Custom 12" L7 Box Questions

[wetsounds1]

Just got with Bad05 on his set up.

Since he now has a pair of 485 and pair of 80's. it is like he has Two 3-Some's on the tower. We recomend the SYN6 for the 3-Some. EACH 3-Some. So his system should be using both SYN6's on the tower. And another for the in boats/subs.

What to look at when looking at the SYN6 as compared to other 5 or 6 ch amps. The SYN6 is the only amp on the market that has high pass or low pass on the 2 larger chs. The others are sub only on the larger chs or they are a 6 ch amp that is the same power across the board.

The SYN6 can do just towers. Like a 3-Some in 3 ch mode. It can run a Double Up in 4 ch mode.

The SYN6 can do in boats and towers. It can do 2 to 4 pairs of XS650 off chs 1-4 and a pair of 2 pairs of PRO 60's on the tower off chs 5/6 doing 155x2 at 4 ohms for one pair or 305x2 for 2 pairs. I would not run more than the PRO 60's like this.

It can also do in boats and subs as the factory tige systems come. You can run 2 to 4 pairs of in boats on chs 1-4 and also a couple XS10FA's, one of each ch 5 and 6. Or you can even bridge chs 5/6 into 4 ohms and get 600 watts. Enough to run the XXX. (if you build the ported box, the XXX likes the ported box and does not need as much power in ported as it does in sealed)

heck, you could even do a pair of 80's off chs 1-4 bridged at 200x2 and a single XXX at 4 ohms mono on 5/6 doing 600x1.

So the posibilites are endless on what it can do. As if you plan on adding more or changing more later, you can do it.

You just have to make sure you look at how you are running it as since it is so easy to configure, it is also easy to wire up wrong or use wrong.

I think what happened with BAD05 is he was ok until he added more and just does't have enough power. Power is the most important thing in a system.

A speaker reproduces what it is sent. Crap in Crap Out. Too little power and a clipped signal which can happen on any brand no matter what. Speakers will sound bad no matter what they are or how much they cost. So whatever you do. Don't skimp on power. You will be happier in the long run.

Tim
Wet Sounds

[philwsailz]

With Phil being very busy at the show, I thought I would post a few more questions about the building the new box. The weather is supposed to be very boating prohibitive this weekend so this would be the perfect time to get going on the new box.

I have removed both the L7 and the 7500. I have finally decided to leave the 7500 out completely.

1. Should I mount the L7 in the same fashion that the 7500 was? If you remember, it was mounted with the woofer exposed in the bulkhead under the drivers helm with a sealed box on the back side. Don't worry, the box will be ported.

That would work fine. You just want to use the old port out of the old box and install it in the new box, through the bulkhead.

2. What diameter port should I go with. I remember Phil stating the the length should be twice the diameter but I can't find anything about the diameter.

Use the old port, or one the same diameter and length. Just make sure the end inside the box is far enough away from any interior walls to prevent restriction. This usually means have at least a diamter's distance away from any wall.

3. After much research, I think the ZX1500.1 is the only amp that will push the L7 properly right?

You have dual 2-ohm woofer coils, so yes, that one is the logical choice, or a ZX850.2 if you want to use a class A/B amp...

5. One more. If I increase the size of the cutout in the bulkhead to 15 1/2" X 15 1/2" I can build a box that will be 2.27 cu ft. Internal dimensions of 20X14X14. Does anyone see a problem with cutting the bulkhead to increase the opening size?

There should be no problem with that.

6. I lied, one more. In another thread, someone stated that you must subtract the voicecoil/magnet assembly from the air volume equation. Is this correct?

To be totally correct yes, but that is really getting way too far into the nuts and bolts of it. You will not hear a difference between the two either way, so give the brain a rest... IF the old box worked great, the new one, with the same gross volume will have the same net volume.

[Dan and Christy]

If you go this route, i've got a low-profile grill to cover the existing sub hole, it's yours for the shipping only.

http://cgi.ebay.com/ws/eBayISAPI.dll...m=280274716628

You are the man I appreciate the offer but the hole is 13"X13" square. Thanks man.

[chpthril]

You are the man I appreciate the offer but the hole is 13"X13" square. Thanks man.

I thought the 12" MTX in the bulk-head was round?

[Dan and Christy]

I thought the 12" MTX in the bulk-head was round?

The MTX is round, you're right. They essentially enlarged the original hole to 13"X13" in order to put the box for/with the MTX there. I'll go snap some quick pics just for clarification.

