THT + TLAH = AWESOME

[AndreasMergner]

I built a couple of TLAHs for fronts a couple of weeks ago. I have the review in a separate thread. I plan on making another for a center once I get an audio transparent screen for my projector (using an O10.5 for center currently). I also plan on making TLAHs for surrounds with less drivers.

I finished my THT and got it upstairs yesterday. It took about 8 hours over a few days to build the THT, but I did not paint it. It actually took longer to build than I thought, but compared to most of the build threads I did it quickly. The thing seems to weigh a ton and I cannot get under it well to pick it up by myself. I had it sitting outside my porch all day before I could get help to move it!

The combination is impressive. I had a musician/audiophile friend hear it and he asked me about building a set of TLAHs. The THT goes at least 30 hz lower than my current sub and has tons more output, but is easier to listen to. It doesn't seem to hurt my ears even though my wife was mentioning how windows on the other side of the house were vibrating. I have never heard anything like it - so low and smooth like butter! I guess most subs just don't get nearly as low.

I look forward to creating my new dedicated HT space. With sound treatments and another few TLAHs I am going to have incredible sound! I almost want to make a second THT now. Maybe it's for the best that I don't!

[sine143]

Time to update the sig

[AndreasMergner]

Done!

[Drey Chennells]

nice work Andreas. How did you end up positioning it?

[AndreasMergner]

nice work Andreas. How did you end up positioning it?

I am in a small room right now of approx 12x10x9. I have it in the only corner it can go in (3 other doors) - flush on one wall and about 18" from the other. From the room dimensions you can probably surmise that I sit about 4 feet from the mouth of THT. I have it way down, but it sure is fun to crank it all the way to 30 V or so for a "party trick". That is probably the only reason I would make a second. Although I wonder what I am missing below 20 hz or so since going from 50 hz to 20 hz was so gratifying. I have to do some testing to see what frequency response I'm getting and find someone who has an IB setup to reference to. That would open up a whole can of worms though.

[Drey Chennells]

nice work Andreas. How did you end up positioning it?

I am in a small room right now of approx 12x10x9. I have it in the only corner it can go in (3 other doors) - flush on one wall and about 18" from the other. From the room dimensions you can probably surmise that I sit about 4 feet from the mouth of THT. I have it way down, but it sure is fun to crank it all the way to 30 V or so for a "party trick". That is probably the only reason I would make a second. Although I wonder what I am missing below 20 hz or so since going from 50 hz to 20 hz was so gratifying. I have to do some testing to see what frequency response I'm getting and find someone who has an IB setup to reference to. That would open up a whole can of worms though.

I know exactly what you mean about the party trick...You think youre not getting below 20hz?

[AndreasMergner]

I know exactly what you mean about the party trick...You think youre not getting below 20hz?

"WATCH THIS!"

I can play sines at 10 and 15 hz, but they are much less loud than at 20 hz. 20 hz at full blast will rock, but 15 and 10 -- is much milder. I have it going through a Crown XTI 1000. I know at 22 hz, I don't want more than 28V, I wonder if I use its EQing functionality to boost 10-20 so that it will effectively see more volts, will that work? I wonder how many volts it will take at those frequencies?

If I had a Hornresp plot of max V required to get to max deflection, I could EQ it better, no? Is there a way to do this?

[Bill Fitzmaurice]

I can play sines at 10 and 15 hz, but they are much less loud than at 20 hz.

You can feel 10 and 15 Hz, but you can't hear it. That's because wavelengths in excess of roughly 50 feet long pass right through your body as easily as through the walls of your home, putting equal pressure on both sides of your eardrums. That results in no movement of the eardrum, which means no sound. When you play tones below 20Hz what you actually hear is the harmonics of those tones.

[Billy Joe]

[quote="A It took about 8 hours over a few days to build the THT

It only took you 8 hours to build the THT. It took me three weeks to build mine. I guess i'm slow.

[Bill Fitzmaurice]

[quote="A It took about 8 hours over a few days to build the THT

It only took you 8 hours to build the THT. It took me three weeks to build mine. I guess i'm slow.

It took me 6 hours to build the original, and I didn't have plans telling me how to do it. Not my first build, though.

[Drey Chennells]

I can play sines at 10 and 15 hz, but they are much less loud than at 20 hz. 20 hz at full blast will rock, but 15 and 10 -- is much milder.

