38 cm. woofer in a sealed box, any experience?

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Ex-Moderator
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Hi Geolite

You could search for driver specs and plug then into a modeling program for your box volume,try here ( bearing in mind you can always reduce the box volume with bricks or similar), then when you have found a suitable driver available to you, we can give you inputs as to quality etc.

Good luck
 
diyAudio Moderator Emeritus
Joined 2001
Is there any good reason you wish to go sealed over ported?

With a big box like that, you ought to be able to mount a 15" inch that would pack a wallop if ported.

Ported gives more bass. Sealed gives less distortion, true, but most people who want sealed tend to be purists. Even many hifi fans like the greater output of ported over sealed. If PA work is what you are doing-and Electrovoice makes mostly PA speakers-I would suggest ported.

Suggestions for brands? I have not had the chance to check them out, but Ciare of Italy, judging by their impressive line of horns, etc., seems to mean serious business for PA speakers.
 
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Sealed boxes are okay for hifi,because it gives clean sound without chuffing noises that ported reflex produce at certain frequencies.But for pa,sealed is unsuitable,unless it's for a midrange driver or guitar speaker to go in.
It is unsuitable for a bass driver in pa/disco use because the high volumes of sound;would make increasing pressure inside the enclosure and make the driver move about too far[high excersion].The ported or vented reflex relieves the pressure,so that the driver doesn't get literally pushed and pulled aggressively;which can sometimes damage the surround,cone,and spider; depending on how 'long-throw' the driver is.
If you want to use sealed for pa,Use a driver with a high x max[say over 6mm] and a very high maximum linear excersion [say over 30mm].Otherwise the cone,surround,spider and voice coil former could tear.[Over-excersion]

For midrange drivers without a sealed back,they have to be used in a separate sealed enclosure within the box,or in another box,to stop the giant air pressure waves from the bass driver from damaging the midrange driver by over excersion.

For guitar speakers [They either use open back,sealed or vented]
A closed back gives a good charactistic to the produced sound,or special tone depending on the type of driver used.Eg Celestion Legend loudspeaker gives a warm and hard 'slap type' sound.
This is only good,if your band is after that tonal responce.All guitar players and musicians prefer different tones and characterists.

I hope this help,thanks
Tom
 
38cm. woofer

I need them for hi-fi use. I got them in garage sale.
I'm thinking to keep sealed box for better transient response.
I tried the software pinkmouse linked and it results in a Q=0,41 which quite too low that why I think they give me such unsharp bass response.
If I want to stay sealed I need a driver with Qts 0,4-0,55 but I found only a Emince Kappa pro 15 with Qts 0,38.
Giorgio
 
Ex-Moderator
Joined 2002
Giorgio,

The first thing you should do is work out the EPB for your existing or prospective driver.

This is calculated by dividing Fs by Qes, 50 or less will give a driver that will work well in a sealed enclosure, 100 or more needs a vented box to work at it's best.

Qts is a figure that takes into account all of the loading in your system, including crossover resistances, source resistance, and cable resistance, so manufacturers figures, if given, may not be accurate for your system.

So, do a google search for loudspeaker manufacturers, find some suitable products that you can get hold of, calculate the EBP for them, and then plug suitable ones into WinISD and see how they model for your box size, as I said earlier, you can always reduce the volume to get the response you want.

Some manufacturers are Audax, Monacor, Fane, Precision Devices, Adire, Volt...
 
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