11 ohms speaker actually 4.3 ohms?

[reduiyong]

I have recently found out that a 11 ohms siren speaker is actually about 4.3-4.6 ohms in resistance, I have tested many speakers including FS FS100 and whelen speaker, and they all read similarly; However the code3 speaker (C3500 i think) is about 5.5 ohms, Feniex speaker is about 6.5 ohms, and a chinese made 8 ohms siren speaker is really 8 ohms... another Chinese made so claimed "11 ohms siren speaker" is 9.6 ohms... So all these confused me a lot; I used multimeter on all of those above speakers so the testing method is the same for each speaker.

I guess I should trust the big names eg. FS and Whelen that a "11 ohm speaker" is really a 4 ish Ohm speaker? When connecting all those speakers above individually to my FS PA300 and HHS3200 siren amp, they all performed differently on the actual current drawn; those speakers that are actually 4 ish Ohms produced more current than all those Chinese made speakers, however I didnt notice huge differences on the current drawn between the code3 C3500 speaker and the FS FS100 speaker (5.5 ohms vs 4 ohms).

I understand that "11 ohms" refer to impendance whereas my measurements are in resistance, but shouldnt the resistance be the same to make impendance the same? And shouldnt any speakers that has less resistance (FS100 4 ohms) be lounder and draws more current that those speakers that has more resistance (code3 c3500 5.5ohms for example)?

 

[JazzDad]

Impedance and resistance are NOT the same thing.

 

[reduiyong]

I understand that "11 ohms" refer to impendance whereas my measurements are in resistance, but shouldnt the resistance be the same to make impendance the same? And shouldnt any speakers that has less resistance (FS100 4 ohms) be lounder and draws more current that those speakers that has more resistance (code3 c3500 5.5ohms for example)?

Impedance and resistance are NOT the same thing.

 

[ur20v]

You need to bone up on your electronics fundamentals. I'm no EE, but between my hobbies and interests and my business, I've learned a few things over the years.

First, you need to understand an audio signal is alternating current. Alternating current and direct current are vastly different and behave differently. You cannot measure the values of a component using DC and expect the same results from AC. A resistor can be used to reduce the amount of energy flowing through a DC circuit (converted into heat), but it does not do that in AC. In AC you don't measure resistance, you measure reactance. Reactance is calculated from the capacitance or inductance of a component based on the frequency of the AC signal. Impedance is calculated from reactance, BUT... unlike resistance in DC, the values used to calculate what contributes to impedance in AC can change (depending on the circuit - an audio circuit the signal is constantly changing), so impedance is not an absolute measurement. It's a generalized number calculated from a range of values mentioned above.

TL;DR - you're doing it wrong, stop making assumptions, pick up a book.

 

[ur20v]

Oh, and "loudness" is not defined by the impedance of a speaker. You could have a 4 ohm speaker and a 32 ohm speaker of the same size and depending on other variables the 32 ohm speaker could be louder than the 4 ohm speaker reproducing the same signal at the same power levels, albeit different amplifier circuits. Lower impedance may allow an amplifier to produce more power, but not always, and not always "cleanly", and it gets worse from there. Connect a 2 ohm speaker to a 32 ohm amplifier and you'll wind up with magic smoke and some e-scrap.

There's more to the measurable output of a speaker than just impedance and "power handling". I could audition for you a specific pair of speakers connected to a specific 15w+15w amplifier that would play much louder and far less distorted than a pair of "decent" $300 speakers connected to a "good" $400 100w+100w receiver. Turned all the way up you would not be able to stand in front of the speakers of either system without hearing protection, but from the next room you'd hear the 15w+15w system clearly while the 100w+100w system would be mostly recognizable noise.

You shouldn't base your assumptions on car stereo marketing hype.

 

[reduiyong]

Oh, and "loudness" is not defined by the impedance of a speaker. You could have a 4 ohm speaker and a 32 ohm speaker of the same size and depending on other variables the 32 ohm speaker could be louder than the 4 ohm speaker reproducing the same signal at the same power levels, albeit different amplifier circuits. Lower impedance may allow an amplifier to produce more power, but not always, and not always "cleanly", and it gets worse from there. Connect a 2 ohm speaker to a 32 ohm amplifier and you'll wind up with magic smoke and some e-scrap.

There's more to the measurable output of a speaker than just impedance and "power handling". I could audition for you a specific pair of speakers connected to a specific 15w+15w amplifier that would play much louder and far less distorted than a pair of "decent" $300 speakers connected to a "good" $400 100w+100w receiver. Turned all the way up you would not be able to stand in front of the speakers of either system without hearing protection, but from the next room you'd hear the 15w+15w system clearly while the 100w+100w system would be mostly recognizable noise.

You shouldn't base your assumptions on car stereo marketing hype.

