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Hey! it looks just like Mickey! ;) Looks the beginning of a sturdy box Jim. This is exciting.
 

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Discussion Starter #3
It's definitely going to be over-built (1.5" on every panel). It's not needed, but I'd hate to be in the middle of WOW and hear a buzzing panel. :) I want it to be as heavy as possible too since the driver will be located a little higher that normal in the enclosure.

I just made the cutout on the 1st front panel. I'm done for the night. I need to buy my fill and a few other things tomorrow. I'll do all of the internal stuff tomorrow night and button it up. Well, that's the plan anyway.

Oh, I forgot to mention, I didn't make any of the panels using the table saw in the pic. I'll post a few pics of how I did it later. :scratchchin:

Off to the shower to get rid of all of this MDF ...
 

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Uh.... can you run over to my house and help me with my manifold for my 4 RL-p15's...??? I think I'm gonna end up having to take it up in the attic in pieces and then glue and screw it together. Too hot up there for one person and you have been selected to help ... I'll fan while you put it together. Deal?
 

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Discussion Starter #5
Ouch. That's definitely a night job. The cool thing about IB is, it doesn't have to be pretty. Then again, we're all overachievers here. We tend to over do absolutely everything. :)

My quickie sealed box is a temp fix for LFE until I can talk myself into ordering 3 more for IB. I can't wait. :jump:
 

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Jim, why start a thread about your temp fix for LFE:neener: j/k

How big is your listening room again?
 

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Discussion Starter #10
All that work today and you only mention my clamps. lol

Thanks. They are Rockler pipe clamps with their optional zinc coated pipes. I also just bought their new levers that make it easier to release the clamps. Of course, I haven't installed them yet. :)

As a general rule I don't like Rockler, but I seem to have quite a bit of their products.
 

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Discussion Starter #11
I couldn't sleep so I thought I'd post some pics. Like I said before, my table saw sat this one out. Ok, I used it for glue ups. :) I used a guided saw system from Eurekazone.com called the SmartGuide. I use a Porter Cable 325MAG with a Freud Diablo 40 tooth blade along with the guide to get great cuts even with Oak Plywood. Zero splintering on either side of the cut.

The adjustable table can hold LOTS of weight.


Ever try wrestling a 90+lb. sheet of MDF over a table saw? Leave the wood in one place and run the saw over it. It's safer.


Ripping a 4'x8' sheet of MDF takes just seconds and it's dead on accurate.


For crosscuts I use just one section of the guide


The white plastic edge of the guide is the finish cut line. Make a mark at each end of your piece and lay the guide on them. The saw does the rest.


If I didn't have to watch the kids while my wife was gone, I could have done all of these cuts in just a few minutes.


One part of the front baffle, the back and bottom get glued up.
 

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FlashJim said:
All that work today and you only mention my clamps. lol

Thanks. They are Rockler pipe clamps with their optional zinc coated pipes. I also just bought their new levers that make it easier to release the clamps. Of course, I haven't installed them yet. :)

As a general rule I don't like Rockler, but I seem to have quite a bit of their products.
Yes, that was supposed to make you laugh lol :R
 

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You got a nice setup there with the tools, etc., Jim... looks like you made it easy. Never seen a table like that before. I like those clamps myself too.

Oh... was this thread about a sub or something... lol. Nice work on the sub thus far. :T
 

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Discussion Starter #15
Thanks! The table is pretty cool. It's 2'x4' but can support sheet goods up to 5'x10'. The supports slide to where you need them. They are also wood so you can cut right through them and not worry about it. You just replace the wood section as needed.

The sub box has officially gotten heavy. It's a PITA to move around by myself now. I'm hurtin' today. :)

I decided to wait until it's completely finished before I fire it up. I wish I had this much self control in every aspect of life. :D
 
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From the looks of it the box is overdamped. So you might want to back off a little with regard to the amount of glass.
 

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Discussion Starter #17
Hey Thomas!

It's just laid in there at the moment. I wanted to cut it to fit before I glued the side on. I can pull it out when I cut the driver hole in the baffle. I haven't weighed any of it yet either. With fiberglass is it still the standard 1lb or so per CF to start and tweak from there?
 
