speakers-> difference between guitar and hifi

[black_labb]

firstly ill say that im ignoring frequency response

ive often read that guitar speakers are different from hifi speakers, and using a hifi speaker will cause the speaker to blow due to the distortion generated in a guitar amp.

why is this, isnt distortion just cutting off the top of the waveform in a way (smoothly or not depending on the amp), so how does this "blow" hi fi speakers. is it that you would need a higher rated speaker, as the distortion only happens when you have ore output than the rated "clean" output?

or is this just a myth. i doubt that early fender amps (or guitar amps in general) were using special speakers, but have speakers changed in a way that they cant handle what was normal from "hifi" in the 40's and on?

im asking this as ive been comfused by this for a while. also because i am thinking of using the beast of an amp i bought recently for bass (im playing in a band with my girlfriend who has recently picked up bass as well as singing to fill the gap in the band. might help to have a nicer bass amp) i think that bass speakers are closer to hifi speakers, and just want to know that if i were to get a bass cab of some sort i wouldnt blow the speakers when the tubes are being overdriven. i doubt this would be the case, but id like to be sure first.

thanks
luke

[Enzo]

Well, freq response is an important part of it.

Speakers are speakers, there is no secret things hidden inside.

The fundamental difference is that hifi speakers are designed to REproduce sound from some source. Guitar speakers PROduce sound. They are originators of sound. Hifi speakers are meant to be colorless so they add or subtract nothing from the source material. Guitar speakers are SUPPOSED to add sound of their own. In an electric guitar and amp setup, the amp and speakers are PART of the instrument.

SO amps are not generic, that is why some guys play Marshalls and some guys play Fenders. And closer to your point, that is why some guys like Celestions and some guys like JBLs.

Hifi speakers are meant to have a smooth and wide freq response. Guitar speakers have peaks and valleys and they also tend to roll off in the 3kHz to 5kHz range. You don't need or want freq response up into tweeter land. Never see tweeters on a guitar amp.

One aspect of this wide freq response is that hifi speakers tend to be a LOT less efficient that guitar speakers. The guitar speaker doesn't need to go down to 20Hz, and does not need to pay the penalty for doing so without boosting the upper bass in the process. Efficiency is a matter of how loud a speaker is at a given power.

A speaker that is 3db more efficient will be that much louder for a given power. And 3db is equivalent to doubling the power. In other words replacing a speaker of 98db efficiency with one of 101db efficiency in a 30 watt amp would be the same as keeping the original speaker and increasing the power to 60 watts. So a hifi speaker that is 15db less efficient will be a LOT less loud in a guitar amp than a guitar speaker.

WHat CAN happen is that someone wants their speaker to sound louder than it is. Since the amp is cranking out a power level that would be fine with a guitar speaker, connecting a hifi speaker will produce a lot less sound. This is normal. A hifi speaker at 100 watts will put out less sound than a guitar speaker at 100 watts. But the guy then turns up the amp to get the "normal" volume out of the thing. of course to do that, you go beyond the power rating of the speaker. The problem is not that hifi speakers can't take distortion - after all, they play the distorted music from your records, don't they? - the problem is that guys don't realize they cannot get same volume levels from them at the same power.

I am not so sure a hifi speaker will blow up from distortion. Most people fear tweeters will be damaged by clipping, but that is not a speaker in our sense. The hifi equivalent to a guitar speaker is the woofer.

Guitar amps do use special speakers - guitar amp speakers, "instrument" speakers. Yes, you could use a PA cab speaker, wouldn't sound as nice though.

Cutting off the top of the waveform is called clipping. Distortion is not just clipping. Clipping is distortion, yes, but all distortion is not clipping. Overtones and harmonics added in also are distortion. If it were all clipping then all distortions would sound alike. SCope a distorted overdriven signal sometimes. The high freq spikes on the leading edges can be substantial.

