Do You Need a DI Box for a Synthesizer? Things to Consider + 3 Tips

Geek Musician is reader-supported. We may earn an affiliate commission when you buy through our links

DI boxes are useful for numerous reasons, but do you need one for a synthesizer? Is it necessary or worth it at all?

You don’t need a DI Box to record your synthesizer in a home or professional studio. However, it’s a good idea to use a DI box for your synth in a live setting, especially if the mixing console is more than 15 feet away from the stage. The DI Box will convert the synthesizer’s signal from a high impedance unbalanced signal to a low impedance balanced signal, which is essential for preventing interferences over long distances. 

Many people think DI boxes alter the output sound and give it a specific warmth. While that may be true to some extent, that change is barely audible. You may not notice any significant difference when you make an A/B comparison of a recording made with a DI box and made without. 

So, if that’s the reason why you think you need a DI box, then you should reconsider and save yourself some cash because that’s not what the DI box was designed for. In fact, there are many ways to alter your synth’s tone, and we are going to get into some of that later in this article, but using the DI box certainly isn’t one of them.

We will take a look at the reasons why you don’t need a DI box for your synth, as well as situations where it’s ideal to use a DI box later in this article. Now, let me walk you through the purpose of a DI box.

What is the purpose of a DI box?

The full form of the “DI” in DI boxes is Digital Injection or Direct Insertion, which is just a fancy term referring to the process of capturing an audio signal without the use of a microphone. This was an innovative technology that came around in the 1960s and has helped solve many audio problems. 

For instance, capturing audio signals with microphones can lead to unwanted signals due to background noises and mic bleeds, which can make your recording difficult to process. DI boxes capture the audio signal directly from the source and prevent any signal interference.

The DI box can achieve a cleaner sound from your instrument with these two main processes.

1. Impedance Matching

Explaining the concept of impedance matching in great detail can be overwhelming, especially for those who don’t have a background in electronics. So I’ll make this as simple as possible.

Every musical instrument, like a guitar, keyboard, bass, synthesizers, has an output impedance. It is essentially the electrical resistance of the circuit that is outputting the audio signal from the instrument. Impedance is measured in ohms.

Similarly, every mixing console or audio interface has an input impedance. It is the electrical resistance of the circuit receiving the signal from your instrument.

The input impedance must always be higher than the output impedance to get a cleaner and undegraded signal from your musical instrument into your mixing console/audio interface. A good input impedance must be at least seven to ten times higher than your instrument’s output impedance.

However, that is not always the case. For instance, passive instruments such as the Fender Stratocasters or the Fender J-Bass or P-Bass usually have very high output impedance. When you plug these instruments directly into a mixing console or interface with lower input impedance, there will be many frequency losses in the audio signal. 

This is where the DI box comes in.

The DI box reduces the output impedance signal from your instrument from high impedance to low impedance. The output impedance will be much lower than the input impedance of your mixer or interface, and this will help prevent any signal degradation or frequency loss.

Now let’s move on to the next thing a DI Box does

2. Signal Balancing

Most synthesizers, keyboards, and passive guitars have unbalanced outputs. Unbalanced audio signals have some undesirable limitations, however.

Firstly, unbalanced signals that can be transmitted over a long distance. After transmitting an unbalanced signal for a distance of more than 15 feet or 5 m, it becomes susceptible to degradation, hum, buzz, and frequency loss.

In some cases, there can be radio interference from nearby radio broadcasting companies or even radio communication of the police in an unbalanced signal. You certainly don’t want this to happen, especially when you are recording your instrument.

This is where the DI box comes in, once again.

The DI box converts the unbalanced signal into a balanced signal. Balanced signals can be transmitted over very long distances without any degradation or interference.

With a balanced signal, the audio signal’s integrity will be protected, there will be no hums and buzz, and no frequency will be lost. You are assured of getting the exact signal produced by your instrument.

Why You Don’t Need a DI Box for a Synthesizer

Now that we are on the same page about what a DI box does let me explain why you don’t need a DI Box for a synthesizer.

To begin with, I must acknowledge that most synthesizers, especially analog synths, have unbalanced outputs. So yes, synthesizers are susceptible to signal degradation over a long distance.

However, you don’t need a DI box for a synthesizer in a home or professional studio. That’s because the distance between your synth and the mixer or audio interface is relatively short. You will not need a long TRS or TS jack to connect your synthesizer to your mixer or audio interface.

It’s highly unlikely that your synthesizer will be more than 15 feet away from your recording console in a studio. For this reason, you should not worry about your synth’s audio signal degrading or being interfered with.

Newer synthesizers come with balanced outputs (usually stereo) with low output impedance. So you won’t face any issues at all plugging it directly in your recording console. A good rule of thumb is to check the output ports on your synth to see whether they are labeled as balanced or unbalanced.

Another reason is that most audio interfaces and mixing consoles made these days have very high input impedance. They are much higher than the output resistance of synthesizers, keyboards, guitars, and so on. 

