I've got the horn.......

Actually it's a Siebel Nautilus...........139dB. Thats loud!

I always thought the horns on the stock Blackbird were crap. Ive tried the
"snail" type Fiamms but they were crap. This thing is the dogs.

For £23 (Halfords) I'd recommend it as an essential filtering accessory!

Mark

 

Measured about a foot away from it. It's only really a 118 or so dBa if
measured about a metre away.

 

fx: faints.

Bloody hell, a dB unit used correctly for once.

 

Wouldn't it be the "bell" if used absolutely correctly?

Mark

 

These air horns?

 

I've no issue with someone using the 'deci' part (I think I'm missing a
joke here) it's just that people constantly refer to so many dB... which
given that dB are a ratio is utterly meaningless. Of course, normally
one can guess the units but it's not really the point; being a miserable
old git *is* the point.

 

Well they certainly sound like air horns but there are no tubes. The air is
drawn in through an inlet hole and the compressors are built into the body
of the unit. There is no lag between button and noise.

Mark

 

I only ask as I remember a set i had on a car once from Halfrauds and though
loud, eventually the pipe twixt compressor and trumpet used to come loose
and a few times the compressor would pop it off, and even then there were
times it'd keep running even when the hand came back off the horn.

I'd love a louder horn on the lammy (anyone thats ever heard one knows it's
little better than a ducks fart) though i suspect that the electrical draw
would pretty much kill all my lights :-(

 

I must be the only saddo that agrees with you. dBs must have a
reference or they are meaningless. 'Below 3dBs is bad', you talking
watts, milliwatts, kilowatts, or zardwarks?

 

There already is a reference for SPL. 0dB is the threshold of hearing for a
typical youngster who has never listened to Motorhead, or 20uPa.
So when someone refers to a noise level of 120dB, you know what they mean,
apart from whether they are using A or C weighting.

 

They could be referring to audio power delivered into a speaker; i.e.
dBm.

You're probably correct that there are few alternatives, however it is
simply bad practise to drop the unit and just imply it.

 

SPL isn't my area. The A may not be a unit as such but it references a
specific 'level' of sound; the threshold of hearing (however that will
somewhere be described by a suitable unit; whatever is relevant).

If you use the "A" it's clear that SPL is being discussed, if you don't
then dBm could have been under discussion (for example).

 

I'm tired so I'll just quote from the wikipedia page:

"The unit dB (SPL) is often abbreviated to just "dB", which gives some
the erroneous notion that a dB is an absolute unit by itself"

Which more elegantly states my point than I had; a dB in isolation is a
measure of nothing, it's a ratio.

http://en.wikipedia.org/wiki/Sound_pressure

 

In acoustics, dB refers to a reference SPL of 20 micro Pascal in air
which is the nominal threshold of human hearing (most of us can't get
down that far, in some places, there are people who can get to -10dB).
The `A' refers to a weighting scheme which adjusts the contribution at
different frequencies to make the level more like what the human ear
perceives. It's most sensitive around 1000Hz so the contribution there
is boosted a bit and other frequency bands have their level
dropped. `C' weighting does something similar but weights the bands
differently.

 

What *was* actually measured would be a signal power. What was actually
expressed would be a ratio relative to the reference signal power. This
could be correctly expressed as dB (SPL)[1], or incorrectly expressed as
dB.

Regarding "A", you're right, it's not the reference unit. It does imply
we're discussing SPL though... so gives a clue but I'll happily accept
it's not a correct 'unit' of measure.

[1] Apparently, from memory, from Wikipedia.