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Discussion Starter · #1 ·
Several members have asked me post my impressions of the THT. I am not sure why those members feel that my opinion is at all valuable. I am far from what anyone would consider and expert evaluator, nor do I have 'golden ears'. Regardless, I thought I would oblige them since there is minimal effort involved and after all, this is a fun hobby!


Background:

I have owned or tried many subs over the last couple decades, to include many car audio setups in my younger days and on to HT subs more recently. After purchasing my latest house about 8 years ago, and finishing the basement, I decided to venture into DIY after owning numerous commercial offerings to include SVS and Velodyne. It has been an enjoyable ride thus far and I can’t believe how much I have learned and more importantly how much I don’t know or understand!

After finishing my last project and helping some friends out with theirs, I took some time off from the forums. My last project was a pair of end tables based around the amazing TC Sounds 18” LMS-5400 (see The Gear section). I guess I just wanted to enjoy the fruits of my labor so to speak. My hiatus was also a function of the seasons. Those of us in PA have to take advantage of every nice day so there is not much time for watching movies and building subs...When it’s convertible season!

I returned to AVS a couple of months ago to the sound of horns (pun intended). Meaning that many of the threads were based around horn or horn related builds, purchases and discussion. I initially thought I was in the wrong forum, horns, horns, everywhere! Now, I had heard of horns before and had a basic understanding of what they were and how they worked. But, I was confused as to what the hell happened to the ‘sealed vs. ported’ debates and the myriad of sonosub builds?!!?. I quickly noticed that the Danley DTS-10 was frequently at the top of the threads. I did the usual research/reading and was impressed that Danley Sound Labs was making a foray into the pseudo DIY realm with a kit. And it was nice to hear about the performance to dollar level as well as how owners were impressed with the product. I considered making a purchase just for fun as I certainly didn’t need more output in my room. Then I noticed several, more like many, THT build threads. I initially thought, like most visitors, “what the hell is a THT”? After figuring out what it is, I threw it into the possible mix whilst kicking around what I wanted to do for an enjoyable project. I was immediately attracted to the price of the build and the testimony of others. I thought to myself, “how can I lose!?” with an unused coupon for Parts-Express and my good friend Roger willing to lend a helping hand, and more importantly, the use of his fantastic wood shop. Why not? OK, enough rambling, here’s the meat of it all;

The Sub:

This mini-review is in regards to the Bill Fitzmaurice’s Tuba Home Theatre Subwoofer , commonly referred to by/as the acronym ‘THT’, for short. Please check Bill’s site for further details.

The Plans:

I ordered the $14.95 plans and received them well within 24 hours as promised. The plans are reasonably well documented and do include a valuable Google Sketchup (free download) file that yields a 3-D model that can be manipulated to show panel fitment and layout in great detail. The narrative portion can be slightly confusing, but does provide enough information to proceed with some degree of confidence.

The Materials:

I chose ½” hardwood plywood from Home Depot at $33 a sheet. Three sheets were purchased to avoid scabbing any pieces together and to accommodate any cutting errors. This plywood was selected because it was basically perfectly flat, cut square, and provided possible finish options on down the road. We decided to use a brad nailer rather than screws on most panels, to once again aid in finishing. I also picked up 3 tubes of Liquid Nails and some 1 ¼” screws for the access panel. I used some 1” wide, 1/8" thick speaker gasket tape from a previous build. I purchased binding posts and a 150’ spool of 12 gauge wire from ebay because I would need to make another ~40 foot run of wire for any placement options. The Dayton 15” DVC was purchased from Parts Express (regularly $149.76). Driver mounting anchors where purchased from Lowe's. Finally, I picked up four $3.99 swivel casters from Harbor Freight. (see images)

The Build:

The 24” (24.5”) version was chosen for the smaller footprint and maneuverability.

Overall, I would not call the build overly difficult if you have any woodworking skills whatsoever. However, as I stated in several build threads, you have to pay close attention to what you are doing to get it all correct. 2” brads were used, simply because they were already in the nailer. I would recommend using ~1”, as brads can do crazy things in plywood always having the potential to emerge from one side or the other when interacting with the ply layers and bonding material. That happened numerous times. In addition to the Liquid Nails on the panel edges, a bead of it was run down each side of the joining panels to help seal them up.

