My idea is this:

On the back of my projector (an Epson TW10H) there is an (unused) audio input. I might be (must be) way off track but could I do the following to silence the fan noise?

1) record the fan noise from my usual sitting position
2) invert the sound wave (like speakers out of phase)
3) Play back the inverted sample along siide the usual sound of operational fan noise via the audio inputs.

Is there any way that this could "cancel out fan noise"?

[Mark_a]

That's how noise-cancelling headphones work, so I think there's some merit in your plan. 'Spect it would take a helluva lot of trial and error to get it right though.

Regards

Mark

[ijd]

not to sure if this could be done, but how about fitting a pc water cooler,it may be a bit of a task but well worth it surely. i wonder why the manufactures dont do this???

your idea is valid and works not only in theory but in practice as i have seen it demonstrated with various appliances on a tomorrows world style program a few years back

why it isnt installed on all vacuum cleaners god only knows!

This is sounding good- to think of all of those people who have wasted money on hush boxes. Are there any sound people out there who can give me any more advanced tips. Water cooling is not an option- the beauty of my idea is that if it doen't work the waranty is no invalidated......

What is the number for the patent office?

[cybrey]

I'd love to know how water cooling would work ?? You going to run water over the bulb ? I thought the idea of the fan was to pass air across the bulb ( and other components) to keep them cool ? ( btw this is probably going slightly OT).

[Mark_a]

Here's an idea, possibly ahead of its time, but how about getting a small fridge and cutting a hole in the front door where the lens would be and sit the projector inside? Then you get both cooling and soundproofing. Genius, or what?

Regards

Mark

[stripe]

Mark a

Good idea but, have you heard the noise a fridge makes?

[Mark_a]

You could run the compressor and condenser out through a hole in the wall.

Sorted.

Regards

Mark

[ReggieDaMole]

Get a louder amp.....

[stripe]

Now that's more like it!

[Apollo11]

Originally Posted by stripe

Now that's more like it!

Try mounting your PJ outside your house and shining it through a window, this will be especially effective if you have double glazing, I would do this with my Sony but I live in Ipswich and the locals will soon steel it!!

Isn't it amazing what a bit of lateral thinking can do. I am now thinking that I might apply the same principal to my fridge (with double glazed hole) and get a louder amp.

You know it makes sense....

[David_of_Surrey]

Or how about this idea?

1) Identify dominant frequency of the sound
2) Work out wave length ( 332 metres divided by frequency)
3) make a pipe that is half that wavelength
4) postion start near the noise make it so the mouth is returns to the source (pipe will loop)

should self cancel some of the sound

[Helicon]

Getting a quieter projector might do the trick
Or is that too simple?

I think you are missing the point, a new projector, why would I want to do that when I am about to get a super quiet version of my current projector for practically nothing.

I tell you if I ever get a spare couple of hours and figure this out, who will be laughing then?

I can't believe anyone hasn't come up with this simple solution earlier.

Now where did I put my microphone?

[summat]

I think you have an over simplified view of the problem.

The PJ is not a point source of sound, rather there is a fairly large surface that will emit sound. There's many components between the fan blade and fan motor (and indeed all the other blades and motors) that will together add a serious number of harmonics and distortions.

The PJ then distributes this sound energy with a fairly omnidirectional erm distribution. The sound that you hear will be a complex mix of single-path (direct to ear) and multi-path (reflected from surfaces within the room).

To cancel the sound that you hear, you'd need to consider how all path sources would mix and then (and only then) consider how you're going to *accurately* reproduce that sound (and the easy bit) at 180 degrees out of phase.

This is the reason that noise-cancelling headphones work - being placed in the ear canal (or by the ear) they only need to deal with the (largely) single path noise (i.e. the single-path and multi-path are already mixed once in the ear).

Personally, I prefer the earlier solution(s) - quieter PJ, bigger Amp.

[DEANO-B]

Havr to agree with last post - as the sound does not come from a single point.

Point taken- it seemed such a great idea- thanks for your help