I understand the differences between impendance and resistance, but still do not understand why wouldnt the siren industry also specify the resistance standard to 4 Ohms (ish) as it would match most siren amps to produce maximum power;

Lets just consider siren amps and siren speakers; in terms of the speaker performace, from my experience so far, the federal signal fs100W is the loundest speaker I have when connecting to the same siren amp (hhs3200 or federal signal pa300), and it has the lowest resistance between all other speakers that I have; if "resistance" does not make a speaker better or worse in actual performace, how would we choose a siren speaker that actually works better (louder)

 

[shues]

if "resistance" does not make a speaker better or worse in actual performace, how would we choose a siren speaker that actually works better (louder)

Objectively, by measuring the sound pressure level in anechoic chamber:

 

[ur20v]

I understand the differences between impendance and resistance, but still do not understand why wouldnt the siren industry also specify the resistance standard to 4 Ohms (ish) as it would match most siren amps to produce maximum power;

Lets just consider siren amps and siren speakers; in terms of the speaker performace, from my experience so far, the federal signal fs100W is the loundest speaker I have when connecting to the same siren amp (hhs3200 or federal signal pa300), and it has the lowest resistance between all other speakers that I have; if "resistance" does not make a speaker better or worse in actual performace, how would we choose a siren speaker that actually works better (louder)

There's so much that goes into it from a component perspective and even a design perspective. Industry standards exist for a reason, too. Designing something for absolute "maximum output" is pushing the limits of components, increasing maintenance costs, and shortening lifespan. You're exposing yourself and those around you to increased risk. There's headroom designed into true, heavy-duty public safety sirens for an extra margin of safety and a long service life. This stuff gets used and abused 24/7 and sometimes gets tinkered with by people who don't know what they're doing. Then there's the issue of diminishing returns. Can you design a single 200w siren speaker that is measurably louder than a 100w siren speaker? Of course. But at what cost? It will be larger, heavier, and more expensive. What about that handful of extra decibels it puts out - are they noticeable where the siren's sound is critical? Nope. You might technically be able to hear it from a few feet farther away, but that's so far out of the siren's usable range and critical area it doesn't matter. It's like shining a flashlight on the ground at noon on a sunny day - sure, you're pumping out photons, but they're not making any difference. There's no way around the laws of physics.

As far as lower impedance loads and higher wattage output, again, not all amplifier designs will make more power with a lower impedance load. Then you must consider the signal being reproduced. Unlike an audio recording (even a digital recording which is still analog in origin and converted back to analog to be reproduced) an electronically generated tone is about as pure a signal can get at any given frequency. This makes it easier to amplify and reproduce than music or human voices, but that has implications on the operation of the amplifier (as it is the sum of its components) and has to be taken into consideration. IE, a pure input signal will cause a higher current draw and produce a higher voltage audio signal which has further implications on reactance and impedance and those variables may cause reflection which could lead to oscillation and so on and so forth.

Just because the vast majority of music amplifiers are designed for 4ohm and 8ohm loads doesn't mean those designs are superior. It means they're different. While the overall principal may be the same ("make sound louder"), the philosophy and fine details are very different.

Bottom line is, these guys who design this stuff, the top of the line commercial public safety sirens and amplifiers and speakers, they know what they're doing. To second guess them and make comparisons to inferior, knockoff, consumer grade stuff (or toys you mount on a UTV or golf cart,etc.) is foolish.

 

[ur20v]

Oh, and my Whelen SA315P speakers blow away my Federal Signal speakers, just saying...

 

[reduiyong]

Bottom line is, these guys who design this stuff, the top of the line commercial public safety sirens and amplifiers and speakers, they know what they're doing. To second guess them and make comparisons to inferior, knockoff, consumer grade stuff (or toys you mount on a UTV or golf cart,etc.) is foolish.

I understand what you are saying, and I am not doubting about it; I was just wondering about the resistance not the impendance ; so both of my federal signal FS100W and code3 C3500 has impendance of 11 ohms, but they are different in resistance, the FS100W has resistance of 4 ohms and the C3500 has resistance of 5.5 ish Ohms, and they draw different amps from the same siren amp (FS100W draws more amps than the code3 speaker); this makes me wounder why wouldnt the siren industry just set 4ohms as resistance for standard across all brands (I believe whelen speakers have the same resistance as federal signal speakers which produces similar drawn current, but the resistance of Feniex speaker is about 6.5 I think (if i remember it correctly), and it produced the lowest current drawn from the same 11 ohms impendance siren amp. )?

Oh, and my Whelen SA315P speakers blow away my Federal Signal speakers, just saying...

I do not have any whelen speakers to compare, but I did have a driver from Taiwan SANMING which was claimed to be the original mfg of Whelen speaker, and I could tell the differece in volume between the two (the vintage FS100W beats all of my newer model speakers); I have also compared the FS100W to newer fs speakers models like the ts100N and ES100, and the old FS100W still wins in volume (but a lot heavier and has higher pitch; I believe the FS100 uses different magnent though, dont know if it has anything to do with its volume)

 

[ur20v]

Resistance, amperage draw, etc., are all variables that will be different from one mfr to another, and they don't tell the entire tale. Motor winding wire size, diameter of winding, magnet sizes, baffling, material choices, all make a difference.

And a driver is only part of the speaker equation. The same driver could be terrible paired with one horn design but blow everything else away in another.

 

[shues]

Resistance, amperage draw, etc., are all variables that will be different from one mfr to another, and they don't tell the entire tale. Motor winding wire size, diameter of winding, magnet sizes, baffling, material choices, all make a difference.

Well said! You're spot-on with this.

 

[reduiyong]

Resistance, amperage draw, etc., are all variables that will be different from one mfr to another, and they don't tell the entire tale. Motor winding wire size, diameter of winding, magnet sizes, baffling, material choices, all make a difference.

And a driver is only part of the speaker equation. The same driver could be terrible paired with one horn design but blow everything else away in another.

I guess the only way to buy a decent siren speaker matching a siren amp is to buy from the same brand then...

 

[ur20v]

I guess the only way to buy a decent siren speaker matching a siren amp is to buy from the same brand then...

There's no matching involved - 11 ohms is the industry standard so you *don't* have to have a matched set. Imagine the clusterfuck if this weren't the case...