Copyright 2014 by Martin J. King. All Rights Reserved. Configuration : Extended Range Driver w/ Bass Driver Mounted on an Open Baffle

Transcription

1 Open Baffle w/ 3 Drivers - Acoustic Response 12/3/1 Software : by Martin J. King MJKing57@aol.com Copyright 21 by Martin J. King. All Rights Reserved. Configuration : Extended Range Driver w/ Bass Driver Mounted on an Open Baffle Unit and Constant Definition cycle 2πrad Hz cyclesec 1 Air Density : ρ 1.25kgm 3 Speed of Sound : c 3msec 1 Part 1 : Thiele-Small Consistent Calculation Cable Series Resistance R add.ω Detailed User Input (Edit This Section and Input the Parameters for the System to be Analyzed) Power 1watt (Input Power) Applied Voltage Reference ---> R ref 8Ω Driver Thiele / Small Parameters : Lowther DX3 Average Driver Properties f d R e L vc Hz V ad liter V ad Ω R add Q ed R e R e R add. mh mh Q md Bl newton 1 1 Q td amp Q ed S 132.7cm 2 d 26cm 2 Q td.23 Q md 1 Bass Driver Thiele / Small Parameters : Eminence Alpha 15" High Efficiency f d R e L vc 1Hz V ad 26liter 5.88Ω Q ed mH Q md 7.23 Bl 7.7 newton 1 1 Q td amp Q ed S d 856.3cm 2 Q td Q md 1

2 Instructions : 1. A Zobel, Trap, and L-Pad are available for adjusting the Extended Range Driver's SPL output. 2. Select the crossover frequencies, orders, and types below. 3. Scroll down to the applicable crossover sections below and fill in the values of the circuit components. a. The theoretical values are shown to the right of each schematic. b, Theoretical values are calculated using only the driver's DC resistance, a textbook solution. c. Enter the actual component values, these should correspond to available components. d. Iterate the actual component values to optimize the crossover responses. e. You can mix the crossover orders and types by using only half of each pair of schematics.. Purchase the optimized actual component values and construct the crossover per the schematics. Crossover Definition For Even Order Crossovers : Type 1 = Linkwitz-Riley Type 2 = Bessel Type 3 = BEC Type = Butterworth Low Pass Filter High Pass Filter f LP 2Hz f HP 35Hz (Filter Frequency) LP order 2 HP order 2 (Filter Order :, 1, 2, 3, or ) LP type 1 HP type 3 (Filter Type : 1, 2, 3, or for even order only, for odd order this entry is ignored) Crossover Phase Connection and Extended Range Driver Attenuation LP phase 1 HP phase 1 (Phase : 1 = in phase, -1 = out of phase) L_Pad 3 db (L Pad Attemuation of Extended Range Driver)

3 Compensation Circuits (Default Actual Values Remove Circuits) Extended Range Driver Circuit Elements Zobel Components User Specified Compensation Circuit Values Suggested Values R zobel Ω Actual Values R zobel 1 1 Ω C zobel μf C zobel 1 1 μf Resonance Trap Components Suggested Values R trap Ω Actual Values R trap 1 1 Ω C trap μf C trap 1 1 μf L trap.856 mh L trap 1 1 mh L-Pad Components Suggested Values R parallel Ω Actual Values R parallel 1Ω R series Ω R series 2Ω

4 Woofer Circuit Elements Zobel Components User Specified Compensation Circuit Values Suggested Values R zobel Ω Actual Values R zobel 1 1 Ω C zobel μf C zobel 1 1 μf Resonance Trap Components Suggested Values R trap Ω Actual Values R trap 1 1 Ω C trap μf C trap 1 1 μf L trap mh L trap 1 1 mh L-Pad Components Suggested Values R parallel Ω Actual Values R parallel 1 1 Ω R series Ω R series Ω

5 Crossover Definition - 1 st Order High and Low Pass Crossover Definition - 2 nd Order High and Low Pass Schematic C1 + L1 - Tweeter Theoretical Values C 1 L μf mh + - L2 C2 Woofer L 2 C mh μf Enter Actual Component Values Below High Pass C 1 L 1 36μF R C1 Ω PE Part # mH R L1.7Ω PE Part # Low Pass L 2 C 2.7mH R L2.23Ω PE Part # μF R C2 Ω PE Part # Crossover Definition - 3 rd Order High and Low Pass Crossover Definition - th Order High and Low Pass

6 1 Electrical Crossover Curves Normalized Magnitude LP LP orderr HP HP orderr rdω Hz 1 Frequency (Hz) End of Detailed Input End of Part 1 Input

7 OB Driver Impedance 9 Phase (deg) argz r deg r Impedance (ohms) Z r r Frequency (Hz) Driver RMS Displacements (Red Curve - Woofers, Blue Curve - Extended Range Driver) 5 RMS Deflection (mm) x Lr mm x Hr mm rdω Hz 1 Frequency (Hz)

