How to Get Kick-ass Bass Guitar Records

Those of you who read album reviews by BugJet Editors often found grumbles about lack of definition, thin, dull, lifeless, muddy bass, or whatever minor statement but the point is the bass sound falls beyond category of “kick serious ass” records. To get a kick ass bass sound on a record, it is not about multi-million ultra-expensive studio equipment, it’s all about the technique employed during tracking and mixing your bass.

Mainly in rock-metal music style, hearing lack of bass definition in a song seems like eating Chinese food without spices. Hell, BugJet is not a whiner, here the solution for low budget musicians. The article originally written by Mr. Michael Laskow, Editors have added some relevant material and schematic digested from mailing list, newsgroup, SAE Institute, product manual, and other web sources. Enjoy and let’s make brutal chest-thumping ass-kicking mountain-mover bass sound!

1. The Bass Guitar itself.
The first step in getting a good bass sound is of course, having a good sounding bass. "Good" being a subjective word, of course. With that in mind, let me simply say that the bass should have a nice balance between a rich bottom end and an articulate top end, great intonation, nice sustain, and no rattles or buzzes.

A few basic things to know about recording basses; First, and maybe foremost, the player has a great deal to do with the sound. As with many instruments, it's mostly in the fingers.

Second, the natural sound of the instrument is important. If the tonality isn't there to begin with, it's difficult at best to fake it. All the tube preamps and EQ in the world can't hide a bass sound that's dull and lifeless.

Third, the strings. Round from flatwound, brass verses nickel. They all have a sound. The sound you like will be a personal choice. But, let me add that the song you're recording can and should dictate the type of sound you are going for. In other words, the bottom shouldn't sound alike for every type of song.

I've also noticed that many direct boxes don't have a very fast slew rate. In plain English, that means the signal's rise and fall time is sluggish. What that means to the sound is the attack of the top end is often diminished, not due to the tone of the instrument, but the inadequacies of the box. Keep your ears open, and try several models. You'll be surprised at the wide range of sounds.

DI means direct injection. This is a fancy term for plugging the bass directly into a mixing console. To do this we use things called DI boxes, which are great items of kit. A standard DI box has numerous connections on it including jack and XLR. Now essentially what a DI box will do is convert the high impedance unbalanced line (guitar lead) into a low impedance balanced line (mic lead).
 
It means you can now use a microphone cable (balanced XLR) and have an extremely long cable run all the way to the mixer. For example you can't use a standard guitar lead and expect to get a healthy signal through the desk. For one there will be an impedance mismatch, and for two the signal will be noisy as hell. Get a D.I. box.

Without a D.I. you could not send the signal from a bass guitar or keyboard (any electric instrument) that is on stage, all the way to the mixing console at the back of the stadium. The studio is the same just not quite as far.

Balance the signal and lower the impedance and you'll get a workable sound. This is easy as you simply plug the bass into the DI box and the DI box, with a microphone lead, into the desk.

Virtually all active-DI boxes that feature an instrument input fulfill this requirement, and a number of passive transformer-based models are also suitable. Passive DI Box usually cost cheaper (less electronics and battery/power) BUT the impedance is dependent on the connected device’s impedance. When the impedance of mixer side of passive DI changes, so does the impedance of the input. Hence the frequency response changes too. Passive DI only works well at specified connected impedances.

Active DI, in the other hand, doesn’t have that weakness. Signal from input buffered with an amplifier, input impedance usually so high so it doesn’t affect signal thru or direct out of DI (for example tapping thru/direct out of DI into speaker cabinet as outlined in the picture). The output is balanced and low impedance makes it less susceptible to hum/noise pickup. 

The close mic will give a more direct sound with an accentuated attack, and the distant mic will give you more of the low end (it takes several feet of "air" for a bass wave to develop).

By using various combinations of the two mics, I'm able to get a great sound that often just can't come out of one mic. While two mics can often spell trouble because of phase anomalies, this is a case where those same problems can work to your advantage. By balancing the signals different ways, you are affecting the phase relationship between the two mics and altering the EQ curve, hopefully for the better. The faders on the respective channels of the console of course control the amount you vary the signal. The amount you move the faders to change the sound can often be measured by hair widths. A little dab will do ya!

Miking a good bass amp isn't a problem providing you're working in an environment where you can play the thing loud enough, and of course you need a decent mic. Though you could use a general-purpose dynamic vocal mic to capture the bass guitar, you'll find that most of these have a deliberate low-frequency roll off to compensate for the proximity effect when used up close. Because of this, unless these are placed right up against the speaker grille, you could find the bottom end tends to lose power.

A better bet is to use either a non-vocal dynamic mic that has a reasonably flat low-end response or to try one of the dedicated bass/kick drum mics, placing it around six to 12 inches in front of the best-sounding speaker in the cab. If you look at the frequency plot of a kick drum mic, you'll find the frequency response looks like the back leg of a donkey that's just been hit by a truck, but the results are often flattering and powerful, which is far more important than any misplaced notions about accuracy!

