APX6500 Desktop max number of speakers.

[2wayfreq]

Hey All, We are setting up an APX6500 desktop with multi speakers running line extensions from it to a few different rooms for RX audio. The default Motorola Speakers are 8 Ohm. From what I understand, the Max number is 3 connected speakers per desktop unit. Is this correct?

Thank You!

 

[prcguy]

If you use 25 or 70 volt line transformer at the radio then similar transformers at each speaker you can add quite a few and long speaker lines won't be a problem.

 

[BMDaug]

Alternately, you can wire a network of speakers in series and parallel to end up with an impedance match. Every speaker wired in parallel will halve the impedance, and each wired in series will double it.

So if you have two four ohm speakers in parallel, that will create a two ohm load, but those same two speakers in series will yield eight ohms. If you want to connect four, four ohm speakers, wire two pairs in series so each pair will present an eight ohm load, then connect both pairs in parallel at the the source and the amplifier will see four ohms. This doesn’t require any additional hardware, just some planning. As long as you are matching the load to the amp specs, you won’t damage anything.

-B

 

[prcguy]

If each speaker will be required to cover a wide area with sound, in addition to using high impedance line transformers I would use very efficient horn speakers. This will allow you to keep the radio volume lower and use less power making up the sound with speaker efficiency. With line transformers you can also use an L-pad at each speaker to give some volume adjustment at each speaker.

For the low power, under 10 watts of audio from the radio I would consider this transformer at the radio end using the most appropriate 4 or 8 ohm tap on the radio side and the 15 watt rated wires for distribution. Home

Then maybe this smaller version at each speaker using the appropriate 4 or 8 ohm leads at each speaker then fine tuning the level by testing the various input taps for the desired volume level. Home

And finally a speaker like this if wide coverage is needed like high on a wall indoors or outdoors. https://www.parts-express.com/5-x-8-Indoor-Outdoor-Horn-Speaker-300-060

 

[BMDaug]

All of these options will work great, but more info about this install will help. In a very large system, where amplifier power requirements will exceed ratings, you may want to just run a speaker to line interface such as this: TX-8A ‐ 4 Ohm / 8 Ohm Input Interface This would allow you to convert a four ohm speaker level output to a balanced line level connection, which could be run great distances and distributed to multiple amplifiers in different areas as needed. This would provide the highest fidelity and also keeps cabling cost to a minimum since line level wire is very inexpensive and may be free run without conduit provided plenum rated cable is used. This also allows you to interface with powered speakers or an existing distributed speaker system if necessary. Knowing more about the system requirements would make specific recommendations easier!

-B