[Dan and Christy]

Sorry it took so long. Here are some shots of the box from Saturday.

[chpthril]

^^^ Duh, I got ya now From your original pic of the MTX sub installed, I couldn't even tell that was an insert like that.

So, now that I finally got it, how far of from usable is that box? Are you going to have build a completely new box/insert for the L7? Will the carpeted baffle board atleast be reusable.

[philwsailz]

Dan-

That type of mounting is going to work real well for ya, but you will need the face of the enclosure to be lots larger if you are going to have the woofer AND THE PORT all on the face of the enclosure.

Another option will be to have the port exit the side of the box behind the toe wall and then curve around and exit in a smaller round hole next to the woofer. It is not as tough as what it might sound. If you are intrigued, I will elaborate. Real quickly and simply, it is the total length of the port that makes it work, and NONE of the port really needs to be inside the box.

[chpthril]

^^^ Is it a must to have the port exit the front (woofer side) of the box/enclosure, or just ideal for best performance?

[dogbert]

^^^ Is it a must to have the port exit the front (woofer side) of the box/enclosure, or just ideal for best performance?

I wouldn't think so. My Kliptsch sub on my home theater system is downward firing and is ported to the rear (more for aesthetics than anything else). I think you just need a port to allow the woofer to move back and forth without restriction.

[philwsailz]

^^^ Is it a must to have the port exit the front (woofer side) of the box/enclosure, or just ideal for best performance?

Not a must, but preferred. I detail why below.

I wouldn't think so. My Kliptsch sub on my home theater system is downward firing and is ported to the rear (more for aesthetics than anything else). I think you just need a port to allow the woofer to move back and forth without restriction.

nothing further than the truth. Ports are black magic to so many people, but they don't just let the air out.

Your Klipsch is just a vented enclosure with the port operating in the same listening environment as the woofer. The down-firing method position of the woofer provides its own benefits, but is un-tied to the port issue.

A ported box is louder due to the fact that the port is making sound, and the woofer is making sound, and the two of them together make more sound. They do this by operating IN-PHASE.

Air in the box is compressible, and acts like a spring. When we tune a ported box, we put a column of air in a port. That air, in conjunction with the air in the box acts like a weight on a spring. We adjust the port, and or the air in the box so they behave largely in-phase with the woofer over its usable bandwidth; we tune the box to RESONATE a certain way. The woofer excites the air-spring, and compresses it.

The air moving out of the port moves out at the same time the woofer moves out, and moves in at the same time the woofer is moving in . That is a basic description of an in-phase condition, and explains how the sound of both the port and the woofer add together to create a higher acoustic volume.


Consider this: At usable frequencies, when the woofer cone is moving backwards into the box, the air in the port is moving backwards as well. As a result, in that very instant, the woofer enclosure is seeing a higher internal pressure than if the woofer were mounted in the same sized sealed box!

If you ever have an opportunity, connect a tone generator to your sub amplifier and vented subwoofer enclosure. You will find that the point where it is operating at its very loudest is the point where there is tons of air moving in and out of the port, and the woofer cone is moving very little. That point is the enclosure system resonance, where everything is really hooked up and hammering. It is real loud, yet the woofer is hardly moving due to the high internal pressure I mentioned just above.


I think you want the port exiting by the woofer into the listening area.

Here is why:
IF you put the port on another wall, inside the storage area for example, you are actually creating a weird dual resonant multi-chamber subwoofer enclosure. The woofer is mounted in the wood enclosure you are getting ready to build, and it is connected to the larger lossy enclosure by a tube or port. The larger losssy enclosure is the storage area.
The port in that situation is no longer terminated into the same acoustic space as the woofer is; it will behave differently. The results are unpredictable, but will probably result in situation where you are getting less volume output from the system.

I am trying to get my brain around it, and do not know for sure what will happen, but I think you will be happier trying to find a way to get the port to vent out by the woofer, into your listening area.

[Dan and Christy]

[QUOTE=chpthril;227720So, now that I finally got it, how far of from usable is that box? Are you going to have build a completely new box/insert for the L7? Will the carpeted baffle board atleast be reusable.[/QUOTE]

That box, very unfortunately, is only 1.35 cu ft. I was hoping to reuse it but based on the conversations here and some research, that is nowhere near enough volume. I would like to keep the L7 box in the same location, so I will be doing some cutting of the wall there.

Thanks to the port discussion, I will try to creat a large enough box to handle the port on the same face as the sub.