Got 18" for free, looking for enclosure ideas for HT?

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6L6

6L6

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Stuff the port tight in your existing box with old (clean) socks or something similar.

Listen. You will loose a bit of efficiency, but if you are planning on a big amp, who cares.

I would also suggest using some sort of active Bass EQ. Again, if using a big amp you will be able to get the response you want with a reasonable sized box.
 
6L6

6L6

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woody said:
Back to your sealed box idea. I think I read an old article in The Absolute Sound
saying that a sealed box with FS of 30 hz and a QTS of .707 realy was flat to about 16hz after room gain kicked in.
Click to expand...

Yes, exactly!

Stuff the port in your current box - it's going to be awfully close, or at least tunable depending on how much port stuffing you use. (You are changing the box from a ported to aperiodic.)
 
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Scott L

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20 cubic feet

weltersys said:
Jamie,

Sounds like it could be correct, and it probably will hit the excursion limits with a lot less than full power in that large of a box.

I'd try a tapped horn like the Gjallerhorn if considering a 4 x 4 x 3 foot box.
That would give a lot more "wow".

Series voice coils are not a problem as long as the polarity is correct.
Click to expand...

I did series voice coils for over 15 years and never had a problem. OTHERS would frown upon that fact.
The 20 cubic foot volume for vented is correct as mentioned earlier in the thread.
Ideally, an infinite baffle type of volume would be preferred, if you could:
1) find a closet with 40 cubic foot availble to partition, and VENT
2) you can afford another driver. (if so, study manifold mounting)

** 20 cubic foot is really not that big, if you make it a phone booth style.
*** I had a pair of 17.5 cubic foot jobs along with a happy marriage for years
and years.
 
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toysareforboys

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Joined 2013
woody said:
Back to your sealed box idea. I think I read an old article in The Absolute Sound
saying that a sealed box with FS of 30 hz and a QTS of .707 realy was flat to about 16hz after room gain kicked in.
Click to expand...
Yeah, looks like sealed is the way to go, especially with the box size for some gain down low with ported :(

6L6 said:
Stuff the port in your current box - it's going to be awfully close, or at least tunable depending on how much port stuffing you use. (You are changing the box from a ported to aperiodic.)
Click to expand...
There is no "current" box. I'll have to build it (if it's sealed), or have it built for me (if it's ported or more exotic).

-Jamie M.
 
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bjorno

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turbodawg

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Joined 2004
toysareforboys said:
I received this 18" subwoofer for free:

An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.


It's a dual 2 ohm car sub, so possibly not the best for HT :(

Specs are:
3" voicecoil
Fs : 20.5 Hz
Qes : 0.57
Qms : 5.61
Qts : 0.52
Le : 5.92 mH
Sd : 1140 cm^2
Vas : 237 L
BL : 24.79 NA
Mms : 470 g
Cms : 128 uM/N
Sens : 87.22 dB 1w/1m
Wattage: 1250w RMS

Linear x-max is around ~30mm one-way by 70% BL with a total mechanical clearance of 50mm in the motor. Should move some air :)

I was going to power it with an EP2000 (1300rms at 4ohms bridged) unless you think there's a more appropriate weapon.

I'm currently running a no-name 12" ported sub/box on 350rms, doesn't get as low as I'd like.

Was thinking with the 18" to tune it very low, like 20hz, mostly for LFE for movies (not much music played on this system).

Let me know what you think or if this is a waste of time. If this wasn't going to work out I was going to build a 2 x 12" Infinity 1262w ported box.

-Jamie M.
Click to expand...

Sounds like a great project.

If you don't have an amp yet, I would suggest a behringer nu3000dsp, it will bridge well into 4 ohms and have onboard dsp. Will do about 1500w into 5 ohms.

The response curve in your 40+ cubic foot model indicates that you're using a relatively high tuning for the box volume, you could go with a lower tuning, or more realisticly, a smaller box in the 10 to 20 cubic foot range. Try running more sims while keeping an eye on excursion vs. xmax vs. power.

I would not attempt to build a tapped horn with this sub.
 
jneutron

jneutron

Member
Joined 2004
Scott L said:
One issue no one has brought up yet, is how to handle those 2 each@
2 ohm voice coils (?)

One option is to series them for a more stable 4 ohm load, but the series thing is often frowned upon.
Click to expand...
When it's the same vc, I don't think it's a problem.

Independent drivers in series in the same box will have a problem, the cones tend to walk opposite when played.

jn
 
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