4 radios, 1 speaker

PrivatelyJeff · Sep 24, 2017

I have a small car and can only fit 1 speaker in it but I will be running 4 radios (2 scanners plus 2 radios to be named later). What’s the best way to mix the signals? Would a audio mixer like this work?

https://www.amazon.com/gp/product/B000KGYAYQ/ref=ox_sc_act_title_7?smid=ATVPDKIKX0DER&psc=1

RFI-EMI-GUY · Sep 24, 2017

JeffDS3 said:
I have a small car and can only fit 1 speaker in it but I will be running 4 radios (2 scanners plus 2 radios to be named later). What’s the best way to mix the signals? Would a audio mixer like this work?

https://www.amazon.com/gp/product/B000KGYAYQ/ref=ox_sc_act_title_7?smid=ATVPDKIKX0DER&psc=1

That looks like it has an unbalanced input.

The problem you will have is that most modern radios have a balanced amplifier that works properly only when driving a speaker or a transformer. There were some stereo to mono speaker mixers that used transformers in a passive arrangement. This could be done with four transformers to drive a single speaker. You need the transformer isolation whether you do this with a mixer amp or without, or you will damage the radios.

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PrivatelyJeff · Sep 24, 2017

Do you have a product recommendation? The speaker I’m using is actually two speakers tied together, and I could modify it to separate them into 2 individual speakers in one enclosure.

PrivatelyJeff · Sep 24, 2017

I’m using 2 WS1095s right now, if it matters.

SteveSimpkin · Sep 24, 2017

You could use that 4-channel "unbalanced" mixer (i.e. the mixer inputs/output share a common ground connection) if you added the following parts:

Qty 4 Isolation transformers. One of these plugs into the earphone output of each scanner.
https://www.amazon.com/PAC-SNI-1-3-5-3-5-mm-Isolator/dp/B001EAQTRI

Qty 4 3.5mm stereo female to 1/4" male Adapter. These plug into each input of the mixer and the isolation transformers plug into them.
https://www.sweetwater.com/store/de...s94Ccj-4DhbMCl3XXbY01D3j3zRvPbSMaAgSeEALw_wcB

You will also need an amplified speaker since the output of the mixer is low-level audio. A Uniden BC23A is a good choice.
https://www.amazon.com/Uniden-BC23A-Communications-Speaker/dp/B009TNAGDA

You will need a 1/4 mono male to 3.5mm stereo female Adapter from the output of the mixer to the amplified speaker.
https://www.amazon.com/Monoprice-Metal-6-35mm-Stereo-Adaptor/dp/B004C4UQZE

There are other solutions available but the above should work with the mixer you found.
Doing a quick search, I could not find a 4-input "balanced" mixer at a reasonable price (under $100).

FFPM571 · Sep 24, 2017

You can fit 4 radios in a small car but can't find space for 4 small speakers. Small speakers can be mounted under the seat under the dash . An improperly wired mixer can damage the audio section of a radio

PrivatelyJeff · Sep 24, 2017

The radios will be under the seats with remote heads.

This is the speaker I’m using now.
RoadPro RP-160 3" x 5-1/2" 6W Visor Mount Twin CB Extension Speaker https://www.amazon.com/dp/B001JT5MCC/ref=cm_sw_r_cp_tai_C5fYzbVZNQWSJ

PrivatelyJeff · Sep 24, 2017

Is there some other type of amp that will allow me to use an unpowered speaker. I’m driving a 2011 Ford Fiesta and I’m running out of space on the kick panels. My current speaker is mounted with Velcro by my dome light.

PrivatelyJeff · Sep 24, 2017

At this point it might be easier to just modify the speakers.

RFI-EMI-GUY · Sep 24, 2017

You can do it passively with one of these transformers for each receiver and one for the speaker. For 4 receivers, you would need 5 of them. You would bridge each transformer at the 70V winding. Use the 4 ohm windings for each receiver and the speaker. No power required, mount them on a board or in a box with terminal strips.

https://www.parts-express.com/70v-1...source=google&utm_medium=cpc&utm_campaign=pla

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SteveSimpkin · Sep 24, 2017

JeffDS3 said:
The radios will be under the seats with remote heads.

