Speakers for Bass Guitar
Bass Guitar Speakers are a specific type speaker for the instrument, a musical instrument speaker. You can use any type of speaker which is available, but you will find that if you use speakers which are specifically designed for the bass guitar, or bass amplification, you get much better results. I know what I am talking about, since I have built around fifty or more cabinets for various purposes, and I have used other speakers in vain.
Before going further you should be familiarized with the terminology which is associated with
You can check out my section on
Frequency Spectrum, where most of the terms are defined and used.
In the next sections we will look at the various types of speakers, and their associated cabinets: infinite baffle, vented cabinet, horn loaded cabinets, and others.
You should also look at the important topic of
speaker wiring too.
If your are interested in building your own
speaker boxes, check out this link to Speaker Box Designs too.
Basically, a speaker (also called a transducer) is an electric motor of sorts,
connected to a diaphragm, or cone. The motor part is the electro-magnet
and coil assembly. As electrical signals pass through the coil, the
magnetic field causes the coil, which is attached to the cone, to move. Both the
coil and the cone move together to produce the sound of the speaker.
In general, bass guitar speakers are not the same as Hi-fidelity woofers. Hi-Fi
woofers have a resonant frequency which are usually between 20Hz and 35Hz. Most Bass Guitar speakers have a resonant frequency between
35Hz and 65Hz. This is because the suspension in the speaker unit is stiffer (higher compliance), and because the designer of the speaker is attempting to reproduce frequencies beyond the typical range of a woofer. This explains, in part, why a bass guitar sounds different when it is fed into a large PA system (the other major factor being how the EQ is set for the instrument channel). Bass Guitar speakers are in reality a bass/midrange speaker. Most bass guitar speakers are able to reproduce high frequencies at 2500Hz, with some as high as 7000Hz. Generally, the larger the speaker, the lower the range of frequencies which are reproduced.
This brings us to the all important issue of moving air. Bass frequencies need to move lots of air typically. This is especially true if you are in a large room or outdoors. For a head set, there is very little
spatial volume, thus, a significant amount of bass frequencies can be developed between the headset and your ear with a very small speaker. However, if you move the headset from your head, the bass will drop off very quickly. This is because the speaker in the headset cannot make a significant pressure change in the room which it is attempting to do. A larger speaker is needed. This is also why smaller speakers generally produce less bass.
This is really just a function of physics. Since a speaker box is really an atmospheric pressure pump, the larger the piston (the speaker size) is for a specific volume size
(i.e. the room), means that the pressure can be increased or decreased quickly. A smaller piston would require that a longer stroke
to occur to get similar results. And while you can put more power into a smaller speaker and get the same volume, the trade off is more power required from your amplifier and more distortion created by longer excursions of the woofer and by the amplifier. Remember, that all speakers have compromises imposed in their design. There is no perfect speaker. However, some are better than others. Ideally, it would be best to have a complete wall of speakers for your bass. This would allow little movement of the speaker cone (low acoustic distortion), and large surface area for your target audience. In most cases this is impractical. Usually, if you have eight 10 inch woofers in your bass cabinet, or two 15 inch speakers, or two 18 inch bass speakers you will be in good shape for most situations.
This brings to the next issue of large verses small woofers. While a large
woofer can and does move lots of air, the larger the woofer, the more
compromises which are designed into the woofer. Larger woofers have less ability
to reproduce higher frequencies, and it becomes harder for the larger woofer to
control the mass of the cone. The magnetic motor (the coil and magnet structure)
moves the cone back and forth, to produce sound waves from the cone surface.
Ideally, the cone needs to have a mass of zero (but no cone has this
characteristic) so that the motor part can start and stop the cone at will.
Because of the mass of the cone and the coil structure, which is connected to
the cone, raises the total mass, the cone therefore has inertia. Therefore, it does not start moving exactly when it is told to move, and it does not stop exactly when it is told to stop. With smaller woofers, there is better control over the cone movement by the coil and magnet structure. Also the cone needs to be relatively stiff and not flex over the surface area. This is the problem with large woofers (15 inch and greater). Clusters of 10 and 12 inch woofers will produce better quality sound than an
18 inch woofer or a huge 24 inch woofer. By the way, a four by 10 inch group of woofers is equivalent to a 20 inch woofer.
And a four by 15 inch group of woofers is equivalent to a 30 inch woofer.
Below is the famous Speaker Lab Seven speaker photo, with the Old Victrola Dog
listening to the speaker. The company stopped selling this photo because
the animal rights people complained that it was promoting cruelty to animals,
back in the late 70's. I will let you be the judge here. Personally, I
love this photo. My wife hates it!
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