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Tech Tips

Recording - Guitar - Bass - Keyboards - Computer Music
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A/D D/A Converters

Question: I notice that some DATs and CD recorders have a 16-, 20-, or 24-bit A/D D/A converter, while others have a 1-bit converter. Which provides better quality? Or is the sample rate the key to quality?

Answer: There's a large amount of information available about A/D D/A converters and digital sampling rates, most of it too technical to make sense to anyone other than an engineer. However, in general, 1-bit converters are high-speed converters which process digital data 1 bit at a time and are considered superior to multi-bit converters. They provide higher linearity (smoother wave output) and, theoretically, no switching noise.

Higher sampling rates are also better. The higher the rate, the higher the frequency range which can be reproduced. For example, a 44.1 kHz sampling rate can reproduce frequencies up to 22 kHz.

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Balanced Line Defined

Question: What is a balanced line?

Answer: A balanced line is a cable that has two conductor wires surrounded by a shield. When used in conjunction with the electronics for balanced inputs and outputs, one conductor wire carries the negative phase of the audio signal, while the other conductor carries the positive phase. The purpose of this balanced input/ouput system is to cause stray signal induction (noise) from outside sources to be phased out (canceled).

Balanced lines are used on audio equipment that has built-in electronics for balanced inputs and balanced outputs, which normally means professional equipment. Professional equipment is designed this way, because the long wires often used with it are especially prone to pick up stray signals (hum).

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CD Burners vs. CD Recorders

Question: Are CD burners different from CD recorders?

Answer: CD burners and CD recorders use the same laser technology and produce the same sound quality.

A CD burner, however, can't be used by itself to record CDs, and it can't record vocals or instruments in real time. It requires a computer running CD burning software to transfer data to it, typically from a hard drive. Older models use only CD-Rs, but newer models use either CD-Rs or CD-RWs.

A CD recorder doesn't need a computer, and it can record vocals and instruments in real time. That's because it already contains all of the hardware and software it needs. It can also record from a computer using the digital output from a soundcard. Because a CD recorder is self-contained, it's usually higher priced than a CD burner. Older models use only CD audio discs, while newer models also use CD-Rs and CD-RWs.

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Chaining Guitar Effects

Question: What's the best chaining order for guitar stomp boxes?

Answer: The arrangement of guitar stomp boxes and other effects is mostly a matter of personal taste and creativity in producing whatever kind of sound you want. They can be chained either serially or in parallel. End-to-end serial chaining is probably more common. But you can also parallel-chain multiple effects by splitting the output of the guitar to the input of each effect, and then feeding the output of each effect to a separate channel on a mixer. This allows you to mix the effects according to your taste.

There are no technical or electronic barriers to the order. However, there might be other considerations. For serially chained effects, for example, most guitarists place compressors first in the chain, because they can amplify the noise from any effects that precede them. Also, filter effects, such as wahwah pedals, are usually placed after distortion effects. But neither of these is a hard and fast rule. No matter what order anyone recommends, there's ultimately only one rule: experiment to find the most desireable results.

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Controlling Distortion Effects

Question: Is there a chaining order that provides better control over distortion effects?

Answer: Distortion effects create a hotter high end in sound by adding harmonics. But some harmonics are not as desirable as others, and the distortion can become very uneven as volume levels change. For better control over the final sound, try this effects chaining order:

  • Use a compressor or limiter at the beginning of the chain to narrow the dynamic range of the signal.

  • Next, apply EQ to select and boost those frequencies you want distorted. Because distortion effects devices are level sensitive, only frequencies above their threshold will be distorted.

  • Next, add the distortion device to the chain and set its levels.

  • Finally, apply EQ again - this time to attenuate or boost selected frequencies in the distorted signal.

As a result of this chaining order, the signal level fed into the distortion device will have less variation, and the harmonics can be varied greatly.

Note: A compressor increases the note sustain of string instruments. In this chain, that causes a more consistent distortion effect on note decays.

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Dull Vocals, Muddy Mix

Question: When I'm recording music with my band, using a minidisc four-track, the main instruments sound fine. The guitars, for example, sound especially good - meaty, yet defined. My major problems, however, are the following.
  • Vocals are dull, lifeless, muddy and even distorted on high-pitched parts, even though I use a compressor and peak limiter.