8 Part 2 : Detailed SPL Response Calculation Calculation Includes : Position of Drivers on the Baffle. Open Baffle Defraction for the Drivers. Floor Reflection for the Drivers. Geometry Coordinate System : Origin is the lower left corner of the front baffle y = horizontal direction z = vertical direction The variables num_r, n_low, and n_high control the number of simple sources used in the calculations. Increasing each will improve accuracy at the expense of longer calculation times. Increase each variable until final plotted SPL stops changing at which point the solution has converged. Enclosure Geometry Input X Y θ θ 1 Z 2ft 1.5ft 5deg deg 8ft stand m num_r 5 (Front Baffle Distance from Rear Wall > Depth of Enclosure) (Front Baffle Distance from Side Wall) (Rotation Towards Room Center) (Rotation Back of Baffle) (Floor to Ceiling Distance) (Height from Floor to Bottom Edge of Front Baffle) (Number of Points per Unit Length of Baffle Edge) Corner Coordinates Y coordinate y o y o1 y o2 y o3 2in Z coordinate 2in z o1 6in in z o2 6in in (Bottom Right Corner) (Top Right Corner) (Top Left Corner) (Bottom Left Corner) Extended Range Driver Geometry Input y dc z dc 12in in n_high 8 (Driver Center y Coordinate) (Driver Center z Coordinate) (Number of Points Across Diameter) Woofer Driver Geometry Input y w1 z w1 y w2 z w2 1in 9in 1in 26in n_low 15 (Lower Driver Center y Coordinate) (Lower Driver Center z Coordinate) (Upper Driver Center y Coordinate) (Upper Driver Center z Coordinate) (Number of Points Across Diameter)

9 Listening Position (Default Location is at 1 m Distance Along the Driver's Axis) n_listen = radius 3m θ z p deg 38in (Listening Position Relative to Speaker) (Calculation Radius, Effective Radius is Greater if y p is Changed from Default) ( deg is along the Driver's Axis, -8 deg < < 8 deg) (Default Height is Equal to Driver Height) n_listen = 1 X p Y p 1ft 7ft Z p z dc stand n_listen (Listening Position Relative to the Room Corner) (Default Height is Equal to Driver Height) (Method Selection) Floor Condition Reflect 1 ( = hardwood or concrete, 1 = carpeted) Refective Surface Selections (if 1 reflective surface is included, if reflective surface is removed) Inc_floor (Floor, Z = ) Inc_rear (Rear Wall, X = ) Inc_side (Left Side Wall, Y = ) Inc_ceiling (Ceiling)

10 Extended Range Driver and Two Woofer : Simple Source Pattern with Baffle Edge Outline 1.5 z d 1 z m z w z o y d y m y w y o

11 Three Dimensional View Axis Length (m) axis 2 <---- Change value of "axis" to rescale plots Room Corner is the Origin 2 Side view z driver 1.5 z outline z woofer 1 Side View - looking out from side wall z mic x driver x outline x woofer x mic 2 Front View z driver 1.5 z outline z woofer 1 Front View - looking towards rear wall z mic y driver y outline y woofer y mic 2 Top View y driver 1.5 y outline y woofer 1 Top View - looking down from ceiling y mic x driver x outline x woofer x mic

12 Plotted Response for the Extended Range Driver Dashed Red - Infinite Baffle Response Dashed Magenta - Baffle Response Dashed Brown - Crossover Response Solid Red - Combined Response SPL (db) 1 5 SPL IBr 5 X_over r 1 SPL 15 BFr 2 SPL nr rdω Hz 1 Phase (degrees) Phase r deg SPL (db) rdω Hz SPL Hr rdω Hz 1 Frequency (Hz)

13 Plotted Response for the Lower Woofer Driver Dashed Red - Infinite Baffle Response Dashed Magenta - Baffle Response Dashed Brown - Crossover Response Solid Red - Combined Response SPL (db) 1 5 SPL IBr 5 X_over r 1 SPL 15 BFr 2 SPL nr rdω Hz 1 Phase (degrees) Phase r deg rdω Hz 1 SPL (db) SPL Wr rdω Hz 1 Frequency (Hz)

14 Plotted Response for the Upper Woofer Driver Dashed Red - Infinite Baffle Response Dashed Magenta - Baffle Response Dashed Brown - Crossover Response Solid Red - Combined Response SPL (db) 1 5 SPL IBr 5 X_over r 1 SPL 15 BFr 2 SPL nr rdω Hz 1 Phase (degrees) Phase r deg rdω Hz 1 SPL (db) SPL Mr rdω Hz 1 Frequency (Hz)

15 Plotted Combined Response for the Woofer Drivers Phase (degrees) Phase r deg rdω Hz 1 SPL (db) SPL Lr rdω Hz 1 Frequency (Hz)

16 Plotted System Response for the Extended Range/Dual Woofer Open Baffle Design Phase (degrees) Phase r deg rdω Hz 1 SPL (db) SPL r 1 95 SPL 9 Lr 85 SPL Hr rdω Hz 1 Frequency (Hz)

17 System Time Response for an Impulse Input 3 Woofer Sound Pressure in Time Domain 2 p wooferr Pa rdt 1 System Sound Pressure in Time Domain 5 p summedr 1Pa rdt Time (sec)

18 Anechoic Horizontal Polar Response - Free Space Radius and Frequency Inputs radius ω 3m 37Hz (Calculation Radius Along the Driver's Axis) (Calculation Frequency : 1 Hz < < 1 Hz where must be an Integer Value) TOP VIEW B A C K SPL Hθ SPL Wθ SPL θ 18 5 F R O N T θdθ

19 Anechoic Vertical Polar Response - Free Space Radius and Frequency Inputs radius ω 3m 37Hz (Calculation Radius Along the Driver's Axis) (Calculation Frequency : 1 Hz < < 1 Hz where must be an Integer Value) SIDE VIEW B A C K SPL Hθ SPL Wθ SPL θ 18 5 F R O N T θdθ

20 System (no subscript) radius 3.m System Driver r Midrange Woofer r r r exp j rdω radius c System r SPL 2log r 21 5 Phase arg r System r Pa Phase (degrees) Phase r deg rdω Hz 1 SPL (db) SPL r rdω Hz 1 Frequency (Hz)

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