NatalieP

[wrz0170]

Hey everyone,

I am most likely going to tackle this project, I didn't want to hijack the other thread on the Modula MTM NatPs.

Anyway, from reading the other thread, you could do a bookshelf or tower version of the Modula MTM.

Would someone be willing to provide me with cabinet dimensions of the tower version?

Thanks! I may use this thread for my own Q&A as I start this project.

Thanks!

William

[GMorris]

I was thinking about making a trapezoidal shaped cabinet to help with internal standing waves (I'm not sure if this will actually make a huge difference but it did give me the required height to have the tweeter at ear level and it gave the box a bit more depth which I think is more aesthetically pleasing if nothing else).

Using these software tools:

http://grapevine.abe.msstate.edu/~fto/tools/vol/trapezoid.html

http://joshmadison.net/software/convert/

I came up with these dimensions based on 3/4" mdf:
front external width: 9"
back external width: 7"
height: 47"
internal depth: 11"

This would give a volume of 53.3 liters which should give around the required 50 liter volume once bracing and driver volume etc is accounted for.

[wrz0170]

I was thinking about making a trapezoidal shaped cabinet to help with internal standing waves (I'm not sure if this will actually make a huge difference but it did give me the required height to have the tweeter at ear level and it gave the box a bit more depth which I think is more aesthetically pleasing if nothing else).

Using these software tools:

http://grapevine.abe.msstate.edu/~fto/tools/vol/trapezoid.html

http://joshmadison.net/software/convert/

I came up with these dimensions based on 3/4" mdf:
front external width: 9"
back external width: 7"
height: 47"
internal depth: 11"

This would give a volume of 53.3 liters which should give around the required 50 liter volume once bracing and driver volume etc is accounted for.

Thanks. do you think bracing will be simliar to the smaller PE cabinet? I may order the drivers this weekend to get started. I have three days off next week and my table saw needs some exercise.

[GMorris]

I was thinking about bracing more like the way shown in post #26 on this thread:

http://www.htguide.com/forum/showthread.php4?t=3430

[GMorris]

I was also planning on using this 4" flared port, extended to the proper length to give correct port volume, but I'm not sure if there is a downside or not.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-403

[ThomasW]

I was also planning on using this 4" flared port, extended to the proper length to give correct port volume, but I'm not sure if there is a downside or not

There's no up side to it since these little midwoofers don't move enough air to justify using a 4" port.

[GMorris]

The 4" port would have to be around 6.18" long and I just found some other cheap flared ports I didn't realize P'express carried including this 3.75":

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-480

A 3.75" diameter port would need to right at 7" long for equivalent volume so this one actually seems better suited.
Both would fit cabinet facing front or rear without any problems.

[ThomasW]

Those aren't what you want. These are what you should use PE P/N 268-350

[wrz0170]

Newbie question: Is the entire tower cabinet utilized? Meaning no "dead" space per se? I hope that made sense.

Would the tower design require any stuffing? The driver portion or entire cabinet?

Thanks!

[Evil Twin]

The entire tower cabinet is utilized. While a rearward firing port could be used, downward firing is recommended.

The cabinet is usually lined with an acoustical deadener, a combination of acoustical foam and weighted vinyl (see the Modula MTM thread), and light stuffing (dacron polyester(cheapest, good midrange absorbion), long fiber wool (most expensive, very good wideband absorbtion), or fiiberglas (more bass absorbtion) used behind the midwoofers.

[wrz0170]

The entire tower cabinet is utilized. While a rearward firing port could be used, downward firing is recommended.

The cabinet is usually lined with an acoustical deadener, a combination of acoustical foam and weighted vinyl (see the Modula MTM thread), and light stuffing (dacron polyester(cheapest, good midrange absorbion), long fiber wool (most expensive, very good wideband absorbtion), or fiiberglas (more bass absorbtion) used behind the midwoofers.

Thanks! Since it may be awhile to get the RS180 (back ordered until March :E ) I guess I have a lot of time to plan...

Two questions come to mind.

I do have a sub, would I want to have it sealed or do I want to still port it?

Secondly, you suggested downfire port is the way to go. Would that mean I should have the base of the cabinet raised a bit so the air has somewhere to go?

Sorry if they are newb questions, trying to learn

[ThomasW]

If they're always going to be used with a sub then sealed is fine.

