Hi,
I have a siren driver that I wish to use in a promotional vehicle for fundraising purposes, the unit is from an ex Police vehicle, it is a 12v unit and its output is 100w. I do not know what the average impedence of a police siren speaker is, 8-10 ohm?
My question is I have a new 40w 8 ohm horn speaker, what is the best way to reduce the power output from the siren unit to match the 40w speaker?

Many thanks SAJA.

 

my first thought is to add a resistor in series with the speaker

 

Another way is called a "pad" with resistor in series and resistor in parallel. Not knowing the impedance is what is stopping a good answer here.

ps, Is that Johnny Depp from the chocolate factory?

 

I have locked this duplicate post. You can find the original here.

 

Sorry, new to this.

SAJA

 

No problem. Duplicate threads tend to be confusing with some members replying to one and other member replying to the other. The continuity of discussion is lost when this happens.

hgmjr

 

PWM at 40% dutycycle at 12V should reduce the 100W horn to 40W.

 

ps, Is that Johnny Depp from the chocolate factory?

I was also thinking this ....

 

Your "40W" speaker might be rated in Watts or rated in phoney Whats.
Many cheap speakers are rated in Peak Watts which is the real power number doubled.

A speaker is usually rated for music or speech which have intermittent power, not continuous power from a siren so maybe you should reduce the power into the "40W" speaker to 10W or less.

An amplifier's output power is reduced when its supply voltage is reduced.

 

ps, Is that Johnny Depp from the chocolate factory?

No, it's me!