Isobaric - less then $20

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You willing to try something different for the new year? ;)
 

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NEO, that’s looks intriguing, and yes I would like to build something like that but just to stay on the isobaric topic; just a couple of thoughts and maybe a new build.

DH,

Had not thought about series vs. parallel (a question on the older modeling program) and that the outer driver will hit its excursion limits well before the inner driver.

Putting two driver’s clamshell in a tunnel, I will do that next!

The next build that I’m considering is clamshell (using the smaller woofers) in a keystone shape box, with the 10” PR mounted on the back.

I ran the idea in WinISD, and got a few ideas. I’m not sure what the max grams is for the PR. but a 1.5cf box with a 10” PR with 50 grams looks pretty level.

Q. what’s the max grams for a inexpensive PR?

Dayton Audio SD270-PR 10" Passive Radiator 295-494
 
But Dan....where's the bow?
Thanks Dan, I have no idea where you all come up with this stuff.
I will send you a 6 layer tunnel if you ever want to try the MCM Iso box, then all you’ll need is 2 pieces 17" x 19" (sides) and about 84” of 10" rips.

Thank you again for the design, this is for the 6 ½”, 299-114 woofer?

[This Iso box is not too bad, as long as it is not played too loud]
 
Your welcome Doug,
I figured I'd give you a taste of something different instead of whining. Although the 299-114 is not a strong driver this should be an interesting contrast in an A/B comparison. I would rate this as a ~30Hz box and it should be a good deal more efficient, no shark tale on this one though. :D
 

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Don, thanks for the advice

I went with #2 since the supply stores are closed today and I couldn't buy material.

It is about 2x as powerful (maybe more), hard to believe these are $8 woofers.

The crossover issue is gone, i.e. no more ringing.

This is not much of a box at this point, but there are no rattles. As far as weights I guess at 50grams (a USA quarter is 5.6grams) so I used 10 fender washers.

Okay, it won’t break glass, but somewhat amazing for what it is.

box size 8-7/8" (rips) x 17-1/2" x 12-7/8".
 

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@ODougbo, sorry for the delay in responce. Te vifa woofers are PO21W-20-8. I might have mied up a letter or two but youget the drift,also I have 4 jbl ME120HE 12" woffers I got at a surplus store very cheap. Three in the box one not. I think these were used in the S5500. I was thinking of playing aroun with a version of that speaker using a pair of altec 511 horns and drivers I have sitting around. We'll see. Interesting boxes here.
 
typo

oh I've been busy.....check em out.
A pair of Fostex 125wks - aprox $120.
New sub box - aprox $40.
The sound is very, very nice.

Now I do need to rebuild the test sub box shown, I was going to go with the keystone shape, PR in the back.

This design has a 1.75db rise at 34hz, according to computer modeling. Now if there was a fellow that was wizard in WinISD, I'd sure like to know if I should go with a slightly bigger box. (existing box 1.16cf, tuned at 33hz)

Dayton 10" PR (not on sale now)
FS 20Hz
Vas 3.88
Qms 2.50
Cms .67 mm/N
Rms 4.89 kg/s
Sd 340 sq. cm
xmax 10mm

 

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oh I've been busy.....check em out.
A pair of Fostex 125wks - aprox $120.
New sub box - aprox $40.
The sound is very, very nice.

Now I do need to rebuild the test sub box shown, I was going to go with the keystone shape, PR in the back.

This design has a 1.75db rise at 34hz, according to computer modeling. Now if there was a fellow that was wizard in WinISD, I'd sure like to know if I should go with a slightly bigger box. (existing box 1.16cf, tuned at 33hz)

Dayton 10" PR (not on sale now)
FS 20Hz
Vas 3.88
Qms 2.50
Cms .67 mm/N
Rms 4.89 kg/s
Sd 340 sq. cm
xmax 10mm

How sweet widdle baby onkens. :D

You really should learn Hornresp.
That's kind of the plan.
Those little drivers work well in a small TH.
Yesser fer $5 they sure do. It don't take 80l neither.:rolleyes:

rouges? Did you mean Redcoats? They were 17th century. Or did you mean ruddy complexioned rogues? :)
@ Rev
:fim:Grammar Girl
 
Oh Dough,
You are a Doug right?
The 8” speaker baffle board would have to be “behind” the 9” outside board.
Really? Whatever keeps the OCD twitch at bay man.:p

If you think about it the sides are braced every 3"-7", so 1/2" material is more than adequate IMO. You could always build in ply, but no need really. I'd save the good stuff for something down the line once you get a handle on what you want from a TH.

If you get your handle changed it should be Verdana:
HTML:
[FONT=Verdana]Dan, I thought I would build the TH project next; the illustration is a little off, I think.  [/FONT]
[FONT=Verdana] [/FONT]
[FONT=Verdana]The 8” speaker baffle board would have to be “behind” the 9” outside board.[/FONT]
[FONT=Verdana] [/FONT]
[FONT=Verdana]Also, was considering using ¾” mdf for the 20” x 24-3/4” sides. The 9” boards would be need to be ½” wider.[/FONT]
[FONT=Verdana] [/FONT]
[FONT=Verdana]Looks like fun, thanks.[/FONT]
 
Yes, Doug. Sorry about the code, some glitch in the compter :-/

Thanks for the reply.....I'm on it.
No problem, this post is fine:D

I Just bought 4 of these because of this thread, I would love to see someone design a TH for these, I saw the pictures posted of one using 2 of these, but maybe we can designate a thread for this on its own... The only TH I have built is JBells ss15, I have 4 of them, I would love to make some of these for smaller home parties.
1-40Hz dual driver TH at full output with these drivers is roughly what you get out of a SS15 with a few watts. Why not build the jbell bass sticks with the 55-2421 for a small rig?
 
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