Do You Need a Direct Box for Home Recording?

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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.

The Hosa Sidekick is a reasonably priced passive direct box available at many music stores.
The Hosa Sidekick is a reasonably priced passive direct box available at many music stores.

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.

The Countryman Type 85 is an active direct box known for its reliability and rugged construction.
The Countryman Type 85 is an active direct box known for its reliability and rugged construction.

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.

The inside of the Hosa Sidekick shows the simplicity of its design. The transformer that converts your unbalanced signal to a balanced, mic level signal is in the center.
The inside of the Hosa Sidekick shows the simplicity of its design. The transformer that converts your unbalanced signal to a balanced, mic level signal is in the center.

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.

The Countryman packs its electronics into the white isolation block beneath the 9V battery, which powers the DI when you don't have access to phantom power.
The Countryman packs its electronics into the white isolation block beneath the 9V battery, which powers the DI when you don't have access to phantom power.

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.

Bassist Giulio Cetto provided the technique and licks to put our test units through their paces.
Bassist Giulio Cetto provided the technique and licks to put our test units through their paces.

The Results
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.

Digidesign's M Box 2 Mini in action during the test session
Digidesign's M Box 2 Mini in action during the test session

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.

Story Links

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

25 thoughts on “Do You Need a Direct Box for Home Recording?

  1. It seems to me that if what a D.I. box mainly does is color the sound, then I will just plug directly into the digital mixer and use the board’s extensive EQ, to get that thicker, fatter, organ, with bell shaped harmonic sound. Since any extra gadgets in your signal chain will degrade your signal slightly, it only makes sense to only try using a D.I. when you have an issue such as a ground hum or hiss or other issue where you might need one.

    1. I agree. This week I tested a cheap Live Wire passive DI on a passive pickup bass, to split the signal to record direct, and mic the amp. Seems the extra load of the DI to the amp really sucked the tone of the Amp signal. Thus, I had to do some serious ninja EQ and gain settings on the amp to get the desired tone. Also, the built in preamps on my interface are high quality, so there was no improvement using the cheap Live Wire DI. Today’s high quality interfaces have huge amounts of headroom that make direct recording easy with great results.

  2. An interesting discussion is worth comment. I
    think that you should publish more on this subject, it might not be
    a taboo matter but typically people don’t discuss these issues.
    To the next! Kind regards!!

  3. That is a very good tip particularly to those fresh to the blogosphere.
    Short but very accurate information… Thank you for sharing this one.
    A must read article!

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  8. With everything which seems to be developing within this specific subject matter, your viewpoints are generally quite refreshing. However, I appologize, but I do not subscribe to your entire suggestion, all be it radical none the less. It seems to everybody that your commentary are not completely validated and in simple fact you are yourself not even entirely certain of your assertion. In any event I did enjoy examining it.

  9. Hey guys,
    Here’s a great link that explains the advantages of using a DI box, specifically the Radial JDI:
    http://www.youtube.com/watch?v=QYVk3TJfKOQ

    If you’ve spent time in a recording studio, chances are you’ve stumbled across the Radial JDI as it is a commonly used DI box.

    If you want the driest sound possible, then you could make an argument that the DI box fails if it provides coloration. That said, I would not say that Keith’s test was a failure at all. In fact, the main selling point of the Radial JDI is the use of the Jensen transformer to provide analog saturation to the signal vs. clipping. It just depends on how you like to work with your audio.

    I’ve used a lot of different home recording interfaces and you often get a weak signal running the instrument into the box. I’ve tried using cheap passive DI boxes, and noticed no change. That said, my current interface is a Focusrite Saffire, and the signal is much better i.e. less noise, higher gain. I will be picking up a JDI radial passive DI tonight or this weekend and can post A/B testing results.

  10. <<>>>

    Jim, I think it would be more accurate to say that your ideal DI strives not to affect the tone. I have about 8 different options for DI in my studio and they all sound different. This is part of my creative pallet at a producer-engineer. As a matter of fact the one I use the most (an A Designs REDDI) gets used because it colors the sound the most in a beautiful way

    Everything that affects the level or impedance of an audio signal will change its tone. Sometimes almost unnoticeable and other times quite dramatically. This is why the world has such a large range of pres, DIs Line Amps…..

