FUQ (eff -yu - cue) - FAQ's with an EDGE

Tagged As: Bass Guitar Amplifiers

Question:
Ok, isn't it true that an amp is just a basic amplifier with a speaker? If it is, then what is the difference between a guitar amp and a bass amp? Is it just that the bass is rated for a lower tone?  What’s the difference?

Answer:
Yes, in general bass amps will reproduce lows better than a guitar amp. The biggest difference is in the speakers and speaker enclosures, they need to work a lot harder to reproduce the lower frequencies at, and guitar speakers are just not up to the task in most situations. Another big difference is the amount of output power output - you rarely see guitar amps above 100w. For bass you need 3 or 4 times the power to achieve the same decibel output as a guitar.  IMO anything under 350w for bass in a live situation would not stand on it's own...unless all you intend to do is provide some background music. As far as the amplifier goes a bass amp is mostly just a straight amplifier, guitar amps are usually designed to be over driven to give masses of distortion - generally bass guitar doesn't want that. Speaker wise a bass speaker has to go a lot lower than a guitar speaker - but usually the drivers in a guitar cab will go a lot lower than they need to for a guitar - if you look at drive units specs, many are suggested for use with guitar or bass. I think you need to distinguish between solid state and tube amplifiers. It seems to me that there is some difference in the circuitry, but I wouldn't be able to tell you. I know that things like the 'deep' switch on a Fender guitar amp might be centered at a different frequency than in a Fender Bass Amp. I know the speaker has to be different. The differences are matters of choice, generally, but you should know: Tube and solid state is divided into pre amp and power amp, tubes or not in each. Many bassists like a tube in the pre amp but don't care for the characteristics of tubes in the power amp. Other swear by them. What each means to an individual can vary by quite a lot, sometimes. It tells you, however, without even a need for technical knowledge, that amplifiers of different types perform similar tasks better or worse, within a range wide enough to cover much common ground and tender controversy, sometimes heated. Bass amps are also no different than guitar amps in that there are many brands which offer widely varied design and function. Well and poorly, *s*. It also should be mentioned that some do want that, and that that desire is darned old. Early recordings typically added a bit of overdrive, and early bass amps, in any size, were often overdriven by choice, though not intended to be. Add other tube characteristics like the difference between a power tubes compression effect when driven by a low frequency signal or a high one. And I'm sure there's more... I'm not all that knowledgeable. And yet there's a lot of discussion about this to be made, too. To last under conditions which are considerably more difficult for a bass signal, low frequencies push a lot more air than highs, response times vary, ... this all leads to magnet type, cone type, even the frame, the surround... then there is the voice coil.. size, gauge of wire…Then specs, graphed and charted and poured over by great minds. The preamps are designed differently to cater to different frequency ranges. Many bass amps have graphic equalizers, where most guitar amps do not. This is usually because bass frequencies are more susceptible to acoustic anomalies because of room shape/size so they usually need a little more tweaking. The bass control in the EQ is around 50Hz to 100Hz and all the way down to 20 or 32Hz.Guitar amps don't need to drop this low because their fundamental frequencies are higher. The power amp section needs to be much stronger in bass amps, usually about 4 times to reproduce the same perceived volume as a guitar amp. Much depends on the cabinet design as well. Most guitar cabinets are open back design, meaning that as the speaker cones move in and out they are allowed to breath equally from both sides. Bass cabinets are closed back and usually have small ports on the front of the speaker for air flow. This volume of air inside the cabinet is restricted from moving easily, and as a result of some physics stuff allow for better reproduction of low frequencies. I agree with the previous posts.  However, I'm picking up an Ampeg Jupiter for evaluation.  These were built for both guitar and bass, and both were to be plugged into the cab at the same time.  I understand a number (small) of other companies have done this in the past. Gibson made an amp called the Magnum 800 that came with an integral 200 watt solid-state amp built into the cabinet. This amp utilized 8x12 speakers (all in one enclosure) and was offered with bass and guitar preamps. It is possible that it was also intended for keyboard usage, but I don't remember if they offered a separate preamp for that purpose. It would have served that purpose well with either preamp of which I was aware. While I kid around about this amp being as portable as a block of limestone from the Great Pyramids, it actually was quite a good guitar and bass amp, with the correct preamp. If one was into non distorted guitar playing in large venues without sound reinforcement, this was the baby to have. I have heard of amps that fit your description, but the name eludes me. Magnatone? I had an Acoustic amp that was designed for this some years ago.  It had a switch for bass or guitar, which basically enhanced the lows for playing bass.  I think all in all it functioned better as a bass amp as it was all solid state.  I generally prefer tube amps but can tolerate solid state more in a bass amp than a guitar amp. The cool thing about the ampeg jupiter is that it is all tube.  I prefer the warm bass sound.