2' x 2' x 4' TH sub feasibility? - diyAudio
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Old 27th October 2010, 04:25 AM   #1
aceinc is offline aceinc  United States
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Default 2' x 2' x 4' TH sub feasibility?

A challenge for those whose spatial imagination is better than mine.

I would like to build two tapped Horn subs with these approximate dimensions. This is for HT use. Would like < 20hz response with an 80hz xover. Cabinet impedance needs to be no less than 4 ohms. Will be driving them with an Emotiva XPA-2, one cabinet on each channel (300 WPC at 8 ohms, 500 WPC at 4 ohms).

My form factor criteria is that it needs to be more or less 2' square by 4' in the other dimension. If one were to cut a TH-Spud, and fold it in half that would be about the right size. The mouth should be near one of the ends on a long side.

The driver compliment is less important, I currently have 2 CSS Trio 8" drivers that performed well in my TH-Spud prototype. (BTW, that cabinet is free to a good home, pickup near Ft. Lauderdale Fl.) I also have 2 Titanic 10" drivers. I am willing to purchase additional or different drivers that would be < $400 per cabinet.

The main problem I see is folding the horn in 3D, as most builds I see are folded in one dimension only. If anyone has a successful HT - TH that could be refolded to meet these criteria, let's see what we can come up with.

At 364 liters the volume should be OK, I am having a hard time visualizing how the folding might work.

As always, smaller dimensions are acceptable.

Paul
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Old 27th October 2010, 05:09 AM   #2
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That's likely possible using the type of folding I used in my POC tapped-pipe. See The Subwoofer DIY Page v1.1 - Projects : A "Proof of Concept" tapped pipe** - introduction . The paper can be varied by adjusting the internal panels.
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Old 27th October 2010, 08:38 PM   #3
tb46 is offline tb46  United States
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Default TH-THSPUD folded

Hi aceinc,

Your standard TH-SPUD is just about a shoe-in for that format.

Regards,
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File Type: pdf TH_THSPUD_folded.pdf (10.5 KB, 114 views)
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Old 27th October 2010, 10:11 PM   #4
blamus is offline blamus  United States
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hmmm how did your spud design come about? I saved the schematics I found sometime ago from the "leaked th spud" thread and the design look completely different. Are they equivalent?
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Old 27th October 2010, 10:37 PM   #5
soho54 is offline soho54  United States
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He just split it half way up, and folded it over on itself. It look like he may have fixed the error in the old plans as well.

Looking at the original the sound leaves the driver, and goes up. At the halfway point here the path ends, and moves though the back wall of the plans to where the top half is now bent over, and going back down. Imagin the paper plans folded in half through the horizontal center line. It follows along the same path on the back side until it gets to the top left corner where it jumps back to the front side of the plans, and continues to the right towards the back side of the drivers.

It should work out alright.
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Old 28th October 2010, 12:04 AM   #6
tb46 is offline tb46  United States
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Hi soho54,

That's exactly correct, thanks.

Regards,
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Old 28th October 2010, 02:13 AM   #7
aceinc is offline aceinc  United States
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Oliver, I like the looks of that design. Has anyone built it?

If so, is there a build thread, or more details anywhere?

I don't know if cross posting is allowed here but I have a build thread for my TH-SPUD over on Hometheatershack.com. It actually came out OK, considering I modified it slightly to make it easier to build, and used CSS Trio-8 drivers. I was driving it with a NAD 2200 PE amp. It would probably sound better now that I have a Emotiva XPA-2 providing power to my subs.
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Old 28th October 2010, 04:07 AM   #8
aceinc is offline aceinc  United States
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Oliver, the only thing that I see that might be problematic with this design is it seems to shorten the run from the speakers to the first bend.

Of course you may have already thought of that and compensated by making the cabinet an inch or so longer in which case never mind.

Thanks for the clear description, soho, I pulled out my design for the TH-SPUD I built and between Oliver's drawing and your explanation it makes sense. I could probably wing it with this, but if there is a more complete set of dimensioned plans, it would be great.

Paul
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Old 28th October 2010, 04:29 AM   #9
tb46 is offline tb46  United States
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Default Folded Spud.

Hi aceinc,

Sorry to say, that's just one of my doodles. At the time I was looking for the same general form factor. I haven't put any numbers to this, but would think that it should duplicate the performance of the TH-SPUD just fine.

I remember your post from the shack, and don't think you would have any problems building this one. By the way, your change of the driver mounting, and associated tapers is probably more significant than a small change in L23. Folding the box also changes the taper in front of the S4 section, I think for the better.

I always thought it would be interesting to compare an "original" SPUD to a modified one, e.g.: with about half the volume, but, I'll have to leave that experiment to someone else. Would make for a much smaller box though.


Regards,
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Old 29th October 2010, 02:23 AM   #10
aceinc is offline aceinc  United States
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Oliver, I recently had a chance to sit on a couch on a pair of real TH-SPUDs for a short demo. It was pretty impressive.

I think CSS has discontinued the Trio-8s, so I would need to find another pair of 8" drivers. The Tang Band seems to be 4 ohm which would yield either an 8 or 2 ohm cabinet, I would prefer a 4 ohm cabinet.

It's a shame you didn't move forward on that design, it looks promising.
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