say there wee two speakers of exact desing except for ohms.

one could be 8 and the other 4

what does this mean in the real world to the reciever and the listener...i guess on paper too...what SHOULD be the differenece?

thanks


dave

The amount of power the reciever has to handle. A 4 ohm load is too much to handle for many recievers.

so its the hose theory...the reciever would be trying to force too much energy out that it cant really do?

ok...so do swithcable amps solve this? or just more watts?

I guess i could ask are the Yamaha 2400 etc and the Denon 3805 etc..others in this class..cna they HANDLE a 4 ohm Axiom 80? or the like?

Dave, one form of Ohm's law is that current(in amps) is equal to voltage(in volts)divided by resistance(in ohms), i.e. I=V/R. So, if the voltage delivered remains constant, but the resistance(or impedance)of the speaker is 4 ohms instead of 8 ohms, the current is doubled. Some amps might not be able to handle the increased current, would overheat, which would start a fire, which would burn down the house, which would burn down the rest of the city, etc.(if the protective circuit in the amp didn't simply shut it off). A switch or setting for 4 ohms doesn't really solve a problem if it would exist, but just covers it up. The switch reduces the voltage available and therefore the current, even if the speaker is of 4 ohms impedance. Since this also reduces the power available(power in watts equals current in amps times voltage in volts, i.e. P=IxV)it should only be used as a last resort if the amplifier keeps shutting off. The majority of receivers can handle the situation, but each combination of receiver, speakers and sound level is a different case.

So you could say using lower ohm speaks contencrates the energy-- somewhat like force per sq inch? And this does what? makes the speakers louder?

if this is so or not..why are so many oohs and ahhs about lower impedance?

When I was younger loud music was definatley the thing...in my ripe 30's he ehehe louds is fun but not th norm. Which suggest good speakers at low levels are very nice indeed.

But any way the market is mainly 8 ohm...any particular reason?

Hi guys!
Virtualexister raised a very interesting issue. Strip those heavy techno stuff down to a layman's level where I could understand, suppose I spent half of my life's savings on an Axiom Epic 80 HT system with 4 ohms impedence, what would the more experienced readers here recommend that I spend the remaining half on the most ideal AV Receiver to would bring out the best of these speakers?

DC

a lower ohm speaker, means either

A, you will have to buy a more expensive receiver, because the speakers will want more total power from the speaker..

or

B, your speakers will never be as loud, as they possibly could be, because the receiver you bought can not provide the necessary power the speakers would want at a high volume.

JohnK's post is 100% correct, but for those that are not mathematically inclined, its just a bunch of gargle... i know..

if you have 2 speakers that are the EXACT same, accept for the impedance, they are not the EXACT same, there is something in the 4ohm speaker, that is different than the 8ohm speaker, either an extra resistor has been placed inside of the speaker, or something else has been done to modify the power capabilities of the speaker, the driver, or (speaker) could be the same, and sound the same, but one will most likely be louder than the other one, the louder being the one with the lower ohm rating, because that speaker will be able to handle more power, and more power=more volume, as we all know


hope this helps someone.

Impedance in your situation having 1 4 ohm and 1 8 ohm speaker leaves you in somewhat of a bind. Wiring them in parallel = 2.7 ohms, in series = 12 ohms. Ohms law to calculate total impedance in parallel is R1 X R2/R1+R2+etc. = Rt. In series the Rt = R1+R2+etc. Most amps will not handle this 2.7 ohms without causing series damage, as previously mentioned, and a 12 ohm load will require the amp to work harder to produce higher volume levels to the listner and probably produce distortion. Using the 4 ohm configuration is always the optimal wiring config. The amp runs cooler, almost idling, produces the highest quality of sound and with plenty of headroom to increase the volume. i.e. A 100W. amp @ 8 ohms produces 100W. However, a 100W. amp with a 4 ohm load increases the total Wattage to approximately 2/3 of the stated wattage power or approximately 166W. of total output power.

In reply to:

"Using the 4 ohm configuration is always the optimal wiring config. The amp runs cooler, almost idling, produces the highest quality of sound and with plenty of headroom to increase the volume. i.e. A 100W. amp @ 8 ohms produces 100W. However, a 100W. amp with a 4 ohm load increases the total Wattage to approximately 2/3 of the stated wattage power or approximately 166W. of total output power. "

I have to disagree. (to a point) You just can't give a blanket statement that 4ohms is always optimal. This will only happen in a moderate to high-end receiver/amp. Most power supplies in "average" consumer electronics do not have enough current to do what you say. The protection circuits will shut down the fun long before you get anywhere near the 2/3 increase as you claim. See JohnK's first post in this thread.

However, if you are using an amp with high-current capabilites, you will extract more performance with a 4ohm load instead of the 8.

ok is there a problem matching any of the Axioms together?

for example many are 8 ohm, the 150 center is 6 ohm and the m80 s are 4 ohm...the QS8s are 6ohm

At the moment I have 2 M20's a 150 center, and 2 QS8's. so where does this leave me and my receiver?

NOTE: I had auto protect problems on rear with other speakers (all were 8ohm) but still have same issue---reciver is on the blink (i checked the wiring as well)

any way at the moment I have 8, and 6 ohms paird together, and i might add the 80s some great day..with a new reciever that is.

but as for the mix of ohms...is it bad? if so---then I guess i should have a different match of speakers? Even in the Axioms this could be hard to do???

Virtual,

The ONLY differnece that impedance makes is how much power they can handle. There will ne NO sound difference between an M60 or an M80 at normal to low volume levels. Amplifiers can simply supply more current to the lower resistance loads than they can with higher resistance ones.

If your amplifier is rated to handle 4 ohm loads, you could use a 4 ohm center speaker, and have 8 ohm speakers for your surrounds and mains. You could also use an 8 ohm center, with the rest all being 4 ohms... Mixing and matching speakers of different impedances is perfectly fine as long as the amplified can handle it.

Cool

my Sony has a MANUAL switch for 6 or 8 ohms...I imagine many newer recievers are automatic?

but the point is as long as the reciever can go low..say 4..then the 8ohm is not really an issue...where the oppisite would be?

I think i got it man.

i hope

dave