If you're using a valve amp, you may find you don't need to add further compression, or at least not much, but if the amp is solid-state and doesn't have a compressor of its own, then it's probably a good idea to at least try adding compression to see what can be achieved. The safest approach here is to leave the compression until you mix unless the levels are so erratic that clipping might be a problem.

Tonal changes can be made by moving the microphone -- the brightest sound is found by pointing the mic at the center of the speaker, while moving it to one side will produce a warmer, less in-your-face result. It's also worth varying the distance to see what result that has.

Try adjusting the mic position for the best results before adding any EQ at all, and if you can save the EQ until you mix, you'll keep your options open. After all, what may sound great in isolation may not sound so right when the rest of the mix is up and running.

Tricky this one but generally many engineers use large diaphragm mics for bass sounds. The ElectroVoice RE20 is a good one as can be the Sennhesier 541 and AKG D112. It sound obvious but you need to think about the frequency response of the microphone. If you use an SM58 to "mic-up" the amplifier you just wont get all the rich low-end tonality that is needed for a cool sound.

Placement is subjective and there is no right way or wrong way but to use your ears. You want to be in the control room listening to the bass player play the bass while your helper moves the mic in front of the amp to find the "sweet spot". In fact use that technique for all your mic techniques; just moving a mic a couple of inches will radically change the sound you get.

The basic miking techniques for the speaker itself are the same as with a guitar as far as placement is concerned.
The classic "Dead Center" miking position, this is the most obvious and most common positioning. Sometimes, with certain mics this may want to be avoided because it does put a huge amount of pressure on the mic because the sound is coming from right in the center of the cone. It does give a clean, pure representation of the speaker, but is sometimes prone to overdrive the mic.

Placing the mic on the center of the cone. I have seen many live sound engineers use this method, I don't use it myself, but it is a nice sound, with, some say, less pressure put on the mic. Still, it is a nice, close-proximity option for you to try with you amplifier.

Putting the mic at a 45-degree angle with the cone centered on the cap. I have seen this method used more for the second mic on a cabinet rather than the first, but none-the-less, it is an option. Used further back from the amp it can be good for grabbing extra bass. Theoretically, the highs will just shoot right past it and the booming bass will the picked up more with this position.

Putting the mic perpendicular with the speaker. This is even a more radical approach to getting more bass in your sound. Same theory as above, just a greater angle to let more highs zip past.

Though the direct method is probably the most common, as stated above, but a miked speaker can add some very big fullness to the sound. And the bass, more than the guitar, uses much of the body of the instrument to create some of the tones that they produce. This is why miking the body itself can be so effective in getting some great bass sounds.

If you are of the style that uses a lot of slap & pop-style bass, miking the body, especially at the neck-meeting-the-body position, will help pick up those sharp pops against the frets that give that style it's unique sound.

Often you can get away with a smaller amp than if you rely on the amp sound alone, as the DI will provide the entire bottom end you need. The D.I. signal will give you the very clean sound of the instrument. So the signal is just the pure sound of the bass. Sometimes this is a great tone to work with in the mix. It's usually a very tight and crisp sound, depending of course on the player's technique.

Many professionals take this combined approach. The relative phase of the miked and DI'd sound has a profound effect on the final result, so you may need to phase-reverse one of the sources to get the best result. Also, experiment with the EQ of the individual sources as well as their balance, as the EQ controls may not have the same effect as they do when the sources are heard in isolation. Similarly, changing the mic-to-speaker distance will also affect the phase of the combined sounds, so this can be useful in fine-tuning the result.

As you can see, there are several ways of recording the bass guitar, but if you like to keep your options open until the final mix, there's nothing wrong with DI'ing the bass flat via a DI box, perhaps in combination with a limiter to catch any excessive peaks, then applying one of the techniques outlined here at the mixing stage. Or if you have enough spare tracks, you can record the processed and the clean version of the sound on different tracks.

I'd certainly try to do this if I was miking the amp -- all that's needed is a DI box between the instrument and the amp (most have an audio thru connector) with the DI out connected to a spare recorder input. Computer users also have several options open to them when it comes to treating sounds after the event: in addition to the usual compression and EQ, there are now numerous software amp simulators that can produce very convincing results.

The beauty of the home studio is that you don't have the same time pressures as a commercial facility, so you can afford to experiment and see what method works best for you.

Using a mic on the other hand will give you the player's sound according to what she hears through the amp. Naturally in most cases you will want to use a lot of this sound because after all that is the "sound" of the bassist when he plays with his band. But if you use DI along with a mic you'll have two different bass sounds to play with.

Balance them. You’ll be able to experiment with the two channels that you have for the bass. Sometimes I'll EQ The two channels differently, concentrating on using the DI sound for the upper mid and high frequencies or use some channel splitters and create some bizarre panning effects.

