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  • The official "How Recording Works" thread

    Check it out,
    weather you care or not, i feel complied to state that by trade, i am a professional recording engineer. I went to school(2 actually), have degrees, and have been working in this field approaching 10 years. I have worked in some of the biggest studios in the New York/NJ area.
    The starting of this new sub-forum is an excellent opportunity for people here who are interested to gather important and CORRECT information, and since it hasnt yet been done, i feel it should be in one thread.
    this is not going to be a thread about how to mic drums, or what interface/mixer/module to buy. This is going to be technical details in laymans terms, and important information regarding recording.

    Step 1. The signal chain:
    A "Signal Chain" is the path your audio follows, from sound source, to the recording device, and back out of your monitors[speakers to you civilians ]

    A typical complete signal chain might go something like this:

    1] instrument/sound source
    2] Microphone/Transducer/Pickup
    3] Cable
    4] Mic Preamp/DI Box
    5] Analog-to-Digital Converter
    6] Digital transmission medium[digital data get recoded for usb or FW transfer]
    7] Digital recording Device
    8] DSP and Digital summing/playback engine
    9] Digital-to-Analog Converter
    10] Analog output stage[line outputs and output gain/volume control]
    11] Monitors/Playback device[headphones/other transducers]

    Important Terms, Definitions, and explanations[this will be where the "core" information is]:

    1] AD Conversion: the process by which the electrical signal is "converted" to a stream of digital code[binary, 1 and 0]. This is accomplished, basically, by taking digital pictures of the audio...and this is known as the "sampling rate/frequency" The number of "pictures" determines the frequency. So the CD standard of 44.1k is 44,100 "pictures" per second of digital code that represents the electrical "wave" of audio.
    it should be noted that in order to reproduce a frequency accuratly, the sampling rate must be TWICE that of the desired frequency. So, a 44.1 digital audio device can, in fact, only record frequencies as high as 22.05khz, and in the real world, the actual upper frequency limit is lower, because the AD device employs a LOW-PASS filter to protect the circuitry from distortion and digital errors called "ALIASING."
    confused yet?

    2] DA conversion: the process by which the digital code[the code that represents the electrical "wave"] is transformed back into electrcal energy in the proper shape. In a oversimplified explanation, the code is measured and the output of the convertor reflects the value of the code by changing voltage.

    3] Cables: An often overlooked expense and tool, cables can in fact, make or break your recording. The multitudes of types of cable are determined by the connector, the gauge(thickness), shielding, type of conductor, etc...
    Just some bullet points on cables:

    -Always get the highest quality cabling you can afford. Low quality cables often employ shielding that doesnt efectively protect against AC hums(60 cycle hum), RF interference(causing your cable to act as a gigantic AM/CB radio antenna), or grounding noise introduced by other components in your system.

    -The way cables are coiled and treated can determine their lifespan and effectiveness. A kinked cable can mean a broken shield, again, causing noise problems.

    -the standard in the USA for wiring an XLR(standard microphone) cable is:
    PIN 1= Cold/-, PIN 2= Hot/+, PIN 3=Ground/shield.
    -pin 3 carries phantom power, so it is important that the shield of your cables be intact and in good condition if you want to use your mic cables without any problems.

    -Cables for LINE LEVEL and HI-Z(instrument level) gear are not the same!
    -Line Level Gear, weather professional or consumer, should generally be used with balanced cables(on a 1/4" connector, it will have 3 sections, known as TRS-or- TipRingSleeve)...a balanced 1/4" is essentially the same as a microphone cable, and in fact, most Professional gear with balanced line inputs and outputs will have XLR connectors instead of 1/4" connectors.

    -Hi-Z cable for instruments(guitars, basses, keyboards, or anything with a pickup) is UNBALANCED, and should be so. the introduction of a balanced cable can cause electricity to be sent backwards into a guitar and shock the guitar player. you dont want this to happen, especially on stage, where the voltage CAN BE LETHAL. When running a guitar/bass/keyboard "Direct" into your interface, soundcard, or recording device, you should ALWAYS use a "DIRECT BOX", which uses a transformer to isolate and balance the the signal. It also changes some electrical properties, resulting in a LINE LEVEL output.

    4] Digital Data Transmissions:
    this includes S/PDIF, AES/EBU, ADAT, MADI.
    im gonna give a brief overview of this stuff, since its unlikely that alot of you will ever really have to think about it.

