Speak to me about speakers

[Axtman]

What is the difference (physical and sonic) about guitar, bass and PA speakers?

What determines how much wattage a speaker can handle? Or.....how can you tell how much a speaker can handle just by looking at it?

What is the physical difference between a 4, 8 and 16 ohm speaker?

[Enzo]

Juan would be the guy to answer, but my humble reply:

You can't tell what a speaker can do by looking. You sometimes CAN tell the speaker was asked to do more than it was capable of and destroyed itself. Of course a large 54 ounce magnet likely means the speaker handles more power than a little 10 ounce magnet.

PA speakers have the job of reproducing sound accurately. They should have a relatively flat response over a relatively wide frequency range. Some are meant for full range, like in a 1x12 stage monitor. Others are meant to be more specific, like a mid-range or a woofer. It isn't supposed to color the sound.

A guitar speaker is the opposite, it is designed to color the sound, to have its own sonic influence. A guitar speaker is part of the instrument. It tends to have a more limited range. Guitar doesn't go down to snorting bass, and really rolls off over about 3kHz or so. Peaks and valleys in the response curve? Just adds to the fun.

A bass speaker is somewhere in between. It tends to be cleaner, and is made to handle the low end. Bass is a much bigger signal than guitar. The cone has to move a lot farther and pump more air.

The current through the speaker voice coil creates a magnetic field, and that field pushed against the magnetic field of the magnet on the speaker. The voice coil wire doesn't want to get too hot or it can catch fire or warp the voice coil form. SO the wire in part determines power capacity. Even the strongest voice coil has to have a magnet field to push against, SO a tiny magnet won't allow huge power output.

4-8-16 ohms? essentially the voice coil. Specific models might make subtle changes in the cones for different impedances, or something, but essentially, the coil. You will likely hear nuanced arguments about OT phenomena and why 16 ohms is better/worse compared to others, but aall those are subtle factors.

I have over simplified it all and no doubt left out important stuff, but that is how I see it.

[TomCarlos]

And here is the Level 1 answer...

As for the physical difference.... I have three Eminence Legend speakers. There are one each of 4, 8, and 16 ohms (as I have three open back test cabinets). If I were to put tape over the back magnet, I could not tell them apart. The overall physical dimensions, weight, etc, they are identical. The paper and cone are identical. So that leaves the Voice Coil. The diameter is different, the number of wire turns is different, the wire might be different, but that might be the big difference. Of course, there are differences because of the power handling capabilities too.

The simple answer for part one is due to the frequency range of a speaker. A PA speaker is designed for a more full range. Bass speakers are designed for power, ability to throw longer distances, etc. Guitar speakers have a limited frequency range.

Ok, I over simplified my answer but that should get the conversation going.

Oh yeah, you can visit site like Eminence and dive into the specs and details if you like - Understanding Loudspeaker Data

[glebert]

Here are the differences between types of speakers. Guitar speakers are for when you mash your fingers way up high on the tiny strings like: meedely, meedely, meedely, meedely, meedely, meedely, MEEEEEMEEEEE!!! Bass speakers are for stuff like: dow, dow, dow, dow, do dow, do dow, do dow. and keyboard speakers are for: boop, boo, bppp, boo, boo, boo, boop. Yeah, stuff like that.

[Mick Bailey]

The power handling is a balance between how much electrical energy can be converted to mechanical movement, and how much is converted to heat (and how this heat can be dissipated). Once the cone has reached the maximum physical excursion, then any more energy pushed into it can only be converted to heat. Apart from the signal distortion, it's a matter of how long the winding and former can survive before failing. Within normal operation, materials and construction have to stand up to the unwanted heat and it's not easy to tell just by looking how much power a speaker is rated at. Efficiency also has to come into it - I have a dummy load that will dissipate 1KW all day long, yet produce no sound. You don't want a speaker that's more dummy load than sound-producing device.

Bear in mind that there are some incomprehensible ratings for speakers (I'm thinking car stereo).

[Axtman]

I will occassionally see speakers with a rating of 300, 400, 500 or more watts. I have a really hard time believing that claim. I thought most speakers could really only handle only 200 watts (RMS).

[Leo_Gnardo]

I will occassionally see speakers with a rating of 300, 400, 500 or more watts. I have a really hard time believing that claim. I thought most speakers could really only handle only 200 watts (RMS).

It's true that wattage claimed by manufacturer can be misleading. For instance, I wrecked a perfectly good JBL E120 rated 300 watts, playing a 100W Marshall through it. How that happen ? ? ? Suffice it to say, I never tried it again. High power amps - it's always good to have multiple speakers to share the wattage wealth.

Another speaker killer is driving them with solid state amps run at levels beyond clipping. The squared-off top & bottom of the waveform have the amp delivering maximum current to voice coil while holding them motionless if only for an instant. Repeat that a few hundred times and your voice coil turns into an expensive fuse. Tube amps are more forgiving BUT as mentioned in the above example, there are still limits to how much punishment a speaker can handle, and no easy way to figure it out from specifications alone. Some common sense, earned the hard way - pay attention & you'll learn some here & hopefully avoid destroying good speakers.

[Axtman]

Yes I have heard that it is better (relatively speaking) to over power a speaker with a clean signal than underpower with a heavily distorted signal. I too learned that lesson the hard way when I put a distortion pedal in front of my Yamaha bass amp.

[Enzo]

Don't look too hard for rules like that.

Why does 200 watts sound reasonable to you but 300 watts doesn't?

Ignore all specs which discuss peak watts, or anything other than RMS.

If I yank up on a 900 pound piano I can lift it enough so you can pull a $20 bill out from under the wheel. But can I lift 900 pounds? Of course not. SO 900 pounds peak is a meaningless spec for buying an Enzo.

[glebert]

SO 900 pounds peak is a meaningless spec for buying an Enzo.

They really don't make Enzos the way they used to...

[Axtman]

Look at some of the power ratings of these speakers: https://usspeaker.com/15.htm

I wish I knew how they actually accomplished those power ratings!

[Mick Bailey]

Or these;