Hello! New guy here. (long read)

[Seth]

Hi I'm Seth. I live in Sacramento California and have been here for about two years out of Wisconsin, but I am a California native growing up on the beaches in LA. I'm 35 on the outside, 25 on the inside and intend on staying that way til I have grandchildren. I like fast cars, fast boats, sexy ladies, and loads of cash... none of which do I actually have. I've had a fascination with audio systems since I was a child listening to my dad talk about how cool his Pioneer speakers were. He used those things forever and finally gave them to Goodwill a year or two back. Most of my personal experience with audio has been in the car audio field, obviously starting in high school right when the whole boom car thing was the rage. Granted that's cool and all, I've always put quality of sound over quantity of sound. I did DJ for a couple years in the bar of one of my hometown restaurants, which was THE happening place back then. Which is the first time (other than Michael Jacksons World Tour back in 1980-whatever) that I ever had the experience of a full blown professional sound reinforcement system. How can you not love it? In my early-mid twenties I drooled over the JBL stuff in Guitar Center, then somewhere along the line I learned of EAW and a horn loaded sub they have with 2 12"s that outperformed the twin 18 cabs I was used to hearing. My ears perked up and I thought, no way! So, I did a little research. That's a lie, I did TONS of research. I read anything I could get my hands on. I was in love with the theory and comprehended every bit of it. I sketched out designs, calculated everything I could until the buttons on my calculator wore out. I was enthused, I could talk the talk, but I never did anything about it. I never walked the walk. And years pass by. And interests change to engines and blowers or turbos or boats or gas turbines or whatever my mind finds challenging and intriguing, and all the intricate details of the things I'd learned about whatever subject I was into in the past slowly fade away. Like the saxophone I'd learned to play in the 3rd grade. Give it to me today and squeeeeeek honk.

So anyway, I've got the audio bug again. I've been without any quality sound in my car for quite a few years now and I remembered this website as a place that had some pretty reputable plans and I don't want to spend all that time re-learning everything just to make some untested, unproven design. So, here I am. Spent a bunch of days reading everything and bought the plans for the AutoTuba, DR200, and the Tuba 24.

The plan is to make one standard AutoTuba and transplant my existing PC surround sounds 8" sub into it and stand it on end in the corner on 6"legs. Just a test subject to hone my wood skills back into tune. Then the plan was to build one for the car, a 1997 Jeep Cherokee. After a little measuring, I decided it would be best to build the tall version... and my mind started ticking. If you look at the profile of the vehicle itself and you were to place a horn sub against the back seat facing rearward, the resultant profile resembles a SERIOUS horn extension, opening up to a mouth of over 13.5 square feet!. I started to get excited, thinking of all the possibilities and the benefits of coupling horns, until I figured I might as well just build it (them) to just about as wide as I could fit in the space allowable. Let's see here... 42" between the wheel wells minus a little room for wiggling gives me 40", or two 20" cabs. Wait a minute. An 8" driver is only about*" wide. I may be able to fit two of them in there for added sensitivity and power handeling. So, that's plan #2. Two 20" wide AutoTubas with two 8" drivers each. Having a little difficulty figuring out which wiring option will be best. But, I'll figure it out.

Next on the drawing board... I can't decide yet. Not sure weather to do a DR200 or a Tuba24.

We'll see I guess.

Thanks for reading and nice to meet all of you.

[crockettnj]

That's dual DUAL TAT in one car!??!?

Your gonna be able to blow your windshield out of the car at will!!

good luck with the build, and welcome!

[Tom Smit]

Veery interesting (said in my best Klink voice)....interested in the result!

Two drivers in series will be 8 ohms. Add the cab impedance and you'll have 12 ohms. Have a second cab in the same fashion, and you'll be down to 6 ohms. And that's not too bad, really, when one considers the efficiency of these cabs.
Or, two drivers in parallel equals 2 ohms. Add the cab imp. for a 6 ohm imp. Second cab, in the same fashion, when paralleled to the first, will bring imp. to 3 ohms. Ooooo, that would be nasty.
Probably a 10 watt amp would be sufficient, lest the windows blow out.

