Block 2t22 projectors facing empty fields?

[hobbeekid]

Robert,

I don't think that the siren will be able to displace more air than the squirrel cages can feed it cause those blowers do move quite a bit of air at the exaust. A db meter would also be needed to measure any sound increases.I'm clueless as to how to get hold of one .Perhaps somone with knowledge of db meters could make a suggestion. Let us know how it works out........
Jeff

[Robert Gift]

Robert, I don't think that the siren will be able to displace more air than the squirrel cages can feed it cause those blowers do move quite a bit of air at the exaust. A db meter would also be needed to measure any sound increases.I'm clueless as to how to get hold of one .Perhaps somone with knowledge of db meters could make a suggestion. Let us know how it works out........ Jeff

I used to know the CFM of the two squirrel-cage blowers. I just can't remember.
A friend has a dB meter. RadioShack sells them for about $50.
(It is 7:07 on 7-7-07!)
Today my wife will operate the siren and I'll take videos and photos.

Maybe next month I'll be able to "supercharge" Lassie.
I can always try the squirrel-cage blower and growl Lassie. It will make her growl louder, but at a certain high rpm and above, the rotor intake may exceed the blower output so a direct feed would restrict output.

Another experiment I want to try is to place a tuned cavity below the bottom intake to match the D5 which the 10-port stator attains.
Better would be to place a tuned cavity over the top intake tuned to F5 of the 12-port stator.
It would act as a rain cap and could be larger in diameter because it is not restricted inside the tripod leg assembly.
A tuned cavity for the lower 10-port stator would need to fit inside the legs and it's length is restricted by that leg plate/brace which rests on the top of a pole when pole mounted.

[q2bman]

What would that do? Act like a box for a subwoofer?

[Robert Gift]

When the siren reaches it's peak pitch, if that is the pitch of the tuned cavity, the resonation of that cavity would significantly increase dB output.

Also the sound would be louder at other harmonic frequencies of that tuned cavity, but the louder tones would only briefly sound because the siren is passing quickly through those frequencies. Only the top tone would be steady and match the frequency to which the cavity is tuned.

If you can place a bucket several inches above the rotor intake of one of your sirens, and slowly increase speed of the siren, you will notice that certain pitches which happen to match the resonance of that bucket will be much louder.

The only other thing to do is find what the top pitch is, and tune the bucket to that pitch.

[q2bman]

Cool, that actually worked. I guess the vibrations from the bucket add to the db output. Weird!