What is a DI Box and Do I Need One?

When it comes to recommendations for hardware and accessories to buy for your guitar, DI boxes haven’t been at the top of the list. So it’s not surprising to go “huh?” if you hear someone mention one for the first time.

The first time I heard about DI boxes, I was in college and we built one. That was quite a fun project, not just because I got to construct a working piece of hardware, but it was the first time I got to solder too. Electronics aren’t my strong suit… this may be why I am not a sound engineer despite being qualified (a miracle), at least for 11 years ago’s tech… but I felt awesome after making this bit of practical hardware.

I still have it and haven’t had to use it. But there are some good reasons to use one under the right circumstances.

Well, I won’t torment you any further, let’s get into what a DI box is and whether you need one.

What Is A DI Box?

DI stands for direct injection. That is exactly what a DI box allows. You may hear them referred to as direct boxes too. With a direct box, you don’t need to haul an amp around since it’s designed to convert the signal into a balanced signal that goes through an XLR (microphone) output.

To stick the jack directly into a PA system or mixer is a no-go. You can cause some serious damage to the equipment doing this. They usually don’t have ¼ inch jacks anyway. If you’ve played in venues that have a permanent setup, you are likely to have stuck your jack into a box with jacks for different channels at some point. This is why.

Instruments that use a ¼ inch jack, like guitars, bass, and keyboards have an unstable signal and are very prone to electrical interference. This interference comes from the lights, speakers, and other electronic equipment in the vicinity, just as it does with subpar cables used for your home entertainment system.

This noise is known as radio frequency interference (RFI) which is radio frequencies in the more immediate vicinity and electromagnetic interference (EMI) which is electrical interference from a wider area.

This isn’t only to make it easier to play with your regular cable instead of linking cables or using an extra-long cable that degrades the audio. It creates a stable signal so that everything works together harmoniously and there isn’t a risk of damage to the equipment.

Do You Need a DI Box?

If you play at venues or record your music, the answer is likely yes. Here’s why:

Sometimes Hardware Malfunctions

If you’re like me, you know deep down inside that technology is spiteful… While those who know better (I freely admit it) believe otherwise, the fact remains that sometimes, technology gives us hassles.

You don’t want to go to the place you’re performing or recording and discover that their DI box is misbehaving. DI boxes are generally small, lightweight, and generally affordable, although you get some that are expensive too. While it might only be used as a backup on that very rare occasion (well, if you play in a lot of dive bars or the like, it might be a more regular occasion), you’ll be happy you have it.

You Like to Use the Whole Stage… and it’s Big

Remember I mentioned that long cables degrade the audio quality? No one wants lost frequencies and/or crackling.

You may have come across this if you’ve used a cable longer than 5m (around 16.5ft). You may be able to use up to 7m (23ft) if you have a higher quality cable without issues. The signal just degrades after this.

Because DI boxes balance the signal, you will be able to use longer cables to move all over the stage without losing any sound quality.

Noise-Free Recordings and Gigs

Noise free recordings

Electrical noise, as I mentioned, is a thing. If you’re organizing your own concerts where all the equipment is yours or doing your own recordings, you want a DI box.

You’ll get a clean sound, and the only distortion or crackling is the stuff you put into your mix on purpose.

Which Type DI Box Should You Buy?

There are two types of direct boxes. Active and passive.

Active DI Boxes

Active DI boxes need to be powered using phantom power (48V), which mixing desks that allow for use of condenser microphones will have, or 48V in the form of batteries. Older active DI boxes will shut down the phantom power if there is noise or you need to unground an instrument. The batteries will then take over.

Some of the newer models don’t shut down the power so there isn’t any need to use batteries as long as you have a mixer that can supply phantom power.

It’s this power that converts the signal into a stable one. The benefit of an active direct box is that it can add a little oomph to low output instruments whereas passive direct boxes rarely have the juice to do this.

There is also a common theory that if the pickups on your guitar or bass are passive, an active direct box is the way to go and vice versa. But if you choose a direct box with an attenuation, this might get the job done just fine.

Passive DI Boxes

Passive DI boxes don’t require any external power to work. The audio transformer inside does all the work that it needs to do. The higher the power output of the instrument, the warmer the tone gets without any distortion.

