Date: Wed, 27 Apr 2011 11:00:19

Author: Andrew Morrison

Subject: Re: speakers

Post:

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But the way that the amp delivers the max power to the speaker is if the
impedance of the speaker matches the output impedance of the amp. You're
right about audio amps generally having low output impedances, which are
close to the impedance of a speaker. That is why, in general, most speakers
can connect to most amps with little problem.

Usually you don't run into any problems if the impedance is not perfectly
matched. Some amps have a switch on them to change from 4 ohm to 8 ohm
(I've even seen 6 ohm options on some). If you connect an 8 ohm speaker to
the 4 ohm output, it doesn't really sound much different or perform much
differently over much of the range of the amplifiers capability. You're
right about possibly getting distortion at the high end of the amp's output
on mismatched impedances, but you can also get distortion if the speaker is
not rated to handle the total power that an amp can deliver.

--
Andrew Morrison
Department of Physics
DePaul University

On Wed, Apr 27, 2011 at 9:35 AM, George Herold wrote:

>
> Dear tapers, I'd like to try and correct what appears to be a common
> misconception.
> Audio amplifiers will be 'rated' by what impedance they are designed to
> drive. This has to do with the maximum current/voltage that the
> amplifier can produce. This 'rated' impedance has nothing to do with
> the output impedance of the amplifier itself. Typically audio
> amplifiers will have a very low output impedance. (After all you don't
> want to be wasting a lot of power in the amplifier, you want it all
> dissipated in the speaker or load.)
>
> Now the only time you will find distortion problems when using speakers
> that have a different impedance than the 'rated' impedance of the
> amplifier is when you are driving them really hard. When you start to
> push either the maximum current or voltage that the amp can produce. (Of
> course even when the speaker is matched to the rating of the amp, if you
> drive it hard you can still get distortion.)
>
> George H.
>
>
> > -----Original Message-----
> > From: tap-l-owner@lists.ncsu.edu
> > [mailto:tap-l-owner@lists.ncsu.edu] On Behalf Of Jerry DiMarco
> > Sent: Tuesday, April 26, 2011 2:12 PM
> > To: tap-l@lists.ncsu.edu
> > Subject: Re: [tap-l] speakers
> >
> > At 4/26/2011 10:30 AM, you wrote:
> > >......
> > >1. Does the impedance of a speaker affect the sound quality/loudness?
> >
> > The sound quality may be affected indirectly. One
> > example is the case of an amplifier with an 8 ohm output
> > impedance connected to speakers with 4 ohm input impedance.
> > If the amplifier cannot handle the increase in current drawn
> > by the lower impedance speakers, the music signal peaks may
> > get clipped and sound distorted. A 16 ohm speaker in the
> > same situation would not cause signal distortion since it
> > draws less current from the amplifier.
>
>
>
>

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But the way that the amp delivers the max power to the speak=
er is if the impedance of the speaker matches the output impedance of the a=
mp. =A0You're right about audio amps generally having low output impeda=
nces, which are close to the impedance of a speaker. =A0That is why, in gen=
eral, most speakers can connect to most amps with little problem.=A0
Usually you don't run into any problems if the impedance=
is not perfectly matched. =A0Some amps have a switch on them to change fro=
m 4 ohm to 8 ohm (I've even seen 6 ohm options on some). =A0If you conn=
ect an 8 ohm speaker to the 4 ohm output, it doesn't really sound much =
different or perform much differently over much of the range of the amplifi=
ers capability. =A0You're right about possibly getting distortion at th=
e high end of the amp's output on mismatched impedances, but you can al=
so get distortion if the speaker is not rated to handle the total power tha=
t an amp can deliver.
=A0--=A0Andrew MorrisonDepartment=
of PhysicsDePaul University=A0On Wed, Apr 27, 2011 at 9:35 AM, George Herold w=
rote:

=A0Dear tapers, =A0I'd like to try and correct what appears to be a com=
mon
misconception.
Audio amplifiers will be 'rated' by what impedance they are designe=
d to
drive. =A0This has to do with the maximum current/voltage that the
amplifier can produce. =A0This 'rated' impedance has nothing to do =
with
the output impedance of the amplifier itself. =A0Typically audio
amplifiers will have a very low output impedance. =A0 (After all you don=
9;t
want to be wasting a lot of power in the amplifier, you want it all
dissipated in the speaker =A0or load.)

Now the only time you will find distortion problems when using speakers
that have a different impedance than the 'rated' impedance of the
amplifier is when you are driving them really hard. =A0When you start to
push either the maximum current or voltage that the amp can produce. (Of
course even when the speaker is matched to the rating of the amp, if you
drive it hard you can still get distortion.)

George H.


> -----Original Message-----
> From: tap-l-owner@lists.=
ncsu.edu
> [mailto:tap-l-owner@list=
s.ncsu.edu] On Behalf Of Jerry DiMarco
> Sent: Tuesday, April 26, 2011 2:12 PM
> To: tap-l@lists.ncsu.edu
> Subject: Re: [tap-l] speakers
>
> At 4/26/2011 10:30 AM, you wrote:
> >......
> >1. Does the impedance of a speaker affect the sound quality/loudne=
ss?
>
> =A0 =A0 =A0 The sound quality may be affected indirectly. =A0One
> example is the case of an amplifier with an 8 ohm output
> impedance connected to speakers with 4 ohm input impedance.
> If the amplifier cannot handle the increase in current drawn
> by the lower impedance speakers, the music signal peaks may
> get clipped and sound distorted. =A0A 16 ohm speaker in the
> same situation would not cause signal distortion since it
> draws less current from the amplifier.





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