THTLP Build - 12" Driver - Conversion from sealed enclosure

[premiertrussman]

Hey All,

After a year of stalling, I'm jumping back into this build finally!

Here's the deal, I'm converting my old Adire Audio RAVA into one of BFM's THT LP's. From what I remember from my previous research, the driver from that sub matches specs really closely to the recommended dayton 15".

Here is what I'm breaking down and using the components from

Adire Audio Rava

Uses the Shiva MKII Driver and a 250 watt plate amp.

Here are the specs for the Driver. T/S Parameters are on page 4 for anyone interested.

The Rava has served me well through the years, but I'm hoping for big things from the THTLP. The sealed rava is really punchy and fast, sounds great with music and does a fair job with most HT stuff (impressive to most novice HT goers) but falls off quickly with the lower frequencies.

The reason I'm tearing apart my sub instead of just buying new components is simply cost. The specs are the Shiva Mk II driver should work well, so I figured for the cost of 3 sheets of plywood, some adhesive and a few pieces parts, it worth a shot.
Everyone talks so enthusiastically about their THT's I can't wait to see what kind of a difference going from a small sealed enclosure to a large horn enclosure will do.

Wish me luck!

[premiertrussman]

Here is the theater its going in.

It'll go behind the screen wall. Which is the reason for the low profile choice. Its going to be a squeeze to get in even the LP. I'm hoping i can make a 24X18X72 fit.

[Radian]

You're gonna crap your pants when you experience the difference in output between the two alignments.

Here's mine pounding away on less than 5 volts. Essentially the same driver as the Shiva and in the original THT "cube" profile:

[premiertrussman]

You're gonna crap your pants when you experience the difference in output between the two alignments.

Can't WAIT! I started the whole process last year, even had the driver out...but we were still working on the house and still putting the theater together, and it just lost priority, so i stuck my rava back together and have continued to use it. But I'm finally putting the last touches on my theater, so I think its time to get back into it.

First thing im going to listen to is that THX mushroom hit thing at the end of avatar....I'm hoping I have to pick my guts up off the floor.

[premiertrussman]

Here's mine pounding away on less than 5 volts. Essentially the same driver as the Shiva and in the original THT "cube" profile:

BTW what are your mains and what did you record that audio with? Sounds pretty good for being a "handy cam"

[Radian]

The mains are 90's era Klipsch La Scala and filmed using the stock mic on a Canon GL1.

There's a lot more to that sound than just the mic on a camera though. A bit of elbow grease goes into to recording and presenting a good sounding audio track.

[Radian]

First thing im going to listen to is that THX mushroom hit thing at the end of avatar....I'm hoping I have to pick my guts up off the floor.

Beautiful theater room you've got there. THTLP would be a worthy addition.

I've got mine wall-loaded, and at -0 dB REF if it hadn't been for using a multimeter to see what it's actually doing, I've often thought I was going to literally break something when that mushroom shows up on screen. It gets that vicious. Seriously, unless you dial-in the system before hand, you'll be jumping for the remote.

I hope you've got good walls because it will gladly find any loose paneling for you.

[premiertrussman]

First thing im going to listen to is that THX mushroom hit thing at the end of avatar....I'm hoping I have to pick my guts up off the floor.

Beautiful theater room you've got there. THTLP would be a worthy addition.

I've got mine wall-loaded, and at -0 dB REF if it hadn't been for using a multimeter to see what it's actually doing, I've often thought I was going to literally break something when that mushroom shows up on screen. It gets that vicious. Seriously, unless you dial-in the system before hand, you'll be jumping for the remote.

I hope you've got good walls because it will gladly find any loose paneling for you.

Walls yes...its brick and lath and plaster...windooows....not so much...single pane 100 year old windows....I wanted to replace them anyway....

Whats the least expensive way to EQ one of these? I'm going to be kind of stuck with positioning...its got to go behind the screen wall...and I've got a choice of mostly right, or mostly left. Theres a fireplace mantel behind the screen...plus my two JBL S312II towers. So I've literally got two places to put it...so I may have to do some significant EQing to even things out from my listening position.

[premiertrussman]

Since I'm using a 12" driver is there any limitation to width that I'm not going to see an advantage by increasing the width?

I think I'm shooting for 24 inches, but if the advantages of extra width tails of at say 20" or something, I'd be inclined to build it smaller.

Just curious.

[Radian]

Whats the least expensive way to EQ one of these?

To quote Bill from another thread...

For a lot less money the Behringer FBD, used along with Room Equalizer Wizard software, has the same capabilities, making it worth considering as well.

I would also recommend any AVR that uses Audyssey MultEQ XT32, the Antimode 8033, or the MiniDSP (in combination once again with REW).

[premiertrussman]

Whats the least expensive way to EQ one of these?

To quote Bill from another thread...

For a lot less money the Behringer FBD, used along with Room Equalizer Wizard software, has the same capabilities, making it worth considering as well.

I would also recommend any AVR that uses Audyssey MultEQ XT32, the Antimode 8033, or the MiniDSP (in combination once again with REW).

Hmmm the AVR is prolly a route I will pursue...it seem that any stand alone EQ thats worth a crap is out of my price range for right now....and I'm going to need to update my AVR eventually anyway...My Denon predates HDMI...so....haha

Thanks for the tip!

[premiertrussman]

double post...oops.

[Charles Warwick]

I would also recommend any AVR that uses Audyssey MultEQ XT32, the Antimode 8033, or the MiniDSP (in combination once again with REW).

I'd second that, with perhaps that caveat that the XT32 may not be necessary but as long as it's got the sub-EQ it's sufficient.
http://www.hometheatershack.com/forums/ ... z2DIAstzLO

[premiertrussman]

I would also recommend any AVR that uses Audyssey MultEQ XT32, the Antimode 8033, or the MiniDSP (in combination once again with REW).

I'd second that, with perhaps that caveat that the XT32 may not be necessary but as long as it's got the sub-EQ it's sufficient.
http://www.hometheatershack.com/forums/ ... z2DIAstzLO

Good deal. I didn't even know AVRs had Sub EQ's built in these days. When I finally do get an new AVR i'm sure the built in EQ will be sufficient for what I want to do. I won't be looking for flat, just something to smooth out the bumps.

Thanks again guys....Now i just need to make some sawdust.

[premiertrussman]

Here is the Rava sub disassembled. I'm really sorry Adire Audio went out of business. I searched long and hard for the best bang for buck sub i could at the time. If i remember right I got this sub delivered to my door step for like $375. Its been rocking out for a long time. In fact last night my son was watching finding nemo and it was shaking the whole house and doing it well. I cant WAIT for the THTLP...I think it will be the first time i'll have experience real bass. I'm hoping to get the low end tactile feel...I want to go from wow thats an impressive sub, to OMG WTF was that?!

Also, its not the MK II its actually the MKIII. I think all the T/S parameters are very similar though. Its foam surround with a kevlar/paper cone.

I just got to thinking...that driver is nearly 10 years old....is that any sort of an issue using it in this application? Whats the average lifespan of a driver like that? Its been used but not overly so...maybe abused...once or twice...