    -SDPIF= Sony Phillips Digital Interface Format. using RCA or TOSLINK connectors, this is a digital protocol that carries 3 streams of information. Digital audio Left, Digital Audio Right, and CLOCK. SPDIF generally supports 48khz/20bit information, though some modern devices can support up to 24bits, and up to 88.2khz. SPDIF is the consumer format of AES/EBU

    -AES/EBU= Audio Engineering Society/European Breadcasters Union Digital protocol uses a special type of cable often terminated with XLR connectors to transmit 2 channels of Digital Audio. AES/EBU is found mostly on expensive professional digital gear.

    -ADAT= the Alesis Digital Audio Tape was introduced in 1991, and was the first casette based system capable of recording 8 channels of digital audio onto a single cartridge(a SUPER-VHS tape, same one used by high quality VCR's). Enough of the history, its not so important because we are talking about ADAT-LIGHTPIPE Protocol, which is a digital transmission protocol that uses fiberoptic cable and devices to send up to 8 channels of digital audio simultaneously and in sync. ADAT-Lightpipe supports up to 48khz sample rates.

    -MADI is something you will almost never encounter. It is a protocol that allows up to 64 channels of digital audio to be transmitted over a single cable that is terminated by BNC connectors. Im just telling you it exists so in case you ever encounter a digital snake that doesnt use Gigabit Ethernet, you will know whats going on.

    digital transmission specs:
    SPDIF -> clock->2Ch->RCA cable(consumer)
    MADI->no clock->64Ch->BNC{rare except in large scale pofessional apps}
    SDIF-II->no clock->24Ch->DSub{rare!}
    AES/EBU-13->no clock->24Ch->DSub

    and now everyones favorite topic:

    there are many types of microphones, and several names for each type.

    a] Dynamic Microphones utilize polarized magnets to convert acoustical energy into electrical energy.
    there are 2 types of dynamic microphones:
    -Moving Coil microphones are the most common type of microphone made. They are also durable, and capable of handling VERY HIGH SPL(sound pressure levels)

    -Ribbon microphones are rare except in professional recording studios. Ribbon microphones are also incredibly fragile. NEVER EVER USE PHANTOM POWER WITH A RIBBON MICROPHONE, IT WILL DIE. Sometimes it might even smoke or shoot out a few sparks.
    applying phantom power to a Ribbon Microphone will literally cause the ribbon, which is normally made from Aluminum, to MELT.
    Also, windblasts and plosives can rip the ribbon, so these microphones are not suitible for things like horns, woodwinds, vocals, kick drums, or anything that "pushes air."

    B] Condenser/Capacitor Microphones.
    -a condenser microphone uses an electrostatic charge to convert acoustical energy into electrical energy.
    -the movement of the diaphragm(often metal coated mylar) toward a ceramic "backplate" causes a fluctuation in the charge, which is then amplified inside the microphone and output as an electrical signal.
    -Condenser microphones use phantom power to charge the capacitors and backplate in order to maintain the electrostatic charge.

    there are several types of condenser microphones:
    1] Tube Condenser Microphones
    -Historically, this type of microphone has been used in studios since the 1940s, and has been refined and redesigned hundreds, if not thousands of times.
    -Some of the "best sounding" and most desired microphones EVER MADE are Tube Condenser microphones from the 50's and 60's. These vintage microphones, in good condition, with the original TUBES can sell for hundreds of thousands of dollars.
    -tube mics are known for sounding "full", "warm", and having a particular character, depending on the exact microphone. No 2 tubes mics, even of the same model, will sound the same. Similar, but not the same.
    -tube mics have their own power supplies, which are not interchangeable to different models. Each tube mic is a different design, and therefore, has different power requirements.

    2] FET Condenser microphones
    -FET stands for "Field Effect Transistor"
    -FET technology allowed condenser microphones to be miniturized. Take for example, the SHURE beta98s/d, which is a minicondenser microphone.
    -FET technology is generally more transparant than tube technology, but can sometimes sound "harsh" or "sterile"

    3] Electret Condenser Microphones
    -this is a condenser microphone that has a permanent charge, and therefore, does not require phantom power, however, the charge is not truly permanent, and these mics often use AA or 9V batteries, either inside the mic, or on a beltpack.

    Last edited by Butnutz; 09-30-2006, 11:21 AM.
    Official Recording Tip of the month for November:

    Sometimes, things just need to go to 11.

  • #2
    Sweet. Someone must sticky this.


    • #3
      I'm definitely going to be reading this. This is going to be a great thread, one that will have to be stickied.

