Rike's SLA and Tuba 18 for Home Theater Build Saga

[Rike43]

This is the beginning point . . .

SLA for Home Theater

Left and Right SLA 6 bass/9 tweeter; Center 6 bass/6 tweeter

The drivers:
•Bass: Dayton Audio PC105-8
•Tweeter: Visaton SC5-8 Shielded 1/2" Polycarbonate Tweeter

These will be driven by an BasX A3 Three-Channel Power Amplifier. I already own this and I have no plans to change it.

Tuba18 x 2
Bass support will come in the form of two Tuba 18's in different parts of the room using MCM 55-2421 drivers.

The amp to drive these is still TBD. Currently looking at a Behringer NX1000D with DSP. It's more power than these will need, but the DSP crossover and individual volume knobs per channel for under $300 is attractive. Other ideas welcome. (Equipment will be rack mounted.)

The rest of the system
All of this will be integrated into a Dolby Atmos 7.1.4 system. Surround and ceiling speakers are mid-price-range Monoprice in-wall speakers from several years back driven and processed by a Denon AVR+stereo amp. Changes to the surround speakers are TBD but they will all have to be in-wall due to WAF which I actually agree with as all of this is happening in the living room.

Edit: Fixed link and name of the tweeter driver. . . genius!

[Rike43]

Crossover notes: I will be following the crossover recommendations as closely as I can based on available materials. As far as I can tell, these are 3rd order Butterworth passive crossovers (-18dB rolloff) shooting for a 4K crossover point between the high and low pass filters.

I got some PartsExpress gift certificates for my birthday, so I decided I would get not bargain-basement crossover components. I probably would not have bought ultra cheap components anyway, but this made it feel even more justifiable. I also went a little crazy and bought some PE 4% silver solder.

Most caps will be Jantzen Standard Z-Caps with a Solen Polypropylene Cap thrown in to get closer to the recommended values (all these caps are spec'd for a 5% tolerance from the manufacturer). The coils will be mostly Jantzen Audio 15ga or 18ga with one Dayton Audio 14 ga coil. For five of the caps and coils, I was able to find exact matches for the recommended values. For those I could not find exact rating for (2 caps, 2 coils) , I am well within the recommended ±10% range (1 cap @ -1.7%, 1 cap @ +2%, 1 coil @ +5%, 1 coil @ -6%).

I understand that some people will buy oversized coils and then partially unwind a turn or two to get a custom value, but I'm not there yet (I may never be ).

Some of the crossover parts are on backorder, so it's a good thing I'm not needing to build the crossovers any time soon!

[AntonZ]

Most rack mount pro amplifiers have fans that are always on. Noise from the fans will be no issue for live music applications. In your home theater it can be beneficial when silence is actually silent. You may want to look for specs on the fans in the Behringer amp. And find some reviews of people who have real life experience of use in a home theater setup.

Tuba 18 is very nice for the size (I own one). It is somewhat geared toward music reproduction. Depending on your taste in movies you may miss out on some extreme depth when compared to the likes of Table Tuba or Tuba HT. Think depth charges in submarine movies, extreme explosions, earth quakes. Mind you, Tuba 18 is no slouch. The others go deeper yet.

[jimbo7]

I recommend you spend a little more on a sub driver. The MCM driver is fine, but I was tired of separating the cone from the surrounds. The Dayton DCS205-4 I put in my AT is way better, and only $10 more (holy $hit! I remember when the mcm's were $35!).

I also second Antonz's recommendation of the TT or TTLS (the right tool for the job). The THT requires a 12" or 15" driver.

The Behringer amp's fans are a little noisy (compared to other pro audio brands) and the suck from the rear and blow out the front. I have NU1000 powering my sub and it doesn't bother me, but you can hear it.

[Tom Smit]

I believe that I have read that there are replacement fans available that run much quieter.

[shane2943]

I'm using this to power my THTLP and it's plenty: https://www.parts-express.com/Dayton-Au ... er-300-806

It's also silent.

[Bill Fitzmaurice]

My TT 2x4 is powered with a 75w Dayton plate amp. The power sensor never worked, so it's been running 24/7/365 for twenty years.

[Rike43]

OK, loving the feedback and ideas!

If I were to get one of the Behringer amps, a fan swap will happen. I'm familiar enough with that type of equipment that would be no problem.

