8-ohm Audio on 785 / External speaker match

[Julian1]

The internal speaker on a 785 has 8-ohm impedance.

If the speaker I connect has less than 8-ohms, will the audio amp in the scanner have to "work" that much harder to get the sound to out through the external speaker?

I realize that speaker impedance is not a matter of sound quality. I want to make sure I'm not going to damage the scanner's internal components long term if I use a 4-ohm or even a 2-ohm external speaker.

Thanks and take care!!
Julian

 

[N1508J]

The internal speaker on a 785 has 8-ohm impedance.

If the speaker I connect has less than 8-ohms, will the audio amp in the scanner have to "work" that much harder to get the sound to out through the external speaker?

I realize that speaker impedance is not a matter of sound quality. I want to make sure I'm not going to damage the scanner's internal components long term if I use a 4-ohm or even a 2-ohm external speaker.

Thanks and take care!!
Julian


It's not a good idea to use a lower impedence speaker. Check your owners manual to see if a range of impedence is specified. If you don't still have your manual, assume that 8 ohms is the ONLY value you can use externally. Now, if your unit does NOT disconnect the internal speaker, which most radios do, you can add a 4 ohm or even an 8 ohm in SERIES with the internal 8 ohm with no harm to the radio's audio amp. However, you will have less volume. But, more than likely your radio does disconnect the internal speaker when you plug in an external speaker which means you MUST use a similar impedence speaker if you don't want to draw excessive current thu the final audio amp of the radio. Such extra current causes over heating of whatever discrete componet(s) are used as an amp, but also loads down the power supply as well causing it to overheat. It is a guessing game as to which section will die and in particular which componet(s) will fail. So, it's just plain easier and safer to match the impedence of the external speaker with that designed for the radio.
Best regards!

 

[Julian1]

Measuring speaker ohm

I've got a couple of the old vintage Motorola speakers.

I looked on the speaker and could not find the Ohm spec.

Do I just place the leads of a meter on the speaker leads? Does it need to have audio active at the moment?

Thanks for your help!!
Julian