New to BFM, planning a medium-venue system

[yeahforbes]

Hi everyone,

So I've purchased the full CD and once I receive it I'll be able to figure some more of this out, but the help here is amazing so let's talk about it.

Content Type: Full live bands, very occasional DJing mixed in
Audience Size: Up to 300-400, indoors and outdoors

I'm considering 2 T48's or T39's, and 2 DR250's. I really like superlow bass, so the charts on the Tubas look nice, but I realize that a chest-hitting kick is more important. Seems that only the Tuba 60 can really be the best of both worlds, and that's just too big for my Toyota Sienna minivan. A covered trailer would be ideal, but that's probably another $2000 or so.

bgavin and Mikey have started on this for me:

With the advent of the 3012LF for T39, the only compelling reason for a T48 is lower bass extension.
If you don't need the extra 10 Hz lower, then T39 is ideal.
Think of T39 = 4-string bass, T48 = 5-string bass.

Balls-out T39/3012LF has to be -3dB at 42 Hz.
In English, this means your high pass filter must be such that 225 watts is the max input at 42 Hz.
Typically, this is a 45 Hz filter at 24dB/octave or better.

Note that the vast majority of noise is made in the first 100 watts.
Everything above 100w is a rapidly diminishing return.
The 3dB difference between 225w and 450w is barely audible and harder on your equipment.
If you need this last bit of noise, add more cabs.

And to answer that, I really would like the extra 10Hz even at the cost of packspace in the minivan. Or... maybe 4 T39's in lieu of the 2 T48's? Have to bust out the tape measure again to check the viability of that.

Another thing that might sound silly but has really been a consideration for me is overall height. I'm a fan of groundstacking rather than "speakers on sticks," so a 22" DR250 on top of a 48" T48 puts the top piezo just under 70" off the ground (5' 10"). Another foot is necessary for everyone in the audience to have unimpeded line-of-sight to the HF. Thoughts? Yeah, this means separated subs instead of V-coupling center stage, but that's how I roll. I know the wave propagation theory and have found that in practice the nodes aren't a huge deal.

Next, is there any information on max SPL? All I've really seen are the sensitivity charts and I know the wattage limits from Eminence but then people say not to max out the drivers. I'm a bit confused when a BFM box is directly compared to say an EAW box on the main site for 1-box-to-1-box price/sens comparison and then someone says you really have to compare $x worth of BFM to $x worth of EAW to be fair (x being equal). Basically, higher sensitivity (less amp power) is awesome in many ways, but I need to know about max load. $x worth of BFM can play the same as how much EAW / JBL MRX/SRX?

Finally, I think the best way to understand all of this would just be to listen for myself! Definitely willing to drive a reasonable distance from northern New Jersey if anybody has an upcoming gig or the time to demo outside.

Thanks for helping yet another noob!

P.S. Already read through everything on the main site, and probably 50+ threads on the forum, so I've heard a decent amount of the typical stuff.

[BrentEvans]

Content Type: Full live bands, very occasional DJing mixed in
Audience Size: Up to 300-400, indoors and outdoors
<snip>
I really like superlow bass, so the charts on the Tubas look nice, but I realize that a chest-hitting kick is more important.

In sales training, we learn the concept of "selling out of your own pocket" and why it's bad to do so. Briefly, we have a tendency to sell to others what we like for ourselves. This is a natural human tendency, and I think you're experiencing this a bit with your decision.

Based on your content (unless your live bands are playing EDM) you don't need anything more than T39s. 42hz is low E (fundamental) on a 4 string. 5 string goes down to about 34hz (fundamental). However, with these instruments, most of the power is in the harmonics, so even T39s are usually sufficient.

For many people, what is percieved as "low" bass is not actually that low.

Here's a neat chart that may help you understand this.
http://www.phys.unsw.edu.au/jw/notes.html

[bgavin]

My decision for T48 over T39 is partly due to trailer necessities.
I have to trailer no matter what, so it is just as easy to haul T48.
Four is my space limit.

Mix 'n Match is the smart way to build your gear.
Mine always lives in my trailer, but I can still leave half in the trailer for small venues.
My band plays a number of gigs where a small T39 corner loaded and two OT112 would be over kill.
Others are outdoor venues where six OT212 and four T48 are needed. This is my trailer limit.

My thoughts on the tops:subs ratio favoring the tops is, I like to run more tops and throttle them back for cleaner sound.
I'm not interested in supporting anything that requires more cabs.

As you plan your system, try to be realistic with your needs.
Unless you are a dubstep type, you really don't need 30 Hz, and the huge cabs that produce it.

[yeahforbes]

You guys have me convinced on the low end. But even disregarding the low extension, there seems to be way more sensitivity on the 24" T48s between 60Hz-90Hz (107dB) compared to various T39s. Eh?

Seems like I should put the DRs on sticks downstage and put the subs separate wherever the corners of the room are (upstage)? I've never seen at a gig what I am envisioning. Or, do I just want a pole between each sub and DR to attain proper HF altitude?

And if I decide to build another pair of DRs for outdoor shows, I suppose corner loading goes out the window so I'll have to ground stack and then poles won't be an issue.

