Jack 10s and Tuba 24s?

[jbass]

I just purchased the Tuba 24 plans and have two LaVoce SSF102.50L drivers arriving this week. My current plan is to use them along with my old-style Jack 10s (with tweeters) as the core of a basic PA for small/medium events (duos, full bands, DJ stuff, etc.), and I chose them for their size/weight and pack space considerations (a minivan at the moment). Here are my questions:

1. I know this isn't ideal because the Jacks are fullrange, but is it viable for now? I'll be using a crossover and separate power amps for the Jacks and Tubas.

2. Will two Tubas keep up with the Jacks or do I need more? I know two Tuba 24s are adequate for about 150 people, and I can probably manage a total of four if they're no more than 24".

3. Other than extension, is there any real advantage to building the Tubas beyond 24" given my size/weight limits?

4. How much power will I need to drive this system to a reasonable SPL (i.e., not stupid loud)? I'm thinking 200-300 watts for the Jacks and whatever for each pair of Tubas.

As this is a starting point using what I have available (the Jacks), my future plans include more suitable tops (DR200? SLAPro?), more/larger subs and a trailer of some sort. Right now I'm just looking for a way to get off the ground.

Thanks in advance for any advice.

[Seth]

1. I know this isn't ideal because the Jacks are fullrange, but is it viable for now? I'll be using a crossover and separate power amps for the Jacks and Tubas.

You can definitely use full range speakers as tops with subs, just high-pass them as you would if they were dedicated tops. Somewhere in the 80-125Hz neighborhood.

2. Will two Tubas keep up with the Jacks or do I need more? I know two Tuba 24s are adequate for about 150 people, and I can probably manage a total of four if they're no more than 24".

My guess is the Jacks will outrun two T24's. But, that's not a huge problem. Once the system is properly tuned, the T24's would just be the limiting factor of the system. Once they're into the limiter, you could technically continue pushing the volume up, but the subs won't get any louder and the sound will get thinner the further you push past that point. If you find you don't have enough bottom end for your needs, double the cab count... or just build four T24's from the get-go. If you can transport them, I'd highly recommend and suggest the T39 over the T24 in almost any situation. Not only are they more capable, they're much easier to wheel in, out, and about.

3. Other than extension, is there any real advantage to building the Tubas beyond 24" given my size/weight limits?

No.

4. How much power will I need to drive this system to a reasonable SPL (i.e., not stupid loud)? I'm thinking 200-300 watts for the Jacks and whatever for each pair of Tubas.

You'll probably only need 100 or so watts for the Jacks. For the subs, I'd recommend you get an amplifier capable of putting out a little more voltage than the suggested limiter setting for your drivers in whichever sub you build. To convert watts to volts, simply calculate the square root of watts times ohms. Example: 150 watts times 8 ohms equals 1200. The square root of 1200 equals 35 volts. Conversely, if you want to figure watts from volts and ohms, it's: Volts x Volts ÷ Ohms = Watts... 35 x 35 ÷ 8 = 150 watts

As this is a starting point using what I have available (the Jacks), my future plans include more suitable tops (DR200? SLAPro?), more/larger subs and a trailer of some sort. Right now I'm just looking for a way to get off the ground.

Give heavy consideration to switching to the T39. Way more potent.

Also, definitely plan on getting a Driverack to tune and more importantly, be able to properly limit the voltage to the subs. I think I have one listed in the for sale section. Shoot me a PM if you're interested.

[Bruce Weldy]

+1 To everything that Seth said. Especially about building T39s instead of T24s.....I have both.

[jbass]

Thanks to both of you for your advice. T39s are on my radar, but for now I need to keep the subs as small and light as possible. As such, I've ordered a second pair of the LaVoce 10s and plan to use two or four as needed.

How much of a performance hit would I take by building the Tubas at less than 24"? The cut sheet generator I'm using says I can build all four boxes from the four sheets of 1/2" ply I have available if I use an internal width of 19.5" (21" external).

[Strange Kevin]

If you really like cubes, or they just fit better in your current transportation, the T24 is an option.

Usually the benefit of using Tubas over Titans is a lower high-pass setting on the low-end at the expense of some sensitivity/output.
The High-pass setting on the T24 and T39 are the same 45hz, or 40hz with 4 or more cabs.

Sensitivity is where the 2 designs begin to differ. Looking at the responses charts for both with 10" drivers (S2010) especially in the 40-60hz region.
viewforum.php?f=12

A 24" wide T24 with 2x 10" is closest to an 18" wide T39 with only one 10" driver. So similar output, half the drivers, potentially less footprint (depending on how you stack them) with the T39s..

If planning to grow the system larger in a few years or so, the T39 is a little more scalable. Up to you either way, we just look forward to the build log!

[jbass]

Yup, pack space is one of the deciding factors for now. Do you happen to know if the LaVoce SSF102.50L is an option for the T39 design (I don't have the plans)? If so, I can just repurpose the drivers when I'm ready to move up.

[Bill Fitzmaurice]

It is.

[jbass]

Cool. Do you have any opinion on my 19.5" internal width question? I'm trying to avoid another harrowing drive with plywood lashed to my van, if possible.

[Bill Fitzmaurice]

The wider the better, so do what you must. But remember that you only get one chance to do it right the first time.

[jbass]

Fair enough -- especially with the cost of plywood these days. So, is there a huge difference between 21" and 24" given the greater Xmax of the LaVoce 10s and the fact that I'm building four cabinets?

[Bill Fitzmaurice]

Between 21" and 24" not huge with four cabs. Remember you can use scraps you have lying about for the braces.

[jbass]

Got it. Thanks.