This is what I would recommend if you just want the basics. You don’t need to rely on any external power sources to power it. You can also reverse the signal to create artificial line levels which isn’t possible with active direct boxes. But do bear in mind that if your instrument has a low output signal, the sound may be less than stellar.

As mentioned above, passive direct boxes are often paired with instruments that have active pickups.

Extras To Look Out For

• Thru output, since this allows you to use your amp as a monitor
• Extra channels are handy if you’re in a band and want to share a direct box or want to put through a stereo signal for an FX pedal or a keyboard (else you need single-channel direct boxes)
• Attenuation (pad) for if you’re playing with different instruments with varying signal strengths

Top DI Box Recommendations

If you need some help choosing a DI box, here you go. The second half of the list has higher-priced DI boxes, so if you’re on a tight budget, start at the top.

Samson MDA1 Mono Active Direct Box

You can choose whether to use a 9V battery or phantom power with the Samson MDA1 Mono Active Direct Box. You also get thru output which is a nice bonus at this price. This direct box also sports a two-setting attenuation switch from 0dB to -15dB to minimize distortion. The input is a ¼ inch jack.

To unground your instrument, you simply use the ground lift switch. There is also a balanced output for an XLR cable. The rugged all-metal casing will hold up well in live settings. Many people have confirmed that it’s in fact durable, and although it’s simple, does the job as well as higher-priced direct boxes. I couldn’t find anyone that had anything bad to say about it.

Pros:

• It’s easy to switch between phantom power or a 9V battery
• Thru output allows you to monitor your playing via your amp
• The pad (0dB/-15dB) provides a good way to eliminate distortion and humming
• It features an easy-to-use ground lift switch
• Balanced XLR output
• Very durable
• Very affordable

Cons:

• None that I could find if you just want the basics for one instrument at a time

Behringer Ultra-DI DI400P Professional High-Performance Passive DI-Box

The Behringer Ultra-DI DI400P Passive DI Box is as basic as the Samson but still good value for money if you’re on a budget. Sadly, there is no attenuation switch. This isn’t a problem if you play only one instrument or the impedance of your other instruments don’t differ too much. You get a ground lift switch, a single input ¼ inch jack, a thru output jack, and a balanced XLR output.

You can hook this direct box up to your amp’s speakers up to 3000 watts. The XLR connectors are gold-plated and the box itself is a rugged metal case. The frequency response is pretty flat thanks to the OT-2 balanced line transformer.

Most people are happy with this direct box and say that it’s comparable to more expensive brands in the sound and balance it delivers to the signal. However, there is no marking to help you know if the ground lift is on or off, you will need to get to know your box which is a bit annoying. There is also a complaint that you lose the lower frequencies if you use a high output instrument or your amp is more powerful.

Pros:

• There’s no need for an external power source
• Use your amp as a monitor via the thru output
• There is a ground lift switch
• The frequency response is fairly flat
• The XLR connectors are gold-plated
• It sounds good
• Very durable
• Very affordable

Cons:

• There is no attenuation switch
• The ground lift isn’t marked to indicate whether it’s on or off
• High-level instruments and powerful amps result in some of the low-end getting lost (possibly a defect in one box)

ART dPDB 2-channel Passive Direct Box

If you want a direct box with two channels at an affordable price, you get it with the ART dPDB 2-Channel Passive Direct Box. You get two channels with their own in/thru jacks (which is your output to your amp or monitor), ground lifts, and attenuation switches. Speaking of which, the attenuation switches provide 0dB/-20dB/-40dB for more control over the signal.

Everything is clearly marked, even how much impedance you can put through the box so there is no guessing. Most people are very happy with these boxes. They do what they need to, even in situations where there is a lot of RFI and EMI. This is great for live performances. There are a few complaints about needing to use quite a bit of gain to boost the signal in some cases, especially for bass guitars.

