Playing bass through a non bass amp - how harmful is it?

I have read it shouldnt be done, that you need a bass amp, as the speakers & overall build is sturdier.

But what about if you turn the lows right down, it cant be causing much extra vibration & damage to the speaker -can it?

Does a bass soundmuch better through a bass amp of comparable quality to a non bass amp?

It will wreck the amp, don't play bass through a guitar amp. Guitar through a bass amp sounds pretty good though.
read this, all of it
by Gumbilicious

ok i wrote this a while back for the next time i saw one of these threads.
did a bunch of research about this debate over months and this is the best explanations i can come up with.
also, 'damaging' is a strong and colored word for use in this debate, 'excessive wear' is more appropriate.
on the other hand the term 'catastrophic failure' captures exactly what can happen in the worst case scenarios.
anyway without further ado, my canned response:

truth is guitar speakers can vibrate low enough to produce bass notes; but a guitar speakers construction
and impedance ratings are made for guitar frequencies. what does this mean? how does it effect the guitar

well dealing with construction, a guitar speaker is made to be very responsive. responsive meaning they are
more sensitive to the input signal's dynamics. this has the effect of making the signal sound 'bigger' so to
speak. so in order to make the speaker more sensitive and responsive they have to use lighter, thinner or
loose materials at crucial sections of the speaker(ilke connection points, the spider, etc) to get the
desired performance.

regarding impedance, a guitar speaker's excursion travel starts acting 'non-linearly' when attempting to
reproduce notes outside it's normal frequency range. what this means is the frequency of the note/input
signal directly impacts the resistance/impedance the speaker provides which effects the excursion
(the travel of the cone back and forth). this means that if you get too low from where a guitar speaker
is supposed to vibrate at, then the excursion becomes more pronounced and can exceed it's nominal operating
design constraints.

the results of the 2 factors of construction and impedance in action: the weaker parts of the speaker are
not designed to deal with the over excursion resulting from the non-linear impedance caused by the lower
frequency of the input signal. this over-stresses the speaker and can cause eventual (or instantaneous)
failure. no one can tell how long this takes to happen, but the lower the notes and the higher the volume
do directly correlate to a quicker failure of the speaker.

if you want a speaker that can hold up better, you will need one designed to work more linearly in the
low frequency range(low impedances do this well), that also has more stiff and reinforced parts.

that being said, i know people who have used guitar speakers in the bass rig for years and never had
problems, but it is not worth it imo. also imo, pitch shifters aren't usually operated in the low end for
the extended period of time to cause failure. i also think they attenuate the lower freq's a bit to help
make sure this is more a non-issue than an issue. but i am not totally sure on the pitch shifting thing.

one more point is hearing naturally attenuates low end freqs due to less hairs that are sensitive to low
frequencies. the result is more volume is needed to reproduce enough low end volume to sound as loud as the
guitar. this leads to one of the main reasons why guitar speakers break when used as bass speakers, and
that is they don't 'sound' loud enough so you push them to keep up which may lead to instant catastrophic
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It's not actually the amp it's harming, it's the speakers, guitar speakers arn't designed to handle the low frequencies that bass guitars procuce, it will ruin your speakers, even if you turn the lows right down and play quietly, don't do it.

You're not supposed to play bass guitars through normal guitar amps, they're not designed for it, therefore it will sound bad, you're supposed to play bass guitar through bass amps, hence the name bass amp. So the answer to your last question is yes, bass guitars sound ALOT better when played through bass amps.
"In modern music, a lot of people are really stuck on the example, asif it were the idea. It takes millions of examples to articulate an idea, so don't get stuck on the f*cking example." - Joshua Homme, 2008.
get a cheap bass cab used, problem solved...
I wondered why the frisbee was getting bigger, then it hit me.