Showing posts with label Audio. Show all posts
Showing posts with label Audio. Show all posts

Monday, October 3, 2016

Carnatic Music - Additional Audio Pointers

BHADRAM KARNEBHIH SHRUNUYAAMA DEVAAH !
Oh Gods, May we hear only good thrings with our ears !

Here are some fine points to attend to that will bring you closer to being a real professional:

1. The audio person cannot set the audio once and walk away.  Our concerts are long, and musicians inevitably move or shift their positions.   You need to be watchful and compensate for that.   I am not even talking about major impairments such as the ones to follow.  Sometimes, the violinist turns around resulting in a big hum from his/her mic picking up the monitor speaker.  Someone needs to be there to take care of these exigencies instantly.  During solo, the volume has to be slightly increased for the involved channel; it is true that two musicians together sound twice louder (due to the way signals behave in an additive manner and vice versa.)  This is where people who know nothing about our music and cannot anticipate various distinct parts of the performance do terribly at the board. Be warned, however, that constant meddling with the system can also become disconcerting too, both to the musicians and to the audience.

2. No one appears to use the pan controls properly.  Used properly, in a vocal concert, we should be hearing the violin more from one side and the mrdangam from another.  Perfect stereo sound cannot be obtained in the auditorium as in a studio where musicians sit in separate booths and there is no leakage from one source to another's mic, but one can come close to it with a proper selection of microphones,  the use of pan control, and running the volume at a reasonable level.   Not setting the volume too high (especially on the monitors) is necessary to minimize leakage of sound from one end to the mic at the other end either as echo from the hall or from the monitors.  [Musicians from India especially are used to very high volumes and ask for it, often  affecting negatively the enjoyment of the audience.  My advice to them: if you are serious about your music and sound quality, please take a course on audio.]

3. Sruti: Some musicians keep the electronic sruti box so loud as to drown everything else.  This is very annoying and is something that all musicians should pay attention to when they are performing on stage.  It also makes it hard to discern problems and to make corrections.

4. Microphones:  (a) It is important to pick high quality microphones appropriate for vocal and/or for the specific instrument.  Shure 58 is the minimum, yes the minimum, quality to shoot for.  Try to pick mics in such a way that their response curves do not tail off in the frequency range of whatever frequency range you are trying to capture and remains pretty flat in that range with high fidelity; this is particularly important for violin and the left side of mrdangam.  (b) Be wary of powered microphones.  The slightest movement of the musician towards or away from the mic becomes highly noticeable, with the former making a vocalist look like he/she is shouting.  These may be great for studio recording in a controlled environment with one song at a time, but it is unrealistic to expect musicians to maintain a constant distance throughout a 2.5 to 3 hour concert.  Note also that the closer the vocalist gets to the mic, there will be increased bass in the voice.  With powered mics, if their lip touches the mic or if the violinist's bow touches the powered mic, God help you!  (c) I personally hate the cheap contact microphones that many Indian instrumentalists use; these days, some leading artists do use good mics, but the audio people have not learned to deal with them.  The cheap mics and/or poor audio settings distort sound, and I bet have very bad response curves.  Once the source is bad, there is little the person at the mixer board can do, especially if the channel gets overloaded and clipping occurs.  Musicians who insist on using contact mics should purchase one from a good store with the help of someone with a high level of expertise and after testing in the store with several of them.  (It is customary for professionals in most professions to invest in equipment for one's own trade!)

5. When you have a duet like of various famous sisters, please equalize so that they sound reasonably as one voice when they sing together.  Same for violin duets etc.

6. Speakers: The high frequency cone (which is the uppermost in the speaker) should be above the head of the audience close to the speaker.  Otherwise, they get a headache from the higher frequency sounds.  This is often forgotten by many who do audio.   When the hall is long and deep, it is often a bad idea to blast from just 2 speakers in the front.  Have 2 additional speakers somewhere half way, but run the volume low and just enough so that those farthest from one pair of speakers don't hear two distinct versions of the same music.  Turn the speakers so that they are centered towards the center of the half portion at the back of the hall (or the last row) you want to serve with them.

