Impdence Question


In experimenting with an unusual loudspeaker enclosure for which only a certain high-end car speakers fit the design criteria, there is concern about their low impedance damaging the amplifier. Driver impedance ranges from 2.8 ohms to 3.4 ohms. Will this do harm? And if several speakers are used in a 5.1 surround setup, does this increase the load and the chance of damage?

If the low impedance is indeed risky, is their any means of raising it perhaps by placing something in the chain (other than wiring a pair together for series or parallel operation)?

Thank you in advance.
silas

Showing 1 response by bombaywalla

>> there is concern about their low impedance damaging the
>> amplifier. Driver impedance ranges from 2.8 ohms to 3.4
>> ohms. Will this do harm?
it depends on the model of the amplifier. To get a hint of its performance look @ the amp's o/p specs. Does the output power double each time the load resistance halves? if it does,it would indicate an amp with a fairly robust power supply & the chances that such an amp could handle a lower speaker impedance are reasonably high.
if the amp power does not double the amp could still drive this lower speaker impedance but the amp will run out of juice. This'll manifest itself as lacklustre reproduced sound. If you crank up the volume, the amp could clip resulting in a distorted sound.

>> And if several speakers are used in a 5.1 surround
>> setup, does this increase the load and the chance of
>> damage?
should I read this to mean that you are going to connect 5 speakers to 1 pair of binding posts????
If yes, I'd say that's totally assinine!!
If no, then you must be using a 5 channel amp that has 1 pair of binding posts for each speaker + an output for the sub. In that case, you have 5 independent amplifiers each driving just 1 speaker so the question of overload does not occur if you keep the volume control within the limits of these amps per the amp spec sheet. Yes, there are all getting power from 1 transformer so each is "connected" to all the other amps & all 5 amps are not truely independent but this is a 2nd order effect for this discussion

>> If the low impedance is indeed risky, is their any
>> means of raising it perhaps by placing something in the
>> chain
you can create a Zobel network which'll "fool" the amp that it's seeing a (more) constant load vs. freq but I would advise against attaching such a network if you are not a serious DIYer or if you do not know much about speaker design or if the speaker was never meant to be used w/ a Zobel network. You will surely alter the sound (more often for the worse but you might get lucky & change it for the better! who knows...). Of course contact the speaker manuf for any advice they can offer re. Zobel networks for your speaker OR see if there is any discussion on your speaker model in some audio forum.
The other solutions are to either get a better amp to handle the lower speaker impedance OR get another speaker that is an easier load to your amplifier.
FWIW.
More to discover