[Seth]

Not looking to blow any windows out. While sheer volume can be impressive, my goal with the multiple drivers in multiple AT's is extension. One of my favorite audio experiences is feeling and hearing the sound of pipe organ pedals, just phenomenal when it's reproduced with authority. J.S. Bach's Toccata for example. Beyond that, I'd much rather push 4 drivers 20-25% of their potential than 1 at 80-100%. Seems like common sense for a reliable, long lasting system. And at $35 each for the drivers, I'd say that's cheep insurance. I'll keep you guys informed as I go through the build, just have to get the first one done for my computer/Home Theater first. So, maybe three weeks away from beginning the build for the car.

Thanks for the warm welcome and enthusiasm guys!

-Seth-

[paul_ulrix]

i have one autotuba in my small computer room, just 16 inch wide and with one tangband 8 incher and that's already plenty loud here for movies and music. ... those 2 doubles will sound very impressive, no doubt.

[jcmbowman]

Not looking to blow any windows out. While sheer volume can be impressive, my goal with the multiple drivers in multiple AT's is extension. One of my favorite audio experiences is feeling and hearing the sound of pipe organ pedals, just phenomenal when it's reproduced with authority. J.S. Bach's Toccata for example. Beyond that, I'd much rather push 4 drivers 20-25% of their potential than 1 at 80-100%. Seems like common sense for a reliable, long lasting system. And at $35 each for the drivers, I'd say that's cheep insurance. I'll keep you guys informed as I go through the build, just have to get the first one done for my computer/Home Theater first. So, maybe three weeks away from beginning the build for the car.

Thanks for the warm welcome and enthusiasm guys!

-Seth-

Really, seriously - build -one- double-loaded AT and see how it works for you, I honestly doubt you'll bother with the second one. The AT is designed for the cabin gain of a car, so you'll have all the extension you need. The plans specifically include instructions on the proper output voltage to set your amplifier to - best practices around here is to never run your drivers to 80-100%. I totally see what you're going for, I just don't think you realize you can get there with so little.

For what it's worth, I replaced a double 10" sub loaded with a pair of Boston Acoustic drivers with a single MCM 55-2421 loaded AT. The AT uses 1/6th the power, and is both louder and cleaner sounding. I've been to a few of the install shops around town where friends work and they all swear they've never heard a sub that's so musical, or that goes so low. Most often I get people asking how I got the low end of a 15" or 18" driver, but the tight punch of a 10".

[LelandCrooks]

Pipe organ. Real 20-30 hz tones. I think the bigger setup will be needed for extension if he's really wanting to get pipe organ response. I'm guessing volume is not the goal, as wide response with decent output is.

[Seth]

Really, seriously - build -one- double-loaded AT and see how it works for you, I honestly doubt you'll bother with the second one. The AT is designed for the cabin gain of a car, so you'll have all the extension you need. The plans specifically include instructions on the proper output voltage to set your amplifier to - best practices around here is to never run your drivers to 80-100%. I totally see what you're going for, I just don't think you realize you can get there with so little.

For what it's worth, I replaced a double 10" sub loaded with a pair of Boston Acoustic drivers with a single MCM 55-2421 loaded AT. The AT uses 1/6th the power, and is both louder and cleaner sounding. I've been to a few of the install shops around town where friends work and they all swear they've never heard a sub that's so musical, or that goes so low. Most often I get people asking how I got the low end of a 15" or 18" driver, but the tight punch of a 10".

There isn't any information about setting voltages in the instructions for the AT.

The plans state that you can make a double wide to house two drivers. My whole reasoning of making mine 20" wide was that I'd be able to fit two in the car and two drivers in each. I'm seriously taking into consideration your comments about making just one. A double wide, or double the width of the standard design would be 29 or 30" wide for two drivers. Would that be your recommendation for two drivers? That thought leaves me thinking... might as well just build two standard, to the plans, and have the versatility of using one or two. See. It's these thoughts that get me in trouble. What to do, what to do???

EDIT: See what all this thinking gets me into. If I did a "double wide" for 10" drivers, it brings me right back to the original 40" wide plan I had to begin with. I've always liked 8's though and don't plan on using 10's at all. But just the whole thought process of what = what and how to get what I'm looking for. JEEZ! Does anyone know how to turn that voice in my head off?