7. Recording: Remember that a lot of things can be fixed later but not the overload resulting in frequency clipping.  [When you exceed the maximum level, your system just sets things to the highest level and you lose information totally].  So make sure your gain and volume levels do not overload the channel.  When preparing a recording, please do not shut off the sruti between pieces and let it sound like a continuous concert, and also avoid abrupt starts (what technically is called 'attack') etc. and consider using fade in and fade out if necessary.  Set the recording level at about -6dB (and not at 0dB as most Indian technicians do) to avoid overload.
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The author Dr. V. Ramaswami is a former President and Secretary of CMANA (Carnatic Music Association of North America).  As a volunteer, he has managed the audio for CMANA and some other non-profits for many years.  As a researcher in the citadels of technology - Bell Labs, Bellcore, AT&T - he has also had the privilege of learning many technical aspects of audio and video from experts and sometimes the very inventors.  He himself holds several patents related to video distribution over the Internet and related communication technologies.

Friday, September 30, 2016

Carnatic Music - Audio Engineering Basics

BHADRAM KARNEBHIH SHRUNUYAAMA DEVAAH !
Oh Gods, May we hear only the good !

NOTE:  The goal of this post is to give some general pointers to those managing audio in Carnatic music or Bharatanatyam programs and written for a non-mathematical, non-technical person.  All too often, the enjoyment of a program is really affected by audio problems. Hopefully, these comments will be helpful to some.  I have kept things at an elementary level and avoided jargon as much as one can.  I have to be cryptic to save on space.

1. Frequencies are measured in Hertz.  Also kH stands for kilo Hertz or 1000 Hertz, ie one thousand cycles of the signal wave per second.  Sharper, squeaky sounds are in the higher frequency range. Thus, for example, Balamularali Krishna's voice may traverse a frequency range that is lower than the one traversed by Musiri Subramanya Iyer (or a female vocalist like MS).  The Hz level changes continuously as the singer "goes up or down."    Understand the frequency ranges of voice and various Carnatic instruments.  This is important in setting the equalizer. [Male voice: 100Hz - 1800 Hz; Female voice: 150Hz-2500Hz; Violin: 350Hz - 4000 Hz; mrdangam: 100Hz-2000Hz; these are approximate].  Just to understand how these numbers relate to what you hear consider these: if you push up the higher frequencies, a male voice will start sounding like that of a female and a female voice will become very squeaky,  violin will become unbearably high pitched and squeaky, mrdangam right will start sounding metallic.  Push up the lower frequencies and you distort sound again - some examples: voice and mrdangam right (sollu) will become less clear; violin will boom in lower octaves; left side mrdangam will boom drowning most others.  Got it?  This also gives you a hint on what to change if you see these types of problems.  Play around with your home equalizer if you have one and if not with the treble (high frequency) and bass (low frequency) knobs.  Best is to try doing the experiment with only audio portions where only one musician is performing.   [Unfortunately, many systems today like Bose don't let you do anything; trust me, they provide less optimal sound than what someone who knows, even moderately, what to do with manual controls.  It is just like using your camera in Auto versus Manual. Rarely will a professional put the camera in the auto mode unless they know they won't have the time to compose their pictures!].

2. In terms of equalization thus for a male vocalist, I may set the equalizer with the frequency  around 1200 or so high and tapering down to the sides; for a violin may be centered around 2000 Hz; etc.
Make sure successive frequency knobs form a reasonably continuous curve. [The modern day digital mixers are a challenge to most technicians since it is much harder to get a smooth curve without a lot of experience and a larger screen to work with.  I still prefer analog mixers for this reason.] Since you are not doing some fancy stuff with a separate equalizer for each instrument or musician, use the main person as your guide for this.  Things may have to be changed later depending on the auditorium, the size of the crowd (that alters sound characteristics ), etc. for which your ears are your best guide.  There is no one single set of numbers that work always.  So, treat these as starting points.
After setting the equalizer thus, adjust individual instruments or channels with the frequency knobs low, mid, high on your console which cover different frequency ranges.