  • The keyboard makes a high frequency hiss.

  • The mix is unclear - a lump of noise, rather than a sonic landscape.

Answer: Here are a few things to consider:

Do the vocals sound bad when solo, or only in the mix?

If the problem occurs when the vocals are solo, then you might be using too much compression, which would make the vocals sound flat and lose their dynamics. This could be true in spite of the fact that you're getting distortion on peaks. Distortion can be caused by the input level being too high on the compressor, the mixer or the mini-disc recorder. Use a process of elimination to find out which of these devices might be causing distortion. Also, if levels on each device are set correctly, a peak limiter might not be needed.

If the problem on vocals or instruments occurs mainly in the mix, then other instruments may be muddying the vocal or the instrument by being in the same frequency range. One of the ways vocals and instruments get their space is by being in a unique frequency range. (It's a good idea to select instruments on that basis.) The muddying of a vocal or any instrument can be corrected by using EQ to reduce the level of frequencies on other instruments that overlap with the same frequencies on the given vocal or instrument.

The keyboard problem might be a result of incorrect level adjustments. The output level on the keyboard should be set high and the level on the mixer or recorder set lower. This will give the best signal-to-noise ratio. Another possibility is that the output of the keyboard is simply noisier than it should be. That could mean repair or replacement.

Some of the questions you've asked might also be answered in my article, 10 Brief Tips for Mixing.

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Extract A Track?

Question: Is there any way to remove a vocal or instrument track from a recording while leaving the rest of the recording intact, or - the reverse - to remove the rest of the recording while leaving a vocal or instrument track intact?

Answer: This question comes up repeatedly, but no matter how often it's answered, it never dies.

Actually, removing a vocal or instrument can be done, although crudely, as long as certain conditions are met on the original recording. It must be a stereo recording, and the vocal or instrument you want to delete must be panned to the center with both channels being equal in level. Then phase cancellation can be used to cancel the center. Note, however, that everything panned to the center would be cancelled, and that almost always implies some portion of the other sounds. Note, also, that the center can be cancelled by some sound editors, such as the free AnalogX Vocal Remover plug-in.

It's not practical to use this phase cancellation technique for the reverse purpose of keeping the center and removing the rest. However, if you have a Dolby surround decoder, it's possible to record the center channel output alone. I've tried this technique, but depending on the recording, there will usually be bleed through from the left or right channels.

The final answer, however, is that none of these techniques produce quality results. The only way to produce quality is to work with the original tracks that were recorded for use in the final mix. And, of course, you're not likely to have those.

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Guitar and Effects Direct to Mixer

Question: Do I still need a direct (DI) box if I run my electric guitar and effects device direct to the mixer instead of miking the amp? Also, I've heard that effects don't sound as good when run direct.

Answer: No, you won't need a DI box, as long as you're running your guitar through the effects device first. The reason is that most effects devices for guitar have a high impedance input and a low impedance output. In other words, the effects device does the same impedance conversion as a DI box would.

As you probably know, a lot of guitarists play or record direct using effects devices. So, the idea that effects don't sound as good that way is an overly generalized opinion. Sometimes miking a guitar speaker adds a desirable characteristic to the sound; sometimes it doesn't. How you play or record effects is not only a matter of taste, but also a matter of what kind of sound you ultimately want. For example, it's a common practice to record an effect direct and also simultaneously through a mic to get a particular result.

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Guitar to Soundcard Connection

Question: I don't know how to connect my Boss GT-3 guitar effects processor to my computer that has a soundblaster AWE32. And why should I connect it?

Answer: Actually, there's no reason why you should, but I can think of two reasons why you might want to.

The most likely reason to connect the GT-3 to your soundcard is to use the hard drive on your computer to record your guitar. You would connect the GT-3 by plugging it into the line input of the soundcard. For that, you might need an adapter plug. Also, you would have to make sure that the line level input is turned up in whatever software you are using for the soundcard.

A far less likely reason to connect the GT-3 to the soundcard is to use the computer's sound system as a monitor for your guitar, in the event that you do not already have a monitor or guitar amplifier.