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0.5-1.5 lbs/cu ft.

I start with light fill and add to taste. If you're using T-nuts or clamps so it's quick to remove the woofer you can fine tune it. Add 1/4-1/2lb at a time. Each time the added amount should tighten and define, at a certain point the only effect will be a decrease in overall output. At that point remove the last amount added.

This can also be done with test equipment, here's info posted on the old 'Bass-list' from no less then Ken Kantor.. (note he likes poly I think glass is best)

From: Ken Kantor
Date: 04 Apr 95 03:41:37 EDT
Subject: Stuffing Stuff

"In light of recent discussions, let me share some thoughts regarding cabinet stuffing. I'll do this from a practical point of view, partly because the physics side has been well articulated by Doug. The other reason I'll stay away from theory in that, in the matter of cabinet fill, theory has proven over the years to be of only limited help in real-world speaker design. I'll also confine most of my comments to issues related to sealed systems. Vented systems do share a
few of these same issues, but really the goals and the physics of stuffing a vented box are different.

Most professional designers would agree that practical experience, combined with trial and error, is best way to find the optimum stuffing material, quantity and method for a given design.
This is why good designers routinely experiment with fill in the development of a new system, ala Vance's data cited here. This particular information is a valid data point, but it is important
not to over-generalize. If you are designing a system that differs substantially in shape or volume or source impedance (passive crossover) from a known you will need to iterate for best
performance.

In my practice, adjusting the filling is the last step in getting the bass right, and is used mostly to fine-tune the system Qtc and resonance. As increasing amounts of polyester are added to a
sealed box, the resonance and Q gradually go down. This can be shown mathematically to be due in roughly equal parts to the effects of simple resistive damping and isothermal conversion. At some point, a minimum is reached, and further material simply reverses the trend by taking up volume. During the filling process the impedance curve is constantly monitored, and
convergence to optimum usually takes only a short time. Filling also has the important effect of reducing internal reflections, to reduce standing waves and comb filtering. However, the amount of filling has comparatively little effect on its efficacy in this regard.

[Side Note- it is a common misconception, I believe, that professional designers rely heavily on LEAP and SPICE and CALSOD to define their designs a priori. On the contrary, professional designers use these modeling tools mostly to guide and optimize revisions. Unlike DIY designs, a typical commercial 2-way will go through perhaps 3 revs of each driver, 2 to 4 box trials, and easily a dozen+ crossover changes.]

Lining the walls of a vented enclosure to reduce internal reflections, or filling a transmission line to absorb the back wave, highly absorptive wool or fiberglass are ideal. However, these materials will not generally provide the desired results in a sealed system. It is true that they will provide more reflection absorption than polyester, but the later is quite good in this regard in the critical midrange. In a sealed system you don't want absorption at lower frequencies anyway; you want damping and isothermal conversion. I have tried "all-out" efforts using fiberglass lining and
polyester fill to achieve the best of both worlds. I found the results to offer little practical benefit over polyester alone, but its worth looking into.

All NHT systems now use polyester fill, of one variety or another. We used to use fiberglass in our vented designs, but found a Danish polyester that mimicked the properties of
fiberglass very closely. I don't know if this kind of polyester is available to hobbyists. Excluding this special poly, there are essentially two kinds of fiber available: pillow stuffing,
and audio-spec polyester. The later type allegedly has hollow core fibers, but I have been unable to verify this with my keen eyesight! Sorry, but forget the pillow type. Sure, it's easy
to get. If you use enough, it will damp the midrange, and that's better than an empty box (by a lot). But it will have little effect on the lower frequencies.

Well, that's pretty much all I know about stuffing speakers."

_________________________________________

In another message Ken Kantor added (excerpted):
"Exact enclosure volume is not critical, and stuffing can be added or subtracted to fine tune the response. I recommend adjusting the stuffing by monitoring the impedance versus frequency of the sealed box system. Add stuffing to lower the frequency where the impedance is highest. When that impedance peak starts to rise in frequency, you have added too much. The NHT/SW3p uses 820g of acoustic polyester stuffing with the 1259, but your enclosure may do better with slightly different amount."
 
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