3. Volume and Gain: One big cause of problems is setting the gain high.  Without getting technical, think of gain as the input volume level.  If gain is set high, a small movement towards the mic by the musician can amplify things very much.  Such abrupt moves will make them sound like they are shouting or screaming.  (Hear those awful squeaks in the auditorium? Most of these are due to high gain settings.)  A common mistake I see with most audio people in Indian programs, including so-called professionals, is that they treat the gain control as the main tool for increasing or lowering volume.  That is really asking for trouble.  Golden Rule 1: Try to make do with the minimum possible level of gain to avoid squeaks and overloads of your system.  How do you find it?  Here is a simple trick.  Set the volume control at 0 (i.e., at center), let the person play or sing and increase gain just to the level that is comfortable.  From then on change using only the volume knob!  Volume knob is what controls the output level.  Golden Rule 2: Move the knobs gently and in a continuous motion at a very slow rate; especially so with gain.

4.  If you hear the violin or the left side of the mrdangam booming, reduce the lower frequencies.  Some violinists and vocalists will ask for more "base" without realizing a little bit what it can do to how they sound.  Make them play the lower octaves and use that as a guide.   Pay attention to the right side of the mrdangam; is the sollu clear?  if not ,you don't have enough treble (higher frequencies) for that; does it sound too metallic (then you have too much treble or are using high frequency ranges too much).

5. Never work without a stage monitor.  Make sure you can increase or decrease the volume on the stage monitor without affecting the way things sound in the hall.  Don't run the stage monitor too high.  Then amplified sound enters the mic, gets amplified again, and this process repeats God knows how many times since things travel at speed of light, overloads your channel, and you get a terrible squeak; in the worst case, it blows your equipment (yes, I have seen that happen too!)

6. Unless you have undergone some serious professional training, stay away from things (especially done manually) like Effects (Reverb) which some musicians will ask for although they have no clue whatsoever what it means or how it affects sound.  [You may be able to get away with the automatic setting of Vocal-SmallHall or Vocal-LargeHall for most Carnatic programs giving good reverb but beware of hall reflection properties of sound.  If it feels like you are hearing multiple versions of the same sound, don't use it!]  Smile, nod your head, do what you have to do.  In my long years, the only musician I consider as knowing anything about sound engineering is Sangeethasagara Balamuralikrishna.  How I wish a day comes when no one is allowed to ascend the stage without some minimum training on using the mic and the essentials of audio!

Also, when it comes to recording, please set the peak level at about -6dB.  One common error I see especially from India is to set it at 0dB resulting in frequency clipping.

Some other golden rules: #3 Go  and listen from various places in the auditorium and readjust. #4 Dont respond to each and everyone who comes to you and asks you to change this or that.  #5 Have some trusted people (like those who you know can make a good judgment about sound quality) who can tell you. #6 Don't set up and walk away for good.  Unexpected exigencies do occur.  #7 Don't get too cocky; there is a heck of a lot to learn, and at any stage, what we know is a very small part of what is out there to learn.
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The author, Dr. V. Ramaswami, also wrote the books 'Innovation by India for India, the Need and the Challenge' as also 'Bhaja Govindam - A Topical Exposition'  besides writing and editing several books in his fields Applied Probability & Telecommunications.  He is a former President & Secretary of CMANA, the Carnatic Music Association of North America under whose Presidency its Sangeethasagara award was instituted.  He has penned over 40 compositions in Carnatic music.  A probabilist by profession, he has been a serial inventor with many patents, and among his positions was one as Chief Scientist at Bellcore.  He has published over 75 scientific articles and written and/or edited several books.  He was named a Distinguished Science Alumnus by Purdue University, an honor given to a very small percentage of its graduates.
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Some additional comments related to audio in  future posts.  Your comments are most welcome. Please post them here and only here if they relate to question, additional technical matters etc.  Kudos and criticisms you can place wherever you choose.  If you have not seen the page for my book, kindly visit http://www.innovationbyindiaforindia.com
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NOTE ADDED AFTER SOME SEQUELS TO THIS BLOG:
You may also wish to read
https://veeraam.blogspot.com/2016/10/carnatic-music-additional-audio-pointers.html

and
http://veeraam.blogspot.com/2017/04/audio-basics-for-carnatic-musicians.html