Minimum recommended amplification requirements and amplifier matching

I like to run tube amps, and while 30 watts or so will make tunes on a speaker of 90 db, I think you will need more power. If it were my room, there would be no doubt. My speakers are 98 db and 16 ohms, and I really think 30 watts is about the minimum on them!

If you really want to work with tubes or even if you want your solid state to sound better, you're always better off not making the amp do something hard, like drive a difficult load. The amp will make less distortion!

To this end generally speaking, an 8 ohm speaker will sound better that 4 ohms and a 16 ohm speaker better than that, all other things being equal. This is simply because no matter the amp, it will make less distortion into higher impedances, and that is audible because the amp will sound smoother and more detailed.

So the takeaway here is if you like the tube amp- get a speaker that is more efficient/easier to drive.

To this end generally speaking, an 8 ohm speaker will sound better that 4 ohms and a 16 ohm speaker better than that, all other things being equal. This is simply because no matter the amp, it will make less distortion into higher impedances, and that is audible because the amp will sound smoother and more detailed.

Hello @atmasphere

Please excuse me for asking, and I believe you already know my question comes with the utmost respect for your subject matter knowledge, but given your statement quoted above, aren’t you contradicting what you’ve stated in at least one other thread here on the forum?

It was/is my understanding that you’ve stated (paraphrasing) that *all* amplifiers have a "zone" within which they must operate to achieve lowest distortion. In other words, it was/is my understanding that what you’ve stated elsewhere is that if an amps volume is *to low*, that also creates unwanted and excessive (relative to its least possible) distortion. If that is true, then it seems conceivable that a 16 ohm load could cause an amplifiers volume control to be *to low* and create more distortion than it otherwise would if operated into a lower impedance.

Thank you.

In other words, it was/is my understanding that what you’ve stated elsewhere is that if an amps volume is *to low*, that also creates unwanted and excessive (relative to its least possible) distortion. If that is true, then it seems conceivable that a 16 ohm load could cause an amplifiers volume control to be *to low* and create more distortion than it otherwise would if operated into a lower impedance.

The volume (power) level and the impedance of the speaker are different.

For a given impedance regardless of the power, if the impedance is raised the distortion will be lower.

So ideally the speaker would be of the efficiency and impedance that you can take advantage of both.

For years I drove Proac Response 2.5's with a Cary CAD-301, a rare SE triode 300B beast putting out a max rated 14W.  See the Stereophile impedance plot of the 2.5s, definitely an 8ohm speaker.  Definitely plenty loud enough when required.  Reinforces my belief that not all watts are the same.

The volume (power) level and the impedance of the speaker are different. For a given impedance regardless of the power, if the impedance is raised the distortion will be lower. So ideally the speaker would be of the efficiency and impedance that you can take advantage of both.

Very appreciative of the clarification @atmasphere 

One last question on this if I may. You mentioned in your 12:16pm post "...all other things being equal". Am I correct that you are also speaking of the *sound pressure level*? I ask because if so, again it would seem to me that higher speakers impedance (say 16 ohm instead of 8) would mean that one would need to raise the volume/power to achieve the same SPL, and hence in so doing could increase distortion if the amp is not operating in its "comfort zone".

Thanks again, atmasphere.