DIY sub for Klipschorn based HT (and music) - Tuba HT - build done (except for finish)!

[psg]

Well then, you should be able to flex your drywall by 1/16th of an inch with 100 Watts.

We'll see soon enough! Maybe I have a bad leak in there!! [:#]

[CECAA850]

Peter, you're putting the sub behind you??? That's REALLY less than ideal.

[rennoc442]

Yes! I have belle mains with a klf c-7 center, and reference series rears. I would love to do khorns and an lacalla front w heresy rears! And toss my sub 12 for a tuba! Why not mount the projector from the ceiling? That's what I would do.

[ClaudeJ1]

Peter, you're putting the sub behind you??? That's REALLY less than ideal.

Not necessarily. He should be crossing at about 40 Hz. to the Khorns.......so If the khorns 13 feet away with an additonal 4 feet for the folds, they are acoustically 17 feet from the chair. The Tuba is an 11 foot horn, so 4 feet behind the chair is just fine at those frequencies, it's all feel anyhow. It will not requre much time delay correction then, since it's done acoustically.

Claude

[psg]

The sub is behind me. It could go in front, but it's hidden from view back there and there's more room for it. Low frequencies are not supposed to be directional. I am crossing the KHorns at 40 Hz, the La Scala center at 60 Hz and the Heresy II surrounds ta 80 Hz.

First impression was underwhelming, but in a good way. It was so seemless with music that I couldn't tell it was on!

I am currently a T-splitter on the sub output of the receiver so I can switch between my Hsu STF-3 and the Tuba HT. I played the scene in The Incredibles where the boy runs on water and a rock tower explodes. I remembered it as a good LFE scene but not so much after all. There's a bit of room pressure going on but the Tuba was only getting a couples of Watts. Until I get a real LFE movie in there, and as long as I had my laptop connected for REW, I played this track on my Hsu and my Tuba :

http://www.youtube.com/watch?v=_WcpfeYerps

The Hsu plays to 25 Hz, and it's like the song wasn't playing anything. Switching to the Tuba at the same volume level and the SPL went way up and I discovered rattles that I didn't think were possible. The walls are vibrating and the Tuba is not even breaking a sweat! I measure SPLs and output power and report back. Seems like 20Watts are plenty to undercover vibrations that were unknown to me in the house (doors, light fixtures, walls).

[psg]

I use duck seal paste to make my gaskets for the driver and the access panel. It costs $2 a brick in the electrical department of the hardware store. I used half a brick.

[psg]

A rush-job fuzzy picture (no flash or tripod used) of the sub in place.

[psg]

I still have some finish work to do later on. Remove the screws, insert pegs with glue, sand them down and sand the cube, stain it to match my Klipsch. So far I have only removed the srews, inserted pegs and sanded the edges in order to run the router in the edges. I didn't use a very large radius; i just got the edge off. Here's a peg:

[psg]

Dialing it in right isn't trivial as far as level. The receiver test tone leave it at -10 dB using an external amp without gain controls (with the crosssover to the mains at 200 Hz for the test), so that was close! But then setting the crossover to 40 Hz and running a REW sweep tells me it's is a bit too low. I can crank it up to 0 dB (so 10 dB more) and the REW sweep looks better at low frequencies (< 40 Hz) but I have a bump in the 30 to 40 Hz range (which miniDSP could handle for me). That gets me very good output down to about 17 or 18 Hz. -5 dB is a good compromise until I get EQ in there.

[psg]

A big thank you to all of you who have helped me along with my questions, and for your encouragement!

I would likely not have picked this build without the support.

[Y]

[psg]

I may need high-pass after all. I just put in The Incredibles when the plan explodes over the ocean. I was a few dB below reference and I think I very briefly hit a peak of 1000W (and the house is still standing; I did feel the shock wave in the room more than I heard it loudly). Of course I am currently running the sub 5 dB hot relative to receiver-setup-noise calibrated sub level.

