In article ,
"Mark Zarella" seesigfile wrote:

While what you say below is true, it does not directly address how the
speakers function. It is not voltage that sets up the force, but current.
Therefore, they're current driven and the magnitude of the current can
predict the electrical contribution to the cone motion. The same cannot be
said of voltage.

--
Mark Zarella
zarellam at upstate dot edu

Of course it's the voltage that creates the current, and the current
that creates the force.

The current doesn't determine the cone motion, though; it determines the
cone force. The voltage is a bit better at determining the motion
because back EMF from motion causes some negative feedback. The
force/current of the cone when driven by voltage is (Vin - Vback) / Ohms.

There aren't any audio amps that regulate by current output. The audio
quality would be extremely unpredictable.


"Kevin McMurtrie" wrote in message
...
In article hyD%a.136534$Oz4.26769@rwcrnsc54,
"Lex" wrote:

alright, after rereading a few things I realized my memory of the
situation
was a little skewed.. too much reading not enough soak in time lately and
I
seem to be forgetting a few things. next question is, because I cannot
find
this anywhere... are speakers voltage driven devices or current driven
devices
?

I want to say current, because if I remember my definitions right,
current
is what does the work, not voltage, voltage was more of a potential to be
able to do work.. am I remembering this correctly?


They're voltage driven. The speaker's motion generates a back voltage
so driving them by voltage provides some controlling negative feedback.


Tuned enclosures depend on driving the cone by voltage too. Enclosures
increase the sound levels by increasing the acoustic load on the
speaker. That doesn't work the same way if the speaker is driven by a
constant current (force). It might even work in the opposite way.

Constant voltage:
Watts= Volts^2 / Ohms

Constant current:
Watts= Amps^2 * Ohms

With a constant voltage, an increased load (reduced Ohms) produces more
power. With a constant current, it's the opposite.


Of course both voltage and current are there. It's just that the
amplifier regulates the signal voltage and lets the speaker draw any
amount of current.