Thank you so much for your input. I value it greatly.

-Seth-

[Seth]

Pipe organ. Real 20-30 hz tones. I think the bigger setup will be needed for extension if he's really wanting to get pipe organ response. I'm guessing volume is not the goal, as wide response with decent output is.

Which was my original thought. If I'm going to do it, might as well DO it right the first time and not look back thinking I should have gone bigger. Consensus seem to be I won't need to go with all four drivers. So, the quandary continues...

[DJPhatman]

I'm with you, Seth!

I say, build them, dual loaded and as wide as will fit. You have nothing to lose but your self-control!

Build them with the MCM or the TangBand 8" driver. Finding a 10" that will fit, and work as well, is a crap-shoot at best. For the money, 4 MCM 55-2421s will work very well. I run mine (single TB) band-passes 20-80Hz, and it's quite happy.

[jcmbowman]

For the record - a double-loaded doesn't mean twice as wide as a single. I believe you can do a dual-8" with a box that's 18-20" wide if you offset the drivers a bit. If it were me I'd go with 20" wide.

I totally get your original idea of doing two 20" wide boxes, each box with two drivers - that's a great end goal, My only suggestion was to build one first, and then evaluate and see if you need to build a second one. You'd be able to keep some of that cargo area in your car...

As far as the voltage... the MCM driver is rated for 120 watts RMS, so with a pair of those in an autotuba you'd want to be able to feed 240 watts into 6 ohms.

Following the formula: Watts x Ohms = Volts^2
You get the following: 240 x 6 = 1440 = volts^2
So Volts = SQRT(1440) = ~38 Volts.

Limit to 35 volts off your amp just to be safe, and you're all set.

[LelandCrooks]

HL10c's are still available if the tat can be modified to fit.

[Seth]

For the record - a double-loaded doesn't mean twice as wide as a single. I believe you can do a dual-8" with a box that's 18-20" wide if you offset the drivers a bit. If it were me I'd go with 20" wide.

This is a direct quote from the instructions: "You also may build a doublewide, to house two drivers."

The standard is 15", minimum 13", max 18" for a single driver, double being somewhere between 26" and 36" wide, per the plans. I agree with you though, I think I can squeeze two 8's in a 19" wide panel (20" overall), I just don't know that it'll be "optimal". But, I'd be able to fit two of them between the wheel wells.

I totally get your original idea of doing two 20" wide boxes, each box with two drivers - that's a great end goal, My only suggestion was to build one first, and then evaluate and see if you need to build a second one. You'd be able to keep some of that cargo area in your car...

I really think this is be the best path to take. It would be nice to keep some of the cargo area for coolers 'n stuff.

As far as the voltage... the MCM driver is rated for 120 watts RMS, so with a pair of those in an autotuba you'd want to be able to feed 240 watts into 6 ohms.

Following the formula: Watts x Ohms = Volts^2
You get the following: 240 x 6 = 1440 = volts^2
So Volts = SQRT(1440) = ~38 Volts.

Limit to 35 volts off your amp just to be safe, and you're all set.

AWESOME INFO!!!
Do I measure the voltage while the speakers are hooked up or without a load? Is there a standard frequency to use when setting this or is it going to be the same across the board once it's set?

[Gregory East]

Is there no displacement limit for these boxes?

[jcmbowman]

As far as the voltage... the MCM driver is rated for 120 watts RMS, so with a pair of those in an autotuba you'd want to be able to feed 240 watts into 6 ohms.

Following the formula: Watts x Ohms = Volts^2
You get the following: 240 x 6 = 1440 = volts^2
So Volts = SQRT(1440) = ~38 Volts.

Limit to 35 volts off your amp just to be safe, and you're all set.

AWESOME INFO!!!
Do I measure the voltage while the speakers are hooked up or without a load? Is there a standard frequency to use when setting this or is it going to be the same across the board once it's set?

Rune a sine wave test tone at a frequency within the passband for the sub, and measure using an RMS multi-meter -without- the speakers hooked up.


As far as the displacement limit on the boxes, I remember reading in the past that because of the minimal amounts of power going into the recommended drivers as well as their relative strength that it was not an issue to build a dual-driver too small as long as you're not using the HL10C or a similar displacement beast.