The educated Tanguero

Essential Tango Knowledge

Tango DJing Part 2: Equipment

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Milonga, Music and the DJ – Part 2 (Equipment)

In old times, when we had learned to record cylinders or discs, playing music was simple. Just put a disc on the player. With the invention of the tape recorder we even were able to play pre-recorded lists of music. All this really became easy with the invention of computers and audio file formats.

Today, we can have hundreds of thousand single musical files on hard disk easily transportable. Even the invention of the CD has made that much easier, but carrying 200 CDs is still today a weight not easy to ignore for a DJ. For the DJ everything is quality, handling and easy accessibility of required tracks. This can be really tricky if you juggle with 200 CDs, it also can be a matter of seconds, when you work with tagged music files and a powerful database.

Even if today some DJs like to play vintage vinyl, the days of the record player or even the CD player are over.  Some DJs still use CDs (they have good reasons for this), but most modern DJs use computers, which is really convenient. Today we want to look, how equipment is hooked up to a sound system.

Computers or CD players convert musical information from disc or hard disc to an audio signal with a certain voltage. This system is routed through a mixer into a power amplifier, which drives the speakers. Generally, we use stereo systems, which divide the signal into a left and a right channel. The mixer is an instance, where multiple signals are mixed together (f.e. two CD players, one computer, two microphones) all these inputs are mixed together as channels and the mixer allows for adjusting gain and frequency spectrum (low vs. high tones) for each channel. For preamplified audio inputs (line inputs) a certain voltage is defined as a reference and the actual signal strength is given as a logarithmic ratio comparing the actual signal with the reference ( for consumer audio products, this is called dBV). If a signal exceeds this scale, it will be very likely clipped and distorted, so the signal should be generally kept below that threshold. The signal should also be kept at a high level to avoid the noise generated by the electronics at really low signal levels.

(More information on the definitions and physics can be found at:

http://en.wikipedia.org/wiki/Line_level

http://lenardaudio.com/education/09_mix/09_mix_3.html

The message here is that usually a music signal is handed over as a line signal which should be kept below a certain threshold (usually 0dBV) to avoid distortion.

House Mixer. DJ equipment is connected and the channel is active

House Mixer. DJ equipment is connected and the channel is active

Normally DJs bring their own primary equipment (CD Players, DJ mixers and Computers) and hook that up to the mixer of the venues sound system (equipment from some 1000 $$ to more than 100.000 $$). As professional mixers have sometimes more than 20 lines and are usually located very unconvenient, many DJs have their own mixers with just a few channels and a crossfader that allows for smooth transition between both CD decks. For non- and semiprofessional equipment, the output of the CD player is usually two RCA (or cinch) connectors. A cable with two RCA plugs (Picture 1) connects that to the line input of the mixer. Usually this is also a pair of RCA sockets (Picture 2).

Picture 1: Cheap (lowers) vs. quality RCA plugs.
Picture 1: Cheap (lowers) vs. quality RCA plugs.
Picture 2: RCA line out sockets of a DJ mixer
Picture 2: RCA line out sockets of a DJ mixer

Computers usually have a TRS socket for 3.5 mm TRS plugs (Picture 3). In this case a special cable or a combination with an adapter (Picture) are used.

Computer1
Picture 3: A Notebook´s TRS line out socket (usually green) for 3.5 mm TRS plugs
adapters
Picture 4: Adapters between 3.5 mm TRS and RCA. Use Adapters only in emergency situations. Try to have always high quality cables TRS/RCA and RCA/RCA.

Just a short note on cables. Always buy premium quality cables. A cable for 30$ is strong and reliable, the cable for 5$ will give you trouble when you really don’t need it. I also do not believe in adapters. So I have different cables RCA to RCA and RCA to 3.5 mm TRS. In a small box, I carry cables with lengths of 2, 5 and 10 meters, and adapters for emergency situation. The RCA to RCA cable I normally use is gold plated and comes with a lifelong warranty.

The DJ mixer is now plugged into a line input of the big central mixer and thus connected with the power amplifier and the speakers.

ATTENTION: Whenever you plug in a cable into a mixer, be sure that that respective audio channel is turned off (muted or faded with the channel fader or the master fader) or you are at risk of damaging the PA or the speakers. The reason of this is, that during the insertion of the plug, sudden loud buzz can appear because the hot part of the plug connects before the ground is closed. Generally, equipment should be powered on from periphery (player, mixer) to speaker (PA) and powered off from speaker (and PA) to periphery.

