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Sound Advice

5.1 Sound Treatment by Jeff Szymanski

November 18th, 2002

In response to growing questions about the acoustical treatment of 5.1 surround studios, I would like to offer some advice. I have seen quite a few advertisements and press photos showing the mix position of new 5.1 rooms. In many cases, the wall behind the front and centre speakers (the front wall of the studio), and in some cases the walls to the left and right of the mix position, are treated with a generous amount of acoustical diffusion. While I don’t argue that diffusion increases acoustical control without absorbing a lot of sound energy, I question the application in a room where proper imaging is crucial.

The most popular application for diffusion is in a control room built in the Live-End, Dead-End (LEDE) tradition. Here, a significant distance is desired between the listener and the rear wall of the studio significant enough to overcome the “Haas” effect. A stereo studio of this size may warrant diffusion, usually depending on the material being mixed. However, in the case of the 5.1 room, rear ambiance is no longer needed — that is what the rear channel is for!

It is crucial for a mix engineer, producer, client, etc. to be able to discern exactly what the true sound is for each channel. So why are we seeing applications of diffusion in the front of 5.1 rooms? How did we get from LEDE to LELE? Room influences are detrimental and undesirable in 5.1 environments. Ram Hidley, whose articles and wisdom with respect to studio design have been enjoyed by many over the years, has recently written several articles expressing the importance of room symmetry and absorptive treatments in 5.1 environments. Recently, I noticed a room originally designed with diffusion on the front wall, had absorptive panels placed over the diffusers by the mix engineer. The only explanation I can think of is that perhaps the architect, for aesthetic reasons, adds diffusion to the most visible part of the room.

I have no doubt that a 5.1 surround studio treated with acoustical diffusion is better than the same room with no treatment at all. However, it is more appropriate to approach the design of a 5.1 room with absorptive wall and ceiling treatments as well as bass trapping in mind. Early reflections from both the front and rear of the room (the mix position tends to be equidistant from all sound sources and hence all walls) should be heavily absorbed. The resulting high direct-to-reflected sound ratio provides the mix engineer with the precise aural information needed to make accurate artistic and technical decisions.

Jeff Szymanski is the Head Acoustical Engineer and Consultant for Auralex Acoustics, Inc. His design and consulting experience ranges from vocal booths to 4,000 seat auditoriums. Live-End, Dead-End and LEDE are trademarks of Chips Davis and G.E. Meeks.

Save It Before The Mix by Don Nicklin

November 18th, 2002

The key to getting a great sound on tape starts with the instrument that is being recorded. Before you even think about placing any mikes, it is very important that the instrument itself sounds good in the room. Begin by replacing old strings and drum heads, then take the time to check your tuning.

Once you have a signal coming through the board, instead of relying on equalization for the best sound, try experimenting with several microphones types and placements. The best way to do this is to have an assistant change microphone positions while you listen for a sweet spot. If, after all that, you feel that you absolutely must EQ, try removing the frequencies you don’t like rather than boosting everything else.

Don Nicklin is Assistant Director of the Recording Arts Program of Canada.

Recording Vocals Without Headphones by Doug McClement

November 18th, 2002

Sometimes you’ll find that a vocalist has a hard time monitoring bed tracks through headphones. Here’s a trick I use to overcome that problem.

I set up the vocal mic and put a pair of Auratones, or similar small monitors, about three feet on either side of the microphone; I use a tape measure to ensure that the they are equidistant. I place the speakers 90 degrees off axis and point them directly at the microphone.

I then feed the monitors from a mono cue mix buss, and flip the phase on one of them. Sometimes I roll off a bit of top and bottom as well. The vocalist will hear the speakers, due to the distance between his or her ears, but the speaker output will be 180 degrees out of phase at the mic capsule. Therefore, the bedtrack bleed, though not absolutely gone, will be down by about 30 dB.

Take care not to feed anything to the speakers that you don’t intend to use in the final mix, and don’t run them any louder than necessary for the vocalist to sing in tune and in time. A little bit of bleed won’t kill you. No one ever decided not to buy an album because there was a bit of instrumental bleed in the vocal mic! If you degrade the hi-fi quality by 5%, but improve the performance by 30%, it’s a no-brainer. Always let the technology serve the art!

Doug McClement owns LiveWire Remote Recorders in Toronto.

