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Old 20th May 2016, 01:29 PM   #1
M8e is offline M8e  Sweden
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Default Stepped line array?

First of all, don't know if this belongs here or in the fullrange forum. Using fullrange drivers but not playing all of them FR. (Technically a series 1.5 way?)

I have played around with XSim lately, and came up with a line array with a stepped baffle. Half the drivers playing fullrange, and half low passed at something like 5k hz(?).

The drivers stay in phase up to 6k hz, and at that point there's a ~7.5db diff between them.

Didn't use any driver data as this is kind of just hypothetical. Used 8 drivers in the circuit just to get the right impedance.

Pros and cons of doing something like this? Time smear? Comb filtering? Smaller difference in critical distance between low and high frequencies.
(2^2 * 3000hz)/700 = 17.14m
(1^2 * 12000hz)/700 = 17.14m
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Last edited by M8e; 20th May 2016 at 01:32 PM.
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Old 20th May 2016, 05:24 PM   #2
wmd916 is offline wmd916  United States
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I'm interested to hear what some of the more technically inclined will say about this approach. I am considering something very similar with the 60 Vifas I have. My approach would be much like an MTM/WMW configuration using 8-12 drivers in the center in OB similar to the Nola Grand Reference with the upper and lower drivers sealed to extend the bottom end. Looking forward to what "they" have to say.
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Old 21st May 2016, 09:56 AM   #3
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Hi, M8e, i do not understand the circuit, cannot see, where lines knot and where they only cross. Anyway, it seems, that thy plan becomes right, if thou exchange the step for a ramp, say use filters of first order. This is used, see CBT and Krassolito! As we are in a digital forum, i should also mention Horbach-Keele, which also has a symmetrical driver arrangement but uses finite-impulse-response filtering.

Last edited by Grasso789; 21st May 2016 at 10:05 AM.
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Old 21st May 2016, 04:22 PM   #4
M8e is offline M8e  Sweden
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There is no crossing lines in the circuit.

C1, L2 and C3 is a series 3rd-ish order low pass adjusted to phase match as far as possible(or at least match by a few degrees.) But then do "whatever". As it's series circuit there is no 0.5 way "gain".

L1 and R1 is a BSC circuit.

C2 and R2 is to adjust the high frequency response. Really just to compensate for the weird response caused by the series low pass doing "whatever".

Not really sure what you mean with a ramp. But I had I had in mind an focused/concave array, where the low passed drivers is offset forward. The simulation uses 0.98 inch, but that's just what I ended up with.
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Old 21st May 2016, 05:04 PM   #5
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Usually in line arrays the bass is the only stepped part. The issue is vertical lobing.

Imagine a time-coherent/aligned 2-way speaker, with a tweeter over a woofer. As you turn the speaker, your head remains in about the same distance from the drivers as if it was in front, so there's reduced phase effects and lobing.

Turning the speaker on it's side however, and now you are only aligned with the drivers when directly in front of them. Turn the speaker one way and you are much closer to the tweeter, the other, the woofer. This problem is actually made worse by the stepped baffle.

You'll have better vertical dispersion of a line array with a tweeter and mid in the same plane. See the early Genesis towers. I hear they had terrible crossovers, but the images are sound, or the larger Nola's or the Keele line array.

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Best,


Erik
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Old 21st May 2016, 05:13 PM   #6
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@M8e: Which drivers do you want use?
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Old 21st May 2016, 05:39 PM   #7
M8e is offline M8e  Sweden
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Right now it's kind of hypothetical. Not even sure if I or the idea is sane.

But maybe something like Monacor SPH-30x or Monacor SPX-31M, depending on length.

Full height line = cheaper drivers.
Half height = higher quality.


@eriksquires: In case I haven't been clear. All the drivers would be the same and all off them in a vertical line(seen from the front). ie the drivers playing fullrange would be closest to ear level and the low passed drivers above/below those driver.
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Old 21st May 2016, 05:49 PM   #8
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To get a sound as clean as possible do build every speaker in its own little cube, box. And: Everytime you could order the array in height, depth and so on.
What is the distance listener - speakers and speaker - speaker?
Which amp do you use?
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Old 21st May 2016, 06:33 PM   #9
M8e is offline M8e  Sweden
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Both distances is pretty much 3 metres. Right now I'm using an Onkyo tx-nr636, but I'm looking for something with better EQ.

I kind of like the idea of building individual boxes. Then I could try different configurations (Different focal points, pointing drivers to the focal point vs horizontally, different step depths, half/full height, ear level...).

The same boxes would be used for the surround satellites

Last edited by M8e; 21st May 2016 at 06:43 PM.
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Old 21st May 2016, 07:06 PM   #10
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Tzzz. Tzzzzzzzzzz,-)
A surround-story,-? Very very difficult to implement, in my mind.
X same amps, if possible se, ONE psu for all, including preamp. Same drivers, fullrange, bigger ones, because, my mind, without subwoofer...
Very very difficult to get a homogeneous, clean, clear sound. The most confuse EQ and much technology with clean sound, deepths, spaciousness ...
Tzzzzz,-)

My mind: First you have to build a good surround-amp - in my mind.-) You can not buy, nowhere in business, not for 1.000.000 $,-) I would build some 5 - 10 watt se, ONE psu. Very easy. Use a little cheap preamp, "decoder". Try to use the ONE psu.
My minds,-D

The Monacors will run very very good, stepped or not.-!
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