@blindjim , all the comments regarding speaker efficiency are spot on.
And you are quite correct that different brands of power tubes are going to sound different. Once you settle on a particular power tube type, then you sort out which brand of that tube to get. The choice of power tube type is heavily dependent on which speaker you get!!
The one thing you want to pay attention to is the way SETs make distortion. In that regard, they are very very good at low power; distortion falls to the point of being unmeasurable (which is the source of the ’amazing inner detail’ for which so many SETs are known; the amps we make are some of the very few push-pull amps that share this low power lack of distortion character). But at full power, the typical distortion is in the neighborhood of 10%.
SETs are known for being quite lush and very dynamic. Both of these properties are due to distortion- the 2nd harmonic brings the lushness, and at powers over about 20% of full power, the upper harmonics cause the dynamic properties on account of the way the human ear perceives sound pressure.
You really want to avoid the higher ordered harmonics! Not only do they cause the amp to sound dynamic, but they will also cause the system to sound loud and shouty. You will see a lot of people talk about the fact that their system plays as loud as they want; this is **often** caused by the distortion and not the actual sound pressure. A good system should **never** sound loud!
To avoid this, the speaker simply has to have the efficiency such that you don’t exceed about 20% of full power of the amp you have in mind. This will have the amp playing its most transparent and with its smoothest qualities. Generally speaking, this means that in most cases, a speaker of less than 100db is not going to be suitable. I am full aware that there will be many that read this and will dispute these words; my recommendation is to reread this post! For these people, if your system is not set up by this rule of thumb, you really aren’t hearing the finer qualities of your amp, no matter how enjoyable it might be.
And you are quite correct that different brands of power tubes are going to sound different. Once you settle on a particular power tube type, then you sort out which brand of that tube to get. The choice of power tube type is heavily dependent on which speaker you get!!
The one thing you want to pay attention to is the way SETs make distortion. In that regard, they are very very good at low power; distortion falls to the point of being unmeasurable (which is the source of the ’amazing inner detail’ for which so many SETs are known; the amps we make are some of the very few push-pull amps that share this low power lack of distortion character). But at full power, the typical distortion is in the neighborhood of 10%.
SETs are known for being quite lush and very dynamic. Both of these properties are due to distortion- the 2nd harmonic brings the lushness, and at powers over about 20% of full power, the upper harmonics cause the dynamic properties on account of the way the human ear perceives sound pressure.
You really want to avoid the higher ordered harmonics! Not only do they cause the amp to sound dynamic, but they will also cause the system to sound loud and shouty. You will see a lot of people talk about the fact that their system plays as loud as they want; this is **often** caused by the distortion and not the actual sound pressure. A good system should **never** sound loud!
To avoid this, the speaker simply has to have the efficiency such that you don’t exceed about 20% of full power of the amp you have in mind. This will have the amp playing its most transparent and with its smoothest qualities. Generally speaking, this means that in most cases, a speaker of less than 100db is not going to be suitable. I am full aware that there will be many that read this and will dispute these words; my recommendation is to reread this post! For these people, if your system is not set up by this rule of thumb, you really aren’t hearing the finer qualities of your amp, no matter how enjoyable it might be.