One cool technique I'll share with here is that if you have enough space and room you can use three channels for the bass. Here it is:
1. DI Box out to console.
2. Microphone facing into the speaker and really close (almost touching)
3. A microphone close to where the bass players picking fingers are.

Now for this to work well it is best if you can get the bass player in a different room from where his amp is. So he is in a quiet space with headphones on listening to the mix and playing along. But the mic you use close the where he picks the strings will give you just the acoustic sound of the bass and can sound excellent blended in the mix. Use a capacitor mic for this.

Most engineers use a degree of compression with bass guitar, which is a good idea for a number of reasons. If the player uses a slapping or pulling technique, the note attacks can be very loud, so if you don't compress or limit, you either run the risk of overloading the recorder or you have to set the record level so low that the main body of the bass sound is too quiet.

This type of playing is best dealt with using a compressor that has a separate limiter, as the traditional way of making a compressed sound retain its attack characteristics is to set the compressor attack time to several tens of milliseconds in order to allow the initial transient to get through uncompressed. The release time is generally set to around a quarter of a second, but this will vary from model to model, so always experiment. Auto-attack and release settings (where available) also produce good results on bass guitar as they can adapt to the changing dynamics of different playing styles within the same song.

Allowing the transients to sneak past the compressor might produce a great sound, but it's those same transients that cause recorder overload problems, so having an independent limiter section following the compressor is very desirable. The limiter threshold should be set just below the overload level of the recorder so that limiting takes place only on very loud peaks.

Even if the bass is played in a more traditional way, compression is still beneficial as it evens up the levels of different notes and, equally importantly, it increases the average energy level of the sound -- making it seem louder for the same peak level. You can still back off the compressor attack a little to accentuate the start of the note, but keep an eye on those recording levels.

A useful tip if you don't have a compressor with a separate limiter section is to use a dual-channel compressor and feed channel one's output into channel two's input. Set channel one up to compress as normal, but set channel two to limit by using the highest ratio possible combined with a fast attack time and as fast a release time as you can get away with. Adjust the threshold of channel two so that gain reduction only occurs when the level is within a few dBs of hitting the overload region on the recorder's meters. Of course those still using analogue tape can afford to be that bit more casual about levels -- indeed, a little tape saturation can do wonders for a bass sound.

"If you don't use compression and you want your tunes get played by sound systems it's going to sound horrible and muddy. Compression on bass and kicks is very important. Try settings like fast attack halfway release and 6 or 7 to 1 ratio depending on the strings and or tubes used.

A couple of years ago I was forced not to use a compressor because of a too small wallet. So there were some labels that were going to release my tunes but they asked for new mixes because of the bass and also I got complaints from sound systems that played my tunes that the bass was too muddy” Stonelion said in a mailing list.

The following are suggested settings for bass compression for initial setting reference to event out inevitable level variation of bass guitar when played over a wide range. Since the equipment spec varies, feel free to tweak them or follow manual guide of respective product to suit your best sounding judgments.
Threshold: 9-12 dB
Ratio: 1 o’clock
Attack: 2 o’clock
Release: 3 o’clock or auto

I find that with most basses, I need to add about 4 db @ 80 HZ to fatten up the bottom end coming out of a direct box, and moderate compression gives me the "thump" I'm looking for. The more you can do with a bass's tone controls, the less work you'll have to do with equalizers.

With the right instrument and good playing technique, this simple approach can produce good results, but in my experience, the sound tends to lose power when the other instruments are added to the mix unless the arrangement is very sparse. What's more, the tone you get isn't the same as if you used an amp, as guitar/bass amps don't have a flat frequency response.

The EQ on most simple consoles isn't able to emulate a guitar amplifier very accurately, so an outboard processor is a better bet. Placing a good quality graphic or parametric equalizer after the DI box (usually via the mixer channel insert point) can improve things greatly. Most musicians know that adding an 80Hz boost will fatten up the low bass, but if you listen to the bass sound on records, you'll probably find there's also quite a lot going on in the mid and lower mid ranges -- most domestic hi-fi speakers can't reproduce deep bass anyway.

The key is to experiment with the EQ in the 120 to 350Hz region, as this is where the real character of the sound is defined. Though bass guitars do generate high-frequency harmonics, most of these would naturally be lost when the instrument was played through an amp and speaker cabinets as guitar speakers have a fairly limited frequency response.

You can leave them in if you like the result, but often you'll find that finger and string noise becomes irritating and that you can roll off quite a lot of high end without significantly affecting the main body of the sound. This usually makes the bass sound tighter and cleaner.

Another useful technique involves combining the equalizer with a speaker simulator such as my personal favorite, the all-passive Palmer Junction Box. Speaker simulators are designed to duplicate the high-frequency roll off of real speakers, so you can still use your outboard EQ to shape the low and mid sounds, then allow the speaker simulator to take care of the top end. A well-designed speaker simulator will take away all the grittiness from the sound without killing the transient attack, and will often sound more natural than using EQ on its own.