Pros:

• No need for an external power source
• There are two mono inputs for two instruments or a keyboard in stereo
• There’s a ground lift switch for each channel
• Each channel has an pad (0dB/-20dB/-40dB)
• Both channels have a thru output (in/thru)
• Durable
• Very affordable for a dual-channel direct box

Cons:

• You may sometimes need to adjust the gain for a better sound as with most passive direct boxes

Behringer Ultra-DI DI20 Professional Active 2-Channel DI-Box/Splitter

If you prefer an active 2-channel DI box that’s highly affordable, consider the Behringer Ultra-DI DI20 Active 2-Channel DI-Box. You get the usual setting to switch between phantom power or a 9V battery as with most active direct boxes. You also have a ground lift switch and an attenuation switch of 0dB/-20dB/-40dB. There are two balanced outputs.

You can choose to use the channels as separate mono channels, link them for stereo, or convert the 2nd ¼ inch input as another output to a second amp. The construction is metal. On the downside, there is only one attenuation switch and ground lift for both channels, which can be problematic if you’ve got two instruments with differing impedance plugged in.

Most people are happy with this direct box in terms of it’s durability and versatility. However, there are a few complaints that it’s noisy. I believe this is a defect (unless it’s the equipment or instrument its used with as jacks, cables, and the equipment itself can also be noisy) since there are many more people who say it works well.

There is also a complaint about sound quality, but then this is a cheaper item and expected in comparison to better quality (and sadly, more expensive) direct boxes.

Pros:

• Provides two channels
• Can be used as a splitter to direct the output to two amps
• Use it as two mono channels or a stereo channel
• There is a ground lift
• The pad gives you three settings, 0dB/-20dB/-40dB
• Durable
• Very affordable for a dual-channel active direct box

Cons:

• There is only a ground lift and attenuation switch for two channels
• There are a few complaints that this direct box is noisy

Samson MD2 Pro Stereo Passive Direct Box

Another dual-channel direct box that is pretty good quality is the Samson MD2 Pro Stereo Passive Direct Box. You can switch the channels to mono or use them in stereo. Each channel has its own set of ground lift switches, thru outputs, and attenuation switches (0dB/-10dB/-20dB). This box runs off of two Samson STLX Mu-Metal shielded transformers. The case is 14 gauge steel for durability and protects the switches too.

Most people are happy with how this direct box prevents noise and keeps their instruments true to their natural sound. There was a complaint about the impedance matching especially in comparison to better quality brands, making it a dubious choice for studio situations.

Pros:

• You get two channels that operate in mono or stereo
• No need for an external power source
• The dual pad switches provide three attenuation settings (0dB/-10dB/-20dB)
• Dual ground lift switches
• Monitor your playing via the dual thru outputs
• Durable

Cons:

• There is a complaint about the impedance matching that may be problematic in a studio (not the opinion of most people)

Whirlwind IMP 2 Standard Direct Box

The Whirlwind IMP 2 Standard Direct Box is a passive direct box. You get one channel, thru output, and a ground lift switch. It’s pretty simple, no frills. The TRHL transformer is riveted inside instead of glued which makes it even more durable. In fact, many people have used their IMP 2 for over a decade with no issues.

Most people are happy with this direct box and enjoy its durability, sound quality, and how quiet it is. But there are a few complaints about it being noisy, however, one person said that tightening up the screws inside took care of it. Some people said that the sound quality is muddy. Unfortunately, it also lacks an attenuation switch.

Pros:

• No need for external power
• It has a thru output
• There is a ground lift switch
• It’s very durable thanks to the housing and the riveted transformer
• Most people are happy with the sound quality

Cons:

• There is no pad
• Some people found it was noisy (possibly defective)
• The sound has been described as muddy

Radial ProDI Passive Direct Box

The Radial ProDI Passive Direct Box is very popular among musicians and sound engineers. The sound quality in comparison to many of the cheaper brands is much better. You get one channel, an attenuation switch (0dB/-15dB), a thru output, and a ground lift switch. The transformer is propriety, but whatever it is, it does its job well.

It takes care of unwanted distortion and limits phase distortion. The frequency response is 20Hz-18kHz. Most humans can hear up to 20kHz. There have been no complaints about losing the high-end, so this likely isn’t a problem. The enamel-coated casing is strong and prevents the switches from being pressed accidentally.

Most people are happy with this, in fact, it’s hard to find anyone with anything bad to say about it. They love that it eliminates noise. They are especially happy with the ground lift switch which takes care of humming. I’d say the quality speaks for itself. You also get a 1-year limited warranty with all Radial products.

