If a tube amp with an output transformer has a 16 ohm tap, it will have slightly more power and certainly less distortion when driving 16 ohms. This is because the output transformer is more efficient. In fact it will also exhibit more bandwidth- often with greater bass extension.
With transistors you lose power, but you also lose distortion- causing the transistor amp to sound smoother and more musical. This is because there is a non-linear capacitive aspect to almost any semiconductor junction, which is magnified by current. This aspect contributes to odd-ordered harmonic distortion, which is unpleasant to the human ear. By reducing the current (i.e. going to a higher impedance load) odd-ordered harmonics are reduced. This is evident in the distortion curves of all solid state amplifiers, even class D.
With OTLs, depending on the size of the amp, you may gain some power- in particular with smaller OTLs. For example the S-30 makes 45 watts into 16 ohms. With larger OTLs this may not be true- for example with our MA-1 the output power is unchanged. What is more important is what happens to distortion and efficiency of the OTL! In all cases it will operate with less distortion, meaning that it will sound smoother and more detailed. The increased efficiency also means that you will get less heat with less power drawn from the wall, as more of the power generated by the amp will be dissipated in the load rather than the output section.
IMO there is every argument for 16 ohms **if your goal is sound quality**. There is no argument for 4 ohms regardless of the amp, unless your goal is **increased sound pressure where sound quality is less important**, *and* you have a solid state amplifier. IOW 16 ohms is a simple way of making the speaker seem more transparent, smoother and more musical, as opposed to 4 or 8 ohms.
With transistors you lose power, but you also lose distortion- causing the transistor amp to sound smoother and more musical. This is because there is a non-linear capacitive aspect to almost any semiconductor junction, which is magnified by current. This aspect contributes to odd-ordered harmonic distortion, which is unpleasant to the human ear. By reducing the current (i.e. going to a higher impedance load) odd-ordered harmonics are reduced. This is evident in the distortion curves of all solid state amplifiers, even class D.
With OTLs, depending on the size of the amp, you may gain some power- in particular with smaller OTLs. For example the S-30 makes 45 watts into 16 ohms. With larger OTLs this may not be true- for example with our MA-1 the output power is unchanged. What is more important is what happens to distortion and efficiency of the OTL! In all cases it will operate with less distortion, meaning that it will sound smoother and more detailed. The increased efficiency also means that you will get less heat with less power drawn from the wall, as more of the power generated by the amp will be dissipated in the load rather than the output section.
IMO there is every argument for 16 ohms **if your goal is sound quality**. There is no argument for 4 ohms regardless of the amp, unless your goal is **increased sound pressure where sound quality is less important**, *and* you have a solid state amplifier. IOW 16 ohms is a simple way of making the speaker seem more transparent, smoother and more musical, as opposed to 4 or 8 ohms.