[Vicoaster]

I may need high-pass after all. I just put in The Incredibles when the plan explodes over the ocean. I was a few dB below reference and I think I very briefly hit a peak of 1000W (and the house is still standing; I did feel the shock wave in the room more than I heard it loudly). Of course I am currently running the sub 5 dB hot relative to receiver-setup-noise calibrated sub level.

COOL! I can't wait to have 2 of these in my theatre!

(although I may have to get the plans for the low-profile Tuba, it would be easier to lay them down onder the screen...)

[nyt]

Crossing at 40hz is a waste, bump that shit up. It will be way more efficient / more headroom down low than your khorns.

I just decomissioned all my klipsch speakers, new pics in my sig link, crazy how much more efficient, and working great with the THTs =]

[psg]

So now you know what 104 sensitivity means. Welcome to the club! []

So you are telling me that you are crossing over your big boys at 80 Hz?

[ClaudeJ1]

I may need high-pass after all. I just put in The Incredibles when the plan explodes over the ocean. I was a few dB below reference and I think I very briefly hit a peak of 1000W (and the house is still standing; I did feel the shock wave in the room more than I heard it loudly). Of course I am currently running the sub 5 dB hot relative to receiver-setup-noise calibrated sub level.

Remember that 1,000 Watts is only 30 db Watts, but if you hit a 130 db peak, that's some serious housh shakin bass. Like I said before, it's a feel more than anything. You may want to try crossing at 50 or 60 hz. also.

[tragusa3]

Peter, I have a buddy with Khorns, and he's done exhaustive experimenting with crossover points. He's happiest at either 80hz or even 90hz. Your sub is better up to that point than even the mighty Khorn!

I've played with my LaScala xover and like to keep it at 80hz.

[psg]

Ok guys, I will experiment with higher crossover points as well. but don't forget that i have two KHorns and only one Tuba. The KHorn hits pretty hard at 80 Hz...

[psg]

Crossing at 40hz is a waste, bump that *** up. It will be way more efficient / more headroom down low than your khorns.

I'll admit that I haven't tried different room placement, but...

I just tried a few things. Sent 1W into the THT at 70 Hz and got about 95 dB in the room. Did the same thing with the KHorns (okay, two of them, 1 Watt per channel) and got 102 dB. So at least mine isn't more way more sensitive than my KHorns.

Next, I set my crossover to large and adjusted the volume to read 70 dB in the room at 70 Hz (from the KHorns). Then set the crossover to 200 Hz and adjusted the sub level to read 70 dB (from the sub). If I then lowered the frequency to 40 Hz, the KHorn played louder than the THT when switching crossover points on the receiver, same at 30 Hz and same at 25 Hz. This is weird. I could post some REW sweeps, but I should probably get a fresh 9V battery first and try again. Still, the results were consistent with the levels I heard.

[psg]

It may just be room placement.

I played a test tone again at 1W (didn't take out the voltmeter, this is from the display of the Monster Signature amp that they claim to have true power meters) and repeated my 94 dB measurement at the seating position. But this time I moved a lot closer and the sub was outputting at least 112 dB at the area about a foot or so above the sub, in the gap between the sub and the wall (which explains the constant buzzing and rattle of a light fixture there, even at 1 W.

It would be great if fellow THT onwers would tell me what SPL to expect at a given distance, voltage and frequency. Thanks!

Edit: Moved the sub a bit (along the pole now, facing toward side wall) and SPL increased to 100+ dB at the seat with the same approximate 1W (which turned out to be 3.2V, so 2 W into 5 ohms). I will lengthen my speaker wire (cutting it too close to size was a mistake) and will try it in front of the room. It should do much better there because my KHorns are good to 25 Hz in those corners.

[tragusa3]

I did a lot of placement experimenting in the first few months and settled on what I thought was super performance. Then, after 6 months of listening that way, I added some bass traps to the rear of my room and it so drastically changed the experience that I still can't believe it! I say this to give you some encouragement to experiment as much as you possibly can. Remember, performance in the sub frequencies is a product of the entire "subwoofer system". This includes the sub, the room dimensions, room treatment, etc. It'll be fun to watch you wring out all the performance you can.