Round vs Oval shape

[ColdPlays]

The ultimate peak in the sound that has to be reduced is at 130 Hz. Im allready using 6 speakers which are individualy being calculated (live). Im going to use 12 channels in the next module. Each speaker has its own channel ( so the vetilation duct is devided in 6 (or 12) channels.)
_______
|__|__|__|
|__|__|__|
|__|__|__|
|__|__|__|
approx 808 x 1018 x 250 mm (the height is the killer, I also need to install mics in order to calc the anti-sound)

Like this

[basite]

a good 6,5" driver would easily do that, 70 db is not loud, pretty much any driver will do that with less than a watt of power...

what will drive the speakers? I imagine that on a cruise ship, the 'running times' for the speakers would be pretty long, so i'd look for a pro amp of somekind, basically it's just producing the same tone for a very long while, so it can be a cheaper one too
since there will be moisture & salt too, especially, look out for oxidation on the basket too, and the wires and such...

Good luck, sounds like an interesting project

Keep them spinning,
Bert.

[kexodusc]

max 70 dB

Yeah, shrink down to a 5-1/4" (commonly available at good prices), or smaller as necessary.
That'll be plenty.

What about a helmholtz resonator for the 130 Hz?

[kexodusc]

The ultimate peak in the sound that has to be reduced is at 130 Hz. Im allready using 6 speakers which are individualy being calculated (live). Im going to use 12 channels in the next module. Each speaker has its own channel ( so the vetilation duct is devided in 6 (or 12) channels.)
_______
|__|__|__|
|__|__|__|
|__|__|__|
|__|__|__|
approx 808 x 1018 x 250 mm (the height is the killer, I also need to install mics in order to calc the anti-sound)

Like this

So you have 808 x 1018 x 250mm for each speaker/channel? Or for all channels?

[ColdPlays]

dimensions are for all channels together.

I just drawn oval shaped +/- 5" holes in the body for the speakers - got to say, looks promising.
Ok so the rooms which have the raster on the side will be filled up with isolation. If you look closely you can see the mic holes.
This is what it looks like with +/- 5" round holes.

I think its worth while to test the oval shaped speakers.

[ColdPlays]

a good 6,5" driver would easily do that, 70 db is not loud, pretty much any driver will do that with less than a watt of power...

what will drive the speakers? I imagine that on a cruise ship, the 'running times' for the speakers would be pretty long, so i'd look for a pro amp of somekind, basically it's just producing the same tone for a very long while, so it can be a cheaper one too
since there will be moisture & salt too, especially, look out for oxidation on the basket too, and the wires and such...

Good luck, sounds like an interesting project

Keep them spinning,
Bert.

All wires will be sealed. The noise of the engines change when they vary thrust. We agreed to focus on stationairy and cruise mode. I named the thing a module, because I want to have the ability to replace it in a very short time should it start to malfunction. That way I have all the time repairing the malfunctioning module while the new one allready doing its job. This is also handy when it comes to upgrades. Well - I thing you get the point

Greets ColdPlays

[kexodusc]

You can test oval speakers, in fact for your purposes there's nothing wrong with oval speakers. The only negative I can think of is possibly quality/cost. More durable, quality oval speakers are just not made in the same quantity as round drivers so they're likely to cost a bit more, but I don't know the pricing in your area so who knows? But there's probably still a lot of options so go with whatever works.

[E-Stat]

If you use a Round shaped speaker, you get a perfect sinus when you measure the outcome of a wave.

- What happens when you use an oval shaped speaker? Is the 'shockwave' still a perfect sinus? I need to know because I'm experimenting with sound behaviour. A right awnser would help me alot.

I use high resolution full range electrostats which employ a large rectangular diaphragm. The shape of drivers is likely responsible more for dispersion. Back in the 70s, British speaker maker KEF made oval woofers that were found on their products and that of others like IMF.

KEF oval woofer

Most oval drivers these days, however, are cheap car speakers. The Army commissioned sound reinforcement speaker maker Danley Labs to make a huge subwoofer for similar purposes (although they declined to explain exactly what they were going to do with them.) .

Matterhorn

rw

[hermanv]

A six inch diameter speaker will be smaller than the wavelength (actually a quarter wave I think) below 500 Hz or so. Below that frequency the speaker will output mostly pure sine waves. Like all speakers they will have 2nd or 3rd harmonic distortion which is usually down more than 30 dB at reasonable volume for either round or oval.

The speaker specifications should have the Thielle/Small parameters, they will include X-max (maximum cone displacement) and Fs (speaker self resonance). Speakers have very little useful output lower than the Fs frequency. Note that a cabinet or baffle can influence the Fs spec.

Since you are essentially modeling a woofer many free woofer enclosure design programs are on the net. They will usually model X-max vs input power or output SPL.

The volumes of the individual speaker chambers look a little small to me for efficient 70Hz performance.