Sometimes you will hear a humming sound when you connect the DJ equipment. This is due to the formation of a so called ground loop, which catches  the 50 Hz signal from the power line. In that case, a so called ground loop protector is the usual solution which just has to be inserted into the line cable. (Picture 5)

Picture 5: Ground loop isolator. It will be hooked in between the DJ mixer and the main mixer.
Picture 5: Ground loop isolator. It will be hooked in between the DJ mixer and the main mixer.

Now we have to level the signal strength between the DJ equipment and the sound system. Generally the main output of the DJ mixer should be set to 60 to 70 percent and this should be adjusted at the main mixer for the maximum required volume. The individual channel fader for each deck should be used at 100% to achieve this volume.

Next step is a thorough sound check. It is highly recommended to check the volume and the pan (balance of L to R channels) at different spots of the venue in order to find the ideal level of volume. After that, the signal may be equalized in terms of adjusting high, low or medium frequencies. Some sound systems come with full equalizers with up to 10 frequency channels, so sound adjustment can be tricky. Generally many professional sound systems are already adjusted to the room so do not touch that if not necessary. The fine tuning can always be done with the equalizer of the DJ equipment.

 

Traditional DJing with two CD decks and a DJ mixer

Traditional DJing happens with two sound sources. One player (or also called “deck”) is playing and a second one is ready to play the next song. While the first song ends, the second one is started and the faders of the mixer are used to blend in the new song directly. This can be done with the two channel faders or with a special crossfader. The DJ mixer can also transfer the signal of the second deck to a headphone, making it possible to prelisten to the next song while deck 1 is playing.

The second deck can be adjusted in speed to the first deck, which makes the transition smoother (bpm matching). It is the DJs art to make these transitions smooth and mainly unrecognized by the dancers.

In Tango, generally, we do not want to have smooth transitions. Tango dancers want to finish the song and have some time between that and the next song (2-5 seconds), which usually makes it unnecessary to use speed-matching. This generally applies to old style Tango, but not to Neotango. Here all the modern ways of crossfading (Picture 6) and electronic matching (speed, beat & key) may be used.

Crossfade
Picture 6: Channel fader and crossfader of a modern DJ mixer. The crossfader makes it easy to change between deck A and deck B).

 

The main disadvantage of this setup is that both songs have to be on different CDs. That makes playing songs from the same CD impossible (to overcome this, DJs were used to burn their own CDs to mix with the second deck).

As it is very unconvenient to carry hundreds of CDs and it also can be tricky to find a requested song at once, DJing with CDs is getting very rare, especially in the Tango scene.

 

DJing with a Computer

Converting the waveform of an audio recording into digital data creates huge files. This has changed with the invention of audio compression software. For this, a codec (coder-decoder) software transforms the audio data into a compressed format. This compressed format can later be decompressed and played. The first codec was invented by the German Fraunhofer Institute. This codec is called mp3 and has completely revolutionized our music world. Unfortunately the compression here is not lossless. The quality of the compression can be adjusted and is measured as the bitrate in kbit/s. Using low bitrates for encoding will result in small file sizes, but also in music with audible artefacts. The threshold, where no artefacts are audible is somewhere between 128 and 190 kbit/s and depending on the song and the audio equipment. When I started to convert my Tango CDs in the late 90ies, I used a bitrate between 96 and 128 kbit/s. Today, I start to resample with 256 kbit/sec because hard disc space is not an issue anymore. Mp3 is the mostly used format in the world, but there are lots of alternatives f.e. Mp4 which is mainly used for Apple computers. Alternative codecs like FLAC or Apple lossless are able to compress music without loss and are thus preferred by HiFi enthusiasts. It is very important to keep the music compatible for different player software, so in my humble opinion mp3 at high bitrates is still the best pick. More information may be found at:

http://en.wikipedia.org/wiki/MP3

These Mp3 files can be played by special computer software to an internal or external  soundcard, which converts the music to a line signal. Like a computer program, a list of music files can be used to play many songs consecutive, which is called a playlist.

Music files can be organized in folders on the harddisk or in databases which create a convenient and fast to search metastructure. Very useful is the fact, that music files can include text information regarding artist, songname, album and year. Including these information is called tagging. These Mp3-tag information is frequently used to create musical databases.

The workflow from retrieving the music from a CD (ripping), tagging and storing in a collection is the most important work done by DJs. We will learn how to do this in the next of our little lessons.

The usual music players for our computers are very able to play single songs or playlists, but unfortunately, they are not suitable for professional DJing. For this, we need a software that emulates the traditional DJ equipment with two decks, a mixer and the chance to prelisten.

 

DJ Software for PC and Mac

As always there are cheap solutions and solutions you have to pay for. Tango DJs have to deal typically with large collections of files, so software should be preferred with good database functions.

