Virtually all of today’s home recording digital audio interfaces allow easy connection of microphones as well as various high impedance sound sources such as an electric guitar, bass or keyboard. But are you really getting the best possible sound quality plugging your instrument directly into these interfaces? This month we’ll do a test recording of bass guitar using a typical digital audio home recording interface, and then add a direct box into the equation to see what difference, if any, such a device makes in the quality of the sound.
If you dive into the world of computer-based home recording with any of the various digital recording programs (Pro Tools, Cubase, Digital Performer, Logic, et al.), then you’ll have also purchased some type of audio interface box. These devices perform two main functions: they allow you to bring audio sound sources, be they instruments or something picked up by a microphone into your recording program; and they allow you to monitor your recording session through headphones or speakers. They range in price from very simple units such as the TASCAM US-122 which retails for $79, to high-end interfaces such as Digidesign’s 192 I/O priced at a cool $4,000. Personally, I use my Pro Tools LE system for song demos and for simply having fun with friends and have recorded everything from electric guitar and bass to vocals one track at a time. I eventually build up my finished tracks, only using the mic and line inputs of the M Box 2 Mini audio interface that came with my $249 Pro Tools LE system.
However, having spent a good bit of my time owning and working in professional studios at various points in my career, I wondered what difference a professional direct box would make in the sound quality of an instrument like the bass guitar. In order to find out, I borrowed two direct boxes from a friend. The HOSA Sidekick, a passive direct box based around a transformer with a street price of $22, and the active Countryman Type 85, which uses electronics to match impedance and carries a street price of $165. Both are very ruggedly built and should stand up to years of use in the studio or on the road.
How does a DI work?
A direct box or DI (short for Direct Insertion or Direct Injection, depending on who you ask) converts the unbalanced, high impedance signal of your electric bass, guitar, or keyboard to a balanced, low-impedance signal that is ready to go right to your mixing board or microphone-level audio input. They may also help cure buzz or hum as they can be used to isolate the ground signal, especially if you also plug your instrument into an amplifier, as well as the DI.
There are two main types of DIs: passive and active. Passive DIs are generally less expensive and use transformers to convert and isolate the output signal from the input signal. As a result, there will be a small amount of high frequency loss when using a passive DI. For many musicians, this is more than offset by the fact that most transformers have some inherent tonal characteristics that musicians often find pleasing. I know quite a few bassists who feel that a good quality passive DI helps improve the sound of their instrument by adding richness and body.
Active direct boxes use electronic circuits to convert and isolate the output signal from the input signal, so they need to be powered by phantom power or a 9V battery. Active DIs have the rep of not coloring your original sound quality and having loads of headroom to accommodate almost any input level. One other very cool aspect of using a direct box for home recording is that you can hook up your amplifier’s speaker output to most DI’s input and switch it to the “Speaker” setting, which will allow you to use your screaming 100-watt tube amplifier to record at home, without disturbing a soul.
Testing 1, 2, 3
I asked a local bassist, Giulio Cetto, to help out with the test, as I wanted to have a musician who could play in a variety of styles from a steady walking bass line to a funky, percussive part, to insure I covered all the sonic bases. We started out with Giulio plugging his passive Fender Jazz Bass directly into the M Box using a ¼” guitar cable. We recorded with no signal processing of any type, simply using the Line input level control on the M Box to set a proper level.
He proceeded to play three passages: first, a walking blues; next a series of very percussive funk riffs; and finally, a section that emphasized lots of harmonics in the style of the late bassist, Jaco Pastorius. We would then repeat this same sequence using different direct boxes to interface the bass guitar into a Pro Tools LE system.
After finishing the three takes using the M Box line input, we plugged the Jazz Bass into the Hosa Sidekick passive DI, and with a Mogami Gold mic cable, we ran the DI output into the mic-level input of the M Box. Finally, we repeated the test again, simply exchanging the Countryman Type 85 active DI for the Hosa. With both of the DIs, we were sending a mic level (+4) output signal to our Pro Tools LE system via the M Box’s mic circuit. Since we only had a pair of headphones at the actual recording to evaluate the differences, the next night I invited regular Pro Studio Edition contributor, engineer Jeff Crawford to meet up at our campus recording studio where we could listen back to the results in a well-tuned control room using Meyer HD-1 reference monitors.
We started by listening carefully to Giulio’s performance recorded using the M Box Line input with no DI in the loop. Although the sound was serviceable, as he got to the percussive passages and some of the harmonic notes, we noticed that these strong transients seemed to overdrive the M Box Line input a bit, causing those peaks to break up noticeably. In an actual session, this could have likely been remedied by lowering the input level a bit and using a plug-in compressor to even out the dynamic peaks.
When we started playing back the next track which was done with the Hosa Sidekick passive DI, we immediately noticed that the resulting sound was thicker and fatter than the M Box Line input recording. We also noticed that the harmonics were much more bell-like and that they sustained for a longer time than the first recording. On the funk passages, although there were still some very percussive notes that seemed a bit clipped, Jeff commented that Giulio’s bass sounded “meatier.” Not bad for a $22 device, which also has a ground lift and speaker output option.
Last up was the Countryman Type 85 active DI recording. The Countryman DI is a staple on pro stages worldwide and also used in many of the world’s top recording studios. As soon as we cued up this track, we heard another noticeable leap in definition and clarity. The lowest notes on the bass were almost organ-like, giving us a richness that was not present when we used the M Box Line input, and only hinted at with the Sidekick. A few of the most percussive passages still clipped a tad, which was due to the input level at our original session being too high, so its imperative that you carefully set input levels when recording instruments like bass and drums that can have such strong transients in their peak sound level. In the digital realm, it’s far better to have a slightly lower level than to risk overloading your recording chain.
To our ears, investing in a direct box makes good sense if you are looking for the best possible sound from your electric bass. I repeated the test again a few nights later at home, using my Ibanez GS 200 bass, and although I can’t play bass with anywhere near the skill of Giulio, once again both of the DIs simply delivered a fatter, rounder, more organic bass guitar tone. There are dozens of DI models available, all the way up to exotic tube units costing many times more than the Countryman Type 85, so you can pick how much you want to spend and test out a few units at home before making your final choice.
One other nice feature is that if you have an acoustic guitar with a built-in pickup, using a DI can help you on stage to deliver a professional +4 balanced signal to your PA system even if it’s hundreds of feet from the stage. This will make it much easier for your sound man to get a great tone, and allow you to avoid signal loss from having to run a long high impedance cable to your PA system’s input from the stage. For a few more tips on how to creatively use direct boxes follow the link below.
Home Studio Tips from a Big Studio Designer
Direct Box Recording Tricks by Jon Chappell
Countryman Type 85 DI
Hosa Technology (this links to their latest catalog which include the Sidekick DIB-443 direct box tested in this article)
Digidesign Pro Tools LE M Box family
Radial Engineering – a leader in all types of direct boxes, including DJ and on-stage splitters and switchers