I chose to wire the Dayton DVC driver for an 8 ohm load and to run the wire out of the bottom of the enclosure rather than the access panel. I went that route mainly for aesthetics and because I always put casters on my builds. The finished product can often weigh quite a bit and be a bit unwieldy to attempt to move around if and when necessary. This is especially true in my small theater room with furniture obstacles. Casters really make placement experimentation a snap too. I scrap flake board ring was used on the driver mounting area to provide additional rigidity and a more robust area for mounting anchors.


I decided not to include a lot of build photos since there have been so many build threads. If that is what you desire, I would recommend perusing Dragonslayr's THT Build Thread for excellent photos.Overall approximate build cost: $270

The Environment:

I have a small dedicated HT room in my basement. The room is roughly 13’ x 15’ x 6’6” for ~1300 cubic feet and is strictly used for movies. The acoustics are not great, but multiple subs help. It is primarily drywall and a carpeted floating wood floor over concrete. Since the room is so small, I have a corner sectional that seats about six. The room is well short of ideal and provides few placement options due to numerous doorways and stairwell, fireplace, etc. These limitations are the impetus behind the dual end table build.

The Gear (subwoofer related):

As mentioned earlier, my last project was dual end tables based on 18” TC Sounds LMS-5400s. Here is a link to the old thread .

* Dual 18” TC Sounds LMS-5400 , sealed, ~5 cubic feet

* 3- Crown CE4000 , modded fans, link to mod thread

* Denon 2807 AVR (80 Hz crossover)

* Berhringer DCX2496 as EQ/ Linkwitz Transform Circuit (4 discreet outputs used)

* 8- Aura Pro Shaker , transitioning to Buttkicker LFEs

* Dell D600 notebook, digital Radio Shack SPL Meter , external Creative Sound Blaster USB sound card , Room EQ Wizard (REW)

* 4- 15A dedicated circuits

* 3- Niles AC-3 , trigger powered

+ 100% movies, LFE calibrated 2-4 db hot.

Impressions/Evaluation:

First I have to start off by saying this thing is large! I know, I know, I was supposed to know how large it was going to be, right? Well, I guess I never really had a handle on how large it was because we used a very large wood shop which really skews your perception of size after a while. I didn’t really start to grasp the size until we loaded it into the pickup for delivery to its new home, mine. When we arrived at my small house and carried it into the basement I almost lost my mind. In fact, I was going to give it away for the cost of materials because the area that I had thought it would be placed was nowhere near large enough. Also, I prefer the stealthy look in my HT with the end tables. I am not a fan of seeing big enclosures in a room. I enjoy that fact that no one has any idea there are highly capable subs in the room until…insert adjectives here. After I calmed down for day, I decided to make a new home for the monster that is out of the way. I ended up tucking it in the utility room right behind my normal listening position, perfect! Of course, the casters sure helped out with that process.

I didn’t bother to break in the driver. I immediately connected it to an unused channel on a CE4000. The 8 ohm load should give it about 600w max, probably getting less than 300 at the calibrated levels. The feeds to the existing subs were muted via the trusty DCX to let the THT stand on its own. I ran some quick 5-80 Hz sweeps with REW to get a quick view of the in-room response (I will post those graphs below). During that process, I did notice a slight resonance of some kind around 75-80Hz. I am not sure if the anomaly is due to a building error of some kind, or simply a panel resonance, or the feed wire inside the sub. It is not that bad and I knew it would not be noticeable with normal content so I just ignored it and moved on. If I was wrong I was prepared to investigate it further or to simply cross it over slightly lower. I then calibrated it to the same level as my existing subs and popped in the Terminator Salvation Blu-ray and forwarded to the giant robot scene at around 36:00:00 in.

My first impression was: “Holy !$%@, this thing is impressive!” That was immediately followed with: “This thing costs less than $275 to build, Unreal!” Everything I threw at it the results were the same, excellent!

I could detect the slightly reduced output below 20Hz on some of my favorite demos, ala The Haunting. My LMSs via the DCX are setup to have a gradual roll off towards 10 Hz with the F3 point coming in at ~15 Hz (I will post the LMS response curve later). But, everything above 20 Hz sounded great. As predicted, I never detected the resonance with any demo material. However, it should be noted that the one problem that I have with testing the THT on its own, is that I am unable to remove my LMSs from the room. As a result, I am sure there is some degree of absorption of acoustic energy by the now dead LMS cones. I am not sure to what degree that plays a role in the THT response in my room, hopefully not a lot.