But even with just clipping, the closer to a square wave the clipped signal becomes, the more energy goes into the speaker to try and reproduce it. Instead oif smoothly rising to a peaka dn asmoothly returning, the speaker has to snap out - or in - pretty quickly, then stay there a moment, and then drop back the other way. there is more stress on the voice coil to keep the speaker cone all the way out for that extended moment compared to the briefer instant of the clean sine wave. That is why clipping can be harder on a speaker. Also clipping compresses a signal increasing the overall energy that way. Perhaps that is the same phenomenon thought of two ways.

Rane has a nice tech paper on compression from opverdriving an amp and the damage it can cause speakers.

Speakers for bass guitar are instrument speakers, not hifi speakers. Get real bass guitar speakers.

[black_labb]

thanks for that, it went a bit off topic, but it came together and answered my question. i was not considering using hi fi speakers, just curous what the main differences were that made them unsuitable. didnt realise they were so much less efficient as well.
the questionc ame up when i didnt know why they were unsuitable, and thought maybe bass speakers are closer to hifi speakers as they arent usually distorted, and thought maybe it would be bad to use bass speakers with an amp that was likely to distort.

thanks

[Bruce / Mission Amps]

thanks for that, it went a bit off topic, ...
thanks

I didn't think it went off topic in the slightest bit.
I do think the duty cycle comment was most paramount though.
That DC like pulse in full on clipping is like connecting the speaker leads across a car or aviation battery at 12vdc to 24vdc and letting that poor cone and voice coil fly out to it's maximum excursion hold it there for a while and heat up like a light bub... then nearly instantaneously, reversing the "battery leads" and slamming the voice coil in the opposite direction and holding it there for a while too. YIKES! No Hi-Fi speaker was ever meant to be abused like that, but electric guitar speakers are.
That would surely heat the voice coil up to a destructive level eventually.

[Enzo]

Bass speakers often have higher power ratings since bass amps tend to be more powerful. They are also often designed to have greater excursion - they move father in and out. You might think bass signals are less distorted, but it is quite common to pop strings and to pluck them hard or slap them. This sends huge spikes out the speaker. And the speaker has to handle it. fuzz tone guitar won't stress it any mor than a guitar speaker.

[Synaptic Amps]

One thing that I don't think's been mentioned yet is that even a speaker specifically intended for high gain instrument amplification is heavily stressed in this application. It's common practice for the speakers in overdriven instrument amplification systems to be significantly over-rated (commonly two to three-fold) compared to the amp's stated output power. As an example, in a modern half stack a 100 watt amp is paired with a 4x12 cab with four 75 watt rated Celestions giving 300W of total power handeling. Cranking up a 15 watt amp with heavy distortion through a single 15W rated speaker will predictably lead to premature driver failure regardless of whether an instrument, PA or hi-fi driver is used.

Indeed, old driver's like AlNiCo Jensen's were used in tube hi-fi systems before their use in Fender and other guitar amplifiers. I still enjoy listening to music through a pair of vintage P10Rs mounted in resonant pine cabs. [Running your home stereo through your instrument cabinets is a good way to get a feel for how they color your sound.] The 15 watt power handling of these P10Rs is not that great compared to modern strontium (ceramic) or neodym drivers but sometimes greater efficiency comes at the expense of tonal quality. The obvious solution Fender found to overcome the low power handling of these early drivers was to use more of them in parallel: 2x10, 2x12, 4x10, 4x12, etc... I would hypothesize that you could similarly get reliable long term operation from today's "hi-fi" speakers provided you used them in great enough numbers or paired them appropriately with a low wattage amplifier.

Kevin O'Connor suggests trying Electro-Voice Force drivers (EV's PA speaker line) for guitar cabs in his book, "DIY Speaker Cabinets for Musical Instruments". I tried this in some resonant cab exeriments and AB'd two cabs - one with a 10" Weber Blue Pup (a celestion - like driver) and the other with a Weber Michigan 10" (Weber's EV-take, I was never able to find a source that sold EV Force drivers without buying a full PA cabinet. Anyone have a lead?). To me the heavy-bottomed smooth response curve of the Michigan was a pleasant change of pace from the comparatively cutting and compressed sounding "british driver". While differing from "hi-fi" principly in power handeling, PA drivers are certainly viable alternatives to traditional instrument drivers provided they're mounted in an appropriate cabinet.