New to BFM, planning a medium-venue system

[jcmbowman]

I was reading over this and saw the following:

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.

...

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.

I know you've read a lot of what's on here, but let me put 2 and 2 together for you to help understand why clustering subs is so important...

The average split bass stack that you find in practice will be a stack of traditional direct radiators. These cabinets generate a fair amount of harmonic distortion above the subwoofer passband. Oftentimes, this distortion becomes associated with "loud bass" and since it is at a higher frequency, it does not suffer the same destructive interference that subbass frequencies do when subs are split. I practice, this means that even though the actual thump of the kick drum may come and go as you walk between a split stack of direct radiator subs, you'll still hear consistent volume because of the distortion.

Horn-loaded subs, on the other hand, filter out virtually ALL of that harmonic distortion. This leads to a much cleaner sound, but it also makes it much easier to identify nodes when you split your subs. It becomes clearly obvious as you walk the soundfield in a configuration like this where there is punch, and where there is none.

So, It's your rig, and your gig, and you'll do what you want, but please try doing a comparison of clustered vs. split once you have your BFM subs, and I'm confident that you'll never go back to split.

That said - For getting proper altitude for DRs, several forum members have built frames, stands, scaffold systems, and others to get the proper height and appearance for a groundstack.

[yeahforbes]

Makes a whole lot of sense now, thanks for that. I do have a pair of Proline stands laying around, so they'll be recommissioned. At the end of the day, the sound matters infinitely more than the look. At the beginning of the day though, well, I'll get through it by spreading the knowledge!

I do have some gigs that would be perfect opportunities to V couple. It's just the small rock shows where teens rush the stage that I'm pondering over. Maybe the subs will be clustered in the backline if there is space for them (but always <3' or >10' from the wall).

There's another thing... What are some good principles for happily integrating subs with the bassist's SVT 8x10? I always take a DI but only put it through if the audience can't hear it from the backline.

[sine143]

If your stage is more than 8 feet from the wall, you can just stack your subs up stage left or right, in a vstack. The omnidirectionalness should take care of it. If the stage is elevated, you can v them under stage maybe.

[Sydney]

What are some good principles for happily integrating subs with the bassist's SVT 8x10? I always take a DI but only put it through if the audience can't hear it from the backline.

Dave Rat describes that sort of integration scenario in one of his YouTube vids.
( I don't remember which one offhand )
http://billfitzmaurice.info/forum/viewt ... 18&t=12263

On a linguistic side note: I believe that's omnidirectional-ness

Syd

[yeahforbes]

If your stage is more than 8 feet from the wall, you can just stack your subs up stage left or right, in a vstack.

Sounds good. But if the stage is small and doesn't have room for a V (that's 7' x 3.5' of floorspace for T39s if I know my geometry) and the Titans will be forced upright, should they be side by side (5' x 1.6') or stacked (2.5' x 1.6')? If stacked, should the bottom one be upside-down? Perhaps there is an answer for boundary loaded as well as boundary-less.

[sine143]

The vplated stack is around 68 inches wide I believe. Think about it, the longest dimension on the 39 is well... 39. 39 x 2 is 78. This is the widest they can be with 2 cabs. You stack the vplated cabs on top of each other.

The vplate gives you 3 extra db, thats why its to your advantage to use it.

[yeahforbes]

Measuring a V-coupled pair from left corner to right corner is like measuring the hypotenuse of a square having a side length of 39"+19.5" therefore sqrt(58.5^2 + 58.5^2) = 83 total width across the stage. Yes, I will do it whenever possible. But certainly I will run into a situation with not enough lateral space and my pair will be coupled by a plain stack or side-by-side... which?

[Bruce Weldy]

Either stack 'em on their sides or stand them up next to each other. Another option is to lay them both on their sides in a row with the bottoms together.

[klampykixx]

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

071510 CITP3.JPG

071510 CITP.JPG

that looks like a really neat setup. how did it sound like that?

until discovering BFM cabs, i always thought that keeping the subs left and right helped the dispersion. oh so wrong...

[Bruce Weldy]

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

that looks like a really neat setup. how did it sound like that?

until discovering BFM cabs, i always thought that keeping the subs left and right helped the dispersion. oh so wrong...

It sounded great. A lot of folks were impressed that that little system was so loud. Now that I've gotten better at tuning it up - it's even better.

I've learned a lot here that was counter to what I had always believed. And putting the subs together makes a huge difference. I've both played and run sound at that outside venue in the pictures many times over the last 25 years - and had always noticed the power alleys and never knew why. Now I know and it doesn't happen any more.

[klampykixx]

awesome, so are your bass cabs tubas or titans? will a pair of tuba30's in the same config be ok for a kick drum like that or better suited to EDM?

or better question, do you even run the kick drum thru the horns at all? probly wouldnt need to would you?

[Bruce Weldy]

Subs are 25" T39s. The whole band runs through the system....Sorry, don't know what EDM is...and yes, the kick drum runs through the system.

[yeahforbes]

EDM = electronic dance music, i.e. synth kick/bass instead of acoustic.

My apologies if this will be addressed in the plans, but what do I need to know regarding amplifier power for the T39s and DR250s? In the past with conventional speakers, I've always followed the "2x the program rating" rule with great success. I set limiters on my DriveRack PA such that the amps don't clip but are on the verge. With folded horns, am I to be more worried about overexcursion (peak) than heat (average) or is it basically the same principles as with direct radiators?

[LelandCrooks]

Overexcursion. 1x the power is appropriate. More doesn't hurt anything, just limit it properly.

[yeahforbes]

http://eminence.com/pdf/kappalite-3012lf.pdf
"Watts 450W / Music Program 900W" - The limiting should be at which of those?

I also read somewhere that some people exceed their Xmax by 10% on subs since the distortion isn't a big deal, and the Xlim is still a safe distance away. Any truth to that? Probably not worth the stress.