15" sealed subs - simulated F3 values too high ??

[audfrknaveen]

Hi All,

I am trying to build sealed subs with 15" pro drivers.
In simulation with 100L box, I am getting the F3 values as shown in the attachments.

Aren't these F3 values too high for subwoofers??
Do they even sound like subs with these values?? Or do they just end up like mid bass?? Will they give tight and punchy bass for music??

We expect subwoofers to go down to 20hz or lower. So I am wondering if higher F3 is ok with larger drivers like 15" or 18"??

Should i look at drivers with rubber or foam surrounds?? Does it matter much?
I dont want boomy bass. Good transient responce is important for music.

Thanks in advance

 

[David Morison]

Drivers designed for PA/Pro use accept different compromises than those intended for home/HiFi use.

One of these is that efficiency is more important, therefore they won't go as low in a given box size (Hoffman's Iron Law). Yet box size is indeed also important as portability is usually a factor.

Therefore, Pro/PA drivers are almost universally intended to be placed in vented or other higher order loading types, not sealed.

Even then, it is more typical to accept an F3 in the 35-45Hz ballpark rather than in the 20's.

So essentially the reason you're seeing such high F3's in sealed boxes is that you're trying to use the drivers in a way they weren't designed to be used.

Perhaps something from another market segment might suit better if sealed is a priority - do you have any access to Dayton for example where you are? Something from their RS or UM series might possibly be a better fit for your goals.

 

[audfrknaveen]

please correct me if my understanding is wrong ....

Bass from large drivers sound better even if they have higher F3 compared to bass from smaller drivers with lower F3.

I mean 15" or 18" drivers with F3 is around 45hz. sound better compared to 6" or 8" drivers with F3 around 30hz. Is this correct?

I know "better" is subjective and my statement is too generic.

My whole point is ... with larger drivers 15" or bigger, can we go ahead and build the box if simulated F3 is 45 to 50?? Or will it fail to sound like a subwoofer completely?

Im getting below values with 15" driver in a sealed box:
F3=50hz
F6=40hz
F10=30hz
Is this ok for music?

 

[wonderfulaudio]

See what happens when you port the 100L box to 25hz or 30hz and then simulate.

 

[audfrknaveen]

unfortunately ... i can't port it.
This box is for my friend, and sealed is preferred.

Now all I am wondering is .... are these values ok for a 15" subwoofer (for music)

F3=50hz
F6=40hz
F10=30hz

I just need tight and precise bass (good transient responce)
Low end rumble (like movies) is not needed

 

[wonderfulaudio]

I would suggest two 12" car drivers mounted on opposite sides of the box. They will go lower (unassisted) and the box size may be smaller

 

[audfrknaveen]

Thats something to try out !! Thanks a lot !!

 

[Xoc1]

With a sealed cabinet you will be looking at adding EQ to get the bass response that you want.
Drivers with bigger x max will give you more bass, you will have to take in to account the excursion of the driver and the amount of power that will be needed.
As ever Hornresp will give you the answers you need.
This example is based on the Beyma 15WRS400. in a 100Litre sealed box.
This reaches x.max at about 40watts using a single boost at 41hz.

 

[mashaffer]

There are pro drivers with appropriate fs and qts to get lower but generally will require larger boxes. Have a look at usspeakers and partsexpress web sites for suitable candidates but if you are really limited to a tiny box you will probably be out of luck.

 

[SpeakerBob]

Maybe a Linkwitz transform to lower the F3 to around 30/35Hz could perform well.

Most people here seem to assume some form of PEQ will be used on subs so just build the small boxes and EQ / Highpass to get the required response and use enough boxes to get the required SPL.

 

[audfrknaveen]

Since this is for home usage I can't accommodate huge boxes. 18"x20"x24" is maximum size I can use. With this box, my driver gives 40hz @ F6. Will that be ok for music?

 

[cowanaudio]

For most music and basically all rock/pop, yes. The room will lift the bottom end a little to make the speaker close to flat down to the lowest strings on a bass guitar. Kick drums are usually tuned higher. If you feel like you need a little more a touch of eq will help out.

 

[djn]

Here is my build and these are super tight, clear, and powerful.

New build

 

[audfrknaveen]

Here is my build and these are super tight, clear, and powerful.

New build

nice build with metal rods as bracing

 

[audfrknaveen]

thanks a lot for all your suggestions guys !!!

 

[djn]

I like the threaded rod as it takes up much less space in the cabs.

 

[Think]

If you put the subwoofer in a corner of a room it will have the most room gain; the roll off on the low end will be a lot less then the modeling software predicts.

 

[audfrknaveen]

I will try corner placement. And I'm building dual subs. So let's see how it sounds ....

 

[Juhazi]

Frequencies below 40Hz from a sealed woofer get assistance from boundaries (boundary gain) and room modes, alas pressurization below the lowet mode. These make the room response much "better" than simulated free-air looks. A ported woofer is much worse in this respect.

How will the subwoofer be amplified? Many plate amps have low bass boost option, often adjustable like Hypex and DaytonAudio. A large 15" driver can take this eq guite easily and it doesn't have to use hundreds of watts, at home. I have 2x15" sealed woofers in my HT room and below are some measurements without eq and xo.

 

[djn]

For the cost of two plate amps you can buy a behringer inuke 3000DSP. That's what I use.