Two questions always asked when recording guitars, bass, and keyboards are "I have a great amp and microphone so why bother with a DI box? Or can't I just plug my keyboards directly into the mixing board? Why include a DI (direct injection) signal? YES, you should if you want Pro Level results. Having a clean signal for the mix engineer to work with is a great idea for your overall tone. This gives the engineer an option of Re-amping for guitars and bass, while re-amping can change the entire tone if needed, a lot of times the new tone is blended with the existing one thus creating a much bigger overall sound. Or you can go the other way, after recording your session you realize that you have way too much distortion on your guitar, that can be fixed as well.
There are two types of DI boxes, one is passive and one is active. The active ones like the Radial J48 works best with guitars and bass. Especially if your instrument doesn't have active pickups. You can easily tell if your pickups are active or not with the answer to one simple question. Do you install a battery in the guitar? if so, yes it is active. If you want an active 48v DI then you need to power that DI with either a DC power supply, a battery, or the phantom power provided on your mixer or preamp.
The Radial Pro D2 (pictured above) is a passive DI box which is stereo as well. This is the perfect option for keyboardists, and at times guitarists that already have an active guitar pickup. Getting a clean matched impedance helps your sound and it is imperative. Niles Rodgers and many other Producers are famous for Re-amping the DI signal, and the guys at Radail put out a fantastic DI box. Without a DI box it can be extremely difficult to get a Pro Level sound. You have to eliminate as much noise as possible and a lot of the noise comes from grounding issues. I have mixed for people who have spent thousands on their guitar, then plug directly in the mixing console without a DI box. This where I step in and put one on. The guitarist is now a very happy musician and often surprised at the clearity and headroom that is now available. The Pro D2 is one of the best investments a guitarist, bass player, keyboardist and even a DJ can make if they are serious about recording or live sound. Ground loops can cause hum and distortion and this is a quick fix, it's a great value especially for the money. DI boxes can vary in price between $50.00 and $2100.00 USD, but for the money the Radial brand is the king. The Pro D2 (pictued above) has a street price about $150.00 USD. The Radial J48 has a street price around $200.00 USD. Money well spent or both live stage use and especially recording.
Drew Puzia is a multi-award winning Mix Engineer at SoundBurst Studios in Las Vegas. Drew is certified in Audio Engineering from the world renowned Berklee College of Music. His experience spans over three decades in the music industry and he has recorded and mixed countless musicians in many genres of music.