[aceinc]

I and another local audio hobbyist have decided to build line arrays. They are of two different designs. The core of his system is 23? 3" drivers with 4 ~20" ribbon tweeters which have a high xover (~4khz)

Mine have 16 - 4" drivers with 8 - 8" magnetic planar tweeters capable of crossing over as low as 400 hz.

They both have a similar problem with roll off above 10khz. I mention my friend's speakers in case there is a systemic issue with OB line arrays. I will be providing details on my system, perhaps the lessons learned will help him as well.

To be clear we both like the way our speakers sound. However when measured, the graphs aren't as flat as we would like especially the 10khz+ area. At present I do not have a way of measuring impedance, but here is a chart showing the two arrays (Midwoofer & Tweeter) with xover components installed individually, and the combined output.

The xover currently consists of;
Mid-bass (red) 140hz 6db high pass filter and 1,600hz 6db low pass filter.
Tweeter (blue) 1,600hz high pass filter.
Combined (green).

The measurements were done at the edge of a carport with a ~10' ceiling. The nearest reflection surface (other than the ground) was > 20' away. The microphone was ~10' from the front baffle of the enclosure approximately centered top to bottom & side to side. The bezel of the tweeters are ~1/2" away from the mid-woofers horizontally. The tweeters are physically touching vertically.



There are a few issues to deal with, but for the moment my primary concern is the drop off above 10k. One suggestion I have heard is there could be interference/cancellation/comb filtering between the mid & tweeter. however the mid seems to be 20+db down by the time it gets to 3.5khz. To me this makes interaction at 10khz+ unlikely.

The MFR graph for the tweeter does show a roll off above ~12k but not this steep.

Does anyone have any insight as to what I (we) could be dealing with?

One Idea I have is to insert a single 95db 3" planar tweeter in the center of the tweeter array with a capacitor giving a high pass filter at ~10khz. Any guess as to how that would impact the overall frequency response and sound?

[FullRangeMan]

Ace,
My unsolicited advice is you sell these planar drivers you have and make that OB LA I showed you in another topic, no crossover, no enclosure, no problems to be solved.

This your current project is very complex. If you want high-end sound, it would require years of research from a qualified team in acoustics and electronics. This project will give you only headaches and drain your bank account.
As always IMO.

[FullRangeMan]

But if you make question to own a 3-way boxed planar you could buy an vintage system as Infinity 1B or Infinity IRS Beta etc.
Infinity already had solved many of these operational probs.
https://www.youtube.com/watch?v=B5icAvhE3Dk

[aceinc]

Ace,
My unsolicited advice is you sell these planar drivers you have and make that OB LA I showed you in another topic, no crossover, no enclosure, no problems to be solved.

This your current project is very complex. If you want high-end sound, it would require years of research from a qualified team in acoustics and electronics. This project will give you only headaches and drain your bank account.
As always IMO.

To reiterate. I really like the sound. Additionally, I have had 4 audiophiles and a plethora of casual listeners praise the sound.

So even if I left them alone, they are impressive sounding. But being AR, I thought I'd see if I could fix the high end roll off.

[aceinc]

But if you make question to own a 3-way boxed planar you could buy an vintage system as Infinity 1B or other similar.
Infinity already solved many of these probs.
https://www.youtube.com/watch?v=B5icAvhE3Dk

I have 3 pairs of Magnepans in my HT. I have a pair of Eminent Technology LFT 8c sitting next to my OB line array, and I still find the new speakers head & shoulders above all of them.

[JakeJ]

I have 3 pairs of Magnepans in my HT. I have a pair of Eminent Technology LFT 8c sitting next to my OB line array, and I still find the new speakers head & shoulders above all of them.

As I have a pair of Maggie 3.6r, GR Research Venue One (OB cone & dome coaxial), and a pair of Super Seven's (to be built) I find that very interesting information.  My ears prefer planar treble over domes most of the time but of course there are exceptions.

[aceinc]

As I have a pair of Maggie 3.6r, GR Research Venue One (OB cone & dome coaxial), and a pair of Super Seven's (to be built) I find that very interesting information.  My ears prefer planar treble over domes most of the time but of course there are exceptions.

I am not sure I can say this categorically, but I have certainly gravitated towards planars, as evidenced by the Maggies, ETs and the new OB speakers I designed & built, which use Magnetic planars starting @ ~1,600hz.

[duck851]

As I have a pair of Maggie 3.6r, GR Research Venue One (OB cone & dome coaxial), and a pair of Super Seven's (to be built) I find that very interesting information.  My ears prefer planar treble over domes most of the time but of course there are exceptions.

As in SpeakerLab Super Sevens?

[JakeJ]

Uh...no.  These.

[ThePriest]

The microphone was ~10' from the front baffle of the enclosure approximately centered top to bottom & side to side.

What does it look like if your measure 1 m from the baffle?

The Priest

[S Clark]

What does it look like if your measure 1 m from the baffle?

The Priest

That's not how it's done with line arrays.  You've got to put the microphone further out.