If you’re shopping for direct boxes (aka di boxes), but aren’t quite sure what you’re looking for…
Or how to tell the difference between one and the next…you’ve come to the right place.
Because in this ultimate guide, I’m going to reveal everything you as a musician should know about this commonly misunderstood piece of gear.
So here’s what we’re about to cover:
In this Article:
- What Exactly is a Direct Box Used For?
- PASSIVE vs ACTIVE Direct Boxes: What’s the Difference?
- Acoustic Direct Boxes: What You Need to Know
- Stereo Direct Boxes: for Keyboards and Electronic Drums
- Digital Direct Boxes: The Latest DI Technology
- Re-amps for Recording in the Studio
- Multi-Channel DI’s: For Pro Studios and Live Rigs
- How Much Should You Spend on Your Direct Box?
What Exactly is a Direct Box Used For?
Among the many gadgets we use as musicians…few are more confusing than direct boxes.
Virtually every stage rig and studio will have them for one reason or another…
Yet how many of us can concisely explain what it is they actually do?
So if you’re the least bit unclear on this topic, here’s your answer:
At its core, the direct box has ONE fundamental purpose:
- To convert a hi-z unbalanced instrument signal from your guitar/bass into a low-z balanced mic signal.
Now here’s why you’d typically want to do this:
On-stage, it allows you to split an instrument signal, sending the balanced signal to the mixer and out the PA, and the unprocessed “thru” signal to your amp.
In the studio, it works similarly, except the balanced signal goes to your audio interface instead, which allows you to simultaneously record wet and dry versions of the same track.
In both cases, direct boxes have the added benefit of allowing you to split guitar signals over much longer distances without gathering noise.
PASSIVE vs ACTIVE Direct Boxes: What’s the Difference?
When you start exploring direct boxes, it’s the very first question you’ll likely have.
The part most people already understand is:
- Active DI’s require a power supply
- Passive DI’s don’t
Yet there’s WAY more to the story than just that.
So here’s a rundown of everything you should know when comparing passive vs active direct boxes:
The Best Instruments for ACTIVE DI’s
The first rule of thumb is: Active DI’s work best with PASSIVE instruments, including:
- Electric Guitars
- Passive Basses
- Vintage Rhodes pianos
And that’s because, passive pickups output a weaker signal, and can therefore benefit from the amplification of active DI’s.
The Best Instruments for PASSIVE DI’s
As you might guess, the opposite rule of thumb applies here:
Passive DI’s work best with ACTIVE instruments, including:
- Active Basses
- Electronic Percussion
Since their on-board preamps output a hotter signal, you don’t need the amplification that an active DI provides.
Passive DI’s also have far more headroom than Active DI’s, and can therefore handle hotter signals without overloading.
If and when they DO overload, passive DI’s produce a pleasant saturating distortion, while active DI’s have a much harsher sound, similar to digital clipping.
Why Passive Direct Boxes Work Better On-Stage
When using Active DI’s on-stage, each of their 3 possible power sources presents a unique challenge:
- AC wall power – is a hassle to supply on-stage
- Batteries – always die at the worst moment, and are expensive to replace
- 48V phantom power – is normally not strong enough to provide adequate headroom
Passive DI’s on the other hand, which don’t use power, work better because they avoid each of these potential problems.
In addition, the transformers they use in their circuitry are highly resistant to ground loop hum.
By passing the audio signal through a magnetic field, transformers eliminate any direct electrical connection between the IN and OUT…thus blocking whatever ground loops may exist in the system.
Of course, some direct boxes do this better than others, and up next, I’ll explain why…
The Common Problem with Passive Direct Boxes
It’s a common myth with passive direct boxes that they’re all the same.
But the truth is: The good ones really do sound far better than the cheap ones. And that’s mainly because of the transformer.
Under normal conditions, transformers are constantly exposed to multiple sources of interference which negatively impact the sound.
The most significant source is the magnetic field from your amp.
To avoid this problem, good transformers use various kinds of shielding on the outer-casing to maintain isolation.
And as it turns out, that shielding can be expensive. Which is why with passive direct boxes especially, you really do get what you pay for.
3 great options I recommend are:
The Common Problems with Active Direct Boxes
As I stated earlier, a big problem with most active DI’s is their inability to work well in live-settings.
So one sign of a good active DI, is its ability to overcome these challenges.
For example: with most active DI’s, the 48V phantom power has a tendency to introduce ground loops into the system.
But you can’t engage the ground lift switch without cutting off the phantom power.
So one extremely popular model, the Radial J48, solves this problem by converting 48V phantom power into AC, using a unique switching power supply that allows you to lift the ground without cutting off power.
Another common problem with 48V phantom power is that it restricts the DI’s internal working voltage to an extent that the available headroom is much less than passive DI’s.
Once again, the Radial J48 solves this problem with a unique power scheme that increases its internal rail voltage up to 9 volts, providing way more headroom than typical active DI’s.
No surprise, the Radial J48 – (Amazon/B&H/Thomann) is an industry standard in its field.