I then decided to throw my sealed subs back into the mix. The results were MUCH better than I expected! I was apprehensive in trying to mix the horn based THT with my existing sealed subs. Thankfully, the DCX allowed me to setup everything to address the ~15 ms THT propagation delay. The end result was a noticeably fuller sound as a lack of a better descriptor. The overall sound is more impactful and the summed output has changed for the good. I am really enjoying my time with the THT. I truly am impressed with the sound quality and output, especially with the amount of power being fed to it.

I love my LMSs, still one of the best drivers available for ANY price. Fortunately, I was able to obtain them at roughly half of the current going rate. Even at my reduced rate, they are not cheap by any means, not to mention the wood and other materials, amps, etc. I have always preferred the sound quality and flexibility of sealed setups. However, if I had it to do over again I would definitely consider two, three, or even four THTs and vent them into the room somehow. For the price-performance ratio I could save some serious money. With multiples, the subsonic extension would not be an issue in my small room. The sound quality is excellent for a sub at any price level. I don't think there is much, if any, sound quality sacrifices with the THT. The fact that the build cost is so ridiculously low, it makes the sound even sweeter!

I now realize what all the fervor was and continues to be about. I am thankful that I did not pull the trigger on a Danley kit without at least trying the THT. While I am sure the DTS's performance is probably worth every penny and then some, an enclosure that large and heavy would probably be a negative in my environment. Let alone, if I moved in the near future. It is simply too limited via form factor for my tastes. I also like the fact that the THT uses an inexpensive off the shelf driver, as opposed to the proprietary Danleys. But, I never say never, so who knows? Although, I would still love to see a dual THT vs. DTS-10 showdown. Besides all of that, I would rather have a couple of THTs in individual enclosures to allow for more placement options now and in the future. The THT is a hit in my book! I may even build a twin over the summer, time permitting. I just to have engineer a way to shoehorn another one into a hiding place. A twin would allow for the additional headroom to really experiment with boosting the 15-20Hz range.

As I have more time with the THT I will update this post/thread to reflect any new and additional observations.

Update:

After a few hours of movie material the resonance seems to have disappeared. Also, the 18-20 Hz response seems to have improved as well. There is decent room gain going on here. (see graphs below) However, my choice is placement is definitely hindering the overall performance and ability to do quality in-room measurements.

I am guessing the resonance issue was due to driver breakin (or lack thereof).

Other Notes:

With each new project there are new discoveries and learning. This build is what motivated me to move the Behringer DCX2496 in order to address multiple sub types, differing distances, shakers/Buttkickers, each requiring different crossover, gain and distance settings. What an amazing device, money well spent. I am thrilled with the results and ability to emulate a Linkwitz Transform Circuit for my sealed cabinets.

The other bonus is that the unit can store multiple configuration files, internally, on a PCMCIA card, and on a computer.

Also, the happenstance discovery of the metal wall anchors . I just wish I would have discovered them earlier! After having a couple of hurricane/t-nut mishaps, I was none too eager to take another go with them. Thankfully, I discovered them before the build was completed. No glue required, no alignment issues, can use multiple screw or bolt sizes, removable if damaged, more gripping power, etc. What an improvement. I was even able to remove the driver from the access opening and reinstall it without any issues whatsoever despite the cramped quarters and blocked view for 3 of screws…perfect. If I ever have to remove one of my 75 lb. LMS drivers, I will replace the t-nuts with anchors as well.

Special Thanks:

I could not have done it without my great friend Roger. His kindness and generosity regarding the use of his shop and labor are much appreciated.


The END
 

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Discussion Starter · #2 ·
Images from the build:


Bottom routing of feed wire;



Front view of the 'skirt';



Bottom view of the swivel casters;



Top view of hardwood and assembly using finish nailer;



One side of TV stand/equipment;
 

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Discussion Starter · #3 ·
Here are afew 5-80Hz sweeps done at varying listening positions and SPL levels.

THT only:



LMSs only:



COMBINED THT and LMSs:

WRONG GRAPHS, will correct...

As illustrated by the graphs, the room is less than ideal. Although, I do have very minimal EQ applied, really only LT for the LMSs.

I simply don't have the room for effective bass traps so I just live with what I have, still not too bad in my opinion and I am the only one that matters!
 

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Discussion Starter · #4 ·
Update:


I had a chance to listen to some additional demo material.

I did some A/B comparisons, albeit still slightly tainted with the dead LMS cone issue.


I am still impressed. I cranked things up pretty good with the THT only;

Finding Nemo, Flight of the Phoenix, The Haunting, Lord of the Rings, Star Wars, Terminator Salvation, etc.