To add to what Bill said... As I'm sure you know, you can't underestimate the energy of infrasonics. In nature these frequencies often indicate a pending or occuring disaster, lions use their roar to disorient prey. During hi power infrasonic testing with ear protection I've been affected by a heightened heart rate and anxiety level.The THT is very capable of reproducing this phenomenon.

I have it going through a Crown XTI 1000. I know at 22 hz, I don't want more than 28V, I wonder if I use its EQing functionality to boost 10-20 so that it will effectively see more volts, will that work? I wonder how many volts it will take at those frequencies?

If I had a Hornresp plot of max V required to get to max deflection, I could EQ it better, no? Is there a way to do this?

I'd like Bill's comment here but maybe cutting 22hz plus a few hz both ways would allow higher overall power handling. Is that what you're suggesting?

[AndreasMergner]

It only took you 8 hours to build the THT. It took me three weeks to build mine. I guess i'm slow.

Even 3 weeks is good compared to some!

You can feel 10 and 15 Hz, but you can't hear it. That's because wavelengths in excess of roughly 50 feet long pass right through your body as easily as through the walls of your home, putting equal pressure on both sides of your eardrums. That results in no movement of the eardrum, which means no sound. When you play tones below 20Hz what you actually hear is the harmonics of those tones.

I'm not "hearing" 10 and 15 hz, but I know it's there....unless you are saying the THT won't produce those frequencies at all. The "volume" is low, however. I know the THT rolls off under 20 or so from the frequency response graph. Since the max excursion/per volt is at 22, and I want more of 10-15, can't I boost those frequencies?

To add to what Bill said... As I'm sure you know, you can't underestimate the energy of infrasonics. In nature these frequencies often indicate a pending or occuring disaster, lions use their roar to disorient prey. During hi power infrasonic testing with ear protection I've been affected by a heightened heart rate and anxiety level.The THT is very capable of reproducing this phenomenon.

The THT makes me feel sick....in a good way!

I'd like Bill's comment here but maybe cutting 22hz plus a few hz both ways would allow higher overall power handling. Is that what you're suggesting?

I was planning on cutting 22 a bit and boosting 10-18 or so. Is this a bad idea? I really need to get the equipment I need for REW and see what is happening. I do know 10 and 15 hz sine waves are much "quieter" than 20 hz at the same voltage.

[Bill Fitzmaurice]

I was planning on cutting 22 a bit and boosting 10-18 or so. Is this a bad idea? .

You can, but what you'll mainly get is more harmonic output an octave to two octaves higher than the actual tones. Which, as I said before, is what you're hearing now. As for what's down below 20Hz there are many devices capable of responding to output down there. Your ears aren't among them. If you want the tactile sensations of sub 20Hz output that's something else again.

[AndreasMergner]

You can, but what you'll mainly get is more harmonic output an octave to two octaves higher than the actual tones. Which, as I said before, is what you're hearing now. As for what's down below 20Hz there are many devices capable of responding to output down there. Your ears aren't among them. If you want the tactile sensations of sub 20Hz output that's something else again.

Yes, this would be for HT for the tactile sensations. Is it worth it? I'm not sure. I would like to experience them before I decide I don't want them. There are those with IB and rotary sub setups that feel sub 20 hz and think it is worth it.

So, does that mean that anything below 22 is fairly distorted in the THT? I know that is a dirty word, but the THT sounds great. If it can't really produce good output below 22, seems like it should always be highpassed so you can at least get extra output. Under 22 would require a different tool like an IB sub, a rotary sub or even a butt kicker? Each has disadvantages.

[AndreasMergner]

I have a Crown XTI powering the THT. For some reason, the XTI wont let you set filters down below 20hz. What is up with that?

To get around it, I made one filter at 20 with a Q of 4 for +15db, which boost a large frequency range around 20. Then I made a filter at 22 hz with a Q of 12 and a cut of -15db. This leaves a dip at 20-24 and a boost from 10-20 and 24-35. You can then add another filter or two to make 25 hz and up flat. It was pretty easy to do and it increases the 10-20 hz levels more equal with above that.

Mind you, I haven't run REW yet, so I don't know if those EQ settings are even close to perfect, but it sounds better than without the EQ. Heck, I'm curious as to what frequencies are being output now that Bill says I'm not really hearing the low frequencies.

I played the "pod emerging" scene from War of the Worlds today. It seriously feels like the house is falling down. I can't believe how violent it is and how nauseated I feel afterward. It will be a great demo.