# 6 ohm speaker with 8 ohm amp.



## Pepsione1

What would happen? I have a pair of 60w 6 ohm speakers I want to try on my 500w (? not sure) 8 ohm per channel amplifier.


----------



## amb

Quote:


  Originally Posted by *Pepsione1* 
_What would happen? I have a pair of 60w 6 ohm speakers I want to try on my 500w (? not sure) 8 ohm per channel amplifier._

 

If you're talking about a solid state amp (e.g., not a tube amp with an output matching transformer), there is no such thing as an "8 ohm amp". The amp's own internal output impedance is a small value (probably a small fraction of an ohm). The "8 ohms" is merely a reference load with which the output power specifications are derived. The amp's current output capability is the ultimate limiting factor on how low you could go with speaker impedances, but for most amps 4 ohms and up should be no problem. Some of the most robust amps could tolerate even 2 ohms or lower.

 In fact, the actual impedance of speakers varies wildly across the frequency spectrum, so an "8 ohm" speaker isn't really 8 ohms except probably at a few frequencies.


----------



## max64

Ohms, is a measure of resistance. Audio amplifiers are commonly designed to work with 4, 8 or 16 Ohms of resistance, and optimum system performance will be obtained if the total resistive load (or impedance) of the loudspeaker or set of speakers is exactly correct for the amplifier. If the total loudspeaker impedance is too high, the power delivered to the loudspeakers will be reduced. If the total loudspeaker impedance is too low, the power delivered to the loudspeakers will be increased, which can result in speaker overload and damage to the amplifier.

 You can connect any amount of speakers to one amplifier provided that they are correctly wired and do not fall below the specified output impedance of the amp. Multiples of loudspeakers can be connected together by three different methods, termed Series, Parallel, and a combination of the two, Series/Parallel. 

 In short, first look what the impedance load is from your receiver. Normally you should be ok.


----------



## Pepsione1

So to make my question simple hoping for an simple answer in return. Would the speakers or amp blow up if I plug my speaker (rated at 6 ohm) in an amp stated for 8 ohm speakers only?


----------



## dip16amp

Quote:


  Originally Posted by *Pepsione1* 
_So to make my question simple hoping for an simple answer in return. Would the speakers or amp blow up if I plug my speaker (rated at 6 ohm) in an amp stated for 8 ohm speakers only?_

 

No


----------



## max64

I wouldn't see any problem.

 Most Receivers may have problems adequately driving a 4 or 6 ohm load. However, many of the better Receivers today have a large enough power supply, heat sink area, and current capability in the amp sections to handle 4 or 6 ohm loads. You are usually safe running these speakers on the Flagship Receiver models from: Yamaha, Denon, Onkyo, Harman Kardon, NAD, Nakamichi...

 Although a particular loudspeaker may be rated for 6 ohms ,it may actually provide a more stable load for an amp to drive than another speaker rated at 8 ohms..


----------



## Pepsione1

Thank you
 Can you test a speakers load by using a multimeter?


----------



## AndrewB

To measure resistance yes. To measure impedance, no.


----------



## Jam_Master_J

Yep.

 And I wouldn't worry about using that 6 ohm speaker. It should work fine at reasonable volumes. Just make sure the amp isn't getting hot from pushing the extra current.


----------



## Pepsione1

Thanks everyone. I just plugged in my stereo speakers to my HT amp. They are both crap of the crop but the speakers still sound nicer with the HT amp than the stereo amp. So I guess I'll keep the HT amp after all.


----------



## Jam_Master_J

Quote:


 To measure resistance yes. To measure impedance, no. 
 

Definitions I suppose. The speakers rated impedance is really just an average. An 8 ohm speaker may have dips/peaks in it's impedance based on frequency. This change is basically due to elements in the crossover(circuit that distributes the frequencies to the appropriate drivers). I think box design affects this as well.

 I think a multi-meter should give an accurate result though. I know that when I used a multi-meter to measure the resistance on my headphones I almost exactly the manufacturers quoted values.


----------



## amb

Quote:


  Originally Posted by *Jam_Master_J* 
_Definitions I suppose. The speakers rated impedance is really just an average. An 8 ohm speaker may have dips/peaks in it's impedance based on frequency. This change is basically due to elements in the crossover(circuit that distributes the frequencies to the appropriate drivers). I think box design affects this as well.

 I think a multi-meter should give an accurate result though. I know that when I used a multi-meter to measure the resistance on my headphones I almost exactly the manufacturers quoted values._

 

A sealed-box ("acoustic suspension") speaker always has a large peak in its impedance curve (may be up to 20 ohms or more) at its fundamental bass resonance frequency. A ported ("bass-reflex" or passive radiator type) speaker has two such peaks, the valley between them is the box resonance frequency. In addition, each driver's voice coil is inductive, causing a rise in impedance as frequency increases, and this could be up to tens of ohms or more. The crossover network can of course introduce its own variations to the total impedance curve, sometimes big peaks and dips.

 The rated nominal impedance of a speaker (i.e., "8 ohms") is not really an average. Rather, it is typically the lowest value on the impedance curve above the bass resonance peaks, but before it starts to rise again due to inductance and other effects. For a bookshelf-sized speaker this is usually around 200Hz or so. The DC resistance (at 0 Hz) is what you will get by measuring with an ohmmeter, and that is usually a bit lower than the rated impedance. For example, an 8 ohm speaker might actually measure to be somewhere close to 6 ohms at DC.


----------

