BillFitzmaurice.info

Isn't the THT self limiting at low frequencies? From what I remember (I could be very wrong) the extremely long path length and high mass of air in front of the driver limits the excursion of the driver below 20hz so that highest excursion occurs within the passband (let's say 20hz since I don't remember the exact value) and then tapers off above and below that point. I don't think people run HP filters on the THT for this very reason.

Someone should confirm or deny this for me so I don't give out poor advice based on poor memory.

I'd actually suggest sending the THT 90-100hz and below (or whatever) and limiting the buttkicker to 50-60hz and below. I have a set of transducers that get rather distracting in the 70-100hz range (it vibrates the couch where it just doesn't seem right, like when a deep voiced guy is talking) so I had to set them up with a separate crossover to keep those frequencies out of the couch.

Charles Warwick wrote:the extremely long path length and high mass of air in front of the driver limits the excursion of the driver below 20hz so that highest excursion occurs within the passband (let's say 20hz since I don't remember the exact value)

22Hz.

the distracting of the high frequencies is what I was trying to avoid. I wanted to limit the sub simply to keep it from blowing i9t self up trying to reproduce very low freq at high volumes such as War of the Worlds. Cut off the sub below 20 and crank it, let the shakers pick up what's below 20hz.

Fatso wrote:the distracting of the high frequencies is what I was trying to avoid. I wanted to limit the sub simply to keep it from blowing i9t self up trying to reproduce very low freq at high volumes such as War of the Worlds. Cut off the sub below 20 and crank it, let the shakers pick up what's below 20hz.

Read the posts again. Maximum excursion is at 22Hz. There's no point in high passing below that frequency.

I don't want to sound stupid but I want to make sure I understand what you are saying. As an example sending the sub a test tone of 15hz will not harm the driver? I thought that it would try to reproduce the sound and eventually overheat or tear and die. I really don't want to chance destroying something I labored on for so long. by my tests I won't be able to harm it at 25 hz, the house starts to move and my wife yells at me. I do worry that cranked up very low tones may be a different story.

From the sales page:

Here's what builder 'Tweedpower'has to say about his THT:

Built a Tuba HT, my third Tuba. This is a different animal. I built a 30" wide version. This was the widest size that would fit through my door. The low end output is unreal. It is the greatest for the LF channel in my HT. I have been experimenting with different crossover points and I think that I like crossing it over lower at 60 or 80 hz. The power in the sub 50 hz region is impressive. It lets you know what the sound engineers had in mind. I get great output down to 15 hz and basically flat to 18 hz when using minimal EQ.

At 22hz your limited to 28v before endangering the driver. Above and below that you can add more, but as you pointed out your wife will not be happy at those voltages.

Limiting and high passing are two different things which intesect strangely with the THT.

Above and below 22 Hz the driver takes more volts than at 22Hz.

High passing at 22Hz makes you safe to some other ( unknown to myself ) limit, probably more than the household will stand, drywall may suffer.

Limting to to 28V makes you safe from driver overexcursion but drywall or wife may not approve.

Sorta done!!!!!!!!!

driver braces in, cap done, screws out, holes filled! All that's left is roundover, sand, prime, paint, install terminal cup, enjoy. I think I'll watch a few movies this weekend!

Fatso wrote:

Sorta done!!!!!!!!!

driver braces in, cap done, screws out, holes filled! All that's left is roundover, sand, prime, paint, install terminal cup, enjoy. I think I'll watch a few movies this weekend!

Add to the "all that's left" list is #1 PRIORITY Check of air tight seals everywhere. Ultra important.

Updates, man! I know how excited I was when my first THT was done. I sure didn't wait for the finish before I listened to it. Howz it sound?

well. I turned it on with the driver cap off to check for leaks. In the garage with the door open 25hz test tone. Sounded ok the ceiling and garage door creaked walls moaned. My wife appeared immediately to ask what was going on, the plates were falling out of the cabinets . That's all I've done so far. Tonight I sanded and rounded off all of the corners. No chips by the way routed as well as MDF. Tomorrow prime and paint and a movie or 6.

Question,

This thing is too heavy to hang on the wall, just like you all told me. I wonder if I made another with 2 sides (joining) 90" long (the other two sides 72") and one leg in the other corner (where the 72" pieces join). The two long sides would be against the two walls in the corner and the led facing the room. would that work?

Um, can you draw that? Me nooo understand!

Yeah that will work. Just the same as laying it down along a wall pointing at the corner.

Is it Tom or Tammy?

DJPhatman wrote:

Fatso wrote:

Sorta done!!!!!!!!!

driver braces in, cap done, screws out, holes filled! All that's left is roundover, sand, prime, paint, install terminal cup, enjoy. I think I'll watch a few movies this weekend!

Add to the "all that's left" list is #1 PRIORITY Check of air tight seals everywhere. Ultra important.

Thank for the advice! my ultra tight cabinet had 2 small leaks. They are now plugged with PL. All that is left now is to let the PL cure in the leaks and carry it down to the HT

I can't wait!

1 funny thing my son noticed was that when I was running a 25 hz tone checking for leaks he looked up at the garage door hangers. They were vibrating madly, looked like the Tacoma Narrows bridge.