How non linear are guitar cabs?

[bozmillar]

I'm just curious to know how much the volume going through a guitar cab effects the sound of guitar recordings? Power amp and preamp distortion aside, does a guitar cab sound different when playing loud as opposed to quietly?

so I guess my question is, would it sound any different to put a dummy loud on your amp and record it quieter as opposed cranking the cab really loud?

[jclampitt]

speakers distort too when they have enough volume going through them, so they do sound different when cranked up.

[drgamble]

I have never seen response curve graphs, but would say they are non- linear. Different cabs definitely "color" the sound. When you say "non- linear" I am assuming that you mean flat response? There are companies that make flat response speakers and I have heard of people using this type of cab when using a power amp and some sort of emulator like a POD.

[bozmillar]

non-linearity in an audio and electronic sense means that it sound different at one volume level than another.

I suspect that part of their charm is that they distort at high volume levels, but how loud does it have to be to get this distortion?

[drgamble]

Depends on the speaker. I have 25W greenbacks in my cab and they start to break up with the amp turned to 7. The 75W celestions do not.

[bozmillar]

ah, ok, perfect. So my next question. How much of this breakup do you want in your sound, if any?

I always play through amp sims, so it's just not something I think about ever. Just trying to get the perspective of people who play through real amps.

[Freddy G]

Most guitar cabinets are are very non-linear. The cabinet itself is not built like a speaker cabinet for music reproduction. A monitor or PA speaker cabinet is built for maximum rigidity so as to minimize cabinet resonances and standing waves.
A guitar cab on the other hand is not made for sound reproduction, but for "production"...meaning that the cab is producing a sound, it is part of the instrument. Have you ever seen a 4 -12 cab miked from the back, or the side? I like to record them that way for the cabinet bloom (of course in conjunction with mics in front of the speaker cones).
Look at some of the single speaker guitar classic cabs, they are built out of solid pine, with a thin plywood baffle to boot! These suckers resonate like crazy, they have standing waves galore and they bloom when turned up....absolutely the opposite of what you want from any hi-fi (full range music reproduction) speaker.
I experimented a lot with these theories when I was building guitar cabinets. You can ruin the sound of a 4-12 cabinet if you start monkeying with internal bracing and stiffening. That characteristic low end "chunk" comes largely from the cab resonating.
I have seen other cabs that were built pretty stiff, using baltic birch plywood and some internal bracing, but they just sound too sterile to me. Even the ones that are built stiff though are still way looser that any full range music reproduction cab.

How much of this breakup do you want in your sound, if any?

Depends on the production and your taste. Personally I'd say I always like some. For me preamp gain is the most artificial sounding (albeit necessary to a degree) distortion as compared to output tube distortion, loudspeakers reaching the limits of their excursions, the cab rumbling and blooming and even the way the shear volume excites the room resonances and modes.
There's a fine line between the mojo you get from the combination of all these thing and going overboard and ending up with an "out-of-control-caveman-sound"!

One day I was delivering guitars that I had worked on to Alex Lifeson. Rush was recording in Toronto and I came to the studio. Alex was tracking guitar solos and he invited me in to sit in the live room with him. If I recall he was playing through a 5150 with a PRS. The amp's volume was not at all screaming loud, but it was at a moderate volume where the output tubes were just starting to compress....but then this was not so much Rush's "rock guitar" phase, there was more emphasis on effects, layers and delicacy.