 

1. iTunes ? Love and hate…..

iTunes (Picture 7) is available for Macs or Windows PCs and mainly is a database for your music. iTunes comes for free with a player and a sophisticated and versatile database. More information on:

http://de.wikipedia.org/wiki/ITunes

You either love iTunes or you hate it. Especially the integration of a music store, DRM copy protection and the suspicion that Apple could spy into your music collection is an issue.

Anyway, some Tango DJs use iTunes as a database and play with professional DJ software accessing iTunes.

 

Picture 7: iTunes from Apple. Love it or hate it, it is a high quality database for your music.
Picture 7: iTunes from Apple. Love it or hate it, it is a high quality database for your music.

2. The free solution for DJ mixing: MIXX

MIXX (Picture 8)  is an open source project for Windows, OS-X and Linux and gives you a professional mixing software with two players for free. It comes with iTunes integration, bpm detection and bpm matching. It supports all the major file formats (even lossless) and can handle multiple outputs for prelistening. The new version even supports hardware controllers. Everything is supported via user manual and a large user forum.

More on:

http://www.mixxx.org/

this is a review:

http://www.djtechtools.com/2012/08/07/review-mixxx-1-10-dj-software/

Mixx
Picture 8: Mixx is a free software that ticks all the boxes.

3. Professional Software (Native Instruments Traktor Pro)

Today, a couple of professional softwares are available for DJs. For the Tango DJ, mainly the useability of the database is important. I use Traktor Pro 2.6 (Picture 9) so I will describe this as an example. Other softwares are Serato-DJ, Virtual DJ and BPM-Studio.

Most of these have 2-4 decks, a mixer, a sampler (device to record small pieces of music and play them back on keystroke)and an integrated database. For Traktor pro, the database contains the tag informations and we can store playlists and general lists which can be used to store music of special type or lists of Tandas for Tango DJs.

More on:

http://www.native-instruments.com/de/products/traktor/dj-software/traktor-pro-2/

Traktor
Picture 9: Traktor Pro 2.6, a professional DJ-software from Native Instruments Inc.

 

Soundcards and DJ-controllers

Internal soundcards of notebook computers usually provide one output. This is a problem, because we really need a second line for headphones. So usually an external soundcard is needed to provide that feature. Cheap USB soundcards can be purchased between 50 and 100 $. Example:

https://www.storedj.com.au/products/BEH-UCA202

soundcard
Picture 10: Cheap USB soundcard as a second port for notebook computers.

Using a Computer, especially a notebook for time critical tasks like DJing is really tricky and you will soon find out, that a mouse and especially a trackpad are no precision elements. So special controllers with real switches, sliders and jog wheels are used to mimic the traditional workflow of a two CD-deck DJ setup. Using a DJ controller is very convenient, because it improves precision and speed. These so called DJ-controllers are made to control all the aspects of the DJ software and provide the soundcards for inputs and outputs. They are connected to the computers usually by USB or Firewire (IEEE 1394) cables and the controller includes the DJ mixer with an RCA line output.

More here:

http://www.native-instruments.com/de/products/traktor/dj-controller/traktor-kontrol-s4/

I recently started to use a DJ controller, and I was really a sceptic in that regard, but now I found out, that it really makes things easier, so I learned not to grab the mouse in a reflex action any more during my sessions.

 

What Equipment to carry for a Milonga?

Generally I carry my notebook and the DJ controller in a stable case with the usual cables, headphones and power supplies. Additionally, I carry a smaller case with additional cabling for emergencies (Picture 11).

Picture 11: Two boxes contain all the gear. The big box contains controller and notebook, The small box additional cables for emergencies.
Picture 11: Two boxes contain all the gear. The big box contains controller and notebook, The small box additional cables for emergencies.

With this setup, I just open one box, attach that to a power point and connect the line out to the big mixer. Additionally, I carry a printout of my intended playlist, and a small flashlight. A pencil and some index cards or adhesive notes for music requests also come handy.

Some years ago, I was really late for a Milonga (normally, I try to be there 30 minutes before the Milonga starts). Ten minutes before start, I noticed, that the computer had deleted all my music databases. This is the worst case apart from a full crash of the computer. It took me 15 minutes to restore the databases from an internal backup so the Milonga started late.

Now what happens just in case of ? I personally always try to have a plan B in case my computer crashes. For big Milongas, this is a second notebook with software and collection mirrored on the harddisk. For smaller milongas, I have the music and a playlist on my tablet computer, which I use nowadays instead of the printout. If the computer crashes, I still can start that playlist as an admittedly bad (because there are no options for last minute changes and adjustments to the dancefloor) plan B.

Sincerely your Tango DJ,

-Ricardo (“el Alemán”)

 

P.S.: Next time we will look at the workflow of grabbing a Tango CD, tagging it and storing it into the music database.

 

 

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