      Originally posted by Tay
      I can now officially say you have one of the best Sessions on the Forum...


      • #4

        i updated the original post, more to come very soon.
        Official Recording Tip of the month for November:

        Sometimes, things just need to go to 11.


        • #5
          thanks alot

          forget my thread, this is the one to look at


          • #6
            Wow, that's a lot man!
            Pearl Reference Pure - Ivory Pearl


            • #7
              Thanks for the time to write this up.

              I'm sure it will benifit alot of people, as it has already helped me.


              • #8
                hey, thanks to all of you who gave me rep, ill return it shortly...i am going to type up some more stuff and condense alot of my notes into a more understandable format.

                Official Recording Tip of the month for November:

                Sometimes, things just need to go to 11.


                • #9
                  This is amazing, and thanks a ton for it...but to make it more readable and easier to follow, could you bold/italicize some things?

                  Originally posted by Tay
                  I can now officially say you have one of the best Sessions on the Forum...


                  • #10
                    Originally posted by SMX_Dizzy
                    This is amazing, and thanks a ton for it...but to make it more readable and easier to follow, could you bold/italicize some things?
                    yes, i am actually delaying the next update because i wanted to format it...i might type everything up and attch as .pdf documents or something, because i share your pain with reading long unformatted txt online.
                    thanks for the heads up, ill get on it ASAP!
                    Official Recording Tip of the month for November:

                    Sometimes, things just need to go to 11.


                    • #11

                      You could just refer them to the book: "Modern Recording Techniques 6"

                      Very huge informative book about ALL things recording. You and I should talk some. Your field is definitly my goal. PM me with some info about your usual work!!!
                      PDF Anti-Piracy Nazi

                      Support the artists.
                      Put this in your profile if you actually buy music.

                      PASIC Artist 2009: Middle Tennessee State University Drumline.


                      • #12
                        Originally posted by Drummer_Guy

                        You could just refer them to the book: "Modern Recording Techniques 6"

                        Very huge informative book about ALL things recording. You and I should talk some. Your field is definitly my goal. PM me with some info about your usual work!!!
                        eh, i could refer people, but that would defeat the point of having a thread, and probably only 1 in 10 would actually go out and buy the book anyway. besides, this is an excercise in being up-to-date for me, as it has been forcing me to do some research on the newest digital standards and products, which, as im sure you have been told or know, are constantly evolving...6 months out of date might as well be 6 years. ill PM you in the middle of a mix and this is is my 15 minute coffee, water, pee, and internet break[yes, all roughly at the same time.]
                        Official Recording Tip of the month for November:

                        Sometimes, things just need to go to 11.


                        • #13
                          Butnutz, if you are redoing this or updating it, submit a new thread and I will Sticky it..very informative material that everyone should read..thanks for taking the time to type that up..
                          I play with strings and sticks.


                          • #14
                            DSM, ill be updating it and adding additional information as soon as i have the time. ill let you know.
                            Official Recording Tip of the month for November:

                            Sometimes, things just need to go to 11.


                            • #15
                              Whats up folks, installment #2 with alot of information on microphones.

                              I know, its hard to read without formatting, but im seriously working on putting together a PDF package with diagrams, but it might take a long time, so for now, i suppose yall can make due.

                              Further Information About microphones that you should know:

                              1] Polar Patterns
                              -Microphones, as i am about to explain, are very sensitive to the sound in their environment. This is not to say that a microphone will transduce all sounds in a room, but a microphone will pick up sounds that are oriented properly to its capsule. This is known as “Axial Response”, and you will commonly hear microphones being referred to as “on axis” and “off axis (by ____ degrees)”.
                              It is im portant to understand that A/C [alternating current] electricity is measured in 360 degrees, very much like a circle in geometry. It should be noted that microphone statistics and charts will actually use a circle to notate what the shape of the microphones’ pickup will be. The shape is known as the POLAR PATTERN.
                              -Common Polar Patterns are:
                              a] Cardioid
                              -A roughly heart shaped pickup with excellent rear and side rejection.
                              b] Omnidirectional
                              -True “omni” pattern mics pick up all sound in a 360 degree field evenly.
                              -Omni pattern mics do not exhibit proximity effect.
                              c] Bi-Directional -OR- Figure-8 [same thing, different name]
                              -Bi-directional mics have a pickup that is shaped like the number 8, or the infinity sign. This pattern has null points at 90 and 270 degrees, almost exactly.
                              d] Other unidirectional patterns
                              -listed in order of least to most directional
                              e] Boundry Mics
                              -Boundary/PZM mics use a Hemispherical pattern.
                              -basically the response is a dome shape, with the plate on the bottom of the mic being the flat/floor, and the dome being oriented upwards. The size of the area of pickup can be altered by the shape and size of the floor or wall the mic is mounted on.
                              Other polar pattern information:
                              -Cardioid is the most common pattern.
                              -Some microphones will be switchable between polar patterns.
                              -Most Microphones come with specs that notate graphically the polar pattern, and show the frequency response characteristics along the 360 degree field boundry.
                              -the polar pattern of a mic can be temporarily altered by cupping the microphone around the head/capsule assembly. This is best exhibited by vocalists on stage cupping the head assembly of an sm58 or similar dynamic mic. This causes the mic to become near-omnidirectional in response, and generally causes the FOH engineer to lower the vocal to prevent a very very big problem: FEEDBACK.