The Dayton Audio plate amps are also a very attractive option. I'm definitely going to keep them in mind, especially if it looks like room is getting tight.

Regarding subs . . .

Yes, I would like to go a low as possible, but I have size constrantaints in the room. My thought was a couple of Tuba 18s would help spread out the low frequencies in the room without being very big.

I have no problem with spending more on a driver, however, for subs that met the Tuba18 driver specs, the MCM 55-2421 goes down to 25Hz. Nothing else I've found that fits the specs goes that low. There is an is an SB Acoustics SB23MFCL45-4, 8" driver that is spec'd to 26Hz, but it is more than 2.5 times more expensive. The Dayton Audio DCS205-4 8" is rated to 30Hz. All of that said . . .

I also got plans from Bill for a THT Low Profile. I'm not sure about the implementation in my space. Even this version would have to be to put it in the attic or under the house in the crawl space and then have the outlet of the horn into the room. I know both of these sound a little crazy, but this would actually be doable for me when we gut the living room which is already in the plans. I've already gutted most of the rest of the house in the past and this would be doable for me. I just don't want to end up with too much bass in one part of the room and too little in another. A bass crawl or the equivalent is not a practical option for me since I need to meet my wife part way. (Even if it is the best sound in the history of humanity, a THTLP is not going to fly inside the living room. And a TT will not work with our furniture, no matter how nice I made it look.)

Whatever sub I end up going with, I will pretty much have to choose a spot for it and hope that spot doesn't suck.

[Bill Fitzmaurice]

the MCM 55-2421 goes down to 25Hz. Nothing else I've found that fits the specs goes that low. There is an is an SB Acoustics SB23MFCL45-4, 8" driver that is spec'd to 26Hz, but it is more than 2.5 times more expensive. The Dayton Audio DCS205-4 8" is rated to 30Hz.

The low frequency performance of a horn is determined by the horn, not the driver Fs. Too low an Fs is detrimental. The ideal Fs for the T18 is 35 to 40Hz, but drivers with sufficient Xmax tend to be 10Hz lower than that.

[Seth]

Your absolute best solution is to do the sub crawl, determine locations that work really well, test them to make sure, and do exactly as you stated below.

...put it in the attic or under the house in the crawl space and then have the outlet of the horn into the room. I know both of these sound a little crazy...

It's not crazy at all.

I recommend two of the THTLS, built as wide as possible within the limitations of your installation. You wouldn't need more than an inexpensive GRS driver.

[Rike43]

Well, it looks like I will be building a pair of Tuba 18s afterall. I had a pair MCM 55-2421 drivers on my wish list for Christmas and I got them. No matter how things go, I figure doing the smaller Tuba 18s will be good practice before trying the larger THTLS. And maybe I'll like the smaller cabinets just fine! Still a ways away from starting the actual build, so this gives me something to look forward to!

[Tom Smit]

Enjoy your build, Rike!

[Bill Fitzmaurice]

You can use the MCM in any of the TableTuba variations.

[Keryn O'Shea]

...I would like to go a low as possible, but I have size constrantaints in the room...

What are the actual sized constraints?
could you go for the STTLS, at 48x15x12..?
They can be built side firing and stood up in the corner. You could mock up a couple of carboard boxes that size, place them with a bottle of wine, flowers and chocolates on top.. then ask her if she approves.

[Rike43]

Thanks everyone for the feedback and ideas for the subs. I will take all of this into consideration once I move forward with building subs of one type or another.

Right now I'm slowly working on getting the LCR SLAs designed for the front stage. Please take a look at the attached picture of my CAD models. For size reference, the screen is a 103" diagonal screen (planning for a Seymour roll down acoustically transparent screen). And there is a rough model of a head in the main listening/viewing position about 10.5 ft from the screen.

The right hand side has a wall that extends all the way to the back of the room right near the edge of the speaker. The left side is mostly open into the dining area. For size reference, the screen is a 103 in diagonal screen (planning for a Seymour roll down acoustically transparent screen) . The lines extending from the tweeters are just my pointers, not part of the actual drivers. The L/R SLAs will be partly in the wall. The center will be built into the mantel roughly as shown. Everything will get grills with speaker cloth, but that will be the last thing I design.

How important is it to get the L/R SLAs to tilt down? Should they be even higher?

I think I'm on the right track, but I'm happy to hear any thoughts/feedback. Thanks in advance!