DESIGN OF A 4 WAY PASSIVE CROSSOVER NETWORK

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Elwin O’Neal’
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1 DESIGN OF A 4 WAY PASSIVE CROSSOVER NETWORK PRESENTED BY ODHIAMBO TONNY SILVANCE F17/1453/2011 SUPERVISOR:MR S.L OGABA EXAMINER:PROF NICODEMUS ABUNGU e

2 UTLINE Objectives Theory Design Results Analysis Conclusion Recommendation

3 verall objective design a four way passive crossover network cific objectives To determine the crossover frequency based on the output power versus frequency relation and the sound frequency bandwidth of particular speaker drivers To choose the speaker driver s nominal impedance to use in the design To evaluate, after derivation of the relevant equations, the network s component values that is, the capacitors and inductors based on the crossover frequency, speaker driver nominal impedance and finally the speaker driver s power ratings. To research on and determine the formula used to evaluate inductance based on the physical parameters and thereafter manually coil the inductors to be used based on this formula.

4 hat is a crossover network? the simplest sense, a crossover is a device that separates the audio spectrum different ranges and sends them to specific drivers. The crossover is ponsible for sending bass information to the woofer, midrange information to midrange, and treble to the tweeter.

5 sign TION OF CROSSOVER FREQUENCY SOVER FREQUENCY RANGE FOR MOST SYSTEMS : ype Speaker driver Crossover frequency range stems Bass-treble 3khz-5khz stems Bass-midrange Midrange-treble 500hz-1.5khz 3khz-5khz stems Bass low midrange Low Midrange-Midrange Midrange-treble 200hz-400hz khz 3khz-5khz eeter 5khz-10khz

6 sign continued TION OF POWER PROPORTIONS AGAINST CROSSOVER FREQUENCIES FOR VE CROSSOVER NETWORKS ver frequency % power to bass unit %power to upper units z z z 90 10

7 esign continued omponent values determination crossover point =350 = taking Zo=8ohms while the formula for inductance = =40.19 = =. = =. =.Hence:

8 esign continued 2nd crossover point =1150 = = = =. = =.

9 esign continued 3rd crossover point =4000 = =3.517 = =. = =. e power ratings of the speaker drivers used were: Woofer-100W Midrange1-60W Midrange2-30W Tweeter -10W ak values of currents and voltages were determined using the formulae P= d =,.The highest voltage realized was 40v from the woofer and hence 250v pacitors were used as they would perfectly handle the voltages.

10 esign continued e inductors used were manually coiled using the online coil32 program which is sed on the empirical formula shown below Or =. μ ( ) In this design, similar torus ferrite cores in terms of dimensions were used which were d1=25mm,d2=15mm and h=4.5mm but their relative permeability were different =2770 =3867 =2470

11 sign continued tables below show the calculated and measured values of the inductors and acitors used in the circuit. TORS CALCULATED MEASURED 5.14mH 4.8mH 5.14mH 4.8.mH 1.566mH 1.45mH 1.566mH 1.45mH 0.45mH 0.41mH 0.45mH 0.41mH

12 sign continued APACITORS CALCULATED STANDARD AVAILABLE MEASURED VALUE

13 sign continued overall passive four way crossover network that was simulated and ricated is as shown

14 sults ulated results and response oofer QUENCY( ) MAGNITUDE(dB) m m m m m

15 sults continued ange1(lower midrange) ENCY( ) MAGNITUDE (db) m m

16 esults continued ange2(higher midrange) EQUENCY ( ) MAGNITUDE (db) m

17 sults continued eter UENCY ( ) MAGNITUDE (db) m m m m m m m m

18 sults continued ulated woofer frequency response

19 sults continued range1(lower midrange) simulated frequency response

20 sults continued range2 (higher midrange2) frequency response

21 sults continued ulated tweeter frequency response

22 sults continued plete circuit simulated response

23 sults continued ctical results fer ency(hz) Input voltage(v IN ) Output voltage(v OUT ) Practical Magnitude(dB) Simulated Magnitude(dB) 50mV mv m m 100 mv 102 mv m m 200 mv mv m m 300 mv 291 mv m m 400 mv 370 mv m m 500 mv 434 mv mv 383 mv mv 305 mv mv 269 mv mv 202 mv V 180 mv V 332 mv V 350mV

24 sults continued range1(lower midrange) ncy(hz) Input voltage(v IN ) Output voltage(v OUT ) Practical Magnitude(dB) Simulated Magnitude(dB) 50mV 2mV Mv 10.5 mv mV 82.7 mv mV 204 mv mV 386 mv m m 600mV 795 mv mV 904 mv mV 825 mv mV 740 mv m m 800mV 570 mv mV 344 mv mV mv mV 196 mv V 137 mv V 228 mv V 280 mv V 225 mv

25 sults continued range2(higher midrange2) ency(hz) Input voltage(v IN ) Output voltage(v OUT ) Practical Magnitude(dB) Simulated Magnitude(dB)

26 sults continued eter ency(hz) Input voltage(v IN ) Output voltage(v OUT ) Practical Magnitude(dB) Simulated Magnitude(dB) 50 mv mv mv mv 198mV mv 338mV mv mV m m 600 mv mv m m 700 mv 675 mv m m 800 mv 772 mv m m mv mv m m 0 1V 0.99V m m 0 2V 1.96V m m 0 3V 2.95V m m

27 ldered circuit and speaker cabinets

28 Analysis ctical frequency response as obtained using Microsoft excel ofer midrange1(lower midrange) woofer frequency response lower midrange(midrange1) frequency response magnitude(db) Frequency (Hz) 4 Frequency(Hz)

29 alysis continued range 2(higher midrange) her midrange(midrange2)frequency response 0 Tweeter Tweeter frequency response Magnitude() Frequency (Hz) -25 Frequency(Hz)

30 sults continued Frequency response for the entire network ssover frequencies:f1=313hz,f2=1515hz,f3=4848hz.expected were 350Hz,f2=1500Hz,f3=4800Hz

31 nclusion main objective of the project was to design and implement a 4-way passive ssover network. This aim has been achieved as the system has worked as ected with good quality sound at the output of the four speaker drivers. In design process, the specific objectives were achieved. There were slight erences between the practical from the theoretical simulations and this was ected but it did not adversely affect the output and quality of sound duced.cconclusively the project was a success.

32 commendation project generally involved a demonstration of the possibility of the design use of a 4-way passive crossover network and since this concept is not fully lored and commercialized, for demonstration purposes, a mono instead of a reo set up was used. Stereo systems produce the best quality sounds and ce for future works and demonstrations on this, I would recommend use and ign of a stereo system. department should try and purchase ferrite cores in advance as they are not y easily available and the alternative use of air core inductors leads to very ky crossover network circuits which are not practical incase it s to be lemented in an actual system. tly care should be taken when handling the speaker drivers and especially the es. Any dent on the domes affect the quality of the sound produced.

33 THANK YOU!!

INDUCTOR. Inductors are electronic components that oppose a change in current. Air Core Inductor Symbol

INDUCTOR. Inductors are electronic components that oppose a change in current. Air Core Inductor Symbol BASIC ELECTRICAL INDUCTOR INTRODUCTION are used for their ability to lter high frequencies out of the audio in a sound system. As an introduction to the focus of this lesson will be to discuss the different