Yes a downward firing port means you need to have a space at the bottom. If you look at the NatalieP picture gallery at the end of the very first post in the long NP thread, you'll see a bottom ported design

[wrz0170]

Hey everyone,

Well, I bought the MDF and I am ready to start cutting. In the tradition of measure twice, cut once, I wanted to run the numbers by one more time.

The NatPs will be in a corner, maybe about 6" +- from the wall and I will be using a sub with them. I'm not much of a "2 speaker" person. Usually when I listen to movies or music, I just let all 5.1 fire away.

I am looking at a sealed tower enclosure clocking in @ 48"x11d"x9"w. However, the drivers sealed in a 1.0cubic foot area with the rest of the tower being just dead space, so to speak. Thanks Jim for helping me out in that area :T

Anything I should consider or do different? Or let the table saw start making noise? :B

Thanks!

William

[JustinSC]

Don't know what your MDF sheets come in factory but here they are 49"x97" might want to just increase the height to 49" to make one less cut to the MDF. Just makes things easier IMHO.

[wrz0170]

Don't know what your MDF sheets come in factory but here they are 49"x97" might want to just increase the height to 49" to make one less cut to the MDF. Just makes things easier IMHO.

I bought mine from the Borg (Big Orange Retail Giant). The panels I got are 2'x4'. All I have to do is rip :B

[wrz0170]

Alrighty. Well the panels have been cut . The parts for the XO should be here tomorrow. Down to one final item of buisness.

Since I am going with the 1cu ft design, not ported. What should I use to line the cabinet with? Accoustic foam? Egg crate stuff or other?

If I need to add some stuffing, my fiance` is a quilter , so I have that covered.

Maybe I will take some pics of the progress. Be kind of neat to document.

William

[ThomasW]

If she's a quilter she probably has bonded darcon batting (not loose fill), line the interior walls with a couple inches of that.

[wrz0170]

If she's a quilter she probably has bonded darcon batting (not loose fill), line the interior walls with a couple inches of that.

Thanks! I will ask her. Even if I had to buy some, probably a lot cheaper than "commercial".

[wrz0170]

Question on X-over

I just got the components for the x-over in. However, I think I made an error in the order. On the schematic, under C11, it calls for 1.200uF.

I ordered a 1.00 and a .10uF for a total of 1.1uF. Will this be close enough for government work or should I get one more .10uF Cap?

As always, thanks! :B

[wrz0170]

Update

Hey everyone!

I wanted to show some pics of the progess so far. In a small recap of the project:

I wanted a tower, it will be not ported (for now) as it will be working with a sub and

The contstruction is modular in nature. i.e., I used t-nuts to mount the drivers. If something ever happened like my 2 year old nephew decides that to use the cone as a pitching target, I can easily replace the driver without stripping the MDF.

Also, if I interpeted what I read correctly and wanted to go ported, I made the middle piece solid and the only thing that will hold it in place is silicone. All I have to do is open the back, slide it out and cut out the window hole for it. Cut a hole in the bottom for the correct sized port and it should be good to go. I will have clearance at the bottom as I will be adding spikes. I hope I am doing the above correctly.

Anyway, enjoy and I hope to have more pics to come.

Here are the pieces parts;



The front baffle with the cutout for the drivers



Here is the dry assembly before glue-up

Edit by moderator to change the link below since the picture is so big it throws the thread into widscreen mode

http://www.wrzonline.com/coppermine/albums/userpics/10001/Profile.jpg

The glue-up and the best I could do clamp wise.



And finally, the fun part, the crossover and it worked! I also made the crossover modular in that I can take things off as needed.



Thanks for looking!

[JonMarsh]

Looking pretty good so far! :T

[opt-e]

I am looking at a sealed tower enclosure clocking in @ 48"x11d"x9"w. However, the drivers sealed in a 1.0cubic foot area with the rest of the tower being just dead space, so to speak.

I am planning on doing something similiar: starting with a ported ~1.5cf enclosure with the option to seal.

My question is, what is the benefit of only utilizing 1.0cf of space when sealed as opposed to utilizing the entire 1.5cf? I modelled this up and using the entire volume results in a slower rolloff, which is a good thing, no?

[ThomasW]

I modelled this up and using the entire volume results in a slower rolloff, which is a good thing, no?

Yep that's what happens with a larger box. No problem at all, most are just after the smallest box possible.

[opt-e]

No problem at all, most are just after the smallest box possible.

That's what I thought, it didn't make sense to me why William decided to utilize only 1cf of space in his tower.