If you’re thinking of adding a new guitar or bass amp to your rig, you have two options. Should you opt for a combo amplifier, or get a separate head and cab? There are several key differences that you need to be aware of.
The difference between a Combo Amp and a Cab and Head set up, is that a Combo amp has the Head and Cab all in one convenient unit. A Head and Cab setup has the amplifier and speaker in 2 separate units. Whilst a combo amp offers more convenience, a head and cab often gives you more control over your desired sound.
The argument of combo amps vs. head and cab setups is constantly debated by musicians. There’s no denying that the former is more convenient, with its all-in-one capabilities. However, some would argue that using a head and cab allows you to be more deliberate with your guitar or bass tone.
Even if you have a clear idea of the sound you’d like to get from a guitar or bass amplifier, there are so many options to sift through that it can be a daunting task.
You’ll come across a plethora of combo amps, heads, and cabs, so it’s important to know the benefits and drawbacks that this offers. I have personal experience of getting set up with Combo Amps and Heads and Cabs from spending many years as a touring musician,
In fact, my current favorite setup combines a combo amp AND and head.. More on this later in this article.
In this detailed guide, I’ll provide you with a clear breakdown of combo amps and head and cab setups, so that you can decide which would best suit your requirements.
What is a Combo Amp?
Combo amps are named after the way they combine all of the necessary components required for amplification into one unit. This includes the head and cab, all of the wiring, and potentially preamp and power tubes.
Combo amps are a popular alternative to having separate heads and cabs, mainly due to their undeniable convenience. Rather than having to lug two bulky units around, you can simply transport a singular unit and still enjoy the benefits of having a head and cab at your disposal.
Combo amps are also ready to go straight away, whereas head and cabs need to be compatible with one another to create to sound you’re looking for. They also make great on-stage monitors due to their mobility and convenient sizing.
Head & Cab Explained
Head and cabs are two essential components in any guitar or bass amplifier setup. The head is used to shape the tone of the instrument, and it also impacts how much power can be sent to the output.
The cab, on the other hand, is either a singular passive speaker or in some cases a series of speakers, which receives the signal from the amplifier and is responsible for projecting it.
That’s the simplest explanation of how the dual-component amplifier rig operates. However, there are so many heads and cabs to choose from, all with varying capabilities and attributes, that it can be difficult to identify the best pair.
Can You Use a Guitar Cab Without a Head?
Cabs and heads must be used together for the process of amplifying and projecting the sound of a guitar or bass. Simply put, the cabinet is a set of or one speaker which requires the power from the head for the sound to be generated.
Amp heads commonly contain preamp and power amps, which receive the signal from the vibrations of the guitar’s strings, and amplify them so that they are audible. The cab then receives this amplified signal and sends it through the speaker so that it can be heard.
Using either of these two components without the other will either mean that the amplification doesn’t occur, or that the amplified signal has no speaker to be an outlet. That’s why you either need a combo amplifier or a separate cab and head setup.
Can You Plug Directly Into a Cab?
It may be tempting to bypass the need for an amp head and plug your instrument directly into the cab, but this isn’t a good idea for several reasons. Firstly, the reason the head is so essential to the process is that it includes both preamp and power amps, which prepare the audio signal to be played back through the cab speakers.
- If you plugged an instrument directly into a cab, the signal would not be subjected to the necessary amplification process and this would mean that it would likely be barely audible.
If you were using an amp simulator pedal, this may be able to drive the cab, but again, it’s not advisable.
Guitar and bass signals are unbalanced, which means they are prone to noise. The amp head provides the necessary compression and other processing that the signal requires to sound clean.
Without this, you could potentially blow the speaker on the cab or at the very least subject it to some unwanted pops, hisses, and crackles caused by the unbalanced connection.
Cab and Head Combo Amp
All combo amps include both a cab and a head. This provides you with the advantage of not needing to transport two individual units to rehearsals, live shows, or recording studios. For this reason, combo amps have become increasingly popular in recent years.
There is a vast range of cab and head combo amps available. Some offer high wattage and include several preamp and power tubes, like the Fender Twin Reverb. Others are lower-powered and are better suited to practice. The Orange Crush 12 is a good example of this.
- If you’re looking for convenience, a combo amp is a great option. It comes with ready-made tones and sounds built-in, and the cab and head have both been optimally matched in terms of compatibility with one another.
Take a look at this YouTube video that shows the Fender Twin Reverb in action.
Can a Head be Too Powerful for a Cab?
Matching the power of the head and cab is important, but it’s unlikely that you’ll cause any damage by mismatching. With that being said, it’s always best to try and use heads that have a similar power rating as the cab that you’ve chosen. Doing so will ensure that you get the best sound and optimal relationship between the two.
