Stupid Cheap Line Array

[gmcalabria]

SpeakerDave: yes, thanks, some credibility. Experience helps, experience and a fairly unlimited budget helps even more.

So the question becomes about the tweeter(s) again: what kind of harm does having a smaller tweeter array inside the woofer array create? Also, what does making an "expanded D'Appolito" array make (putting the tweeter in the center of the stack)? My plan would probably be for full floor-to-ceiling.

*After messing around with peizos my conclusion was that they are completly not workable as tweeters due to very uneven frequancy response that would require digital filtering to correct.

So what happens if I do have digital filtering? Are they usable or are they still too awful? It seems like a screechy/peaky 94 db sensitive tweeter will turn into an 89 db or less after eq-ing, no?

[gmcalabria]

what kind of harm does having a smaller tweeter array inside the woofer array create?

What I mean is, short collumn of tweeters on the side of the woofers (centered around ear level).

Also, what does making an "expanded D'Appolito" array make (putting the tweeter in the center of the stack)?

...WWWWWTWWWWW... configuration where the tweeter is in line with the woofers. This seems like it would have some problematic vertical dispersion, but I don't know if experience proves otherwise.

BTW, I'm fully aware of what comb filtering sounds like; I had installed those cheap Technics round "ribbon" tweeters in some old Onkyo towers. They overall were a big improvement in imaging, flatness, FR, etc, but created some NASTY comb filtering effects that could be heart easily by plugging one ear, turning the other towards the speaker, and moving side to side (relative to the speaker) even only an inch or two. Dispersion was horrible. I did wonder if a line of those would create a more even field since they may fill each other's voids.

[sangram]

As far as your stack of full-ranges go, how does the EQ curve look?

I'll be frank, the center driver (there are 11) is cut off below 4.5khz using a single capacitor, and the rest of the array isn't 100% symmetrically wired either. The rest of the drivers are wired to present an overall impedance of something close to 8 ohms, using inequal length impedance lines. It's a little messy in impedance terms but it works because there's no speaker-level crossover and the amp is able to handle it fine.

The EQ requires a 3dB shelf at about 6Khz (above which the 3" drivers have very little response and without the complex wiring, would require a much higher shelf), a cut at the -6dB notch frequency of the open baffle - though you'll notice the baffle is shaped to spread that frequency around a bit and make it easier to EQ, and a bit of tweaking to make the bass merge properly. My biggest issue is the very bad phase shift at the main crossover frequency of 330Hz given the orientation difference between the side-firing woofer and the upper bit of the speaker, obviously EQ is not the answer here but the speakers are 1000 miles away from where I live now so it can wait.

[speaker dave]

Originally Posted by gmcalabria

SpeakerDave: yes, thanks, some credibility. Experience helps, experience and a fairly unlimited budget helps even more.

So the question becomes about the tweeter(s) again: what kind of harm does having a smaller tweeter array inside the woofer array create?

If you mean a row of tweeters and a row of woofers side by side, that should give no particular problem. Each array has its own vertical directivity based on length, spacing and frequency. In addition you'll have a bit of lobing in the lateral plane when you cross over from woofer array to tweeter array. In the end it is no different than having a single woofer and a singel tweeter side by side. Best you can do is keep the two rows tight and try to crossover low. Lots of commercial systems have been configured that way.

Also, what does making an "expanded D'Appolito" array make (putting the tweeter in the center of the stack)? My plan would probably be for full floor-to-ceiling.

I find these more interesting and created a number of system under the XA (eXpanding Array) name at Snell. Done right you can get very constant vertical directivity, wider vertical dispersion than a line array (probably a good thing) and very even frequency response.

Patrick Bateman discussed one of them here:
D'Appolito Arrays with Waveguides

Regards,
David

[Tom Danley]

I couldn’t decide if I should post this earlier in the thread but it’s Friday so what the heck. While this fits your title requirements, I am not sure it is what you want to build.
On the other hand, there is something nearly hypnotic (or possibly narcotic) about this video.
Put headphones on and enjoy this multi-part line array “how to video”.

