xls fs?

[JoJoerg]

I hope someone will be able to explain this.

Iwant to build a sealed sub for home use with a peerless 10 XLS. The model is the one intended for car audio(830514). It has a significant difference if you compare it to the model for home use(830452). The fs is more than twice as high in the car model which I have. Respectively 18,9hz and 39,4hz.
How will this affect the performance of a sub for home use?

 

[simon5]

It will not be able to go as low in frequency response, but I guess you can do something acceptable with it.

I would go for 2.4 cu.ft if you go sealed to have acceptable low end.

 

[JoJoerg]

They seem to be identical with a sim in winisd. Someone else explained that if the Q has the same difference they wont have any significant influence in a small box. But the db loss in low frequencies is quite high for both of them.

 

[simon5]

I agree with you, in WinISD they model quite similarly.

The car woofer is a little bit under the home woofer in a same size box at low frequencies, but not by much.

As we can see, these 10 inchers are not that good in a sealed box IMO...

 

[JoJoerg]

You are right. It wont be a good solution to my problem. I will have to try something else.....get a new driver.
Thanks for helping.

John

 

[Jennice]

I have considered the XLS, too.
However, after advise/suggestions from a former Peerless employee, the SLS are better, unless you have a sincere need to move massive amounts of air. After all, the XLS's have a high moving mass, compared to the SLS.
Considering the cost difference, I have decided to try 2 SLS 12" for my sub.

I don't know how your sub will be powered, but I have been warned about using a passive X-over for XLS drivers due to their coils.
Secondly, I would suggest you to look for the XXLS. They cannot bottom out and ruin the voice coil (unlike the XLS), and are (accoring to my WinISD simulaions) easier to make an enclosure for when you don't want a container-size sub in your living room.

Due to the large quantities of air moved with the (X)XLS drivers, you will want to look at their passive radiators and design suggestions, in stead of a ported design.

Just my 2 cents -
Jennice

 

[simon5]

Maybe the Peerless XLS 12" would be ok, but yeah XXLS is to be considered.

 

[JoJoerg]

I have heard about the voicecoil problem. But I dont when or if it will occur.
Anyway I have decided on a different driver. I am going to use a Scanspeak 23W in a closed or vented sub. It looks really nice as vented. Though I dont now about group delay. It goes high but only under 20hz. According to sim in winisd cone excursion should not be a problem. But is only theory!

 

[simon5]

The theory in WinISD is quite close to the reality.

If you put 225W into the simulation, you'll see how much excursion is left.

Acceptable group delay is usually around 25 ms at 20 Hz or so. If it's climbing under 20 Hz, it's not much of an issue.

 

[JoJoerg]

I done it. Max linear excursion is 13mm and xmax is 20mm. Max input within linear excursion is 70w. Max input within xmax is 170w, with 225w its goes all the way to 23mm. Thats in the vented box.
The sealed box does not have a peak at 25hz and 15hz like the vented. But does go up there. With 60w its 13mm at 20hz and.
I dont now what to think.

I guess this thread changed a bit. But thanks for the advice.

 

[JoJoerg]

By the way, group delay seems to be ok.

 

[simon5]

The frequency response is flat, in room the lowest frequencies will be boosted quite a bit.

This subwoofer will be hard to design with that very long port.
It seems to need a passive radiator.

Btw, usually we try to stay in the linear excursion at all power levels...

 

[JoJoerg]

My budget limited, and I allready bought the ss 23W. The vented will be a bit difficult but possible.
I saw pictures of a closed sub. According to him the results are good. Maybe the roomgain will give the needed boost a low frequencies.
I going for it anyway.

 

[kilowattski]

Sorry for the dumb question because I am new to speaker building but I remember back in college, transmission lines theory dictated that group delay was delta frequency over delta time or the change in phase (or electrical length) over a change in frequency. How does this relate to a speaker?

 

[simon5]

Under the tuning point of a ported subwoofer, you are about 180 degrees out of phase and if the tuning frequency is lower, usually the group delay is also higher, unless the box size is different.

So you are in the right direction!