How do I get the "most" out of a speakers that are rated for 12 ohms?

My amplifier is rated at 125 wpc @ 8 ohms, 200 watt's @ 4 ohms.

I would infer from this that the amp is solid state. Consequently, depending on its design its maximum power capability into 12 ohms could very well be not much more than 2/3 of what it is into 8 ohms. But as Bob noted above that is almost certainly not an issue given the efficiency of these speakers.

Also, while the resistors will increase the amount of power that is put out by the amp they will not increase the amount of power that is delivered to the speakers. The additional power will simply be consumed by the resistors themselves.

Also as Bob alluded to, I would expect the resistors to be useful mainly in the case of some tube amps. In those cases providing the amp with an 8 ohm load might provide sonic benefits by optimizing the loading of the output tubes and output transformer. Also, the resultant flattening of the impedance curve whoopycat referred to is most likely to be beneficial when the output impedance of the amp is a significant fraction of the impedance of the speaker. Which is almost certainly not the case when a nominally 12 ohm load is presented to a solid state amp, and is most likely to make a difference with **some** tube amps having particularly low damping factors and correspondingly high output impedances.

Regards,
-- Al
 

Your speakers are designed to be used with low power amps.  You should talk to Ralph (atmasphere) for suggestions.  Ralph will say that your speakers are medium easy to drive (high impedance) and efficient (sensitivity), though.  Ralph says that as you increase the power of an amp you increase distortion, I think, I can't really speak for Ralph.  He builds amps and really knows his stuff.

Do a member search and ask him for his advice.  He is quite free with it here.

Thank you very much for the responses, they are greatly appreciated!

@barkeyzee1  Your amplifier should be able to make about 150 watts at full power on that speaker.

But as Bob pointed out its unlikely that you are actually using much more than a watt or two most of the time unless your room is quite large and absorptive.

The upside is the impedance of the speaker is helping the amp make lower distortion, which is good. The downside is that the amplifier is operating at such a low power that its distortion is probably higher than it would be if you were able to make more like 5-10 watts most of the time. Push-pull amplifiers in general tend to have a minimum distortion output that is somewhere around 5-7% of full power below which distortion is increasing. This is partly due to how the amp derives its push-pull output (IOW how its 'phase splitter is designed) and and partly due to noise.


Some push-pull amps do not have this quality and so with them distortion continues to decrease as power output drops (our amps are an example of that). SET amps also have this property which is why they are known for that 'inner detail' for which so many of them are lauded. IME this speaker has efficiency in the high 90s which means that a 30-60 watt amplifier is plenty of power in most rooms- with 60 watts you may find it uncomfortably loud without the amp clipping. Just to put a number on this, if your amp is 150 watts, a 60 watt amp will run at full power around 3.5-4dB less output, which is to say its barely detectable to the human ear. We ran ZU speakers at our shop here and our 30 watt amp could play the speakers as loud as we cared to play them.


Where this is all going is there is a very good chance that an amplifier of less power will be able to offer you more finesse. That would serve the speaker investment dollar much better- the whole goal of high end audio is to take you closer to the music and keep you involved. IME on this speaker a tube amplifier will be audibly superior to a solid state amp and no mistake, you should be able to discern the difference easily and quickly as it won't be subtle- smoother, more detailed and not as hard on top.

Your amplifier should be able to make about 150 watts at full power on that speaker.

Why would that be, Ralph ( @atmasphere ), given that the amp is presumably solid state, and is rated at 125 watts into 8 ohms and 200 watts into 4 ohms?  Wouldn't its max power into 12 ohms be significantly less than into 8 ohms?

Best regards,
-- Al