[ColdPlays]

A six inch diameter speaker will be smaller than the wavelength (actually a quarter wave I think) below 500 Hz or so. Below that frequency the speaker will output mostly pure sine waves. Like all speakers they will have 2nd or 3rd harmonic distortion which is usually down more than 30 dB at reasonable volume for either round or oval.

The speaker specifications should have the Thielle/Small parameters, they will include X-max (maximum cone displacement) and Fs (speaker self resonance). Speakers have very little useful output lower than the Fs frequency. Note that a cabinet or baffle can influence the Fs spec.

Since you are essentially modeling a woofer many free woofer enclosure design programs are on the net. They will usually model X-max vs input power or output SPL.

The volumes of the individual speaker chambers look a little small to me for efficient 70Hz performance.

Tnx for the info!
I know space is tight, but actually the focus is between 130Hz and 200Hz (a huge peak of a factor 5 compared to the rest of the bandwith)
I dont exactly understand all factors of the woofer design programs though.

The only thing I'm intrested in now is:
Where, for Pete's sake, can I find 5x7" speakers with no tweeters???
I googled my ass of with only 1 set as result: A speaker with seperate tweeter for 200 euro's. I need 12...
Does anybody has an idea?
tnx

CP

[hermanv]

All these 5 X 7 speakers have tweeters, but they are cheap ($20 to $79) disconnect and/or throw away the tweeter.

http://www.partsexpress.com/webpage....ectGroup_ID=43

[GMichael]

Another good source for the Legacy's. http://www.audio-warehouse.com/web/m...72S/detail.asp

These are cheap speakers but work very well. I've used their brand for several projects over the years. Fairly well made for the price.

[ColdPlays]

2 bad that there arent any standard 5x7 speakers without the tweeter (except the ones with separate tweeters: http://www.amazon.com/Infinity-Refer...f=pd_rhf_p_t_2)

I guess we go for the ones with tweeters and remove them as Herman mentioned.
Thanks for the options you guys offered.

Is there any way we could be in contact in the future in some kind of private channel? (e-mail or closed forum)
Since I dont want to expose any more details of this project to the public...
(GMichael
Hermanv
Kexodusc)
Thanks again for some awesome input!
AR rocks

CP

[Rich-n-Texas]

Is there any way we could be in contact in the future in some kind of private channel? (e-mail or closed forum)
Since I dont want to expose any more details of this project to the public...
(GMichael
Hermanv
Kexodusc)
Thanks again for some awesome input!
AR rocks

CP

Tossed aside, once again, like so much debris...

CP, you can Private Message members from within your individual "User CP".

[GMichael]

[QUOTE=Rich-n-Texas]Tossed aside, once again, like so much debris...

CP, you can Private Message members from within your individual "User CP".[/QUOTE]

Awesome input Rich-n-Texas.

You rock!

[Rich-n-Texas]

What're you setting me up for GM?

[GMichael]

Just trying to be nice. It seemed like you felt left out.

[Rich-n-Texas]

Just trying to be nice. It seemed like you felt left out.

You know me... "Paranoia the destroyaaaaaa"

I just checked Orange County Speaker Repair, which is where I bought my banana plugs, but I didn't find any oval speakers. Here's their link anyway: http://www.speakerrepair.com/

[hermanv]

Tossed aside, once again, like so much debris...

Sometimes you're the windshield, sometimes you're the bug - Dire Straits.

[ColdPlays]

Tossed aside, once again, like so much debris...

CP, you can Private Message members from within your individual "User CP".

Because that was your 1st message here?
But is it a last call attempt or something? Cause Im not trying to be a bad guy here
oh and basite, I'll keep you posted too.

Just bought some oval speakers today. Removed the tweeters. Im testing next days

[ColdPlays]

The oval speakers produce to much distortion.



This was measured at +/- 8 inch distance from the speakers with a 50Hz tone input.

So I decided to go for 6" round speakers.

CP

(end thread?)

[GMichael]

The oval speakers produce to much distortion.



This was measured at +/- 8 inch distance from the speakers with a 50Hz tone input.

So I decided to go for 6" round speakers.

CP

(end thread?)

That sounds about right. Oval is bound to have some distortion. Just part of it's nature. The 6" round should get plenty low enough for you anyhow.

Close thread? Up to you. You never know if someone might come along with a good idea though. May be worth letting it be.

[Woochifer]

I have a rectangular driver. Does that count?

Just found this blast from the past the other day -- it's a write-up on Adire Audio's Parthenon subwoofer. A 24" square diaphragm that can sustain 11 Hz at 134 db!

http://www.audiojunkies.com/blog/120...mate-subwoofer



And remember the Sony APM speaker lineup from the 1980s?

[GMichael]

Now that's just freaky.

[L.J.]

Just found this blast from the past the other day -- it's a write-up on Adire Audio's Parthenon subwoofer. A 24" square diaphragm that can sustain 11 Hz at 134 db!