makepeace wrote:
aja wrote:
makepeace wrote:
Surely the damage you would cause would have to do with the travel of the speakers? Ie bass sounds make the speaker move backwards and forwards a lot further from their origin, treble, less so, but at a higher frequency. Thus if you're putting through a ton of bass into a speaker that only has x travel, you'll damage it, where as if you put a lot of treble into a speaker thats designed to have a lot of travel (ie guitar into bass amp), its not really going to matter.
I may be wrong, but I disagree...
The bass sounds are at a lower
frequency whereas further cone travel implies greater volume I would think
If the cone is moving very slowly (i.e. low bass sound frequency) then the voice coils get hot faster and damage the speaker.
right? um... :-\ Please correct me
Ah, you're right. That makes a lot of sense. Amplitude is proportional to volume.
Not necessarily...... ???
The whole issue of loudspeakers, power, bandwidth etc is a very complex topic. Add in cabinet design and the fun really starts.....
Some basics:
Loudspeakers can only get damaged three ways.
1. Drop them... ?
2. Burn them out
3. Destroy the diaphragms/cones by over excursion.
A typical audio signal comprises two parts 1) an average or RMS power. this is the equivalent DC heating power of the signal. and 2) Peaks, which depending on the overall power, will push the loudspeaker towards it's excursion limits.
When the RMS power is too high, the voice coil in the loudspeaker overheats and will possibly burn the loudspeaker out. This is one of the risks of using too much compression to increase the average volume on a PA.
The second type of damage from over excursion often happens when the dynamic range of the signal is very wide. The peaks can cause the cone to exceed it's limits and could either cause the voice coil to hit the side of the magnets,causing the insulation to be rubbed off, eventually leading to loudspeaker failure, or the cone, spider or surround tears.
Referring all this to guitar amplifiers and bass guitars:
99% of guitar loudspeaker cabinets are design to only operate down to about 100Hz. At these frequencies there is little cone displacement and all is well. Guitar loudspeakers are also designed to handle highly compressed signals such as distortion and overdrive so overheating is usually not an issue either. Tube amplifiers also have an output transformer so when the amplifier goes into distortion, no DC voltages go through to the loudspeaker.
When you put a live bass guitar through a guitar loudspeaker cabinet, the loudspeaker and cabinet is now trying to operate outside of it's design parameters. The result is that there is no control or damping of the cone excursion and damage to the loudspeaker/s can easily result.
The difference with a Bass Guitar Cabinet is that it is designed along similar lines to that of a sub-woofer in that the cabinet is ported to provide loudspeaker damping, thereby controlling cone movement and increasing efficiency. The loudspeaker components are also designed to reproduce the Bass Guitar frequencies.
Getting back to my statement at the top of this post:
Loudspeaker acceleration/deceleration has more of an influence on volume than displacement. Amplifiers with a high damping factor (Less cone displacement but high control) will make loudspeaker louder for a given power than a low damping amplifier (more cone displacement but less control) of the same power. Length, quality and resistance of loudspeaker leads also play a major role.
There is a lot more to this but hope this clarifies things somewhat.....