Alliteratively, here are some other top active DI’s I also recommend:
For the studio:
Acoustic Direct Boxes: What You Need to Know
Since acoustic guitars traditionally use passive piezo-electric pickups…
The standard rule of thumb suggests that an active direct box would be most appropriate.
And while that is true, acoustic pickups have an even higher impedance than those found in active basses.
Which is why there custom acoustic direct boxes designed specifically for the instrument.
The biggest difference you’ll notice with these acoustic DI’s is: They are far better at preserving high-frequency detail, which of course is essential to the sound of the acoustic guitar.
Among the top models on the market, here are the ones I recommend:
- LR Baggs Para DI – (Amazon/Thomann)
- LR Baggs Venue – (Amazon/Thomann)
- Fishman Aura Spectrum DI – (Amazon/B&H)
- BBE Acoustimax – (Thomann)
- Radial PZ-DI – (Amazon/B&H/Thomann)
Stereo Direct Boxes: for Keyboards and Electronic Drums
On electronic instruments with stereo outputs, such as keyboards and electronic drums…
Stereo direct boxes offer an easy solution to process BOTH channels through ONE device.
Another useful feature they sometimes have is a MERGE button, which mixes those channels down to a single MONO output.
The most likely reason you’d use this is:
At live events in larger venues, where fans are spread out over a wide area, stereo imaging can actually detract from the listening experience of those seated off to the sides.
So in this case MONO is preferred, and the merge button makes it easy.
If you need a stereo DI for your rig, here are a few great options I recommend:
- Radial Pro D2 – (Amazon/B&H/Thomann)
- Radial JDI Duplex – (Amazon/B&H/Thomann)
- Klark Teknik PRO DI AV 2 – (Amazon/Thomann)
Digital Direct Boxes: The Latest DI Technology
To send digital files from your laptop to a PA system, there’s 2 options:
- Connect to a mixer – which is risky since activating mixers’ phantom power will destroy your device instantly
- Connect through bluetooth – which isn’t as reliable as a hardwired connection, and won’t retain the same sound quality
To solve this common problems in today’s world of electronic music, Digital direct boxes conveniently convert the digital signal into analog before sending it out to your gear.
This can be particularly useful for bands that play digital tracks while performing live, for example.
If this is the sort of direct box you’re looking for, here are the top models:
Re-amps for Recording in the Studio
When recording electric guitar or bass in the studio…
Finding the perfect guitar tone takes time and experimentation, with amps, mics, and mic positioning.
Meanwhile, it’s a huge waste of time to be losing all those perfectly good takes from your talent.
So for a long time, engineers had to develop clever work-arounds that enabled them to tweak and re-record a track long after the take was finished, and the guitarist went home.
Then finally one day, a man named John Cuniberti designed a device known as the Re-Amp for this exact purpose.
Here’s how it works:
You take the dry guitar track that was previously recorded, and send it out to the reamp.
The reamp takes the balanced line-level signal and converts it back into a guitar signal…which you then feed to the amp through a second guitar cable.
With this tool, you can loop the pre-recorded track and take all the time you need to find that perfect sound.
Once you’ve got it, you just re-record it onto a new track, and you’re done! Genius, huh?
If you’d like to try it, these are the top models I recommend:
- Radial ProRMP – (Amazon/B&H/Thomann)
- Radial Reamp JCR – (Amazon/B&H/Thomann)
- Radial X-Amp – (Amazon/B&H/Thomann)
- Palmer DACCAPO – (B&H/Thomann)
Multi-Channel DI’s: For Pro Studios and Live Rigs
While certainly overkill for the average home studio…
Multi-channel rackmounted DI’s are truly the best-of-the-best in the world of direct boxes.
And they offer enormous benefits to those who need them.
In pro studios and large live-rigs with complex routing, they allow you to connect multiple guitars, to multiple amps, with multiple reamp loops.
And while you may not need one right now, it’s still nice to know they exist if the day comes when you do.
Here are the top models I recommend:
- Behringer Ultra DI Pro – (Amazon/Thomann)
- JD7 Injector – (Amazon/B&H)
- JD6 – (Amazon/B&H)
- ProD8 – (Amazon/B&H/Thomann)
How Much Should You Spend on Your Direct Box?
Now that we’ve covered the full-spectrum of DI options, you may have noticed that prices can range anywhere from $40 to over $1000.
The question is, how much should you spend on YOURS?
Well the guys over at Radial Engineering seem to have all the answers when it comes to direct boxes. And it just so happens they have an answer this question as well.
According to their 5:1 Rule, for every $5 you spent on your instrument, you should invest 1 dollar on your direct box.
Meaning a 1000 dollar guitar, would warrant using a 200 dollar direct box. Makes sense? Now you know.
The 6 Chapters of E-Home Recording Studio
More Guitar Posts in This Series:
Electric Guitar | Acoustic Guitar | Bass Guitar | Amps | Pedals | Cables | Pickups | Bass Strings | Bass Amps | Bass Pickups | Classical Guitars | Acoustic Pickups | Direct Boxes | Cases | Picks | Slides | Straps | Tuners | Stands | Strings | Capos | Tabs | Guitar Accessories