‪Linear Array - Line Array - Fake Bose L1 PAS Part 1 of 6 ‬‏ - YouTube

[18Hurts]

Originally Posted by Tom Danley

I couldn’t decide if I should post this earlier in the thread but it’s Friday so what the heck. While this fits your title requirements, I am not sure it is what you want to build.
On the other hand, there is something nearly hypnotic (or possibly narcotic) about this video.
Put headphones on and enjoy this multi-part line array “how to video”.

‪Linear Array - Line Array - Fake Bose L1 PAS Part 1 of 6 ‬‏ - YouTube

LOVE it, Tom!

After viewing that, I'm feeling much better about my Sony 5" Neo woofers and the Audax/JBL tweeter line arrays. They stand about 6 foot, two inches tall but at least I used 3/4" ply and a proper tweeter line/XO packed in tight. Since I don't have two 12" subwoofers with a "pipe" in them--I'll go with a proper tapped horn. I'm feeling positively exotic to use a Roto-Zip these days.

Thank you for the info, Speaker Dave--I've read about quite a few different designs be they shaded or full output; I went full output so I can stack them mono for guitar or vocals. Good to hear that 6 plus footers should not be shaded. Just something to mess around with in the garage, I might learn something and education costs money.

August project is learn Horn Response and build a single 10" tapped horn in an attempt to match the SPLs of the garage arrays. House paint to match then invite BarryV over so we can imbibe with a few barley pops, play some tunes, eat some BBQ and laugh at my "craftsmanship".

[AdamThorne]

Originally Posted by 18Hurts

August project is learn Horn Response and build a single 10" tapped horn in an attempt to match the SPLs of the garage arrays. House paint to match then invite BarryV over so we can imbibe with a few barley pops, play some tunes, eat some BBQ and laugh at my "craftsmanship".

oh man, you gonna write up your horn resp proj? I just downloaded it and had a look, hoping it would be self evident. It wasn't, and I've got other stuff to build before I do a deep dive on horn resp.... I'd follow your progress though.

[MartinQ]

Originally Posted by Tom Danley

On the other hand, there is something nearly hypnotic (or possibly narcotic) about this video. Put headphones on and enjoy this multi-part line array “how to video”.

Linear Array - Line Array - Fake Bose L1 PAS Part 1 of 6 - YouTube

That video is a trip and hurts so good it's hard to decide when to stop watching. Thanks for bringing it back up Tom, I needed some entertainment today.

Linear Array - Line Array - Fake Bose L1 PAS Part 6 of 6

[gmcalabria]

By price, I'm thinking about using one sensitive tweeter in the middle.
SpeakerDave: I think that I'm likely missing most of the subtlety here, so I'm curious how one picks a waveguide for this application. I'm sure I'm way off "ideal" here, but here's what I've been looking at:

http://www.eminence.com/pdf/APT80.pdf - $30 at PE

Eminence ASD1001 1" HF Titanium Horn Driver 1-3/8"-18 TPI
along with
Eminence BH410 1" Exponential Horn 1-3/8"-18 TPI
or
Dayton Audio H07E 6" x 6" Elliptical Waveguide 1" Threaded

Seems like close spacing is priority #1 in this case, but the small Eminence horn won't cross over as low as I'd like, and the larger Eminence horn is more of a horn than a waveguide. The Dayton seems well recommended, but is large, and the 4.5"x4.5" has a high x-over point as well.

Any recommendations? I know I'm shortcutting a lot of science here, but for one, I can't get that Eminence line array designer to work because I have Win 7 64-bit. Keep in mind that I'll be digitally EQing the hell out of this, so as long as the driver is clean/low distortion, I'm not worried about patchy FR issues.

[Radugazon]

Looks like not said yet, but if you use a single tweeter in the middle of an array of other drivers, you gonna have a problem as the level of a single source (the tweeter) decays twice faster than the level of a line source (the other drivers) according to the listening distance.

In clear, this means that the relative levels will be matched only at a specific distance : too close = too much treble, too far = not enough. Now, if you always listen from the same place it's less an issue as it could be in PA.
Hence the recommandation of an array of tweeters vs a single unit, could it be a compression, that will also extend dramatically the power handling of the whole system, one of the big advantages of an array...my 2 cents.