Ray21

X-max is typically defined as maximum linear excursion.

Output becomes non-linear when the coil starts to leave the mechanical gap. The figure is typically calculated based on the physical specs of the coil and gap (Voice coil height minus top plate thickness, divided by 2) or by distortion measurements. 10% distortion has been correlated with 70% BL. (BL is the strength of a motor - when the coil travels to where motor force is reduced to 70% of its rest position is often where 10% distortion occurs.)

There are different ways a speaker can be designed to change its x-max - top plate thickness, coil length, manipulating the magnetic field, etc... So two speakers with the same x-max figure may have arrived there using two different designs.

Here is a more thorough explanation:
http://www.aespeakers.com/phpbb2/vie...php?f=4&t=1603

But x-max isn't the end all, be all parameter that you should focus on. In a sealed setup, more x-max = more SPL. In a vented enclosure, the port tuning changes the way the sub moves - at tuning the sub is moving at a minimum and the port is making almost all of the SPL. So the RF 8s in a ported setup can be louder.

Of course a speaker can move past x-max, it just become non-linear and distortion increases. X-mech is the maximum excursion a speaker can reach, and then stuff starts smacking together in a bad way.

I apologize for being long-winded and hope this helps.

Wyo11Scab

iTrader: (1)

Wow way over my head!

Ray21

Just a bit more reading and I'm sure it'll all make more sense.

Ray21

Absolutely. Just got around to plotting it out in WinISD.

Build a box with specs similar to what I posted in the other thread.
BUT --> Change the width to 48" and use a 4" port that is 24" long.

Dimensions - 6" H1 x 8.5" H2 x 12" D x 48" W

You'll end up with a box that is 1.22 ft^3 net, tuned to 32hz.

With cabin gain you should get a nice rising response to 30hz and plenty of good deep bass.

Wyo11Scab

iTrader: (1)

Never heard of WinISD but it looks like a great program to use when designing boxes. Should be a sticky on this forum.

http://www.linearteam.dk/?pageid=winisd

SgtxTorque

Hey guys thanks for all the great responses. I stopped checking on this thread when I didnt see any more responses.
I finally got around to building the box and I am stuck with one problem. You reccomended port size of 4" and 24" long. I am assuming that is for a round port? Or is that a slotted. But from the way I built the box I was thinking about doing a triangle port that could Run along The length that the pvc port would go....

Any advice?

Ray21

Yes, I meant a 4" round port. A triangle port will work fine if you think it'll fit best in the box you built. To go with the 24" length (same port tuning), just make the port area equal to the 4" round port area - 12.56" in^2.

A triangle with a 5" height x 5" base will get you very very close @ 12.5 in^2.

I've used round ports in the past with much success as they are easier to install (cut a hole, glue it up) and easy to adjust the tuning (trim to tune higher, add an extension to tune lower).

SgtxTorque

Thank Ray21 for the advice. I actually finished about 90% of the box last night. I have to run to home depot for some bondo, silicone, and fiber glass (I have a few cracks from drilling screws). BTW I DID predrill my holes which is odd.

But now that I am getting to the closing points of the build I had some concerns:
I put a picture of how I built the box.
**The 3 subs share the same air space, considering that the box they came out of was a sealed box and shared the same airspace, I didnt think anything of it. But is this a bad thing since I want to make it ported?
***With what you suggested for a triangle (or round) port- 5"h x 5"b x 24"lenth or (4"x 24" round). Could I achieve the same effect if I was to cut the numbers in half and make TWO (2) Ports Like the example I mapped out on the bottom of the picture?

I get this late in the build the answers could make or break me, and could or could not cause me to have to rebuild all together....This is my first attempt at ever building a speaker box so I understand the trial and errors.

SgtxTorque

Thank Ray21 for the advice. I actually finished about 90% of the box last night. I have to run to home depot for some bondo, silicone, and fiber glass (I have a few cracks from drilling screws). BTW I DID predrill my holes which is odd.

But now that I am getting to the closing points of the build I had some concerns:
I put a picture of how I built the box.
**The 3 subs share the same air space, considering that the box they came out of was a sealed box and shared the same airspace, I didnt think anything of it. But is this a bad thing since I want to make it ported?
***With what you suggested for a triangle (or round) port- 5"h x 5"b x 24"lenth or (4"x 24" round). Could I achieve the same effect if I was to cut the numbers in half and make TWO (2) Ports Like the example I mapped out on the bottom of the picture?

I get this late in the build the answers could make or break me, and could or could not cause me to have to rebuild all together....This is my first attempt at ever building a speaker box so I understand the trial and errors. https://www.f150forum.com/members/sg...speakerbox.jpg
https://www.f150forum.com/members/sg...309-181649.jpg

SgtxTorque

yo