Greetings!

[DavidMW]

I'm a minister in Calistoga California. I do live sound for the community on a small scale. I have borrowed many Point Source speakers, JBL MP415's, Eons, Mackie's C200 to name current. I need my own though and so am looking here and am really excited.

Initially I plan on doing some SLA's and a T24 and if I can handle the woodwork, try a DR200 or 250. I wish I could hear some of these but can't find anyone near by... sigh.

I don't know if this is appropriate here, but I do have some questions...

I am researching a SLA build and am concerned that there will be lobes creating destructive interference between roughly 900 hz and 3500 hz. I have read in the forums that math attempts to model the speaker, so am asking those who have heard these, are there issues in those 2 octaves? Is it pronounced at under 30 feet and diminishes beyond? Off axis worse?

I really need to hear some... Also intrigued as to why the tweeters are set vertically and not horizontally.

Anyhow, good to meet you all!

[doncolga]

Nice to meet you David. Fantastic site you've found here. Good luck on your planning and builds.

[Grant Bunter]

Hi DavidMW,
G'day and welcome to the forum

I know you included your location in your post, but go to user profile and pop your location in there, in case it's missed when someone reads you post.

I can't comment on the lobing in the frequencies you mention. That's for other builders and Bill to address.

Welcome to your world of learning!
You can and will learn heaps here about sound reinforecement from some very knowledgable people with vast experience in the industry, and the rest of us who are trying to catch up.

I can help to some extent about your tweets question (V vs H):
Having tweeters side by side horizontally exhibits itself with comb filtering, as people walk past the cabs from one side to another or reverse.
You will find it said here that it is not a good way to set up cabs side by side in the horizontal plane, but rather stacking vertically is best practice, because of comb filtering.

Having the tweets vertically reduces this effect. It's still there, but people do not tend to go up and down to the same degree they go across (unless they're on pogo sticks or trampolines haha).

Also, placing the tweets vertically has them acting as a line array, raising sensitivity and narrowing vertical dispersion.

Hope this helps...

[DavidMW]

Thanks Grant, I thought I had put that in the profile, just changed it!

My comment about the tweets was misleading. I should have said something more like, "Why are the tweeters arranged like a DR200?" I am sure there is an answer, but by the looks of it the tweeters in the SLA are set to have 90 degree Vertical dispersion and 40 degree (or whatever those horns are designed for) Horizontal.

I guess I should just build some and listen for myself! In the recording program we always said, "trust your ears!"

[Grant Bunter]

Thanks Grant, I thought I had put that in the profile, just changed it!

My comment about the tweets was misleading. I should have said something more like, "Why are the tweeters arranged like a DR200?"

Sorry, you lost me!
Do you mean the various tweeter arrays in the DR200?
Just in case, there are two different piezo based arrays in the DR200.
The melded array, which has around 120 degrees horizontal dispersion (wider than any commercial cab and great for up close audiences) and the flat piezo array which has horizontal dispersion more like 90-100 degrees, better for audiences further away from the cabs.
In both cases the arrangement of the piezo's vertically is for the same principles I mentioned before.
There is another option for HF, the compression driver horn, as well.

I am sure there is an answer, but by the looks of it the tweeters in the SLA are set to have 90 degree Vertical dispersion and 40 degree (or whatever those horns are designed for) Horizontal.

From what I know of Bill's designs, horizontal dispersion will always be greater than vertical dispersion. If your figures are roughly accurate, they will likely be reversed, ie 40 degree vertical and 90 degree horizontal.

No point "wasting" dispersion to ceilings and floors (and their resultant reflections) with 90 degree vertical dispersion.

I guess I should just build some and listen for myself! In the recording program we always said, "trust your ears!"

There's always that

[Tom Smit]

Welcome to the forum!

Grant has most of the answers covered, so........

[DJPhatman]

DavidMW, welcome to the forum!

Are you wanting to get your feet wet by doing a home use build (SLA) or a Pro build (SLA Pro)? This does make a difference.

As for building T24, I would encourage you to build T39s instead. T39s go both lower in extension and much louder, giving you the most bang-for-buck subwoofer enclosure. Spend the extra $$ and build them with the Eminence Kappalite 3012LF, and make them as wide as you can transport.

Once you knock out a pair or 4 of the T39s, take on 4 DR250s. They are time consuming builds, but are so worth the time. You will scowl at the JBL, Mackie and other commercial offerings in the sub-$1500 per cab range, and sound so much cleaner doing it. Imagine doing 500 people, outdoors, using only 4 amp channels and 1 20 Amp 110V outlet! 4 DR250, 4 30" wide T39s and 2 Crown XTi or Peavey IPR with DSP amps get you there. Add in your mixer (you do have one, right?) and wires, and you are golden.

You might also want to think about monitors. How about some Wedgehorn 6s?

[DavidMW]

Are you wanting to get your feet wet by doing a home use build (SLA) or a Pro build (SLA Pro)? This does make a difference.

