What makes an amplifier "bright", "warm", or "neutral"?

[Lumba Ogir]

Glenn,

"Bright" = rising frequency response at top end
"warm" = falling frequency response
"neutral" = frequency response (ahhhhhhhh, just right)

The typical "bright" solid state sound is caused by a large variety of high frequency distortions, feedback effects, low bandwidth, device inferiorities, missing low / even order harmonics, and so on.
Falling frequency response does not give a warm sound. Many amplifiers have flat measured frequency response still producing a harsh sound. Things are more complicated than that.

[megasat16]

Bright, Warm or Neutral usually depends on one's ears and ability to process the information from one's brain. One man's gold is one man's trash!

Nonetheless, there are imperfections and all different factors in any amplifiers design that can be said to attribute the sound quality to make it bright, shrill, warm, dark, forward, neutral, etc.

If you think you are missing something, look at the big picture and not just the amplifier! The problem can be from source, amp, preamp, speakers, room acoustics and even some cables and wires. A good sound comes from a good system that has good Synergy between all components and not from a single component.