The Focusrite Scarlett 2i2 Audio Interface (on Amazon), for instance, which is a well-known budget option interface, has an input impedance of 1.5megaohms. This is the same input impedance as the BSS AR 133 Active DI Box, a very popular and highly sought after DI box.

This means you can plug your synthesizer directly into your mixer or audio interface and record. And you don’t have to worry about signal dropouts and any interference.  

Will a DI Box add color to my synth sound?

Sure, it makes sense to argue that a DI box will alter your synth’s sound in a desirable way. After all, the signal will be processed through electronic components and an audio transformer inside the DI.

However, this is not what the DI box was designed for. Most DI manufacturers focus on how to replicate the exact sound coming from the instrument, rather than adding color to it. For this reason, you shouldn’t expect an overwhelming difference, if any at all, when you record with a DI box. 

Some audiophiles will recommend expensive DI boxes such as the REDDI Di box, or a standard-priced DI like the Radial JDI and swear by it that it adds color to the tone of the synth. That may be true, but the difference will be very subtle — so subtle that you won’t hear it in the final mix.

So if you are buying a DI box for the color it adds to sounds, then you probably shouldn’t. You should probably invest that in some audio effects instead (more on that later).

When do you need a DI Box for a Synth?

Here are the instances where using DI Box for a synthesizer seems plausible

1. For running an unbalanced synth signal over long distances

If you play live gigs with a synthesizer with an unbalanced output signal, then you need a DI box.

That’s because the mixing console will usually be at the back of the room, probably more than 15 feet away from the stage. This means running an unbalanced signal from the stage to the mixer can result in signal degradation.

 To have a cleaner signal with no interference from your synthesizer to the front of house mixer, you should use a DI box.

2. To help fix ground loop issues.

This ties in with my previous point. In most live environments, especially at music festivals, the electrical condition is not that great. That’s because the electricity in such venues is usually provided by a generator, which is usually considered as a “dirty” electricity source.

If the electricity of the venue you are playing at is not great, it can cause ground loop issues. Without getting too technical, a ground loop will cause a hum or a buzz in your synth’s audio signal, especially in the 50 or 60Hz frequency region. Ground loop issues can also occur at your home if you are having electrical issues such as improper grounding.

A DI box will, however, prevent the hum or buzz in your synth’s signal and help send a clean signal to your mixing console or interface. This is particularly helpful when you are on the road and playing in different venues. You never know where you will have a bad electricity source.

I wouldn’t advise you to buy a DI box to fix ground loop issues in your home, though. That’s because it’s an electrical problem and you need to hire a local electrician to fix it for you.

3. When your audio interface or mixer has only mic level inputs

If you own an interface or a mixing console that has only mic-level inputs, then you should definitely get a DI box.

Mic-level inputs are designed to record only microphones which have very low impedance. For this reason, mic level inputs have relatively low input impedance. This means if you want to record a line-level instrument such as a synthesizer with a mic-level input, you will need a DI box to convert the synth’s audio signal into a mic-level signal.

This should not be a problem for the more recent audio interfaces and mixers because their input impedance is high enough to record both mic and line-level instruments.

Ways to Add Color to Your Synth Recordings

As I mentioned earlier, DI boxes are not the way to go if you want to give you synth sounds an extra edge. These are three creative ways to get that unique sound from your synthesizer.

1. Record your synth through a guitar amp

One of the best ways to give your synth sounds an extra edge is to plug it in a guitar amp.

Guitar amps can give your synth patches a unique grit and aggressiveness. And the great thing about this is you can experiment with different sounds, different guitar amps, and amp settings to come up with something you haven’t heard before. 

Personally, I love to do this when I want to achieve a distorted and aggressive lead solo sound without using a guitar. I explained how to do this the right way, in much detail, in this article. Do well to check it out if you want to learn more

Once you love the sound you have achieved, simply place a mic in front of the guitar amp speakers to record the output into your DAW.

2. Record your synths through preamps

It has been proven time and time again that different preamps sound different. Expert recording engineers who have several preamps at their disposal know the right one to use for every record. That’s because the preamp you choose will give the audio you record a unique tone and character.

Synthesizers output a line-level signal, which is a very strong signal. Because of that, we usually don’t use preamps to record them. However, you can record them through preamps just for the purpose of adding color.

Just keep in mind to turn down the gain on the preamp because we are not trying to boost the synthesizer’s signal. Rather we are looking to get an added color from the preamp. 

3. Use Effects

I know this one may seem obvious, but effects are really powerful tools that can drastically change how your synth patches sound. You can experiment with different effect chains and weird effect settings to come up with something totally unique from the synth patch. 

Try different delay settings, parallel and series effect chains, guitar and bass effect pedals on your synth to see what sound you come up with. With effects, the sky’s the limit.


I hope this post gives you a solid knowledge of when to use a DI box and when not to. In essence, you don’t need a DI box to record your synthesizer in a home or professional studio. But if you perform live with your synth, a DI box can help solve issues such as signal degradation, interference and hums, and buzz caused by ground loop issues.