SLA Pro, my apologies for the confusion.

As for building T24, I would encourage you to build T39s instead. T39s go both lower in extension and much louder, giving you the most bang-for-buck subwoofer enclosure. Spend the extra $$ and build them with the Eminence Kappalite 3012LF, and make them as wide as you can transport.

As I tend to do all my own lifting, I was thinking lighter. (I hate 60 lb cabs!) but I will relook at that idea... drool!

Once you knock out a pair or 4 of the T39s, take on 4 DR250s. They are time consuming builds, but are so worth the time. You will scowl at the JBL, Mackie and other commercial offerings in the sub-$1500 per cab range, and sound so much cleaner doing it. Imagine doing 500 people, outdoors, using only 4 amp channels and 1 20 Amp 110V outlet! 4 DR250, 4 30" wide T39s and 2 Crown XTi or Peavey IPR with DSP amps get you there. Add in your mixer (you do have one, right?) and wires, and you are golden.

Yes, using a compact Yamaha right now, but looking at the Mackie 16 channel iPad mixer, sweet!

You might also want to think about monitors. How about some Wedgehorn 6s?

With plate amps built in. YES!

Sounds great, but we'll conquer the SLA Pros first!

[DJPhatman]

SLA Pro, my apologies for the confusion.

Not a problem.

As I tend to do all my own lifting, I was thinking lighter. (I hate 60 lb cabs!) but I will relook at that idea... drool!

The T39s are not that heavy. And, their design makes them super easy to move around like a hand cart. Why lift when you can tilt and roll?

Yes, using a compact Yamaha right now, but looking at the Mackie 16 channel iPad mixer, sweet!

Skip the Mackie, and stick with the Yamaha. The Yamaha has much better mic pre-outs, they just sound better. Want to step up to a digital mixer? Seriously consider the PreSonus StudioLive 16 channel mixer. Less expensive, better quality and features.

How about some Wedgehorn 6s?

With plate amps built in. YES!

Adding plate amps means you would have to run 2 wires to each monitor, power and signal. Also adds unnecessary weight to the Wedgehorns, along with complicating the build. You are better served carrying one 7 pound IPR amp than 2-4 heavier plate amps. A lot of folks think built in amps are "better", but what do you do if one of those plate amps crap out on you? You can't reall power it from another one, but if you use separate amps, you can use another channel in a pinch.

[Grant Bunter]

DavidMW wrote: How about some Wedgehorn 6s?
With plate amps built in. YES!

DJPhatman wrote: Adding plate amps means you would have to run 2 wires to each monitor, power and signal. Also adds unnecessary weight to the Wedgehorns, along with complicating the build. You are better served carrying one 7 pound IPR amp than 2-4 heavier plate amps. A lot of folks think built in amps are "better", but what do you do if one of those plate amps crap out on you? You can't reall power it from another one, but if you use separate amps, you can use another channel in a pinch.

Quite apart from DJP's response, there simply isn't room for a plate amp in a WH6...

[Tom Smit]

Heh, David, you're already finding out that this forum runs a little contrary to what is conventional. But, it is all for the better!

[DavidMW]

Heh, David, you're already finding out that this forum runs a little contrary to what is conventional. But, it is all for the better!

Everyone is entitled to their opinions. If convention on the boards are that one brand is superior to another, then I too may well be contrary... though not argumentative.
As my studio recording said, "Give me a mixer/cassette deck and a few SM-57/58's and I can record a great track." It ain't the equipment, it's the engineer and their knowledge of the strengths and limitations of the equipment. (and acoustics and such.)
I'm aware at 50 I can't hear much above 12K. I know my ability to hear midrange is diminished. I don't get complaints in my work. ( Well, some do say it's too loud... but that's a matter of opinion! )

[Bill Fitzmaurice]

I am researching a SLA build and am concerned that there will be lobes creating destructive interference between roughly 900 hz and 3500 hz.

There is no lobing beyond a couple of feet from the speaker.

Also intrigued as to why the tweeters are set vertically and not horizontally.

Horizontally placed tweeters result in comb filtering. Tweeters should never be placed horizontally unless they're in cross-fired arrays or CBT arrays that put all of the acoustic centers less than 1 wavelength apart. For the same reason speakers should never be placed horizontally unless cross-fired. Read this (and the subsequent chapters):
http://www.gtaust.com/filter/05/07.shtml

[DavidMW]

Thanks Bill!

I meant the SLA Pro, not the SLA for home theater. The thought I'm having is, why not a melded array like the DR 280? I know you've thoroughly designed and tested, just curious.

Read this (and the subsequent chapters):
http://www.gtaust.com/filter/05/07.shtml

I'll read that, thanks. The articles you linked elsewhere on "The Birth of an Array" were great! Thank you!

[Bill Fitzmaurice]

Thanks Bill!
I meant the SLA Pro, not the SLA for home theater. The thought I'm having is, why not a melded array like the DR 280?

SLA is a simple build. It wouldn't be if it housed a melded array.