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MIDI to WAV Recording

Question: As a long-time owner of Cubasis, I have years of recorded output saved as .all or .mid files. Now that I have purchased a CD-writer, I would like to turn these into .wav files and ultimately record them to CD while retaining the sounds of my Korg synth. I have not yet found anyone who can tell me how to do this.

Answer: Essentially, it is the audio output of your synth which you would record as a WAV file and which you would then transfer to CD.

The way you do this is by playing a MIDI file through the synth as you normally would, and then feeding the audio output of the synth to the line input on your computer's soundcard. Adjust levels with whatever mixer application you have on the computer, and then record the audio output onto your hard drive as a WAV file by using whatever audio recording program you have. Thus, the WAV file will be a recording of the sounds from your synth. (Incidentally, if you have a combination MIDI/audio sequencer, you can play and record through the same software simultaneously.) Of course, once you have a WAV file, you would simply transfer the file's data to CD by using either the software that came with your CD-writer or separate CD burning software.

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Mixing for Separation & Clarity

Question: How do you create a strong sense of space and clarity for each of the instruments and vocals in a recording mix? Is there some trick to doing this?

Answer: Creating space and clarity in a mix results from a combination of science and artistry. Here are some tips:

Before doing the mix, make sure that the signal of each vocal and instrument is clean in solo. If a recording is bad, no mixing technique will correct it. You should re-do it.

Vocals and instruments that produce a similar frequency range can sound muddy when played together. The easiest solution is to select only those with differing ranges, or to space them apart from one another in time. A more complex solution is to find the common frequency range causing the problem and use an equalizer to reduce it on one of the sources.

One of the simplest ways to create space is by use of panning to position instruments and vocals from left to right. But a more subtle way is to create depth - front to back positioning. Depth is the sense of distance between the listener and the performer, and it's created in several ways.

One way is by use of the signal level. The louder an instrument sounds, the closer it will seem. This is true even of a soft whisper that can be heard clearly over other instruments. It will sound close, because a whisper doesn't carry very far, and we don't expect to hear it over a distance.

A second method is the use of reverberation. A slight reverb effect added to a signal can make an instrument sound farther away, because our ears interpret reverberation as sound reflected from a distance. It's called ambiance.

Finally, distance can be affected by using EQ either to attenuate or to increase high and mid-range frequencies. Since high frequencies are easily absorbed and do not carry as far as lower frequencies, increasing the high frequencies on an instrument will make it seem closer. And increasing or decreasing mid-range frequencies can have even more effect, because the ear is most sensitive to them.

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Multi-client Soundcard Drivers

Question: I have the classic conflict of two software applications being unable to use the line input of a single soundcard simultaneously. One app uses the music to manipulate a stagelighting rig, taking the sound off the soundcard through its line-in jack. But when I try to stream my performance over the web, the streaming software can't open the audio device while the lights app is running. What's the way around this?

Answer: Your question needs a long answer, because several ins and outs (painful pun intended, of course) must be considered, including what software and what MIDI and audio drivers might be available to you. A long article called Understanding and Using Multi-client Soundcard Drivers at Sound On Sound will give you some essential clues to understanding your situation better and what possibilites for help are available. I think it ultimately covers all aspects of your question and offers a good chance for solving it.

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Overdrive and Distortion

Question: What's the difference between overdrive and distortion?

Answer: Overdrive is the distorted sound a guitar or any instrument produces when the volume of a tube guitar amp - either the preamp or the master or both - is turned up so high that it becomes overdriven.

Distortion includes overdrive, plus a broader category of analog and hard-edged digital effects typically used with guitar and other instruments. Examples are overdrive pedals and effects devices, such as Tube Screamer, Fuzz Tone, Fuzz Face, Big Muff, etc.

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Phantom Power

Question: What is Phantom Power?

Answer: Phantom power refers to the direct current voltage, usually 48 volts, that's used to power a condenser mic. The voltage is applied to pins 2 and 3, referenced to pin 1, of an XLR microphone connector.

