KS-160-21

Img_0439.jpg

Introduction
Prototypes
Enclosure
Crossover
Simulations
Measurements
Sound
Summary


Introduction

I had to try full line array because they are very rare as commercial speaker. I had experience with smaller line array with one planar/ribbon tweeter in the middle and 8+8 small full range drivers around it. Sound is really good; open, detailed, soft, bright and kicking. Main question was, is full line array giving any sound related advantages or not. Vertical listening area must be wider of course, and 2-way overrides possible integration issues between bass and midrange.

Technical specifications

General 2-way, line array, closed
Dimensions 290 x 1845 x 450 mm (W x H x D)
+ alu feet 20 x 50 x 400 mm
Volume 160 liters
Crossover 3300 Hz, 18 dB/oct LeCleach
Drivers 12 x Peerless HDS 6.5" Nomex (830875)
 9 x Fountek NeoCD2.0MB
Impedance 6 / 6 ohm


Prototypes

None.


Enclosure

Enclosure drawing: KS-160-21.pdf

IMG_3742.JPG
Outer walls and horizontal bracing
are 24 mm birch plywood.
IMG_3749.JPG
Support bars for back and front chamber separators
are MDF, 19 x 14 x 330 mm.
IMG_3750.JPG
Chamber separators are 15 mm birch plywood.
IMG_3751.JPG
Back chamber.
IMG_3754.JPG
Support bar of front baffle is MDF,
19 x 30 x 340 mm
IMG_3755.JPG
Both walls of front chamber are covered with Tyrotex.
IMG_3757.JPG IMG_3764.JPG
IMG_3765.JPG IMG_3767.JPG
Back chamber is 50% filled with polyester.
IMG_3768.JPG
The rest of back chamber is filled with 10 cm
E30 (30 kg/m3) plastic foam.
IMG_3771.JPG
IMG_3734.JPG
24 pcs Peerless 830875 and 18 pcs Fountek NeoCD2.0
IMG_3780.JPG
Visible holes in the veneers are filled with epoxy.
IMG_3777.JPG
Assembling of one enclosure took about 6 hours.
IMG_3813.JPG
IMG_3816.JPG
Internal cabling is Intertechnik Silber 2 x 2.50 mm2.
Consuption 7.3 m / speaker.
IMG_3825.JPG
IMG_3826.JPG Img_0439.jpg
Img_0434.jpg


Crossover

Schematic

KS-160-21_passive_filter_V1.GIF

There's no protection cap for the ribbons. Power amp should have output relays.

Behringer DCX2496 as active filter

KS-160-21D_20100625.xpc

Gain of power amplifiers:
- woofers 26.9 dB
- tweeters 19.1 dB


Simulations

None.


Measurements

Room response

HOLMImpulse 1.4.0.2
Distance 310 cm, 0º, smoothing 1/6 oct.
KS-160-21_FR_310cm_L+R.png

RoomEQWizard 4.11
Distance 310 cm, 0º, smoothing 1/3 oct. L, R, Avg
KS-160-21_FR_310cm_L+R+Avg.png
Too much lower bass on the left. Could be at the same level as midrange.

Filter response

830875

830875_FR_Filter.png

NeoCD2.0

NeoCD20_FR_Filter.png

Step response

Distance 310 cm, 0º
KS-160-21_SR_310cm_0deg_R.png

Lobing

Distance: 250 cm, 0° horizontal
- mic height: 100...118 cm
KS-160-21_FR_250x100-118cm_0deg_R.png

Impedance response

830875

12 drivers in closed enclosure of 160 liters
830875_ZR.png

NeoCD2.0

NeoCD20_ZR.png

Non-linearity

Harmonic distortion

1 pcs NeoCD2.0 without crossover
- scale 0 dB = 100 dB/1m
NeoCD2_HD_90-95dB-1m.png


Sound

Sound balance is quite neutral except too high level of lower bass on the left. Midrange is not totally open. Crossover should be lower, but ribbons can't be crossed below 3 kHz. Lower treble has light on-axis compensation for smaller directivity which allows higher sound pressures with loudness war -limited or  edgy material.

Integration of bass and midrange is trouble-free. Acoustiscs and placements may - and usually will cause some integration issues even the speaker is 2-way. Good integration of lower midrange is giving too much body with some recordings. EQ down at 250 Hz will help to emulate smaller speaker with "natural" floor reflection.

Sound is moderately rhythmic but not really fast and kicking with this kind of balancing and placements. Longer distance to front wall will change internal balance of bass range, increasing speed and kick.
Tracing of bass notes is better than average but not perfect. There are still lots of interaction between speaker and room which is attenuating some notes. Flatness of headphones is far and some level variations is generated even the bass is compressed into 1 dB. Pressure transient of bass notes will help bass tracing.

Maximum sound pressure is mostly enough. It's no PA but LF vibration keeps at least voles out of your garden.
Time alignment increases strength of piano and percussion, compared to multi-ways with radical phase distortion.

Sound is more like "they are here" than "you are there". Longer listening distance will increase "they are here" -feeling. Some ambience information of real or virtual recording place is transferred, but it is mixed to room acoustics. Soundstage is high but not needle sharp, deep and wide. Images are located logically, and phase effected in the front (not back). Panned mono voices are not shrunk and they are not jumping to the face if listening triangle is not too narrow.

Placements:

Listening distance 320 cm, elevation 105 cm
Distance between tweeter lines 285 cm
Tweeters on the inner edge of front baffle
Distance from front baffle to front wall 82 cm
Aiming towards listener (depends on delay adjustment in the DCX).

Summary

This is very good speaker but nothing lasts forever. 6.5" is a bit oversized with NeoCD2. Parallel woofer and tweeter lines is causing horizontal lobing. Monopole bass interacts with room more than cardioid, causing some trouble with placements.

Page updated 18.10.2010