Don’t Take Chances With Your CD-Rs by Barry Lubotta

November 18th, 2002

Now that everyone is burning CD-Rs as masters, it might be a good time to review a few important steps to ensure they remain pristine all the way through the manufacturing process.

Even brand new CD-Rs fresh out of a jewel box often have a few particles of dust on them. It is a good idea to get rid of this dust before writing, and the best way is with a jumbo camera lens blower (without brush). Expect to pay about $8.00 in a photography store for this handheld round rubber device. You squeeze it quickly to release a stream of air which quickly removes any dust on the CD. You might not think a particle of dust would interfere with the laser writing a CD, but tests have proven that it can.

You also want to make sure that you handle your CD-Rs by the edges only, both prior to and after writing. Make sure that anyone who will listen to the CD-R adheres to this handling policy or else the result will be a smudged master.

Before a master CD-R leaves the premises, place a piece of tape over the jewel box cover so that it doesn’t accidentally open, causing the CD-R to fall out. If you plan to audition the CD before it goes off to the plant, make sure the tape has a piece folded over. This creats a small tab that can be used later for easy removal.

Place the jewel box in a plastic sandwich bag with a locking to protect it even more. At this point are you can be confident that you have done a professional from start to finish and that your CD is now ready for manufacturing.

A CD-R that is to be used for a master must be treated with the utmost respect if it is to provide optimum results at the manufacturing plant.

Barry Lubotta is the owner of Pizazzudio Recording Studio and Mastering Lab.

Miking by Bruce Bartlett

November 18th, 2002

Suppose you’re recording a singer/guitarist. There’s a mic on the singer and a mic on the acoustic guitar. When you monitor the mix, something’s wrong: the singer’s voice sounds hollow or filtered. What you’re hearing is the effect of phase interference.

In general, if two mics pick up the same sound source at different distances, and the signals are mixed to the same channel, this might cause phase cancellations. These are peaks and dips in the frequency response caused by some frequencies combining out of phase. The result is a coloured, filtered tone quality that sounds like mild flanging.

To prevent this problem, follow the 3-to-1 rule: The miking distance should be less than 1/3 the distance between mics. For example, if two mics are 12 inches apart, they should be less than four inches from their sound sources to prevent phase cancellations.

Bruce Bartlett is a mic engineer, audio journalist, and recording engineer. Bruce can be reached through Professional Sound at mail@nor.com

Helping The Master by Nick Blagona

November 18th, 2002

“Could you make this bigger, louder, heavier, tighter, brighter, polite, less polite, more blue, less green, etc.,” – these are the types of questions I’m asked on a daily basis in connection with mastering. And yes I can do it, with one fundamental catch: in most cases, the mixes I get sound better on analog.

Mixing to DAT is by far the cheapest way of making a decent record, particularly if you use the great converters on today’s market and 24-bit DAT machines. Always – and I can’t stress this enough – ID your mixes properly, highlighting the mix you want mastered. If you can’t be there in person, write/fax the engineer your thoughts about what needs to be done to any of the mixes, the order of the songs and desired space between the songs. Make sure to tell the Mastering Engineer which tools were used, such as the console, DAT recorder, the converter and so on.

Never send a compiled DAT of the album. I’ve had DATs sent to me that were maximized, ends being chopped off and a whole lot of other things that cause me to utter expletives. Always record at 44.1 kHz. All CDs are clocked at that frequency and changing from 48 to 44.1 kHz degrades the sound. And it’s always a good idea to make safeties of your DAT.

Record a 1 kHz tone for about 30 seconds at the top of tape, because that tells me about the left-right balance of the mixing console. What level should I record the tone at, you ask? If the peak average of your mix is, for example, 12 dB, you should record a tone of … 12 dB. This gives you 12 dB headroom above 0 dB from your mixing console before clipping. The difference between 0 dB analog and 0 dB digital is that, in analog recording, 0 dB is normal level and 0 dB digital is the max. That’s why analog is great. When you start hitting stuff above 0 dB the tape starts to saturate. Somehow the music has some “glue” to it. When passing through -12 dB with digital, you’re passing through air. Passing through 0 dB digital, you’re dead.

Nick Blagona is Chief Mastering Engineer at Metalworks Studios in Mississauga, ON.


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