[Bill Fitzmaurice]

I've never seen at a gig what I am envisioning.

That indicates that those sound providers didn't know what they were doing.

Or, do I just want a pole between each sub and DR to attain proper HF altitude?

Only if you want your sound to suck.

[SeisTres]

If you're only thinking about using the minivan, I would highly recommend the t39's as they are almost perfect when it comes to fitting correctly in a minivan. Build them all at 23" inches so you can have two rows of 46" worth of t39's or you could do 27" t39's and have two in rows and and two in a column which still pack really nicely into a minivan. With those four cabs, you'll have as much spl as you need for just about anything you will do.

But if you have a trailer, would like the extra extension, and are fine with the heavier and bigger t48's you could always go that route. But I really think that you'll be fine with t39's.

Here's a chart. (also keep in mind that you still have to eq them somewhat flat and that 50-60hz range is where the "beef" is at)



And last but not least, about using your subs for stands (ESPECIALLY folded horn subs), yeah, what Bill said.

[yeahforbes]

Wow, the line for the 30" T39 rides right between the T48s which I didn't realize previously. Are those graphs averages of a few builds or world records? Regardless, I'm definitely set on T39s now, 39x30x19.5. Since 2*19.5 will fit the width of the van easily, I can go for max cab width (filling the van's height).

Can someone link to a a few posts that include pictures of Titans used for live sound? I saw the DJ setup that made the wedding cake lean over, and corner loading in a situation like that is really easy for me to grasp because DJs very often set up against a wall. But I'm still a little lost regarding practical ways to boundary load on a live stage since the tops are so rarely near a wall. I know it's difficult to localize a point source for LF, but isn't it still fairly disconcerting to hear the LF and HF come from very different places? Must the tops be delayed?

[sine143]

tops pretty much need to be delayed. the subs will add at least 9 feet, then any distance between sub and tops must be accounted for.

[SeisTres]

Actually those graphs from Bill's prototypes. In pro sound, we don't "average" the results like other fields might. A measurement is simply taken from a finished product. Of course, these results should remain constant and are easily replicated since the drivers are usually pretty much identical and, if done correctly, the cab will also be identical.

These graphs are basically what you get from big name manufactures in the "spec sheets". They simply measure a speaker to make sure it has the they want and then, just compare everything else that is produced to guarantee that you get what it is advertised. But I'm pretty sure that the lower priced from cheaper manufactures, they just get massed produced without a final test.

Also, that's actually the reason why subs should not be your stands. Because, usually, a good place for a top will not be such a good place for a sub or visa versa. And if you can actually tell that the subs are somewhere else, they're very likely not being used correctly. When crossed over correctly, with the correct slope, and eq'ed to the tops as they should, they "disappear". Hence the mix becomes "whole" and you're left with a perfect L/R stereo imaging.

As for delaying, it's simple, if you have it, use it; if you don't, then no worries.

[yeahforbes]

Ok cool. Just to go back to the graph for a second... why is the 30" T39 so much better in this graph than on http://www.billfitzmaurice.com/T39.html? They seem to refer to the exact same cab, but
Former: 100 @ 43 Hz and 105 @ 65 Hz
Latter: 100 @ 65 Hz and 105 @ 85 Hz (maybe a pre-3012LF driver? I've gathered that that is a new development - how new?)

[sine143]

3012 came out sometime in 2009. I'm not sure why that graph is different, but the 30" inch titan is noooo joke.

[SeisTres]

Yeah, I believe that the one on the front page is the delta12lf. While most of the graphs on the spl tag tool are loaded with the newer drivers: mostly kappalites. And I think where it just says " 10 inch driver" it is referring to the s2010.

[yeahforbes]

Cool... that older graph was a main reason for my original hesitance in dropping from 48 to 39. The extra 5dB in the "beef" thanks to the kappalite is very reassuring. Hopefully Bill has a moment to update the chart for others in my situation.

I think I am now ready to buy some materials once my CD arrives. Oh, and 4 wedgehorns (not sure which variety) will be the next phase after FOH. Anything in particular I should know about that?

[LelandCrooks]

Use the beta 10a in WH10's. I heard very little difference between it and the 2510.

Unless you need extra power handling, use the beta 8 in the WH8's.

The wedgehorns seem to be the exception to the rule that the premium drivers are always worth the money.

[Bruce Weldy]

Can someone link to a a few posts that include pictures of Titans used for live sound? I saw the DJ setup that made the wedding cake lean over, and corner loading in a situation like that is really easy for me to grasp because DJs very often set up against a wall. But I'm still a little lost regarding practical ways to boundary load on a live stage since the tops are so rarely near a wall. I know it's difficult to localize a point source for LF, but isn't it still fairly disconcerting to hear the LF and HF come from very different places? Must the tops be delayed?

I have my tops delayed 7 feet (I believe that is the correct amount for T39s). I don't have any pics of boundary loading inside, but we've been playing a pavilion with two sides open and I just put 'em up against the wall next to the stage and have ample coverage all over the place and way more volume than we need.

Here's some pics of and outside venue with the T-39s V-plated...