Home Theater Forum and Systems banner

1 - 20 of 67 Posts

·
Registered
Joined
·
88 Posts
Discussion Starter #1 (Edited)
Note: Final enclosure changed to 358L at 15Hz - Images below have been updated to reflect changes, except the Sketchup images. Same overall design.


The purpose/goal for this build is 1) the need for some strong bass in a subwoofer deprived HT setup and 2) a huge learning experience. Hopefully by the end of this I will be able to understand half of these threads. Please feel free to offer an input or point out where I completely off base. So here we go.

Based on a preliminary budget of ~$600 for amp and a preferred 18” driver and really no space limitation, I decided on the Mach 5 IXL 18.2.2 powered by the ep2500. It helped in my selection that people have been very pleased with the results of there IXL 18 builds. Both items have been purchased and the ep2500 has arrived while the IXL 18 should arrive this week.


So I downloaded WinISD, and with the help and suggestions of Mike P, I came to a target enclosure of 350L tuned to 15hz using a port that is 8“x42“. Hear are the graphs.





So with guidelines of 350L and 15hz, I sat down and utilizing excel and the enclosure calculator came up with the following design. I also started messing around with Google SketchUp and came up with the drawing of the box. Man all these new tools are fun to play with. I would greatly appreciate it if someone could please verify that my volume calculations are correct? The box will be finished in the color choice decided by my wife.







The actual building of the enclosure will not be able to take place until at least mid February. I have some commitments that stand in my way between now and then. So at least I have time to make sure that I will have all materials needed to get this completed as quick as possible.

I do have a few more questions.

1. Should I be adding fill to the sub?

2. My plan is the following setup: Receiver => EP2500 => Sub. Is this all I need? Or, do I need to add any subsonic / high pass filters or EQ?

3. What kind of cable do I need for connecting the receiver to the amp?

4. I’m assuming speaker wires are just used to connect the amp to the driver. Correct? What is the best gauge to use? The run for the speaker wire will be about 20ft.

I’ll wait until the enclosure is complete before I start asking how to wire everything up.

Please let me know if I’m missing something.

Thanks for looking!

John
 

·
Premium Member
Joined
·
19,397 Posts
Your numbers are spot on, right down to the cubic inch. Your drawings are excellent, well done! With the EP2500 you have enough power for 2 subs. Maybe build #2 in the future? :bigsmile:

Should I be adding fill to the sub?
No fill is required, but it won't hurt to line the outside walls with egg crate foam. It's a controversial subject, but lots of people do it. I do it to all of my subs.

My plan is the following setup: Receiver => EP2500 => Sub. Is this all I need? Or, do I need to add any subsonic / high pass filters or EQ?
Try the setup and see how it works. If the receiver voltage is too low for the EP2500 then you'll have to boost it. If the sub bottoms out when pushed hard then you'll need a high pass filter. No sense buying anything until you know you need it.

I’m assuming speaker wires are just used to connect the amp to the driver. Correct?
Yes.
What is the best gauge to use? The run for the speaker wire will be about 20ft.
I have 20 ft. and longer runs and I use 10 gauge wire.
What kind of cable do I need for connecting the receiver to the amp?
I'm not familiar with the EP2500. Someone else will have to chime in here.
 

·
Banned
Joined
·
22,577 Posts
3. What kind of cable do I need for connecting the receiver to the amp?
Assuming your receiver does not have balanced outputs, you will need either a RCA to XLR or RCA to 1/4" (TR). The EP2500 will accept either the XLR or the TR. You can also use a standard RCA cable and use a 1/4" adapter on the EP2500 end.
 

·
Registered
Joined
·
88 Posts
Discussion Starter #4
Your numbers are spot on, right down to the cubic inch. Your drawings are excellent, well done!:
Thanks Mike. I greatly appreciate your help on getting me to this point.

With the EP2500 you have enough power for 2 subs. Maybe build #2 in the future? :bigsmile:
That is the plan. Will just have to convience the wife. She is not thrilled about the size of this sub. I think she may change her mind after she hears this.

John
 

·
Registered
Joined
·
88 Posts
Discussion Starter #5
Assuming your receiver does not have balanced outputs, you will need either a RCA to XLR or RCA to 1/4" (TR). The EP2500 will accept either the XLR or the TR. You can also use a standard RCA cable and use a 1/4" adapter on the EP2500 end.

Great. Thanks Sonnie!
 

·
Registered
Joined
·
88 Posts
Discussion Starter #6 (Edited)
Quick update. The driver arrived last night from Mach 5 Audio.:yay2: Seems to have made the trip without any problem. I will get a pic posted for proof tonight. The driver is huge, a lot bigger than I imagined. Next weekend I will pick up the materials and start building the cabinet. One step closer to the finish line.

Edited for pic of driver.

 

·
Registered
Joined
·
2,398 Posts
The internal port opening is too close to inner walls for optimal performance. Maintain a clearance of at least port diameter in all directions to ensure turbulent free air flow. If you're willing to accept that, then everything else looks ok.
 

