KS-585

IMG_3513.JPG

Introduction
Prototypes
Enclosure
Crossover
Simulations
Measurements
Sound
Summary


Introduction

Bass box is resistance enclosure with variable volume, prototyped couple of months earlier. Changes compared to prototype are SLS-12" drivers and two leaking slots more in resistance ports (per side). More leaking area is needed for bigger drivers. After all, leaking area is still too small, only 95% of Sd. Bigger drivers need also bigger enclosure, totally 29+29 liters here. Hole from front to back chamber is Ø55 mm to give same functionality as prototype.

MTM enclosure is "plastic foam burger", kind a side-firing damped U-frame. Mid-woofers are located on a golden section to allow wider baffle. Width of front baffle is Dd x 2.5 which would be too much without two drivers in a different horizontal position. Also 25 x 25 mm bevels enable wider baffle. Front wave of midrange cone travels directly to back about 40 mm longer way than back wave, which is ok. Leaking area of side ports is 132% of Sd.

Technical specifications

General 3-way, cardioid
Dimensions 330 x 1240 x 420 mm (W x H x D)
Volume 58 liters (bass enclosure only)
X/O frequencies 210 Hz and 2000 Hz
Drivers Seas 27TBFC/G, Monacor WG-300 wave guide
2 x Peerless HDS 6.5" Exclusive (830883)
2 x Peerless SLS-12" (830669)
Impedance 4 / 4 / 6 ohm

Prototypes

See:
Resistance enclosure with variable volume
Monacor WG-300 + Seas 27TBFC/G.


Enclosure

Front, back, top and bottom walls are 25 mm MDF. The rest is 19 mm MDF. Note! Side walls should be 20 mm birch plywood for better rigidity.
Enclosure drawing: KS-585.pdf

WW-enclosure
IMG_3458.JPG IMG_3469.JPG
IMG_3470.JPG IMG_3497.JPG
IMG_3502.JPG IMG_3503.JPG
IMG_3505.JPG IMG_3506.JPG
MTM-enclosure
IMG_3464.JPG IMG_3472.JPG
IMG_3474.JPG IMG_3475.JPG
IMG_3507.JPG IMG_3522.JPG

Crossover

LR2 (30.03.2008): KS-585LR2.xpc
LR4 (30.03.2008): KS-585LR4.xpc
Download Behringer DCX-Remote16a.exe to investigate these files.

Gain of power amplifiers:
Woofers +26 dB
Midranges +20 dB
Tweeter +20 dB

Connection of drivers

KS-585_wiring.gif

Simulations

Frequency response with LR4 filter
KS-585_FR-simu_LR4.gif

Phase response with LR4 filter
KS-585_FR-simu_LR4.gif

Step response with LR4 filter
KS-585_SR-simu_LR4.gif
Strong phase distortion is not a good thing with LR4.


Measurements

Crossover is LR2, if not mentioned.

Frequency response

Measuring distance 150...250 cm, 0°.
- time window: adaptive filtered PIR + 300 ms, no smoothing.
KS-585_FR_150-250cm_000deg.gif

Room response, effect of front wall

Measuring distance 260 cm, 0°.
- time window 170 ms, smoothing 1/6 oct.
- from speaker to front wall 80, 100, 120, 140, 160 and 180 cm:
KS-585_fw-080-180cm_000deg_300ms_1p6oct.gif
Response variations at bass range are as small as variations between different measurements in one location. According these measurements, cardiod doesn't generate effective reflections from back sector. Wall behind the listener reflects normally i.e. there will be location dependent response variations in shorter rooms.

Horizontal directivity

Measuring distance 125 cm, 0 - 90°.
- time window: adaptive filtered PIR + 300 ms, no smoothing.
KS-585_FR_125cm_0-90deg.gif

Floor reflection

Measuring distance 25 - 150 cm, mic on the floor, 0°.
- time window: adaptive filtered PIR + 150 ms, no smoothing
KS-585_FR_25-150x0cm_000deg.gif

Near field responses

SLS-12" frequency response
- time window: 600 ms, no smoothing.
KS-585_FR_SLS-12_near.gif

SLS-12" phase response
- time window: 600 ms, no smoothing.
KS-585_PR_SLS-12_near.gif

Responses on driver terminals

Filter LR4 (not the latest version)
KS-585_TF_XO-LR24.gif

Impedance response

SLS-12"
KS-585_ZR_SLS-12.gif
Note effect of resistance enclosure: Z peak at system resonance is very low.

HDS 6.5" Exclusive
KS-585_ZR_HDS-180.gif

27TBFC/G + WG-300
KS-585_ZR_27TBFCG.gif

Harmonic distortion

90 dB / 1 m
KS-585_THD_90dB.PNG

SLS-12" cone, near field
KS-585_THD_90dB_SLS-12-cone.PNG

SLS-12" resistance port, near field
KS-585_THD_90dB_SLS-12-port.PNG


Sound

Listening sector is wide enough. Listening over longer distances without dramatic resolution loss is possible. Longer distances also increase presence because of room interact.
Presence and naturality are no better than average when listening closer than 2.5 m. Reproduction is not very alive and wild. It's controlled, dry and clean - sometimes almost dull.

Tracing of melody is excellent, especially bass range is very easy to hear even the notes are not boosted and kicking.
Bass capacity is limited. Leaking enclosure sucks everything from the drivers and power amplifier. This size is ok for less than 20 m2 or lower sound pressures. Bass extension is adjustable with DSP. Capacity increases by limiting extension e.g. with high pass.

Tonal balance is neutral (adjustable) but some softness and distant of midrange exists regardless of adjustments. Maybe because of directivity steps of MTM-construction.

This kind of speaker is not very polite for bad quality recordings. Unnaturality and differences between recordings wil be relieved ruthlessly. Soundstage is sharp but one-dimensional, limiting between the speakers. Room is not generating soundstage which locates panned voices to small spots. Floating (floorless/roofless) sound is disturbing with vocals if recordings doesn't include natural or processed reflections. It sounds like vocalist and listener would be in anechoic chamber.

Location: 290...310 cm from tweeter to treeter tweeter. Listening distance 260...270 cm. Aiming towards the listener.


Summary

This design is not recommended because of complexity and too small leaking area of resistance ports.

Page updated 24.10.2010

Home

Copyright © Kimmo Saunisto, All Rights Reserved.