                              Pads, Rolloffs, etc...
                              -Some mics have switches or rotating collars that notate certain things. Most commonly, high pass filters/lowcut filters, or attenuation pads.
                              -A HP/LC Filter does exactly what you might think: Removes low frequency content from the signal at a set frequency and slope.
                              Some microphones allow you to switch the rolloff frequency. Common rolloff frequencies are 75hz, 80hz, 100hz, 120hz, 125hz, and 250hz.

                              -A pad in this example is a switch that lowers the output of the microphone deirectly after the capsule to prevent overloading the input of a microphone preamplifier.
                              You might be asking: How is that possible?
                              to which i reply: Some microphones put out a VERY HIGH SIGNAL LEVEL, sometimes about line level(-10/+4dbu), mic level is generally accepted to start at -75dbu and continues increasing until it becomes line level in voltage. It should be noted that linel level signals are normally of a different impedance than mic level signals, which is determined by the gear.
                              an example for this would be: I mic the top of a snare drum with a large diaphragm condenser mic[solid state mic, not tube] that is capable of handling very high SPL[sound pressure level]. When the snare drum is played, the input of the micpre distorts, even with the gain turned all the way down. To combat this, i would use a pad with enough attenuation to defeat the distortion. In general, it is accepted to use a pad with only as much attentuation as you need, plus a small margin of error for extra “headroom”. What this means is that if you use a 20db pad where you only need a 10db pad, you will then have to add an additional 10db of gain to achieve a desireable signal level. This can cause problems, as not all pads sound good, or even transparent, and can color and affect your signal in sometimes unwanted ways that are best left unamplified.

                              Other mic info:
                              -when recording vocals, you should always use a popfilter.
                              -a pop filter mounted on a gooseneck is generally more effective than a windscreen made of foam that slips over the microphone.
                              the foam type often kill the highfrequency response, alter the polar pattern, and can introduce non-linear polarity problems(part of the frequency spectrum will be out of phase.)

                              Terms Related to mics, mic technique, and other important things you should know:

                              1] Plosives: “B”, “D”, “F”, “G”, “J”, “P”, “T” hard consonants and other vocal sounds that cause windblasts. These are responsible for a low frequency pop that can severly distort the diaphragm of the microphone, or cause a strange inconsistency of tonality by causing a short term proximity effect.

                              2] Proximity effect: An exponential increase in low frequency response causes by having a microphone excessivly close to a sound. The force of the air moving actually causes the microphone’s diaphragm to move and sometimes distort, usually on vocalists.
                              Microphones in a true OMNIDIRECTIONAL pattern do not exhibit proximity effect, and cardioid microphones exhibit the most pronounced proximity effect.
                              With some practice, you can use proximity effect to your advantage, or as an effect. For example, if you are recording someone whispering, and it sounds thin, weak, and irritating due to the intenese high mid and high frequency content, get the person very close to a cardioid microphone with two popfilters, back to back...approx 1/2”-1” away from the mic and set your gain carefully, and you can achieve a very intimite recording of whispering.
                              In a different scenario, you can place a mic inside of a kick drum between 1”-3” away from the inner shell, angled up and at the point of impact, and towards the floor tom. this captures[usually] a huge low end, and the sympathetic vibration of the floor tom on the kick drum hits, but retains a clarity of attack without: a] being distorted by the SPL of the drum, -and- b] capturing unplesant low-mid resonation of the kick drum head and shell that is common directly in the middle of the shell.
                              Official Recording Tip of the month for November:

                              Sometimes, things just need to go to 11.