It never sounded distressed AND I continue to be impressed with the subsonic output in its present location.

I did not get a chance to measure the voltage, but I know my CE4000 had to push it hard with 600w RMS on tap.

My THT is on casters so I do get a little cabinet vibration (same thing happens to my heavy LMS cabinets), but even at that, not much at all.


My next task to take some additional measurements (sweeps in room and at the mouth), max in-room SPL, and some power figures.

Here is a detailed sweep 20-80Hz from about 6 inches inside the mouth.

 

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Oh man, im surprised you like it lol! All the goofyness about the THT's lately is somewhat off putting. This was much needed! Great write up. Look forward to your graphs.
 

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Discussion Starter · #6 ·
Thanks Reece.


I will be making some edits as well. I just threw it all together and didn't get a chance to get it all totally sorted out. It's too late for today...
 

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Very informative write up.... you got some of the best drivers there that you compared it to... I am very satisfied with my THT's...
 

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Something isn't right there. Your last graph of LMS is almost exactly the same as when you add the THT's. Seems very unlikely.
 

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Discussion Starter · #11 ·

Quote:
Originally Posted by Erich H /forum/post/18240648


Real nice graph with both combined. I bet that sounds impressive.

Ya, not bad at all.
 

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Discussion Starter · #12 ·

Quote:
Originally Posted by PassingInterest /forum/post/18240801


Joe--so, are you saying that as the THT driver breaks in, the 10-20 Hz output improves and that you might not need the sealed LMSs at all?

Well, put it this way, things definitely improved all around.


Ya, I think in my small room with all the room gain, I could get away with a couple THTs.
 

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Discussion Starter · #13 ·

Quote:
Originally Posted by Fatawan /forum/post/18240840


Something isn't right there. Your last graph of THT is almost exactly the same as when you add the LMS's. Seems very unlikely.

Believe it not, they are the correct curves.

You have to consider that they are all not the exact same listening positions.


I simply just held the meter up and measured so things vary a little.
 

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Great writeup! I'm still planning on building one of these "for fun" when I run out of other projects


Quote:
Originally Posted by Fatawan /forum/post/18240840


Something isn't right there. Your last graph of LMS is almost exactly the same as when you add the THT's. Seems very unlikely.

Note that the SPL range on the graphs is 5dB - 100dB so any differences are difficult to see (any chance of getting a tighter look?). A couple obvious differences are the absence of the 14dB null at 25hz and the addition of a null at 80hz in the combined graph.
 

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Discussion Starter · #15 ·

Quote:
Originally Posted by lennon_68 /forum/post/18240994


Great writeup! I'm still planning on building one of these "for fun" when I run out of other projects





Note that the SPL range on the graphs is 5dB - 100dB so any differences are difficult to see (any chance of getting a tighter look?). A couple obvious differences are the absence of the 14dB null at 25hz and the addition of a null at 80hz in the combined graph.

Yep, if I get some more time I will head down and do some additional sweeps.
 

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Quote:
Originally Posted by jpmst3 /forum/post/18241115


Yep, if I get some more time I will head down and do some additional sweeps.

No rush
I mostly just wanted to point out the dB range as I fear some see a nice smooth graph without checking the dB range.


Thanks again for posting this review (I know I was one of those asking you for it
). I've read tons of positive reviews of THTs but without knowing the person's experiences or biases it's hard to determine how much stock to put into the review. As you have experience with the finest drivers available and have very little bias toward this sub (as it's just a "for fun" low-cost side project) I knew your review would be a worthwhile read
 

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Discussion Starter · #17 ·
Thanks man.



Ya, I was going to save the sweeps so I could simply change the scale. But, I forgot and closed REW.



I will try to post some additional comparison info as well.



I would definitely recommend building one for fun. After all that is what we are here for, right!
 

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Nice write-up!


Since i'm nearing completion of the build myself, I'm hoping my results come close to what you're hearing.
 

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Discussion Starter · #19 ·

Quote:
Originally Posted by Kevin A /forum/post/18241398


Nice write-up!


Since i'm nearing completion of the build myself, I'm hoping my results come close to what you're hearing.

Thanks!

Good luck with the remainder of your build. I am sure you will be pleased.
 

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Discussion Starter · #20 ·

Quote:
Originally Posted by Kanaris /forum/post/18239997


Very informative write up.... you got some of the best drivers there that you compared it to... I am very satisfied with my THT's...

Thanks Mike,

What sub(s) did you have before?
 
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