Altecs have controlled directivity in the mids and highs. Your panel speakers need to use the wall behind them to work properly- that needs to be about 5 feet minimum and you can’t have side walls too close or the reflections will mess with the soundstage and make things sound harsher.
The Altecs are likely 16 ohms- all amps make less distortion into higher impedances, and your tube amps tend to make lower ordered harmonic distortion, which is far less audible to the ear than the higher ordered harmonics that are typical of most solid state amps. Plus they are efficient enough to properly take advantage of the very lower power of your SETs. This all works in your favor. In order to get the most out of SETs, they should not be driven past about 20% of their total power, as those higher ordered harmonics start to show up, making them sound loud. A good stereo won’t sound loud even when it is!
There are ways to improve what you are hearing even further. In the Altecs the horn tends to resonate due to its construction; if you can damp it with some proper extensional damping materials it will get smoother. But the horn itself has issues since it was designed (and fairly well for the time) before computer optimization. Modern horns can be smoother and more detailed as a result.
Believe it or not there are also modern tube amps that are more revealing than the SETs on Altecs. The technology has advanced...
BTW the solid state amps you were playing very likely had insufficient Gain Bandwidth Product to really allow them to be musical. Gain Bandwidth Product is a tricky bit to explain, but in a nutshell it means that while you might have adequate feedback to control distortion at low frequencies, you don’t at high frequencies, which causes the latter to be harsher. This has been a problem with all amplifiers over the last 50 years, including tubes, but because tube amps tend to make lower ordered harmonics they tend to sound smoother. This has fueled the tubes vs transistor debate for the last 50-60 years! But its really not about tubes, its about getting enough gain bandwidth product to really allow you to run enough feedback, and that is a real trick- its really only become practically possible fairly recently.
The Altecs are likely 16 ohms- all amps make less distortion into higher impedances, and your tube amps tend to make lower ordered harmonic distortion, which is far less audible to the ear than the higher ordered harmonics that are typical of most solid state amps. Plus they are efficient enough to properly take advantage of the very lower power of your SETs. This all works in your favor. In order to get the most out of SETs, they should not be driven past about 20% of their total power, as those higher ordered harmonics start to show up, making them sound loud. A good stereo won’t sound loud even when it is!
There are ways to improve what you are hearing even further. In the Altecs the horn tends to resonate due to its construction; if you can damp it with some proper extensional damping materials it will get smoother. But the horn itself has issues since it was designed (and fairly well for the time) before computer optimization. Modern horns can be smoother and more detailed as a result.
Believe it or not there are also modern tube amps that are more revealing than the SETs on Altecs. The technology has advanced...
BTW the solid state amps you were playing very likely had insufficient Gain Bandwidth Product to really allow them to be musical. Gain Bandwidth Product is a tricky bit to explain, but in a nutshell it means that while you might have adequate feedback to control distortion at low frequencies, you don’t at high frequencies, which causes the latter to be harsher. This has been a problem with all amplifiers over the last 50 years, including tubes, but because tube amps tend to make lower ordered harmonics they tend to sound smoother. This has fueled the tubes vs transistor debate for the last 50-60 years! But its really not about tubes, its about getting enough gain bandwidth product to really allow you to run enough feedback, and that is a real trick- its really only become practically possible fairly recently.