Tube amplifiers sound different mainly because their high output impedance alters loudspeakers

Evidence

Most power amplifiers are designed to be constant-voltage sources so, unless an unfortunate interaction between amplifier and loudspeaker provokes limiting or protection, all is well. Sadly there have been some notable examples of high-end loudspeakers having impedances that dipped very low: to an ohm or less. This is a problem of incompetent loudspeaker design. However, sensing a market, amplifier designers responded with monster “arc-welder” devices that can drive these problem loudspeakers, but it is overkill for most circumstances. It was amusing at the time to read that these incompletely designed loudspeakers “revealed” differences between power amplifiers, as if it were a virtue. They were the cause of the differences. — , Toole, Floyd E - Sound reproduction-…, 1769 (#corroborates, via linked claim)

Power amplifiers need to be able to drive loudspeaker impedances that routinely drop below the specified value, and not clip on crescendos. Most tube amplifiers change the sound of loudspeakers in measurable and audible ways. As loudspeakers become more neutral, this is an unfortunate situation. — Toole, Floyd E, Sound reproduction- the acoustics and…, 43 (#corroborates, via linked claim)

Categorization

• XREF: connects to: Badly designed loudspeakers cause audible amplifier differences reviewers attribute to the amplifiers — , Toole, Floyd E - Sound reproduction-…, 1769; Tube amplifiers audibly color loudspeakers as those become more neutral — Toole, Floyd E, Sound reproduction- the acoustics and…, 43; Resonances are the primary problem in loudspeakers (+1 more)

Related

• Badly designed loudspeakers cause audible amplifier differences reviewers attribute to the amplifiers (similarity 0.92)
• Tube amplifiers audibly color loudspeakers as those become more neutral (similarity 0.92)
• Damping factor varies from 200-800 for solid-state but only 2-11 for tube amps (similarity 0.86)
• Distortion rarely drives subjective ratings of consumer loudspeakers (similarity 0.84)
• Well-designed loudspeakers converge on neutral, nearly identical sound. (similarity 0.84)
• Amplifier damping factor above 20 produces no audible effect on loudspeaker transients (similarity 0.83)
• Sub-2-ohm speaker designs caused the amplifier differences reviewers praised (similarity 0.82)
• Even professional monitor loudspeakers showed measurable defects in early tests (similarity 0.82)
• Audible distortion in quality loudspeakers is rare within intended limits (similarity 0.81)
• Speaker wire resistance is negligible compared to tube amplifier output impedance (similarity 0.80)
• Loudspeakers at high power and low frequencies become highly nonlinear. (similarity 0.80)
• High-power loudspeakers often trade timbral accuracy, while accurate ones are limited in level (similarity 0.79)
• Resonances are the primary problem in loudspeakers (similarity 0.79)
• Modern loudspeakers converge so closely that choices become statistical ties (similarity 0.79)
• Highly regarded hifi loudspeakers had wildly non-flat anechoic responses (similarity 0.78)

Broader Connections

• Badly designed loudspeakers cause audible amplifier differences reviewers attribute to the amplifiers #corroborates (0.88) — , Toole, Floyd E - Sound reproduction-…, 1769
• Tube amplifiers audibly color loudspeakers as those become more neutral #corroborates (0.85) — Toole, Floyd E, Sound reproduction- the acoustics and…, 43
• Resonances are the primary problem in loudspeakers #expands (0.72)