BillFitzmaurice.info

Hello all, its been a while.

I'm finally setting out to build a 2nd T48 to couple with my first 30" wide one.

The first was loaded with 2 x12s for lower impedance when running off of 12volt amps. In the end i've only used it occasionally in the 12volt setup and more often with mains power amps indoors.

I want to build my second T48 with a single 15", the recommended Kappalite 3015LF and if possible build it 29" wide instead of 30" (just a bit easier through my doors, and into the van).

Will either of these differences cause problems when coupled with my original Cab with a V-plate?

Also, is it correct that I can already lower the highpass for my subs to 35 hz when there are two of them at this size - As the mouth area is already large enough?

Nice to be back planning and building speakers

Ta,

Welcome back!

Bill will have to verify, but I seem to recall him saying that the phase response of the same cab, but with different drivers is generally okay to use together and that any mismatch in phase would be negligeable.

I'm just going from memory, but didn't we find out that the Vd of the two 12's you used in the last T48 equaled more than a 3015LF? Maybe I'm getting the memory mixed up with someone else's project.

The only issue I see with going 29" wide is easily solvable... When v-plating them you'd just have to put a spacer on one side. Otherwise, I don't see too much of an issue going an inch slimmer.

How has the one been doing for you? Obviously got you wanting more, but...

Hey Seth!

Thanks for getting back to me . In the end I just cut my panels to 29" so the cab will be 30" same as the other one. I figured the difference in manoeuvrability given by excluding the single inch wasn't worth it .

I love the wide T48. And recently I got a second crown macro-tech 2400 amp very cheaply - a little bar/club closed down nearby and was selling everything off quick - So i figured why not experience how these front loaded folded horns are meant to excell - in groups. Eventually i'll build more tops as well and have one amp for the 2 subs and one for 4 tops. I also really look forward to hi - passing a little lower as we are playing music with content lower than 40Hz.

the 12s in my first t48 are these:
https://loudspeakerdatabase.com/Fountek/FW322_4ohm
So the Vd for the 2 of them comes to 1030 cm3, In the single 3015LF its only 846cm3 So maybe i should just go like for like again? for long story reasons i actually own an extra identical Fountek 12 already, unused, I havent cut my baffle yet , and i havent opened my boxed 3015LF so i think i can return it . It would be cheaper to return the 3015LF and buy another fountek 12 and when looking at the Vd it seems like doing that would make a louder sub. The down side of 2 of the fountek 12s is that it makes the cab 11kg heavier and I think the drivers are built to a lower standard of quality.

What do you reckon?

Nice to be back

Hmmmm..

Unfortunately the supplier is being difficult about me returning the 3015LF driver I bought. Can anyone confirm that it will work well enough to V-plate couple a T48 with 2x12s and Vd of 1030cm3 with a second titan with 1x15 and a Vd of 846cm3. I'm wondering if the discrepancy in output will compromise the benefits of V-plate coupling them.

Thanks

Go for it!

Mishkin wrote: ↑Fri May 15, 2026 2:48 am I'm wondering if the discrepancy in output will compromise the benefits of V-plate coupling them.

The advantage of V plating is a longer horn path and larger mouth, so it always gives a better result.

Bill, I think he's more specifically looking for verification of whether it's okay to run a single 15 loaded T48 together with a 2x12 loaded T48 of the same dimensions. If it's no big deal, he already has the 15 and will just use that for the build. If it's less than desirable to mix-and-match in this case, he'll invest in more drivers and build the second cab as a matching 2x12.

The only issue is if he has to separately power and limit the two. If separately limiting isn't possible he'd have to limit to the lower capacity of the two.

An unopened 3015LF should be easy enough to sell on? Keeps it simple.