General Siren Questions II

[System 7000]

Since my first questions, I have come up with a few more queries, and I am combining them into this post rather than clog up the forum with multiple separate threads. I have numbered the questions for ease of answering.

1. Apart from the production tag, what are the visible differences between the Whelen 2700 / 2800 / 2900 series?
2. Apart from the decibel rating, is there an audible difference between the FS Modulator 6024 / 6032 / 6048?
3. In my personal opinion, this recording of an ASC AL-4000 is the best sounding electronic siren I have heard, with an effective dual-tone sound and a decent wind-up and wind-down. Is the modern ASC i-Force available with a sound card to make it sound like the AL-4000 in this recording?
4. Why did dual-tone sirens fall out of favor, to the extent that today only Sentry offers mechanical dual-tone sirens in the US? Surely it can't cost that much more to cut an extra row of ports in the chopper and stator?
5. Why did no company other than H.O.R. produce sirens with the 7/10 port ratio?
6. What is the audible difference between a mechanical siren running on single phase power as opposed to three phase power?
7. On Thunderbolt models, what does the 'T' in 1000T stand for? If it means dual-tone, why isn't the 1003 called the 1003T?
8. Excluding the signals that the 1003 creates with its solenoids, is there any audible difference between the Thunderbolt 1000T and the 1003?

Thanks in advance for any replies!

Regards,
Jerry.

[500 AT fan]

3. I think the iForce line uses it's own tones.

4. Single tone carried further.

5. May not have worked as well at long distances.

6. Single phase sirens usually have longer wind up and lower peak RPM. Not always, though.

7. 1000T, 2T, 500T, etc. meant the siren was dual tone. 1003 only came in dual tone, so there was no need to call it the 1003T.

8. No.

[guitarguy1985]

2. I doubt there's any audible difference other than the volume levels.

4. For a given siren design and power consumption, single tone sirens are louder.

5. There's little significance to the 7/10 port ratio other than it produces a diminished 5th interval which most people perceive as an eerie or scary sound. The purpose of sirens isn't to scare people but just to warn them, hence there's no reason why it's a better port ratio than any of the other dual tone ratios.

6. It depends on the siren. Single phase sirens with universal motors (which seems to include most if not all Federal Signal single phase sirens) have a distinct non-linear windup that starts strong and eases into the final pitch. Three phase sirens usually have a linear windup with a more abrupt transition from windup to the peak motor speed. In sirens with single-phase induction motors, there is sometimes a "hiccup" in the windup and winddown when the start capacitors are taken in or out of the circuit.

8. In alert and attack, the 1003 and 1000T sound identical.

[System 7000]

Thanks for the replies! I can really hear the difference between single-phase and three-phase sirens now I know what to listen out for!

In terms of the Whelen 2700, 2800 and 2900, keoghjacob wrote a comment on YouTube about the versions:

Yeah I agree. Here's a graph to tell versions.
2900:Slightly Higher
2800:Like This
2700:A Imatation Of The WPS-3016
I am also a Thunderbolt fan.

I mostly understand how to tell them apart audibly, but is there a way to visually determine the version?

Regards,
Jerry.

[Mantis]

7. I've always assumed 'T' stands for 'two,' as in 'two tones.' I'd bet that the 1003 did not carry the letter because it wasn't necessary, as there was no single-tone 1003.

[carexpertandy]

The 1003 needs to be dual-toned to produce the high-low and pulsed signals. When it sounds high-low, it is switching between the two tones the chopper has. While one solenoid is closed, the other is opened letting one tone sound, then when the other solenoid closes and the first one openes, you hear sound from the other tone.

[Jpressman8]

The 1003 needs to be dual-toned to produce the high-low and pulsed signals. When it sounds high-low, it is switching between the two tones the chopper has. While one solenoid is closed, the other is opened letting one tone sound, then when the other solenoid closes and the first one openes, you hear sound from the other tone.

Yeah if the 1003 were a single tone it would just do a rapid pulse signal. I think I hear some light bulbs lighting up.

[System 7000]

Thanks for all of your replies! I knew that a Federal siren with a 'T' in its name meant that it was dual tone, I just didn't know what the 'T' actually stood for. Do I assume that it is 'two', as Mantis suggests?

Thinking about it some more, I should have realised that FS didn't include the 'T' in the name if the siren was only ever available as a dual-tone model - the SD-10 proves this.

After doing some more research, am I correct that the way to visually differentiate a Whelen 2700 / 2800 / 2900 is by some difference in the screens in between the driver modules?

Also, another question that has occured to me: aside from the decibel ratings, are there any audible differences between the Sentry 10V2T, the 15V2T and the 20V2T? I notice that the Sentry website has one common audio file for these three sirens.

Regards,
Jerry.

[holler]

The 10v, 15v, and 20v all use the same rotors and stators. They just bump up the horsepower in each model and the rating.

[coppercarl]

Also, another question that has occured to me: aside from the decibel ratings, are there any audible differences between the Sentry 10V2T, the 15V2T and the 20V2T? I notice that the Sentry website has one common audio file for these three sirens.

The only audable difference would be between a Three phase motor and a single phase motor. Here are two comparisons below. Pay close attention to the wind downs.

Three phase
http://www.youtube.com/watch?v=_XLasNFT ... re=related
http://www.youtube.com/watch?v=2hyhaSBo-QQ

Single Phase
http://www.youtube.com/watch?v=u4jqr3eniog
http://www.youtube.com/watch?v=kCioUPxdvCw