Tuba Home Theater Build - Page 5

You should try one. You may be surprised

It would be even flatter with 50db between hash marks, but only a wee bit more misleading than the 30 you show. I prefer the reality of the graph bosso posted in your thread.

http://www.avsforum.com/avs-vb/showt...8#post17493538

Fatawan,

Astute observation. The Table Tuba page also says "You want a horn loaded home theatre sub that can deliver over 110dB at 20 Hz". IMO, both of these claims are not responsible, and are there to lure audio knowledge deficient folks into buying plans (worked for me when I bought the TT plan almost 2 years ago).

The TT may hit 110dB at 20Hz, but with so much THD that it would sound like total ass. I can only get low 80s dB-wise at 20Hz before I decided that more power in was not the answer to good sound for a TT. A good highpass is.

The THT may be able to do the 1Hz thing in a sealed concrete bunker, but saying that 1 Watt will give you 110dB at 1m at 1Hz in a typical room is kinda 'off', IMO. The quotes further down the page for the THT both say that useful output for the THT is in the teens (one of them mine), so that should temper the 1Hz claim.

The 1Hz claim is even stranger coming from the very person who does not believe that sub-15Hz content is important.

"A word about response below 15 Hz.
If you have a speaker capable of doing so, and the necessary test gear, run a 12 Hz sine wave though the system to a 105dB level, outdoors so that you'll hear the speaker and not the house vibrating around you. Do an RTA to see what's in the output; if you have a direct radiating speaker you'll see that you don't have a pure 12Hz sine wave, you've got 12Hz plus a lot of harmonics. If you've got a folded horn the harmonic content will be lower, but it will still be there. And now, as to what you'll hear: not much. If not for the meter telling you it's there, and the whoosh of air rushing about, you'd be hard pressed to tell that there's anything there at all. What you do hear is those harmonics. And that's why I'll never build or design a cab with the intent of going lower than THT, unless one of you is nuts enough to pay me my $2,000 one-off fee.
Yes, some DVDs have content below 15 Hz, and measuring gear can detect it. You can't. If you think you can that's all well and good, but just as you can't get around the physics of how large a speaker must be to reproduce those frequencies you also can't get around the physics of how large your eardrums, ears and head must be to hear them. If you crave the low frequency vibrations, get some Butt Shakers"

That being said, these designs DO NOT NEED these exagerrated claims. They work VERY well. They are great bang-for-buck. If you are on a budget, I cannot think of a better deal. If you need above 30Hz, TT. If you want more extension and volume, THT. Just like any other design, they have strong points and weak points.

If you have stud and drywall walls, you won't get as much room gain as myn gets with cinder block construction.

Either way, how else can you get low distortion playback to 20Hz (and depending on your room, lower than 20Hz) at reference level at your listening position for $400?

JSS

Depends on the frequency you are using for break-in and how you are wiring up the coils...

JSS

I was hoping for a more technical answer. Such as what is the phase shift over a specific range. Say for example slightly below the horn loading range to the upper LFE channel specification 16Hz-120Hz? I suppose I could figure out how to model it if you want to keep it a secret.

Dr V

It's no secret, it runs 45 degrees at 20 Hz, 0 at 25 Hz, -90 at 100Hz. But since it's not audible it's not something I concern myself with.

Is the only way to make uniformly round those edges is with a router?

*very roughly*, it looks about like this.

Why didn't you use the hurricane nuts?

nice job revolt.

thanks for posting the pics.

you can probably remove the screws, but i would pl all the holes and then sand flush. you may have one or two screws that missed the mark and so would let out air if not filled in.

Interesting. I don't think I've seen those before.

Another way I can think of doing it is with a sanding block that is contoured to the roundover you want, use spray adhesive to mount the paper to it, or just manually sand the roundover with a flat block. You'll be surprised how good you can make one with a little practice.

The easiest way is with a router. They are very handy tools.

JSS

Air Supply,

Drill a pilot hole then hammer 'em in.


dbl

Bill, Thanks for the data. Its about what I expected, no complaints!

LTD, Thanks for the graph too.

Looking good Revolt. I'm anxiously awaiting the reviews and possible measurements from these builds.

Dr V

Looking real good!

You're on the home stretch.

Did you use a router for those edges? Did you end up removing all of the screws?

that might confuse people. they are screwed in with a hex drive.

Excellent!!!

I think the first thing you should do is check for leaks. Play a low tone at a low volume and you'll hear it for sure. I ran 10-20Hz tones at a very low volume and could hear a small one right around the access panel.


dbl

If you have a high pass filter enabled I would say punch it .