads are 'live' (fed by the unit's audio amplifier, much like many car audio system speakers are). In this case, you need to connect to the unit's chassis or PCB ground instead of the Ext SP OUT (-) terminal. This isn't very common in consumer-grade transceivers (ham & CB units for example), though it is fairly common on commercial-grade gear.
Then you have CB units that mute the speaker while transmitting by disconnecting the speaker's ground when the PTT button is pressed, which might not mute properly if there are connections being made to the speaker output that might bypass this feature.


As I think more & more about this, it just seems best to maintain separate speakers for each radio regardless of how technically savvy you are (I run separate speakers on all my gear). The probability of running into problems with a shared speaker setup of any type just seems too high to recommend it.