·
Registered
Joined
·
88 Posts
Discussion Starter #8 (Edited)
Steve - thanks for the feedback. I'm guessing you are referring to the location of the internal port opening to the wall opposite of the driver and the end of the box. Will this cause a significant problem? I'm not sure what I would be accepting. I have been looking to see how to change the box but have not been able to come up with a way to keep the 8" port at ~41" to get the 15hz tuning. Any suggestions would be greatly appreciated.
 

·
Banned
Joined
·
22,577 Posts
You could go with a 6" port 23" long for flexibility if that will help with changing the design... provided you use a 10Hz HPF to curb the air port velocity.

It looks like to me that you could even go with a 4" port 9.25" long and air port velocity is still safe and only peaking at 35 m/s ... and that at 1700 watts input... provided you use a 10Hz HPF, which you may need if you plan to really crank this sub.
 

·
Banned
Joined
·
22,577 Posts
That was the stealth version.... :huh:

Strike that last option. I had two WinISD screens open and must have been looking at something else... or misread something somewhere.

The first one is still an option though.
 

·
Registered
Joined
·
88 Posts
Discussion Starter #12 (Edited)
It looks like my best bet is to go with 3 4" ports that are ~33" long. Below is the WinISD graphs of the air velocity of various port setups. SPL and cone excursions are all pretty close. All are at 350L, 15Hz with power of 800 watts.

Blue - 8" port x 40" long - no filter (current design)
Green - 6" port x 23" long with 10Hz HPF
Grey - 3 4" ports x 33" long - no filter
Yellow - 3 4" ports x 33" long with 10Hz HPF



If I go with the 3 4" ports x 33"long will I need to use the HPF? or a better question is, how do you know when a HPF is required?

What would you go with?

I can start the redesign of the enclosure once these ports are worked out.

Thanks
 

·
Premium Member
Joined
·
19,397 Posts
With a 8 inch port maximum air speed is under 25 m/s at 13.5 hz, and lets face it, how many times is that going to happen, especially with 800 watts input, the maximum the sub can handle. At 18 hz the air speed is 15 m/s, turbulence is a non issue. Ideally the port should be one diameter away from the side walls, but less will work, as in this case. I would have no problem building this sub as shown in the plans.
 

·
Banned
Joined
·
22,577 Posts
800 watts is conservative with the EP2500, so you do need to be careful, but you will know if you are pushing it too hard.

HPF is mainly for the person like me, who really likes to push things to the limit. A HPF can also allow you to push your subs to their limit.

Mike... I am showing 1000 watts power rating for this driver... did I download a bad file?


If you manage 1000 watts of power, which is very possible since it is only about 118db, then you would very likely stand to damage this driver is you were watching something like WOTW with super low bass. Why? Because the excursion limits are exceeded at 22Hz and greatly exceeded at 13Hz and below. However, with a HPF set to 13Hz (Reckhorn B1) you will stop the excursion at it limits and be able to achieve the loudest SPL possible, which may ultimately be more with room gain. This is not beyond something you would do on occasion, I don't think.

I have modeled this again and I come up with you being able to use only two 4" ports at 21.3" long... with the 13Hz HPF, you reach excursions limits with 1000 watts power. Air port velocity is 32 m/s at 15Hz, which is acceptable. Make sure you flare the ports... actually I believe Kevin Haskins with Exodus Audio offers 4" flared ports that will work well for you.

Maybe I don't have my wires crossed this time.
 

·
Registered
Joined
·
2,398 Posts
I'd definitely stick with the 8" diameter port. Can you not just add a couple more inches of depth and a couple more inches of length? Not only will that allow you to have a diameter's worth of clearance, but the slightly larger enclosure will also allow you to use a slightly shorter port while achieveing the same tune, so it's a win win.
 

·
Registered
Joined
·
88 Posts
Discussion Starter #18
Thanks to all.

Is there any guidance or restrictions on how far an object (port, wall, or brace) should be from the back of the driver magnet? I could add a few inches to the depth of the enclosure and shift the port closer towards the driver. If the driver is flush mounted it will go about 9" deep into the enclosure. Moving the center brace 2" towards the driver wall will give a clearance of 1/8" between the back of the driver and the brace.
 

·
Registered
Joined
·
88 Posts
Discussion Starter #20
That would be fine. My IXL-18's butt up tight against a brace with no problems.
Excellent. At least something does not have any specific requirements.

Well, I'm finally back in town and able to starting working on this again. Unfortunately wife is not thrilled about the size of this beast as is and has killed the idea of increasing the size, even by a few inches. So I have decided to move the center brace and port towards the driver. This will give just over 4" between the back wall and port. Will have to do. The port will also stick out of the end of the cabinet by 1.5". This accomplishes two things 1) over 8" of clearance with the end wall and 2) I can make grill, modeled after Mike P's grill for his IXL 18, to keep the kids toys and cat out. If I have problems with turbulence it will just give me reason, which she will not be able to say no, to make a bigger cabinet. I will update the plans and post as soon as I get a chance.

This weekend there will be a trip to Lowes for materials. :bigsmile:
 
1 - 20 of 67 Posts
Top