Pros:

• Doesn’t need an external power source
• It has an pad (0dB/-15dB)
• Use the thru output if you want a monitor
• Get rid of humming with the ground lift switch
• Durable
• 1-year limited warranty

Cons:

• None unless you want a dual-channel direct box

Radial Pro48 Active Direct Box

If you want an active direct box from Radial, here’s the Radial Pro48 Active Direct Box. It’s designed to be able to handle high output instruments, in other words, active pickups too. It does this by providing more headroom to prevent distortion and you get improved dynamic range too so you can play pretty loudly or very quietly without issues.

This direct box features one channel, an attenuation switch (0dB/-15dB), a thru output, and a ground lift switch. The 14 gauge steel construction is durable and prevents switches from being pressed accidentally. The Pro48 has an even wider frequency response from 20Hz to over 100kHz. While you may not be able to detect frequencies so high, unless you have dog superpowers, it provides a natural sound.

Most people are happy with the quality of the Pro48 and the good sound quality it produces. There are a few complaints about it not working, but these people may not have realized that the Pro48 only uses phantom power, not batteries at all. Make sure you use good a good-quality XLR cable that’s in good shape to have an uninterrupted phantom power supply.

Pros:

• It’s great for low output instruments with passive pickups
• It can handle high output instruments too
• Use the pad if you need to eliminate distortion from hot instruments (0dB/-15dB)
• Wide frequency response (20Hz to over 100kHz)
• It has a thru output
• The ground switch eliminates humming
• If you hate batteries but still want an active direct box, here you go
• Durable
• 1-year limited warranty

Cons:

• You can’t use it without phantom power since it doesn’t take batteries

Whirlwind DIRECT2 Dual Direct Box

The Whirlwind DIRECT2 Dual Direct Box is a passive direct box that gives you two separate channels. Each channel has its own set of attenuation switches (-20dB/-40dB, no 0dB), thru outputs, and ground lift switches. Essentially, this is two Whirlwind DIRECTOR direct boxes in one. The frequency response is 20Hz to 20kHz so no frequencies will be lost. They’ve included the impedance ratio (input to output): 133:1.

Most people are very happy with how quiet these direct boxes are and the convenience of having two channels. There was a complaint about louder signals being too much for this box, but with attenuation of up to -40dB, that was probably a defective unit.

Pros:

• Two channels
• No need for external power
• One pad (-20dB/-40dB) per channel
• One thru output per channel
• One ground lift per channel
• Frequency response of 20Hz to 20kHz
• Impedance ratio of 133:1

Cons:

• The pad is either -20dB (out) -40dB (in), I could be wrong about how it works, but it would be best if there is also just 0dB

Tech21 SansAmp Para Driver DI

If you want an active direct box with all the bells and whistles and then some, the Tech21 SansAmp Para Driver DI is for you. Not only do you get a thru output, ground lift, and an attenuation switch (0dB/-20dB), you also get a 3-band EQ, you can boost your signal, add some top end with the air button, and add distortion. There is also a level dial, a blend dial, and a mid-shift dial.

You get a preamp, DI box, and effects pedal in one go. At its price point, it would be nice to have more than just a 1-year limited warranty, but you are getting a lot of value if this is what you need. If all you need are the basics, this box is excessive. People love how versatile it is and enjoy the sound.

There was a complaint about the tone but as long as you use the EQ right and all your other equipment works fine, this issue would be due to a defect.

Pros:

• It’s very versatile (direct box and preamp)
• You can add distortion, blend your tone, and boost the top end
• You have a lot of control over your tone with EQ
• Includes a ground lift switch
• Use the pad for hot instruments (0dB/-20dB)
• Monitor your playing with the thru output

Cons:

• It only comes with a 1-year limited warranty which is a bit steep for a product of this price
• There was a complaint about the tone

Conclusion

If you are into recording or playing live you could really use a DI box. Not only does it cut out the need to lug an amp around, but you can really get the best tone out of your instrument.

Check out the recommendations and see what’s right for you. Just remember that if you are going to go cheaper than these, you need to read the reviews. You want something that will really do the job.

Happy recording and/or performing!