Just about everyone who picks up the bass as a beginner has a marginal practice amp to start with. Which is why I’m going to talk about what to look for when you buy your second amp – your first real “play it loud and proud” bass amp.
Combo vs Separate Head and Cabinet
Every speaker needs an amplifier to drive it. You can not plug your guitar cable into the back of a speaker cabinet and expect any sound to come out. So every guitar amp (or PA!) must have a pre-amp with signal processing, a power amplifier, and one or more speakers.
The truth is that there is very little difference between a combo amp and a separate head and speaker cabinet. The “head” is the electronic part that has the pre-amp, signal processing (effects and EQ), and the power amp (Watts!). A combo amp is just the two pieces bolted together in a common box. Combos tend to be a little bit cheaper than buying the items separately, and
some combo units have fewer ins and outs, but it has very little to do with the sound quality.
The main attribute of a bass speaker cabinet is that it needs to move a lot of air. This means that the speaker diameter needs to be very large, and it needs to move in and out a long way. One problem when you do this with a standard guitar speaker is that it builds up enough momentum that it actually wants to jump out of itself. This is one of the reasons behind why a bass cabinet must be sealed or ported. At the lowest frequencies, the speaker needs to have the air inside the box push back a little to keep it under control. The size and length of the port tube helps the speaker stay under control at even lower frequencies.
This is why you do not want to play your bass loudly through a guitar amp. Most guitar cabinets are open in the back – part of their tone comes from allowing the speaker to move freely.
Big Speakers vs Little Speakers
Since we need to move a lot of air, you would think that bigger is better. But there is a problem: even the bass guitar creates higher frequencies. All those good harmonics from a warm J-bass, or from slapping and picking, need to go through the speaker as well. And for a large speaker to create high frequencies, it needs to be flexible. It’s just not mechanically possible to move the entire 15″ speaker at 1KHz, only the central few inches can move that fast. This is OK, but it creates a dilemma for the designers. For good tight low frequencies, you want a stiff speaker, but to get higher frequencies, you need a flexible speaker cone. In addition, in order to make a big speaker rigid, it becomes heavier, which makes it harder to move quickly. They are more expensive to build too, because it takes more power to move those huge cones, requiring bigger coils, frames, and magnets.
One solution is to use several speakers. Two 10″ speakers have about the same area as one 15″ cone. By designing the speaker to be able to move in and out more (a longer throw), it is possible to use these 10″ speakers for the bass. But because the area and radius is smaller, it is easier to make it both light and rigid, and thus able to produce the higher frequencies as well.
Here is a table of areas for different types of speaker cabinets:
In most cases, you will find that a 2X12 or 4X10 is more than enough, and it will sound much better than a 1X15 or 1X18. Note that the different manufacturers have become very adept at getting the most from their speakers. SWR is very good at getting a very clean low sound from a single 12″ speaker.
For most practice or rehearsal rigs, you can get by with 100W or less, but for your new amp, you should be thinking about 200-400W. Low frequencies suck up a lot of power, moving those big heavy speakers back and forth. In this power range, you should be able to get a good range of features including dual-channels and several patch points.
Dual channels are nice because you can set up two different EQ and effects chains – say one for ballads and the other for hard rock – and easily switch between them. Having two gain controls are helpful if the internal overdrive is desired, so you can turn up the distortion and turn down the volume with these two controls. Usually the EQ will be either a simple 3 knob version, or a more sophisticated parametric or graphic EQ may be available.
As noted above, this applies the same whether your amp in part of a combo, or it’s a separate head.
If you have determined that you need the biggest and loudest setup available, you can get a 4X10 with a 1X15 under it, or even a 8X10, but these are huge, and heavy, and expensive. And you can drive this with 600-1200W. If you go with the split 4X10 and 1X15, I recommend using a crossover and two amps (300W each), because you don’t want to send the high frequencies to the 15″. Many people drive both speakers with the same amp, but I think the mid-highs will not be as clear as you’d like. This is the type of rig you might consider if you’re playing on a large stage and you have to compete with several guitarists and a manic drummer. As noted in my Sound Engineering columns, I am not a fan of extremely loud stage levels, but if you want it, you can get it.
Oh my, there are so many different brands of bass amps, and they all look exactly the same, and yet they sound different. And the cost range is incredible. A Carvin 4X10 cabinet is $399, and the same thing from SWR is $799. Most people agree that the SWR sounds better, but TWICE as good? And there are many 1X12 and 1X15 combos made by Fender and Ashdown that sound pretty good. So it’s really a personal choice.
There are only two things I will warn you away from. First, don’t get a folded horn cabinet. The sound doesn’t properly form until about 10 feet in front of the cabinet, so you can’t hear yourself on stage. And second, be very careful with Hartke speakers. The cones are made from aluminum, and while some people like them, I have heard several reliability concerns about that brand.
My personal preference would be for a 4X10 with a 300W head, made by Carvin or Peavey or Ampeg. This is going to be loud enough to cut through when I need to, have a wide range of features, and still be cost effective. If size in a problem, I think that SWR gets the most sound out of a small package.
And as always, I’d buy it used!
Let me know what kind of bass amp you own, and what you like about it. I look forward to hearing from you.
List of brands:
- Bag End
- Trace Elliot
And several other smaller brands…