are loud speakers actualy inductors in series

[topkat]

any one know the answer for instance do loudspeakers in series affect the frea. response of the other speakers in the circuit or series

 

[Richard Ellis]

Inductance?

Just to get things rolling...Have you ever heard of the expression First approximation, Second approximation or third approximation?
First of all lets' consider a single full-range driver with the common 8 Ohm rating.
Yes it does have a coil of wire thru it so you would indeed consider it an inductor....However, since the definition of a capacitor is two conductors seperated by an insulator...wouldn't it by DEFINITION be a capacitor also?....two terminals seperated by an insulator(Air)?
Also a speaker has a DC resistance.
Sooo...a resistor, a capacitor and a coil....all three in one.
For practicality at the frequencies were working with only the Resistance and the Inductance are of any relevant value.
Connect your Ohmmeter and you won't get your "rated" eight ohms.
_________________________________________Rick....

 

[Salas]

If you connect say 2 loudspeakers in series, you get impedance addition Z1+Z2. An amp sees just that. And an amp normally is designed to be a voltage source. I.e. its job is to provide constant voltage gain on 'any' impedance as long it isn't too extreme in practice. Because speakers are voltage controlled devices, all swell. You get half the wattage amp output for same 2 speakers in series but same spl (half the current but double the cones). And ok, less distortion when maxing out since you split the speaker burden and ease the amp too.


*For complex reasons there are small differences in final perceived sound, especially in the dynamic envelope, and fidelity arguments arise also, but technically you are mainly ok to connect in series. Purists go parallel.

 

[Geoff H]

I beg to differ on the assumption that speakers are voltage driven devices. It is the current that reacts with the lines of force in the gap that provides the force to move the voice coil.

Generally speaking, a speakers z is inductive above resonance, capacitive below.

 

[Geoff H]

Getting back to the original question, if speakers are connected in series, the frequency response will be "bumpier" than that of of the same drivers connected in parallel.

Each dip in SPL will have a rise in Z at that freq. That rise in Z will cause
the output of the other driver to drop.

Connecting the drivers in parallel reduces the effects of one driver on the other, and will more than likely flatten the response curve.

One thing to note: even matched drivers will differ slighty with the peaks and troughs in their Z plot.

HTH

Geoff.

 

[soongsc]

any one know the answer for instance do loudspeakers in series affect the frea. response of the other speakers in the circuit or series

In short, yes. For example, if you have a tweeter in series with a woofer, at the higher frequencies, in increased impedance of the woofer will cause the tweeter to have less current running though it, thus less output.

 

[Salas]

I beg to differ on the assumption that speakers are voltage driven devices. It is the current that reacts with the lines of force in the gap that provides the force to move the voice coil.

Generally speaking, a speakers z is inductive above resonance, capacitive below.

I wrote 'voltage controlled' not voltage driven. So we say the same.

 

[Curmudgeon]

Drivers are designed to be run from a voltage source. The inductance rise from the coil leakage inductance should be taken into account as one of the design characteristics; for example, it will tend to counter a rising frequency response caused by cone/motor characteristics. The amount of inductance varies quite a bit; more complex motor designs, with copper shorting rings have quite a bit less inductance.

Another issue is low frequency resonance. If the two drivers' resonant frequency is not identical, the high impedance of each at resonance will cause a hole in the response of the other. You'd get equal voltage division over the low frequency range only when the low frequency impedance curves are identical.

 

[v-bro]

Actually every component (even the amp) has an equivalent--circuit diagram, all of them influence eachother...


Look upon a speaker as an inductance and a resistor indeed.

L:
A 6db/oct filter for a driver consists out of one coil, so in series the high freqs are going to be attenuated by the other driver's voice coil..

R:
A resistor also attenuates (especially suitable for high freqs.). Most voice coils are within the range of 4 to 10 ohms DC resistance on a normal hifi driver...

C:
Capacitance of a voice coil is so low it doesn't really influence things..

I don't know what your "goal" is at this knowledge? If for instance a driver has a high enough value of R or L take this within your calculations, and try to estimate how great influence it has on the end result.

I personally don't like ANY obstruction between one power-amp channel and one driver (or indeed parallelled) NO components there will let you (the driver) benefit fully from the dampening-factor of the power-amp, but some just want to go the "lossy" way...

I would recommend a small passive filter on the amp input....

 

[XEAGLEKEEPER]

Its a parallel-series capacitive -inductive resistor or how bout a compound RCL network or as my wife just calls it "a noisy wooden box"

 

[Svante]

I had problems understanding the question, but I think I understand what you mean now.

A loudspeaker has a voice coil with an inductance. One can use an indictance as a lowpass filter if it is connected in series with the loudspeaker. So, does connecting two loudspeakers in series result in that the response will be lowpass filtered, ie do the drivers act as filters for one another?

The answer is no. Since the impedances of the drivers are identical, half of the amplifier voltage will be present over each of the drivers, independently if the frequency. The formula for voltage division is

G=Z1/(Z1+Z2)=1/2 if Z1=Z2.

Otoh: The voice coil inductances will cause a roll-off towards higher frequencies for the drivers even when used as single drivers. This roll-off will be identical if the two drivers are connected in series. So there will be no change in the response by conecting two drivers* in series.

*Apart from acoustic effects like directionality etc.

 

[Salas]

Regarding the original question again, to put it simply, we don't get less hf in series connection in the same manner we don't get more hf in parallel connection.