  11. There tends to be confussion by most non-technical folks about DIs. Steve’s post is an example of this. Unfortunately, this is just a quick post and I don’t have a training URL handy to drop in here. His mis-statements about impedance and such can be very confusing to those learning about DIs. I’ve been a certified engineer (and musician) for roughly 30 years who has worked with many artistic talents who share Steve’s misconceptions. It’s SO easy to learn this stuff from good sources.

    Sorry Steve.

    1. Sorry Jon.

      There’s some confusion by some well meaning people about communication. Jon’s post is an example of this. Fortunately, though this is just a quick post, I have a suggestion handy to drop in here. His statements about “confussion” about impedance can be very confusing for someone actually wanting to learn something. I’ve been a person for roughly 40 years who has known many people who share Jon’s miscommunication habits. It’s SO easy to debunk someone and then not provide a positive solution.

      So Jon, unless you just wanted to come off like a debunking know-it-all, in the future, a helpful post would actually take the 5 minutes it takes to dig up a “training link” or other resource (for example, for DI units: http://en.wikipedia.org/wiki/DI_unit), and drop that into the correction, instead of just making poster Steve look bad, and then disingenuously saying, “Sorry Steve.” Failing to do so is not helpful.

      Hope this helps!

      1. Oy vey!

        Man, I don’t want to sound as if I’m an English nut, but your sentence and I quote, “I’ve been a person for roughly 40 years who has known many people who share Jon’s miscommunication habits.”, has a slight flaw in the sentence structure.

        I may be wrong, and correct me if I am, but maybe if written this way, “I’ve been a person for roughly 40 years, and have known many people who share Jon’s miscommunication habits.”

        Just taking one for the team here.

        steve

        P.S. IMHO, I think poster David hit the nail on the head when he mentioned that the ‘colour’ we hear in the sound when using DIs is really just the actual sound of the instrument coming through, especially with the more expensive units.

  12. It a good thing to have all you have to do is mic your amp have the guitar plug into the di box and run one out to you amp and one to a separate track this way if the amp didn’t record good you still have the guitarist licks to effect off the other track to get the sound you wanted. see There was a test there 🙂

  13. Like Jim, I never comment on these but on this I have to.
    I’ve been playing bass guitar for about 26 years. And recording professionally for the past 12. The DI box was designed to match a high impedance (HiZ) output source to a low impedance (LoZ) source. Such as a “live” console or in this example your home recording setup. True, most interface boxes have an instrument input these but I wouldn’t trust them. Always use your DI box and connect to the “balanced” or LoZ input. But as Jim mentioned, you HAVE to have a gain stage. You must have some way to maintain the input signal. That plus some compression is the only way to maintain you “clipping” problem.
    DI boxes really only need to be used in your recording setup because you like the tone of them. In my setup the first part of my signal is my Avalon U5. Why? Because I think it does the best job of capturing the sound of the bass right from source. I like its “color”.
    All DI boxes will color your sound. You just have to try them out. What’s more important in your home recording chain is mic pre (gain stage) and compression. But thats another discussion.
    Thanks for the article Keith!
    Steve Barber

  14. Jim, while it’s true that you don’t want a DI to color your signal, you have missed the point of the test.

    I would like to disagree that Keith’s test “failed miserably”. Through his test, the big discovery is that the lower quality DI’s were simply not capturing all of the original signal.

    With the Countryman, the bass sounded fuller and richer, not because the original tone was colored, but because it was actually captured.

  15. This was a very helpful blog and I’m always searching for a smoother bass guitar sound both live and in the recording aspect. Thanks for the help and research with direct boxes, very cool to know!

  16. I don’t normally comment on things, but here goes . . .

    A good DI strives to affect the TONE of a signal not at all. So if your DIs were changing tone, then they failed miserably. The artifacts you describe, the clipping, are most likely due to improper gain structure. The studio pros I know occasionally use a pre-amp of some sort for instruments like guitars, but these intentionally affect tone – like a Sansamp or other cab simulator. The only times I generally prescribe a DI is for long cable runs where we need the benefits of common mode rejection (balanced) or if we need ground isolation.

    Most I/O boxes these days include an “instrument” input which will not load the instrument – which can theoretically affect tone, though I have never seen a good example to prove it.

    Especially with Bass, DI vs no DI really shouldn’t make a noticable difference if everything else is done properly.

    So thanks for the article. I would like to politely disagree with your conclusions and methods.

    (Not that it matters.)

    Sincerely,

    Jim

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