This is the speaker I’m using now.
RoadPro RP-160 3" x 5-1/2" 6W Visor Mount Twin CB Extension Speaker https://www.amazon.com/dp/B001JT5MCC/ref=cm_sw_r_cp_tai_C5fYzbVZNQWSJ

How does that speaker sound when plugged into one of your scanners?
Is it loud enough?

PrivatelyJeff · Sep 24, 2017

Yeah. It’s plenty loud and very clear. I barely have to turn the volume up on the scanner.

BushDoctor · Sep 24, 2017

Speaker locations

JeffDS3 said:
I have a small car and can only fit 1 speaker in it but I will be running 4 radios (2 scanners plus 2 radios to be named later). What’s the best way to mix the signals? Would a audio mixer like this work?

https://www.amazon.com/gp/product/B000KGYAYQ/ref=ox_sc_act_title_7?smid=ATVPDKIKX0DER&psc=1

LOCATE SPEAKERS
One in each kick panel L&R or lower front of front doors and the rear shelf in front of the rear window should be pre-drilled for 2 speakers

PrivatelyJeff · Sep 24, 2017

There are already stereo speakers there in the front door and the rear speakers would go in the rear doors, not the rear shelf. There is metal bracing below the shelf, not allowing for any speakers.

iMONITOR · Sep 24, 2017

Four audio sources into on speaker will be badly distorted if all four sources are active at the same time.

Have you considered modifying the headrests and installing speakers inside them? Or installing them in the kick panels, or door panels?

RFI-EMI-GUY · Sep 24, 2017

iMONITOR said:
Four audio sources into on speaker will be badly distorted if all four sources are active at the same time.

Have you considered modifying the headrests and installing speakers inside them? Or installing them in the kick panels, or door panels?

Not if the power levels are reasonable.

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PrivatelyJeff · Sep 24, 2017

iMONITOR said:
Four audio sources into on speaker will be badly distorted if all four sources are active at the same time.

Have you considered modifying the headrests and installing speakers inside them? Or installing them in the kick panels, or door panels?

They probably won’t. It will be two scanners and then eventually a ham radio mobile unit and either a CB or GMRS radio for traveling.

If any of them are being overly talkative, I’ll just turn it down.

Project25_MASTR · Sep 24, 2017

RFI-EMI-GUY said:
You can do it passively with one of these transformers for each receiver and one for the speaker. For 4 receivers, you would need 5 of them. You would bridge each transformer at the 70V winding. Use the 4 ohm windings for each receiver and the speaker. No power required, mount them on a board or in a box with terminal strips.

https://www.parts-express.com/70v-1...source=google&utm_medium=cpc&utm_campaign=pla

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Just for clarification, is that 4Ω lines for the speaker outputs, a series loop on the 70V lines and then the finial for the speaker on the radios + 1 4Ω line?

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RFI-EMI-GUY · Sep 24, 2017

MCore25 said:
Just for clarification, is that 4Ω lines for the speaker outputs, a series loop on the 70V lines and then the finial for the speaker on the radios + 1 4Ω line?

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No series loop.

70 volt taps all bridge each other. Example all 10W 70V wires tied together, and then all the corresponding 70V common wires tied together. The receivers can drive 4 or 8 ohm taps, the speaker taps the last #5 transformer at the appropriate 4 or 8 ohms.

I think Philmore used to make something like this to bridge the stereo output of a car radio into one mono speaker. It is no longer sold. Motorola used to sell a dual voice coil speaker , but that was decades ago.

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SteveSimpkin · Sep 24, 2017

JeffDS3 said:
At this point it might be easier to just modify the speakers.

You may be right. If you can find room for two of these dual-speaker assemblies (4 speakers total) AND you can wire each speaker to its own separate speaker cable, that will greatly simplify things. If you do this be certain that the speaker cable from each scanner is only connected to its speaker ONLY and than no connections are made from a scanners speaker output to another scanner or to ground. This is critical! In other words you are making four separate speakers with four SEPERATE cables.

4 radios, 1 speaker

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