Several things can be discussed relative to amps and volume:
1. Some speakers put out more volume than others because the speaker in the box is itself more efficient. Speaker efficiency is usually expressed as how many decibels the speaker will put out at 1 Watt. Speaker efficiency involves various audio choices and trade-offs.
Efficiency is also affected by whether the cabinet is closed back, open back, or ported. Example: closed back cabinets are akin to acoustic suspension cabinets in the hi fi world, and are less efficient. This is neither good nor bad - a less efficient system may require more amp power, but that means the amp can clip and “give up the goods” sooner. Etc.
2. Tube Watts aren’t louder than solid state watts; a given speaker will put out the same volume at X tube watts as X solid state Watts. The differences relate to other factors, such as tubes generating output power exponentially, and solid state amps generating power in a more linear fashion. So a tube amp can seem louder, because it’s more dynamic.
3. All amps, tube or solid state, interact with the speaker’s impedance, and control the speaker via a damping factor. Different amp designs vary in how they do this.
4. In the tube world, the output transformer plays a large role, has a “sound”, and different output transformers affect how the amp behaves in respect to volume. In the studio world, where I live, transformer-equipped designs add weight and color to the sound, and are often more highly sought after than transformerless designs, even though a solid state transformerless design will often be truer to the source.
5. A multi-speaker design like a 212 or 412 can sound louder simply due to its greater speaker area, spread, etc., and therefore sound fuller even at the same volume as a 112 The larger cabinet required resonates differently. All of this affects the ear’s impression of volume, just as an acoustic guitar with a larger body sounds louder and fuller, with more bass than an acoustic guitar with a smaller body.
6. Don’t confuse the taper of the volume control with how loud the amp ultimately gets. The MT15 has a fast taper, and reaches a certain volume early on, but its 15W is still only going to be able to make the speaker as loud as another 15W amp at max volume.
The issue isn’t how loud the amp gets once it’s dimed; it’s how fast it gets there. An analogy is a car that goes from 0-60 in 4 seconds vs a car that goes from 0-60 in 9 seconds. Once the cars are doing 60, they’re still driving at the same speed, but one gets to that speed more quickly than the other.
