2 way speaker crossover

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TieBravo

Joined Aug 21, 2021
50
What are these two coils doing in this 2 way speaker crossover? Can anybody tell me? The total impedance of the speakers both are 8ohms (I don't know each of their impedance). Resistor 2.2 ohm, capacitor 3.3 uf. Speaker with red and black wire is the woofer, and speaker with green and black wire is the cone tweeter.
 

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LesJones

Joined Jan 8, 2017
3,701
The top speaker is the low frequency one. The inductor in series with it will have a low reactance at low frequencies so it will not attenuate low frequencies very much but as the frequency rises it provide moor attenuation. On the lower (High frequency.) speaker the inductor will tend to short out low frequencies but will have less of an effect on the high frequencies. The capacitor has a lower reactance at higher frequencies so it will allow them through with less attenuation.

Les.
 

Thread Starter

TieBravo

Joined Aug 21, 2021
50
Can you please tell me each of the speaker's impedance (if it's possible). Driver units are provided. The entire Circuit is one of the two boxes that is used for a cassette amplifier. Is it possible to use each boxes for modern amplifiers with 8ohms output? As for the coils its written SX 555 A, SX 555 B. Coil connected to the woofer got more wire than the cone tweeter.
 

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KeithWalker

Joined Jul 10, 2017
2,295
The inpedance of the whole assembly will be approximately the impedance of one speaker, which you mentioned in post #1, is 8 Ohms.
 

Thread Starter

TieBravo

Joined Aug 21, 2021
50
The top speaker is the low frequency one. The inductor in series with it will have a low reactance at low frequencies so it will not attenuate low frequencies very much but as the frequency rises it provide moor attenuation. On the lower (High frequency.) speaker the inductor will tend to short out low frequencies but will have less of an effect on the high frequencies. The capacitor has a lower reactance at higher frequencies so it will allow them through with less attenuation.

Les.
Thanks for your reply, but is it possible that both inductors got same impedance? When i checked their resistance using multimeter both got a fixed reading 0.7ohm (i was using 200 ohm setting on the multimeter) several times. As you can see the simplified diagram of the impedances connected to the circuit.
 

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eetech00

Joined Jun 8, 2013
3,087
T

The woofer ?
Since a filter network is used, its very likely that each speaker has an 8 ohms impedence and should be matched to an amplfier with an output inpedence of 8 ohms. The inductor/capacitor network filters the frequencies sent from the amplifier to each speaker. The woofer presents an 8 ohm impedence to the amplifier for mid/low frequencies, and the tweeter presents an 8 ohm impedence to the amplifier for high frequencies.

If you want to be certain, look for a part numbers on each speaker, inductor and capacitor.
 

eetech00

Joined Jun 8, 2013
3,087
Just guessing...but going by the value of C=3.3u, crossover point might be about 2.5-3Khz.
Woofer inductor about 3.5-4mH, tweeter inductor about 100-200uH.
Woofer is probably woofer/midrange type speaker.
 

Thread Starter

TieBravo

Joined Aug 21, 2021
50
You are ri
Just guessing...but going by the value of C=3.3u, crossover point might be about 2.5-3Khz.
Woofer inductor about 3.5-4mH, tweeter inductor about 100-200uH.
Woofer is probably woofer/midrange type speaker.
You are right its a midrange too
 

Audioguru again

Joined Oct 21, 2019
4,523
Since a filter network is used, its very likely that each speaker has an 8 ohms impedence and should be matched to an amplifier with an output impedance of 8 ohms. The inductor/capacitor network filters the frequencies sent from the amplifier to each speaker. The woofer presents an 8 ohm impedence to the amplifier for mid/low frequencies, and the tweeter presents an 8 ohm impedence to the amplifier for high frequencies.
No. Modern amplifiers do not match their output impedance to be the same as the speaker impedance. If it does that then the speaker power will be low and the speaker will have poor damping of its resonances. The output impedance of a modern amplifier is extremely low, 0.04 oms or less. The amplifier must be rated to be able to drive the impedance of your speaker.
 

eetech00

Joined Jun 8, 2013
3,087
No. Modern amplifiers do not match their output impedance to be the same as the speaker impedance. If it does that then the speaker power will be low and the speaker will have poor damping of its resonances. The output impedance of a modern amplifier is extremely low, 0.04 oms or less. The amplifier must be rated to be able to drive the impedance of your speaker.
But haven’t seen an audio amplifier output typically rated that way.
 

Ian0

Joined Aug 7, 2020
4,822
Most modern amplifiers are rated to be able to drive speakers that are 4 ohms to 8 ohms. Some car audio amplifiers can produce enough current to drive speakers that are 2 ohms.
Hifi amplifiers have a rating called "damping factor".
And damping factor is rated load impedance divided by output impedance.

(All amplifiers can produce enough current to drive 2Ω loads when used by a DJ, but perhaps not for very long)
 
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