In today’s article, we’ll talk about using multiple instruments through an amplifier.
There are many ways to do this and many ways to work around some complications that you can encounter while trying this. In this article, we’ll cover all of this, starting from how you can use the multiple inputs on your amp—all the way up to how you can use various instruments through one input.
We’ll also talk about what’s needed to do this safely. And even on the different types of setups recommended for what you need, from live sessions to recordings and jams.
Can you play two guitars through one amp?
Yes, you can, and it’s pretty safe to do so. There are multiple types of amps able to do this, but you can pull this off on every guitar amp with two main inputs. However, you will need to be careful, as having two signals through the same amp with too much gain will damage your amplifier.
Although not many amps are designed for this, it’s really common to do so. But in the beginning, the reason to have a secondary input was to plug in guitars that had too much gain. This gain problem could come from pedals or processes along the way, so a secondary input was added with high impedance. That means that the second input has -6db overall.
Having a secondary input is great, but its sound will be quieter most of the time. You’ll need either some pedals help or to lower your main guitar. Even with something as bothersome as this, you can fix it with enough patience.
That being said, multiple amps have two separate channels, where you can plug different instruments and EQ them separately. Frequently you will find they also have a microphone input. To be able to play and sing at the same time, they made amplifiers this way. These amps are the ones truly meant for this function.
You’ll see an example of an amp with only one input on the image below. Without the tools to do so, you normally couldn’t plug another guitar. But with some extra equipment, we’ll be able to.
This amp is a Marshall MG50CFX, and even though it’s a really good amp, it just has a regular input. This can happen, and it’s really common. We can make our way to plugging two guitars onto amps like this.
Can I Equalize both guitars differently on the same amp?
Yes, but you need an amp that’s able to do so. Sometimes amps have various channels that are meant to display different effects. You can take advantage of this to use the EQ of the side that has, for example, vibrato. That being said, your second guitar will have the effect, so that might not be the best fix.
An example of an amp with a different entry for effects is this 65 twin reverb. Here you can use the vibrato channel to equalize a second guitar.
Some amps also come with different mixes for both channels. For example, this Marshall AS50D is widely known as it’s a really good one for acoustic players that also use a microphone; because it has a cannon input to plug it in. But that isn’t its only option. You can also plug in another guitar and use its treble, mid, and bass knobs to EQ your instrument as you want.
Unfortunately, these are the only options you have for EQing both guitars within the amp. All other amps that don’t have this function will need external sources to handle equalizing two guitars.
Can I break my amplifier by plugging two guitars into it?
Yes, you can break it when plugging in two guitars. However, this is not so common, and it mostly affects old amplifiers. Speakers accumulate damage over time, and things like highly boosting low frequencies will make them clip. And this will slowly harm your amp.
When two signals are opposite to each other, they cancel themselves out. But when they are the same, they add up, which we want to avoid. Playing the same on both guitars will eventually lead to signals having too much gain, and this will result in permanent damage to your equipment.
As a rule of thumb, don’t do anything you wouldn’t do with one guitar, and keep your volume slightly lower. When you have a low-end amplifier, you never want to use it at full volume; you shouldn’t do this while two guitars are plugged in.
Also, things like unplugging your guitar while your amp is still on can clip and damage the speaker. Normally you would lower your volume, and you’re good to go, but when playing with others, it can be tricky. You need to pay attention and communicate when you’re putting away your instrument; It’s easier to forget when you are not in charge of the amplifier, so be careful.
How will my footswitch work while having two guitars plugged in?
It will affect both guitars because most amps only have one signal for both of them. And since footswitches trigger the effect on the signal it’s plugged to; its effect will affect the whole amp. However, if you have an amp that separates their signal, you will be able to use your footswitch on only one guitar.
When playing live, effects are needed, and sometimes your rhythmic guitar won’t use the same effects as your melodic one. So in these cases, you’ll need to have two pedal racks. It can be troublesome to carry both of them, but it’s better than taking a second amp with you.
How can I plug two guitars into amps with only one input?
There are many ways you can work around just having one input and plugging in two guitars. But do keep in mind that an amp that only has one input is meant only for one guitar; you should keep your volume low while doing this.
- RCA to plug input
This option is the easiest one. You’ll need an RCA to plug adapter and two RCA to plug cables. Once you’ve got them, you are done. The only thing you have to do now is plug in your instruments. But what you need to know about this method before trying it is that if your adapter is stereo (like the one shown in the picture below), Your guitars will be separated into left and right. This method lowers overall volume because the signal is split into two, so keep in mind that this is a low-volume fix.
The RCA to Plug method isn’t the best, but it’s cheap and doable. If you’ve got no other choice or want an inexpensive alternative, this will save your rehearsals with your band. But it would be best if you didn’t carry it on to live shows.
- Using a console
The console is the best option because it gives you a chance to EQ your guitars differently. But it’s also the most expensive option. Buying a console just for this isn’t the best, but if you have one lying around, it’s a really good fix. You don’t need a really large console; I’ve used this one in the picture below many times, and it works completely fine.
In the image above, you can see a four-channel mixer. This one, in particular, I’ve used with some friends. Having one like this will help manage the volumes and frequencies of multiple instruments while using an amp as its output.
Additionally, small mixers don’t have the chance to EQ your instruments separately, but they’ll do the work. For example, this Behringer mini mixer or this Rolls one.
- Audio interface
You probably have a two-input audio interface laying around if you are into DAW. You can send the output to your amplifier if you have a computer to plug your interface. Using your interface’s knobs to control their volume, you can plug and play. That being said, this option doesn’t have the best mixing tools by itself. However, if you want to take some extra time, you can use your DAW to EQ or put effects into different instruments.
