Reducing Speaker Volume for Siren Testing

[Jennifer Rose Towing]

So I am not totally clear and have 2 different projects I am thinking of.

The first is to use a Motorola speaker with a Federal or Whelen siren on the display (so pretty quiet). The speaker is 3.2 ohm/30 watt. A volume adjuster would be nice to fine tune it but I wouldn't need to adjust after setting it. Without knowing the voltage put out by the siren I am not sure how to be sure I would have the correct resistors. Looking for a volume level equivalent to quiet television or office speakerphone.

The other possible (and lower priority) would bet to run an above siren with a 58 watt speaker quieted down for the display.

Thoughts or info?

 

[shues]

For the voltage produced by the siren, 33 volts AC comes to mind.

The L-PAD design from @Henry455 would be ideal for your application.

 

[Jennifer Rose Towing]

For the voltage produced by the siren, 33 volts AC comes to mind.

The L-PAD design from @Henry455 would be ideal for your application.

I have read this thread several times, done some other research and still not comfortable. I dont want to play around with expensive stuff when I don't understand it all. I totally get low voltage/wattage/amperage for lights. I do not have a good understanding of the siren ac output and speaker properties (been reading up on it but not comfortable enough to test it out without recommendations from those in the know).

I know enough to know I don't comprehend enough to do this properly and safely!

 

[CHIEFOPS]

Review post #26 it can't be easier- install the resistor inline on one of the speaker leads and your work is done, you can use a simple radio speaker

 

[firebuff17]

My vote is for the LPAD. I bought one and wired it up. It works great.

 

[Jennifer Rose Towing]

Review post #26 it can't be easier- install the resistor inline on one of the speaker leads and your work is done, you can use a simple radio speaker

I am looking for the reasoning and effects behind something, that does not explain any of it. I have a hard time believing that one resistor is compatable with every siren and every speaker. If so, why have others used different values with results that they are happy with? I have and continue to research it but not coming up with an answer I am comfortable with testing.

 

[firebuff17]

@Jennifer Rose Towing
I don’t fully understand how it works either. But the L-Pad is designed for the audio world and designed for speakers and amps. So in my mind it works for me reducing my siren output for indoor use. I can’t find where I bought mine from. But I am sure it was relatively cheap. ($20-$40 I am guessing. I wouldn’t have paid more than that for my project)

 

[CHIEFOPS]

I am looking for the reasoning and effects behind something, that does not explain any of it. I have a hard time believing that one resistor is compatable with every siren and every speaker. If so, why have others used different values with results that they are happy with? I have and continue to research it but not coming up with an answer I am comfortable with testing.

It's straight from FedSig, for well over 10 years I've been using this method testing sirens indoors running for as long as 5-10 mins on a simple 2-way radio speaker. I'm not an electrician so I don't know the science but it's simple, reliable and safe.

 

[Jennifer Rose Towing]

It's straight from FedSig, for well over 10 years I've been using this method testing sirens indoors running for as long as 5-10 mins on a simple 2-way radio speaker. I'm not an electrician so I don't know the science but it's simple, reliable and safe.

Do you have any bulletin or paperwork where they say that is ok? I would be fine with the specs/info from the manufacturer (or someone here who could give a basic explanation of it all).

 

[shues]

Have a look at the Federal Signal Unitrol Omega 90 manual at https://www.fedsig.com/resource-document/file/8143 and you will see the following:

 

[Jennifer Rose Towing]

Have a look at the Federal Signal Unitrol Omega 90 manual at https://www.fedsig.com/resource-document/file/8143 and you will see the following:

Thank you. That should be fine then for a siren speaker, any idea about a smaller speaker? Says 4-100 ohm but the main speaker I want to use is a Motorola external 3.2 ohm for its size and portability. I figure only w couple of watts to the little speaker would be more then plenty. I'll try to reverse engineer the numbers for the Omega and see what else I can learn.

 

[CHIEFOPS]

Have a look at the Federal Signal Unitrol Omega 90 manual at https://www.fedsig.com/resource-document/file/8143 and you will see the following:

I was just getting set to post exactly the same image

 

[CHIEFOPS]

Thank you. That should be fine then for a siren speaker, any idea about a smaller speaker? Says 4-100 ohm but the main speaker I want to use is a Motorola external 3.2 ohm for its size and portability. I figure only w couple of watts to the little speaker would be more then plenty. I'll try to reverse engineer the numbers for the Omega and see what else I can learn.

I keep telling you it will run a speaker as small/low watt as a 2-way radio speaker

 

[ToddLara]

Wow, 35 watt resistor, seems like overkill to me.

Henry is no longer with us.

Here's the relevant circuit:

View attachment 213013

Can you or should you ground terminal 1? I've read that L-pads should be grounded at terminal 1 to ensure a smooth audio range down to zero volume.

 

[emcom]

Are you guys soldering on your wires to the LPAD? Any issues there? I just ordered one to quiet down my Omega 90.

 

[ToddLara]

Time to breathe new life into this thread.

 

[firebuff17]

Are you guys soldering on your wires to the LPAD? Any issues there? I just ordered one to quiet down my Omega 90.

Yes. I soldered mine. No issues noted.