BillFitzmaurice.info

A friend of mine wanted a subwoofer so I said I'd help build a horn box for him. He drives a Hyundai Genesis Coupe and wanted to retain a lot of trunk space. We decided on a 4" wide TruckTuba with the recommended MCM driver. We're tapping into the stock subwoofer line to power it, as his budget is very limited, but it should be more than enough to rattle the ricer wing on the trunk lid. I used MDF and one tube of PL.

Horn path laid out and panels cut:




Ready for the final side:






I finished this thing in about 6 hours total with just a circular saw, jigsaw, and drill. It's also fairly lightweight and will have no trouble making a lot of high quality noise in his small car.

BM (that didn't sound right),
I am curious how it compares to vs. your other TrT with the MCM and also vs the other TrT with the Infinity. Please post reviews!

Pics of it installed?

The 4" TrT sounds good. On paper it doesn't hit as loud or as low as my 8" TrT, but in real life it sounds about the same. No pics of it installed, but it fits well in the Genesis Coupe trunk. For the small size of this subwoofer box, it packs a lot of heat. It has no problem rattling the life out of the cheap interior and impressing the bros, so I'd call it a success.

Installing the Infinity 860W turned my 8" TrT into a bass monster , considering it has 5mm more Xmax and double the RMS power handling of the MCM. The 860W will be my go-to driver from now on. Obviously neither of these can match the performance of the dual TT, but the Infinity 860W 8" TrT does a pretty good job keeping up until about 40Hz and below, where the dual TT then runs away from it.


I think a slim TrT loaded with the Infinity 860W (TrT just wide enough for the 860W's considerable mounting depth) could possibly be the perfect car subwoofer.

bassmonster wrote:
Installing the Infinity 860W turned my 8" TrT into a bass monster , considering it has 5mm more Xmax and double the RMS power handling of the MCM.

Does RMS rating in and of itself indicate greater SPL? I know greater Xmax does, as does cone area, but I thought greater power handling only directly means greater power NEEDS. All things being equal, that is (if that's possible. ) And then efficiency is in there, somewhere.

Rich4349 wrote:
Does RMS rating in and of itself indicate greater SPL?

Depends on at what frequency, we're comparing excursion limits to VC thermal limits at that point. Excursion at low frequencies is usually the limiting factor. Greater xmax= greater Vd. Efficiency isn't as relevant because it's the horn box, not the driver.

So a driver with greater efficiency, and everything else being equal (if that's possible. Ok, all relevant specs being equal) WOULDN'T produce more SPL?

Rich4349 wrote:So a driver with greater efficiency, and everything else being equal (if that's possible. Ok, all relevant specs being equal) WOULDN'T produce more SPL?

Go have a look at the T39 in the SPL charts section.
You'll notice that the S2010 and 3012lf charts are pretty much the same at 1 watt, as described in the text by Bill.

What's different between the 2 drivers?
Sensitivity is almost the same, within 1dB. Vd (as you'd expect from a 12" compared to a 10") is greater and Xmax is greater in the 3012lf , So is power handling and thermal limit. That explains it's +6dB maximum SPL compared to the S2010.

Lets look at the BP102 Vs S2010 though.
The BP102 is less sensitive than the S2010 by 4dB, but has greater Vd and Xmax in the same size package. With slightly higher Power rating and Thermal limt, the BP102 ends up with a +7 volt greater maximum output than the S2010. That's a couple of dB I guesstimate, maybe 3.

All this tells you, that in horns at least, it's Vd, Xmax, power rating and thermal limts that provide greater SPL, not sensitivity as such.
If 2 different drivers were otherwise = except 1 had higher sensitivity, the 1 with higher sensitivity may have a slightly higher measurable SPL, but that may not convert to a audibly louder SPL...

edit: Bassmonster, sorry for sidetracking your build thread. Nice work!

a bit late to the game but
Bassmonster or any one else,
what is " the dual TT"

is there a design for a dual TruckTuba?
can someone give a link or ow point me in the direction for such a build/
thank you

6 hours , sounds like fun . . .

His dual TT is a dual 8" driver Table Tuba.

I imagine my Infinity loaded 8" TrT would turn a small truck (say, a 90s Ford Ranger) into a pressure chamber. It would be intense.