"Richard Kuschel" schreef in bericht
...

wrote:
Every year or two CU tests popular speakers, and while most speakers
claim to be 8 ohms, CU finds most to measure 4 ohms. Although CU's
opinions should to be taken with a grain of salt, measurements are
measurments, and not opinions.



CU may be measuring the DC resistance of the speaker, and that will not be
the
same as Impedance, which is AC resistance and changes all over the place
with
frequency.

Just accept the manufacturers rating and don't worry about it


I have measured many loudspeaker systems en still do. My advice: Don't ever
trust the manufacturers ratings.
Ronald Berger.

I have measured many loudspeaker systems en still do. My advice: Don't ever
trust the manufacturers ratings.
Ronald Berger.



I wouldn't trust frequency response, but impedance is a pretty simple thing to
measure with the right gear.

It is highly unlikely that two "8 Ohm" cabinets will be all that far off that
it will be a consideration plugging thm into an amplifier rated for 4 ohms.

I have been running a set of 6 ohm speakers from a power amp designed for 8
ohms for years with no problems.
Richard H. Kuschel
"I canna change the law of physics."-----Scotty

"Richard Kuschel" schreef in bericht
...

I have measured many loudspeaker systems en still do. My advice: Don't
ever
trust the manufacturers ratings.
Ronald Berger.



I wouldn't trust frequency response, but impedance is a pretty simple
thing to
measure with the right gear.

I think it isn't a question of whether measurements are simple or difficult
, but can we
trust the specifications of the manufacturer? It is very, very easy to print
any curve and specs you want. I have measured rated 8 Ohm speakers
with minimum impedances of 2.3 Ohm and that was not the DC resistance of a
driver! The question is can we trust the manufacturers or not. Some we can
and
some we can't.


It is highly unlikely that two "8 Ohm" cabinets will be all that far off
that
it will be a consideration plugging thm into an amplifier rated for 4
ohms.

I agree, most of the time it wil be no problem. But if you have very low
efficiency loudspeakers with very low impedance properties mentioned above
you can run into trouble. Your amplifier has to deliver high currents to
obtain reasonable sound pressures and can be running out of steam when you
demand higher volumes, with risks of damage to the speakers as well. If
your amplifier is overloaded it starts to produce bits of DC (chopped signal
waves). This is very dangerous for speakers. The speaker can be damaged in a
split second. You haven't even the chance to react. But if you have a
massive amplifier and you are overloading the speakers you have time
to readjust the volume of your amplifier.

I have been running a set of 6 ohm speakers from a power amp designed for
8
ohms for years with no problems.

I believe you. If the 6 Ohm speakers are reasonable efficient and don't have
very low impedances there are no problems for an 8 Ohm amplifier. The point
is how much current a loudspeaker needs to play loud enough for you and if
the
amplifier can deliver this current without problems. If it can there wil be
no problems.

Ronald Berger