In the '50s and '60s, it was usually provided by a separate power supply that came with the microphone. Later on, manufacturers provided a source for the power at the mic input to mixers or preamps. Originally, only devices that needed phantom power were wired to use it. But, nowadays, almost all condenser mics and active direct boxes are able to use it, and most mixing board manufacturers include the feature in their products. The reason it's called phantom power, by the way, is because most dynamic microphones and other passive devices with balanced outputs are not affected by it. To them, it's just a phantom presence.

Some important tips and cautions about phantom power:

  • It will not harm dynamic mics or direct boxes when they are plugged into a mixer that includes the feature, as long as they have balanced outputs.

  • A condenser mic receiving less phantom power than it needs might produce more distortion, more noise, or a lower dynamic range, but it will not be damaged.

  • Although phantom power can be directed through a patchbay that has balanced TRS (tip ring sleeve) connections, TRS patch cords must be used. Otherwise, the phantom power will be shorted. Also, the phantom power should be turned off before you plug or unplug the connectors. Otherwise, it will be momentarily shorted.

  • To avoid surges, it's a good idea to turn phantom power off before connecting a mic.

  • When phantom power is turned on or off, it usually causes a very loud pop, which can damage speakers. Be sure to lower the levels of your sound system when you turn phantom power on or off, or if you connect or disconnect phantom powered mics while the power is on, or when you turn the mics on or off.

  • Never use phantom power on unbalanced mics, wireless mic receivers, or ribbon mics.

  • Although it's often said - correctly - that phantom power can harm some line level devices, you should never connect line level devices to mic level inputs anyway.

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Power Conditioner vs. Power Strip

Question: What is the difference between a power conditioner and a power strip which has a surge protector?

Answer: By strict definition, there is a major difference. Most power strips have a surge protector, and some have a radio frequency filter. A true power conditioner, however, would have both, plus voltage regulation to maintain constant voltage output if there is a lowering or rising of line voltage.

In general, there is little need for a genuine power conditioner in the studio, because most solid-state electronic equipment already has voltage regulators built into the power supply. In addition, because of complex circuitry, power conditioners which fail can cause damage to equipment that would not occur if no power conditioner was present. (This happened to one musician I know.) For that reason, many power conditioners come with a lifetime insurance policy which will pay for damage to equipment as a result of the power conditioner's failure.

But the term "power conditioner" is often loosely and incorrectly applied, even by manufacturers, to include power strips and other kinds of devices, making the term meaningless. And some of those devices are not appropriate for music equipment. For example, I've known musicians to use an uninterruptible power supply for their audio equipment, such as the kind meant to prevent data loss in computers in times of power failure. But many of these can be a source of noise because of their high-frequency switching circuits.

So, what should musicians use to protect their equipment from power surges and power line noise? Usually, a power strip that includes a surge protector and a radio frequency filter will be sufficient. But if your power source contains noise which you cannot eliminate, you might also need a balanced isolation transformer, which cancels extraneous noise in the power line by means of phase cancellation.

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Vocals Equipment Setup

Question: What equipment do I need to sing in cafes, night clubs and at fairs?

Answer: At the very least you will need a microphone, an amplifier and 2 speakers (because you get 4 times the acoustic output with two).

For use with vocals, I recommend a rugged dynamic mic, such as a Shure SM-57 or the SM-58. They're both very popular and reasonably priced.

The amp should be in the form of a mixer with a power amp built into it (called a powered mixer), such as Mackie, Fender or Yamaha makes. (By the way, if you are accompanied by another singer or player, you can connect them into the system through the extra inputs on the mixer.)

For speakers, I recommend high-quality two-way speakers (meaning they have two drivers - one for lows, one for highs) with 12" woofers or larger, such as Electro-Voice, JBL, Mackie, or Yamaha makes. Those companies make highly efficient speakers. Efficiency is very important in PA (public address) or sound reinforcement systems in order to get good sound at high volume with minimum distortion.

Although many people feel that the quality of the mic is the biggest factor in good sound, most mics made today are high-quality. Because of that, the quality of the speakers will make the biggest difference in the quality of sound in your set up.

Finally, you will need a set of cables (about three) for connecting your microphone, mixer and speakers, plus a power cord.

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