I am a newbie in electronics and i am working on an outdoor audio device. The device would consist of a speaker (anything capable of producing 30-60 watts) with a 12v battery. My goal is to be able to produce a sound like that of Fire Truck/Paramedic Siren(115 db).So probably something like this https://www.wboxtech.com/north-america/product/203/30-watt-2-tone-119-db-siren/

My question is , what amplifier should I use and any necessary components to be included while building the circuit/device of this caliber? Eventually, I expect to commercialize this for mass production. So the choice of the amplifier should account for that.
Because I heard some of the old Audio amps are obsolete.

Thank you in advance

 

Pretty amazing that they can get 30W of power out a device that draws only 5W from the battery!

For prototyping I wouldn't bother building an audio amp. You can buy ready-built modules at eBay for instance that are fine for what you need and are very inexpensive. Work out the kinks and figure out your business plan before you worry about saving a couple pennies by making your own amp versus just buying it.

 

Pretty amazing that they can get 30W of power out a device that draws only 5W from the battery!

For prototyping I wouldn't bother building an audio amp. You can buy ready-built modules at eBay for instance that are fine for what you need and are very inexpensive. Work out the kinks and figure out your business plan before you worry about saving a couple pennies by making your own amp versus just buying it.

Thank you Wayneh.Yes that is true its better to just buy for now. Do you know any prebuilt amplifier that would meet my requirements above? Because that is my biggest challenge at the moment.

 

And just remember, if you are going to market a unit used for an alarm, it must be very reliable. Think lawyers if the unit fails.

 

Thank you Wayneh.Yes that is true its better to just buy for now. Do you know any prebuilt amplifier that would meet my requirements above? Because that is my biggest challenge at the moment.

I can't make a specific recommendation but these guys have a number of options: https://www.parts-express.com/dayton-audio-dta-2-class-d-digital-audio-amplifier-module--300-385
And there's a lot of stuff on eBay.

 

Like these...
https://www.ebay.com.au/itm/TPA3116...d3daa53e:m:mMuGKxfRzwSdIT7BJ3zK26A:rk:15:pf:0
I have used the 2x120W version.

 

The spec's for the "30W" siren speaker have no details:
1) 30W of heat but only 5W of sound?
2) What two frequencies? Are they audible frequencies or very high pitched squeaks that only young people can hear?
3) 119dB at what Distance? Held to an ear?

 

The spec's for the "30W" siren speaker have no details:
1) 30W of heat but only 5W of sound?
2) What two frequencies? Are they audible frequencies or very high pitched squeaks that only young people can hear?
3) 119dB at what Distance? Held to an ear?

I used that product as an example(sorry maybe it is misleading), what I was trying to say in general i just need to build a outdoor device with power similar to the one used in fire truck or paramedic siren which i believe is at least 115db at 0 feet and 105db at 20 feet. I am willing to double up power supply if needed (up to 24 volts), I just need some rough guidance on picking up the right components, for example which pre-built amp that would work with 12V or 24V to produce sound power like that of fire truck siren?

 

Do you mean something like this?

https://www.ebay.com/itm/12V-DC-400...h=item4b3012482f:g:eSwAAOSwCtJaKkcY:rk:6:pf:0

 

The loudness of a loudspeaker is measured at a distance of 1 meter and with a low distortion sinewave signal.
If its sensitivity is 100dB at 1m for 1W, then its output is 103dB for 1m, 2W and is 106dB for 1m, 4W (+3dB for doubling of power).

Distance reduces the sound level -6dB for doubling of distance. Then 100dB at 1m, 1W is 94dB at 2m, 1W and is 88dB at 4m, 1W.

An ordinary amplifier produces an output of 1.5W into an 8 ohm speaker with a 12V power supply. the output is about 2.8W into a 4 ohm speaker with a 12V power supply. A bridged amplifier produces about 10W into a 4 ohm speaker with a 12V power supply.
A bridged amplifier produces about 40W into a 4 ohm speaker with a 24V power supply.

 

Do you mean something like this?

https://www.ebay.com/itm/12V-DC-400...h=item4b3012482f:g:eSwAAOSwCtJaKkcY:rk:6:pf:0

Yes Something like that

 

The loudness of a loudspeaker is measured at a distance of 1 meter and with a low distortion sinewave signal.
If its sensitivity is 100dB at 1m for 1W, then its output is 103dB for 1m, 2W and is 106dB for 1m, 4W (+3dB for doubling of power).

Distance reduces the sound level -6dB for doubling of distance. Then 100dB at 1m, 1W is 94dB at 2m, 1W and is 88dB at 4m, 1W.

An ordinary amplifier produces an output of 1.5W into an 8 ohm speaker with a 12V power supply. the output is about 2.8W into a 4 ohm speaker with a 12V power supply. A bridged amplifier produces about 10W into a 4 ohm speaker with a 12V power supply.
A bridged amplifier produces about 40W into a 4 ohm speaker with a 24V power supply.