- Cd / Aux input
This option is useful with amps that don’t have an “input two” but instead have an extra input to plug audio. Their function is to play some backing tracks, ideal for street players. However, you can plug a second guitar here; its sound will be much lower because it isn’t made for that, but it’s an option that can save your rehearsals.
If you look in the middle of this amp, you’ll see it has an AUX input, where you can plug another instrument.
Can I record audio while plugging two guitars onto my amp?
Yes, you can. It’s safe. But, it won’t be the best way, and in the long run, it will end up taking away more time than it saves. Because when you need to change something on the recording, you’ll have to change both guitars. So one mistake will count as double the work.
The best way is to take your time and do two recordings. It’s completely normal to miss or even re-record some lines that weren’t as clean as they could be. However, you can record both via line on an audio interface and air through your amp. This will let you separate both of your guitar’s signals, so it’ll be easier if you have to change anything.
Also, if you use an interface to record, you can not only use the output as a return for hearing what you’re playing; you can also record that. Mixing between line and air recordings is pretty common nowadays. So if you have long parts where there’s no need to re-record a guitar, you can add it to the mix and spice it up.
What’s the best way to play while having two guitars on my amp?
The best you can do is divide and conquer, leaving the low end of the spectrum to one guitar and the high end to the other. Doing this will not only give you a better-sounding mix but also let you have more space to try different equalizations on your amp.
You can vary between parts. In some cases, you can have your rhythmic guitar playing some funky groove on the higher frets; while your melodic guitar plays a riff on the lower spectrum. And that’s interchangeable. You can play some open chords while the other guitar plays a solo on the higher octave. Keep in mind this is not needed. Rather, it’s a way to help the clarity of your sound while playing two guitars through an amp.
Also, if your amp doesn’t have two separate channels, try to keep things like distortion pretty low; using such effects will make both guitars sound muddy and won’t let the listener distinguish between them. Even though you can use pedals, keeping your volume low and sound clean-ish will make your mix more understandable.
Can you use one pedal to affect both guitars?
Yes, it’s ok. However, your sound will get compromised, so this isn’t ideal for live sessions or recordings. You can do this to try different arrangements on your songs different types of sounds. But don’t use this on lives. It would be best if you got another pair of pedals for this.
Regarding doing this, you need to use any of the previously mentioned methods to wire both guitars to the pedal; a mixer or RCA cables. Remember that RCA cables are not the best. You should try this with a console.
Sometimes mixers have effects added to them. Trying this can be a better way to test effects on both guitars. Although they can be very confusing to grasp, here’s a video I found that explains how you can use them.
Can I play guitar and bass on the same amp?
Yes, you can, but you need to have a bass amp for this. Playing your bass through a guitar amplifier will hurt its cone. It’s ok if you do it once or twice with your volume low, but constantly using your guitar amp for bass will damage its cone. Don’t do this for extended periods.
As you might know, most bass amps have two inputs, one destined for passive basses and the other for active ones. When this is the case, you can use both inputs. I have done it plenty of times. In my case, I used my active bass on the -6db (or low) input, and my bandmate used the high one.
In the image above, you can see the high input (passive bass entrance, or guitar in the case mentioned earlier) and the low input (meant for active basses).
The audio is cleaner when playing bass and guitar through the same amp than when playing two guitars. Because of the bass register, being an octave lower helps a lot to distinguish between them. And even when the amp is not designed for two instruments, you’ll be able to play just fine. Only remember, don’t put your volume at max.
Using a speaker as an output for my amp, is it ok?
It is fine as long as your speakers are relatively good ones. An example where doing this is ok would be; if you have a low wattage amp and want to plug two guitars, you can compromise your amps health. But if you have a pair of speakers laying around, you can plug your output into them.
Another possibility is to use your speakers with a mixer. I do this every day with my setup. I have my console wired to an amplifier, and that output goes to my speakers. A structure like this is really good for jams or a home studio; you have the opportunity of mixing multiple instruments while only having one output and keeping your cables relatively simple.
As you can see, having a console with multiple channels will allow you to get two guitars, a bass, and a microphone. This is a really useful way to set up your sound. Keep in mind to have decent speakers, and you are good to go.
Is having a stereo amplifier better for plugging two guitars?
No, not always. Stereo amplifiers are strange. Guitars output a mono signal, so they are not looked for, nor are they common. But what we need to process the sound of two guitars isn’t a stereo signal but channels. The stereo amps that would work best are the ones with multiple channels.
Maybe you are wondering, what’s the point of a stereo amp when my guitar outputs a mono signal. You are right, but many pedal effects turn your signal to stereo. Examples of this would be some reverbs, chorus, or panning effects. So if you want to use these kinds of effects, it’s best to have a stereo amp. If you have a stereo amp with two different channels, this is the best scenario for using two guitars on a single amp.
Using multiple instruments through an amp is fine. It would be best if you were careful not to force your amp’s cone, but it’s doable and safe at low volumes. You can even use effects on both guitars. But always keep in mind that if your amp isn’t meant to be played with multiple instruments, don’t overdo it.
Leave your equipment some room, don’t go all out while doing this. If you follow that rule, you’ll get away with it. I’ve done this for years, and my equipment is in top condition. And if you have some piece of equipment lying around, try to understand what it is and how you can use it to your advantage. You might have some RCA to plug cables like the ones we mentioned, or even a small mixer.
Just remember that while doing this, we aim to have two separate channels for each guitar (or bass). Separating both channels will greatly help you understand your sound in the mix. But if you can’t, know that plugging two guitars into an amplifier is completely fine.
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Nicolas Rotondaro is proffesional bassist, producer and luthier based in Buenos Aires, Argentina. He has a bachelor’s in arts and is currently finishing his studies on popular music in EMPA. With over 15 years since he started playing string instruments, he teaches, produces, and fixes instruments to request.