The most popular drivers for high end Home Theater subs are
long-throw low fs fifteens. But in a reflex or sealed cabinet you just
can't get all of their potential from them. Enter the Tuba HT, a big
(36x36x24 inch) folded horn specifically designed to get the most out of
Take a look at this SPL chart, which compares the performance of a Tempest
Classic 15 driver in a sealed and vented box, and when loaded in a 24 inch
wide Tuba HT, all three cabinets with corner placement:
Want more? Got it. If you've got room for it build your THT 36 inches wide,
stick it in a corner and this is what you'll get:
Not impressed yet? Add in the cabin gain of an average room (12dB per octave
below 30 Hz) and you can end up with response to 10Hz with 110dB sensitivity.
Not even the most expensive theatrical subs made can make that claim.
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.
The sensitivity advantage of the Tuba HT means bass more solid than you've
ever heard before. The folded horn geometry reduces distortion to levels that
no direct radiator sub can even approach. Here's what builder MaxMercy
measured from his THT:
20Hz: 114dB at 4.5% THD. I did not push any further, as the panes in my
windows were moving about 1/16" at the time. I think they would have broken
if I went further. Above 20Hz, you can get damned near as much as you want
dB-wise, all clean. Basically, from 16 or so Hz on up, you have strong bass,
from 20Hz on up, INSANE bass. I designed the system to give me great sound at
-10dB from reference (with Dynamic EQ frequency correction to account for equal
loudness curves), which it does with flying colors flat down to around 16Hz
before dropping off. Useful output down to 12Hz. All at less than 5% THD.
In a sweep and distortion test of a $9950 sub, the Genelec HTS6...
the Genelec runs over 10% THD at 115dB. This is significant, in that a sub
almost 20 times less expensive to build can seriously compare with one of the
best subs available.
The THT also may be loaded with a twelve, for a minimum cabinet width of 15 inches.
If the 36x36 profile of the standard THT doesn't work for you there's the
THT Low Profile version.
18 inches high, 72 inches long, with a minimum width of 15 inches, it can be
laid down or stood up on end as shown, giving the
highest output possible from a 15x18 inch footprint. The exit mouth may be
placed at one end or on the side.
If you crave bass in your home
theater that shames real theaters, look no further, Tuba HT is the one. Loaded
with the recommended Parts Express Dayton RSS390 HF4 driver, you can build a THT
for $500, including an amp that will take it to +126dB levels.
Construction Degree of Difficulty: 4
Performance Quotient: 10
Equivalent Retail Value: $ 2,999
Plans are $14.95, delivered within 24 hours as email attachment in Word MS
format; PDF available on request. 15 pages, 12 photos, 19 diagrams.
The THT and THT Low Profile are two separate plans. If you want the THT
Low Profile version you must specify it when you order, otherwise you will
be sent the standard THT plans.