Thank you AudioGuru. I think 24V with 4 ohm speaker , sounds like something I am looking for.Do you have an example of amplifier that i can use to build a prototype with? or if i could replicate something like this https://www.ebay.com/itm/12V-DC-400...h=item4b3012482f:g:eSwAAOSwCtJaKkcY:rk:6:pf:0 Any idea?

 

The 400 Whats siren has a label saying 200 Watts MAX which is 100 real Watts. It draws a current of 12A from 13.6VDC which is a total of 163W so the heating is 63W.

The very cheeeep ebay 2 x 50W amplifier produces 30 real Watts per channel into 8 ohm speakers but you cannot add the channels together to make more power.
Most very loud and powerful horn speakers are 8 ohms, not 4 ohms.
The amplifier makes no sounds, you need a siren circuit to feed the amplifier.

 

The 400 Whats siren has a label saying 200 Watts MAX which is 100 real Watts. It draws a current of 12A from 13.6VDC which is a total of 163W so the heating is 63W.

The very cheeeep ebay 2 x 50W amplifier produces 30 real Watts per channel into 8 ohm speakers but you cannot add the channels together to make more power.
Most very loud and powerful horn speakers are 8 ohms, not 4 ohms.
The amplifier makes no sounds, you need a siren circuit to feed the amplifier.

Ok correct me if I am wrong ..if I am able to find 200watts class Damplifier, 8 ohm speaker that can tolerate atleast 100watts and use 24V power supply, would I be able to get the power/loudness I am aiming for (It doesn't have to be exact)?
Regarding the sound signal ,i already have the mp3 module that i am planning to use.

 

Ok correct me if I am wrong ..if I am able to find 200watts class Damplifier, 8 ohm speaker that can tolerate atleast 100watts and use 24V power supply, would I be able to get the power/loudness I am aiming for (It doesn't have to be exact)?

Yes, I think that will produce an amazingly loud result. But if you're using audio-quality equipment for this, that's overkill. You don't need 20Hz-20,000Hz, you don't need low distortion and low noise, and so on. You need LOUD for a narrow frequency range. Overkill is fine for testing but for production you'd want to optimize for the application.

 

The ebay amplifiers are very cheap and might not use REAL Texas Instruments ICs, they might be poorly copied Chinese clones.
Can you find a high power 4 ohm horn speaker? Most are 8 ohms then the amplifier power is half.
The amplifier rated power is not true, MAX power is simply double the REAL power, into a 4 ohm speaker. Frequently a 4 channel amplifier is rated at 200W which is 50 MAX Watts per channel which is 25 real Watts per channel which is 12.5W into an 8 ohm speaker.

Did you calculate the loudness you want at the distance you want? Then find a horn speaker and from its spec's calculate how much power it needs to be loud enough. Then pick a suitable amplifier.

 

Hello,

My goal is to be able to produce a sound like that of Fire Truck/Paramedic Siren(115 db)

Why do you want to make such a loud siren?

Bertus

 

The ebay amplifiers are very cheap and might not use REAL Texas Instruments ICs, they might be poorly copied Chinese clones.
Can you find a high power 4 ohm horn speaker? Most are 8 ohms then the amplifier power is half.
The amplifier rated power is not true, MAX power is simply double the REAL power, into a 4 ohm speaker. Frequently a 4 channel amplifier is rated at 200W which is 50 MAX Watts per channel which is 25 real Watts per channel which is 12.5W into an 8 ohm speaker.

Did you calculate the loudness you want at the distance you want? Then find a horn speaker and from its spec's calculate how much power it needs to be loud enough. Then pick a suitable amplifier.

Thank you Audioguru for your help. I am thinking of going with this horn speaker .My goal is to have at least 90db or close at 20 meters away.I assume using 24V power supply with 100watts/per channel class D Amp should work?

 

The extremely cheeeeep Chinese horn speaker is a piece of junk. It is powered only from 12V and a video shows it on a childrens car making its low sound level with a power of only maybe 2W but they used a 6V battery. It already has an amplifier but it is no where near 100W.
A few people said it is loud (they did not say the distance) and a few other people said it does not work.

For 90dB at 20m with a horn speaker rated at 100dB/1m/1W then the amplifier must produce 40W but most horn speakers are 8 ohms, then you need an amplifier that produces 80 real Watts per channel into 4 ohms.

 

Yes, I think that will produce an amazingly loud result. But if you're using audio-quality equipment for this, that's overkill. You don't need 20Hz-20,000Hz, you don't need low distortion and low noise, and so on. You need LOUD for a narrow frequency range. Overkill is fine for testing but for production you'd want to optimize for the application.

The extremely cheeeeep Chinese horn speaker is a piece of junk. It is powered only from 12V and a video shows it on a childrens car making its low sound level with a power of only maybe 2W but they used a 6V battery. It already has an amplifier but it is no where near 100W.
A few people said it is loud (they did not say the distance) and a few other people said it does not work.

For 90dB at 20m with a horn speaker rated at 100dB/1m/1W then the amplifier must produce 40W but most horn speakers are 8 ohms, then you need an amplifier that produces 80 real Watts per channel into 4 ohms.

Thank you so much Audioguru.This was very helpful. I will try to get few components and start doing some experiments.