Stupid Cheap Line Array

[18Hurts]

WR,

My Line Array Project Log

Here is the page that will show you what 49 of the Apex Jrs do when wired 7 series/7 parallel. 95dB from 5KHz to 16KHz with a 5dB down point at 90dB. Considering one tweeter is 90 to 93dB across the 5KHz to 20KHz band, it is not a large rise... I'm going to lower the impedance of my lines to bump it up to around 97dB which will work for me.

Since the tweeter lines don't have deafening output, I don't think running one 12 feet tall will increase output much--the mids would overpower them.

Greg, your RTA chart show a gradually increasing output with your 14 3" array then compare it to the bumpy output of a single driver. This is making the large assumption that your RTA picture was in 5dB segments?

If you change the filters for the mids to 2nd order, does that hump still stay there?

[gmcalabria]

Originally Posted by 18Hurts

WR,
Greg, your RTA chart show a gradually increasing output with your 14 3" array then compare it to the bumpy output of a single driver. This is making the large assumption that your RTA picture was in 5dB segments?

If you change the filters for the mids to 2nd order, does that hump still stay there?

yes, 5dB segments. The bump is increased by about 5 dB. Keep in mind that there's an L-pad in there, so where the peaks match, the shoulders are rounded like a bodybuilder's. The filter's curve is the darker, smoother line. Notice how it doesn't look like a table but a hill, and see how the peak between 2-3k is increased greatly by the filter. It sounds like the bump in the fr of that driver is electrically driven and the x-over designer is picking up on that. Again, I can work around it, but I'm having to use a 5k LR4 low pass on the mid and a 7k LR4 high pass on the tweeter in order to keep FR flat.

Greg

[WR Sugar]

Quick update - all drivers are on hand. I whipped up a couple 8 unit micro-lines with the 16 ohm NS3s (cute little guys) nudged the EQ on the top end (DEQ2496) and let em run open-baffle. I gotta say, this is a pleasing, natural mid-range sound. I also brought in a few Eminence APT200s to play with. I'm thinking of centering it in the line of NS525s and seeing what happens, forgoing the line of Audax Jr.s, altogether.

[18Hurts]

Good to hear you like the sound of the NS3s

A box appeared under my tree and it smells like NS3's to me

So are you going for a single line of the 5.25's with a line of NS3's next to it then squeeze in your bullet tweeters as needed? A much, much easier build than messing with the little tweeter lines--that would get old wiring in 24 feet of them.

[WR Sugar]

Hey congrats on that "new driver smell!"

It's not so much that I mind wiring and drilling for the tweeter line, it just seems like a compromise that doesn't need to happen with the 3s. I'm certainly going to give it a listen several ways. The little butt-cheek horns showed up busted, literally shattered, but man, do they ever match the scale of the NS3. So I gotta try it.

I'd like to think that 12 of the 525s and an APT200 would play nice together without needing to head up to the 3". Lots of options on the table. I'm making 3' test modules out of everything. Funny thing, the 3s already have started to sound very different than 4 hours ago. Much more relaxed. Just a good, solid sound. Fun stuff.

[18Hurts]

Good to hear the 3s are breaking in nicely,

Since it is winter in the garage--I'll make a cardboard box to lay the 3 inchers in
to break them in by groups of 8--hook em up, run some music through them and run back into the house.

Give the 5.25s a shot with the tweeters--ya never know. Always an option later to run the 5.25s with the bullets along the line somewhere with the 3s sitting next to them.

I've already drawn up the 3-way line box--they have swelled to 17.5" wide and I'll mount the Audax Jr 48 tweet line from the side of the box with hinges. If I need to move the things, just swing the tweet line forward and grab the handles on the side of the box. The boxes are 13" wide so that will work.

Might look weird when I move them but with 12 five inch woofers, 21 three-inch mids and 48 tweeters in each box--looks are rather bizarre anyway.

[WR Sugar]

Oh, then you'll be happy to know the NS3 packaging lends itself to spreading them around and hooking them up. Each driver has a little U shaped cardboard "upside down cradle" with a single hole for the magnet. They just sit there, looking up at you... all nice and cute, like.

[WR Sugar]

FYI: published impedance specs are way out.
NS3 measure 13.6 /published 16.
NS525 measure 6.6 ohm /published 9.

[18Hurts]

Originally Posted by WR Sugar

FYI: published impedance specs are way out.
NS3 measure 13.6 /published 16.
NS525 measure 6.6 ohm /published 9.

If you are reading it with an ohm meter, the DC resistance (RE) will be lower than the AC impedance (Z)

The NS3 does not have an Re rating but the NS525 does at 7.4 ohms. Generally they are rated +/- 10% so it is close to spec.

To get a wild guess at the impedance of a speaker, I just take the resistance with an ohm meter and multiply it by 1.2 or 1.25 to get close. 6.6 x 1.25 = 8.25 ohms so it is close.

Ohm meters put out basically a 0 Hz DC signal, impedance is AC and varies by frequency so that is why you get readings that you mentioned. The main thing to remember is not the ohm reading but the difference in ohm readings between each speaker.

If you want to see the resistance fluctuate....lightly press on the cone with the ohm meter on....it will jump. This also generates electricity so don't go crazy with it but something to notice.

[WR Sugar]

Yeah, just an LCR meter. The drivers are exceptionally consistent. Anyone have passive xo suggestion for the 525?