Power is increased when the volume of the amp head is cranked up. Therefore, if you do want to use a head that is more powerful than a cab, it’s important to start with the level set low, and gradually increase it. You’ll be able to hear when the cab is reaching its limits because saturation will start to occur.
If you ignore the sound of the cab breaking up and push the volume higher, this is where you’re in the territory of potentially causing damage to the speaker.
Providing you are careful with combos and don’t set the levels ridiculously high or use a really cheap amp head, you can get away with using a head that is more powerful than your cab. However, it’s best to avoid this where possible and ensure that the wattages match up.
Can You Connect a Head to a Combo Amp?
Although this may seem like a pointless endeavor, it is possible to connect a standalone head to a combo amp. There are a couple of reasons you may want to do this. Firstly, you might find that the built-in cab on your combo doesn’t produce the amplification or tone that you’re looking for. Secondly, you may want to increase the power you have at your disposal by using an external head.
The majority of combo amplifiers have a connector on their rear panel where you can see the connection between the cab and head.
To connect a head to the combo amp, you’d need to disconnect the inbuilt head and use the same type of cable to connect your external head. Make sure that the impedance levels match before doing so, to be on the safe side.
Do Bass Cabs Need a Power Cable?
Compared to guitar cabs, bass cabs need to project a lot more of the lower frequencies of the instrument. This is because the bass guitar is generally tuned down at least an octave compared to the standard tuning of the electric or acoustic guitar.
Bass frequencies require more power to be amplified and projected, therefore it’s highly likely that you’ll need a power cable for the bass cab. Most use standard power cables which are easy to get hold of, but it’s always a good idea to get the best quality power cable you can to avoid it cutting out while you’re playing!
Can You Use a Guitar Head with a Bass Cab?
One of the best things about using separate heads and cabs is that it affords you the freedom to experiment with different combinations. Using a guitar head with a bass cab may be of interest to you if you are experimental in the way that you like to create your tones.
This is possible because bass cabs are essentially just speakers that possess the ability to produce more low-end frequencies. So in theory, this could result in your guitar gaining some more prominence in the bass notes. Likewise, it might result in your bass taking on some of the qualities more commonly associated with a guitar.
You might find that your tone becomes more distorted and naturally fuzzy when you combine a guitar head with a bass cab. If this is what you’re looking for, then by all means experiment away! Just be aware of dramatic power mismatches to avoid breaking your gear.
I have written an article that explains the difference between guitar and bass amps. You can read it here.
Can a Bass Head be Too Powerful for a Combo Amp?
Perhaps you’re unhappy with the capabilities of the built-in head of your combo amp, but you enjoy the sound of the speakers. Or maybe the head has malfunctioned and you’re hoping to use a makeshift solution for the time being. Connecting a bass head to a combo amp is certainly possible.
One worry that you may have is that the bass head could be too powerful for a combo amp, and although this is technically a concern, you can get away with power mismatches providing they’re not too extreme.
Again, you should be able to hear when the level on the bass head is getting too hot for the combo amp’s cab to handle.
Unless you keep pushing the levels and therefore increase the amount of power that is being transmitted from the bass head to the combo amp’s onboard cabinet, then you should have nothing to worry about. This combination can be a great way to carve out a unique tone, especially if the cabinet in your combo amp is of a decent standard.
How do You Match an Amp Head and Cab Up?
Matching a head and cab seems like a complex process, and in many ways, it can be. However, if you follow some basic rules you can’t go wrong.
The first thing you need to be aware of is impedance.
- If the impedance is mismatched between the cab and head, this can potentially cause irreparable damage to the speakers.
The vast majority of cabs have an impedance of either 4 ohms or 8 ohms. You need to find out what the impedance of your head is, and check that it matches up with the rating of your cabinet. As I described previously, you can get away with slight impedance mismatches but this will require you to be cautious when turning up the level on your head.
Likewise, if you use an amp head that doesn’t supply the required impedance power to the cabinet, you will likely be left unsatisfied by the weak tone it produces. This won’t cause any harm to your gear, but it will lower the level and the overall quality of the sound produced by your speakers because they won’t be receiving adequate power.
What is a cab simulator?
Cabinet simulators are designed to mimic the process and results of a guitar cab. They do this by coloring and processing the guitar’s signal, based on the way a genuine cab speaker would.
What does full-stack mean?
A full-stack rig is a term used to describe the head and cabinet of a guitar or bass setup being stacked on top of one another. This was popularized by guitarists in the 60s and 70s, to afford them more volume for live shows.
What does half stack mean?
A half stack rig is simply an amp head with a singular cabinet. It provides less volume than a full-stack but is better suited to smaller venues and more intimate performances.