T-128 vs. T-135

[Midnight Drifter]

They look alike. They sound alike. All the videos I've seem of 'em suggest they're around the same size.

That said, what separates these two single-toned American Signal beasts and why does ASC bother making two of them?

Also: Is anybody here willing to specify whether or not the T-135 has a Thunderbolt-style speed adjustment? 8)

I miss the dual-toned ROAR of the original P-50/T-135, but I understand how ASC has to stay in step with Federal in offering a new battery backup T-135 AC/DC

edit: While we're on the subject of the T-135... the old dual-tone model, I've noticed, without fail, in every single video, you get this 'whir' wind roar-like noise under the growl of the siren itself. What causes that sound?

[CJ]

The T-128 has a more sloped horn whereas the T-135AC/DC has a far less sloped horn.

No, they don't have a speed adjustment, only sirens with a blower could use that effectively.

Of course the T-135AC/DC is louder than the T-128, because it has a more powerful motor.

Most likely that noise you're hearing is the resultant pitch. Any siren where the two pitches meet into one horn, you will get that.

[Midnight Drifter]

So... all those different pitched videos out there...

...are they signs of dying batteries? >_<

[CJ]

Nope, from what I hear the newer ones are slightly lower pitched than the older ones, or was it the other way round...

Batteries have nothing to do with it, unless they are purely solar powered or designed with a battery charger instead of a rectifier.

[Midnight Drifter]

Oh, well hell...

>.>

I swear, sometimes ASC's model lines are hard to follow. Although the previous question remains;

Was it really worth the R&D money to produce a siren that is (per manufacturer specification) only nominally louder than the other?

A T-125 and T-135 I can understand, with a 'T-125' series cranking out 125 dB @ 100 ft. and the T-135 cranking out 135 dB @ 100 ft., but...

T-128:
129 dB avg. @100 ft

T-135:
132 dB avg. @ 100 ft



Though I'm guessing the 128 came first, and the 135 was a direct beneficiary of its development

[Nelso90]

I always thought that roar was just air moving, that monster has an 18" intake tube, and it needs it.

[CJ]

I've never heard the 'roar' when i listen to it. The resultant pitch is both added together, so that kind of says it already. Try synthesizing a P-50, with and without the resultant...

It probably was just the air moving, now i can see it in a different context.

[guitarguy1985]

The resultant pitch is the difference of the two frequencies, for a P-50 it's an octave below the lower note.

Batteries have nothing to do with it, unless they are purely solar powered or designed with a battery charger instead of a rectifier.

From what I understand some T-128s always run off the batteries, while others only use the batteries if the main power fails. A T-128 I recorded about a year ago kept sounding a lower note each attack cycle, unless there was a problem with the motor it was probably the batteries dying. It sounded fine the next test though.

[holler]

All ASC mechanical sirens can be ordered in AC only (uses inverter), AC/DC (runs off inverter unless power goes out), and DC only (runs off batteries all the time and uses either a solar panel or light duty electrical service to charge the batteries).

DC only is the cheapest, and often times the only one that will fit into the strict bid requirements imposed by some cities. For example Macon, GA specifies a 40 amp single phase service or smaller to power the siren, a larger service requires extra cost to the contractor. You can thank electronic sirens for that little restriction, since they run off two 12 volt batteries.

[Jim Z]

That said, what separates these two single-toned American Signal beasts and why does ASC bother making two of them?

the (new) T-135 is physically larger, has a larger chopper/stator assembly, and a more powerful motor. I believe the motor is 72 VDC instead of 48 like the T-128.

Also: Is anybody here willing to specify whether or not the T-135 has a Thunderbolt-style speed adjustment?

no, you could only do that with a switching DC-DC converter. Something robust enough to handle the power of running these sirens would be extremely expensive. Plus, lowering the pitch by slowing the chopper also reduces the sound output.

So... all those different pitched videos out there...

it's probably the difference between the -AC or -DC models out there, as has already been explained. The current T-135 has two different dB ratings depending on if it's running off of battery power, or pulling from the AC mains.