The Tower Sub, my latest design

department76

so i've had this 8" Dayton Reference HF sub sitting around for about two years collecting dust, since i didn't use it in my car and got an 8W7 instead.

i've finally conecptualized something that i want to do with it! i'm going to put together a floor-standing sub that will have maximal LF frequency extension and a TINY footprint for it's output capability. down-firing fits the design goals well and since it's only an 8" driver that will work perfect.

sub & amp (total project cost, hopefully under $300):
http://www.parts-express.com/pe/show...number=300-805
http://www.parts-express.com/pe/show...number=295-456


here's the plans:




since the sub's sealed and the towers are vented, they'll need to be crossed at the same point. i may try going without the HPF on my towers if i can get good enough of a calibration with the amp's phase control, since my towers are huge and do already have amazing bass.

department76

found a mistake in that first SPL plot, i had typed a value in wrong and that wouldn't have been stable/realistic. i've since added the idea of doing a vented design.

here's the new sealed (yellow) vs. vented:



two possible variations of the vented design, undecided on which bu i'm really liking the idea of the tower still:

furball zen

Why vent then? Sealed has much more 'longitude' in that the bass travels farther. Venting gives you the 'closeness' but lacks real depth IMO. Since youre already firing it at the floor, itll really pound in a sealed. Most people dont know to place a sub firing at a solid object amplifies the low end, and the thump you want.

Or, you could go bandpass...

department76

leaning towards the vented at the moment due to a lower f3 and it's got 3.5db on the sealed, as usual.

UNLIKELY1

I like the vented as well. How big is your room?
Like'n that second tower design D!!

department76

OK here's an update. the following is the final box design, and unlikely1 is building it for me!



SPL & excursion w/ 240W & 60Hz LPF:

furball zen

Here, check out :25. Its a 50 kHz blast. I was in the bathroom at an SPL contest when they were testing a Fox body Stang with a single 15" in a totally enclosed box where the speaker was buried in it and only the cone was exposed through a tuned port to emphasize that freq. Thought the building was coming down....

http://bot-racing.com/xoxupload/15%2...%20Toccata.mp3

department76

lol just saw the room size question. the room is about 11x14, so not very big.

UNLIKELY1

Here's some pics of what I have done so far.
D76 and I figure there is at least a few people here at
XFN that would be interested in seeing a little woodworking going on.
This is a great down firing sloted port design that D drew up. Its not huge and has a
small foot print. I am thinking of building one like it for my daughters system.

This design use's about 1/3 of a 4'x8' sheet of 3/4" MDF.


we where worried about making the top strong enough in case
somebody picked it up by its vent. We figured a few screws and glue
would be enough, but decided to take it a little farther and do some
Dado style joint's. not only on the top but on all the internal port
panels as well. This adds alot of overall strength cutting down on vibration.

I could have done this on the tablesaw with a dado blade but since we
are rounding of the edges of the baffle panels, a router with a 3/4" straight bit seemed to be the way to go.
The bit is set at a 1/4" depth. and I am using
a base plate with a flat edge on it. The measurement from that edge to the blade is 2 1/2".
This is important for cutting the dados acurately.



I layed out the cuts on the side panels first. These are just rough guide lines.


I made a jig by rip cutting a peice of MDF at 2 1/2" (the distance of the base edge to the blade on the router from above).
I then used my square set at the distance of the panels edge to the bottom edge of the first port panel. ( coincidentally also 2 1/2").


then ran another straight edge behind my jig. This will be my guide for the router.


Clamped everything down. Double checked using the jig to make sure nothing moved.


Then removed the jig and made my cuts using the second peice of MDF as my straight edge/guide.


Repeated this process for all the cuts on all panels (sides,front,back).
For the top I used a 3/8" bit set at 1/4" depth of cut (same as above).And used the same straight edge as above.
I didnt bother cutting another jig because it was only going to be 2 cuts. instead I just mesured the distance of
the routers base edge to the blade on the bit. set my square at that distance pluss 3/8" and cut.


For the top peice itself I used a rabbeting bit with a 3/4" bearing. This gave
me a 1/4" wide cut (the depth of all the dados cuts). and the depth is set to 3/8" (half the thickness of 3/4 and the size of my set back from the edge shown above).




her are a few pics taken before I cut the joints for the top.






Holes from dados will be plugged.





Next I will be adding gussets in some places to add more strength.
Glueing and clamping.
And then I will start on the base.

department76

brilliant on so many levels. gotta love watching a pro at work

furball zen

Huh huhuhhuhuh. He said wood. Huhuhhhuhuh.

Very niiiiiiiiiiiiiiice ;)

department76

here's the exact up to date plans, including the dados and gussets. lost an inch in the port length due to the rounding, but that is negligable

UNLIKELY1

HHMMM Yea I didnt think about that. Is it the loss of length or is the lower overall port volume what we should be concerned with. I think the performance gain, i.e better directional, less turbulant flow of air (also probably negligable) with the rounded gussets will help offset any size loss. None the less something to be aware of.
What I was thinking when I came up with the rounded gussets, was trying to keep it exactly 1" threwout the length of the port. It didnt even occur to me that we may be messing with the tunning. It is something that you probably cant model for either.

department76

oh ya it's no biggie, in fact i think the reduced possibility of chuffing from the smooth airflow will be a bigger benefit. the actual tuning numbers shifted from 30.8Hz to 31.5Hz, which is not a problem at all . in fact, hardly noticable on the SPL plot

"volume" of the vent itself is in fact negligible in terms of performance, it's cross-sectional area and length that matter most. the little air pockets in those corners were in fact wasted space, anyways.

UNLIKELY1

PHEW!! good to know. thank you.

Zenshi

Wow this looks awesome! It probably will shake the walls down.

I am going to keep watching this build.

UNLIKELY1

Ok so here are some updates. Its been a busy week at work so I havnt done a whole lot.
Focusing on the base, here is how i am mounting the feet. Department has decided to use these feet from Parts express and Dayton audio

http://www.parts-express.com/pe/show...number=240-718

Just so happens that I had a pair of chrome ones waiting for a future project of my own. This made life alot easier.

The baffle/base is made out of 2 layers of 3/4"mdf. So in order to conceal the mounting hardware I first installed the "T" nuts in the bottom most layer before laminating the 2 peices togrther. first I drilled the holes for the threaded inserts using a standard 9/32" bit then I used a forstner bit on the drill press to give a recess for the nuts.



Then pressed the T nuts in useing the supplied bolt and washer.



Then off to "The Rack" for glue and some clamp time.



here is what it looked like after lamination.



Next up I cut the hole for the woofer. Using a crappy tool that is effective but not very fancy, I was able to cut through one side...





Then I flipped it and cut threw the other side..





Lined up pretty good if I say so myself.



Good Gawd who gave this man power tools???


And he's breeding..


Next up I will recess the woofer using a rabbeting bit on the router and the baffle will be done.
I am going to do that today so I will have more pics this evening.

furball zen

I love my ACC, one of the best <$20 tool purchases ever :)

UNLIKELY1

Ok I know I should Know what your talking about but Iv had a few already.
Whats ACC?

furball zen

Adjustable circle cutter... ;)