header image header image

Archive for the ‘Uncategorized’ Category

Interconnecting Multiple Sound Systems by Bruce Bartlett

Monday, November 18th, 2002

At concerts, you often see three audio systems in use: house PA, recording, and broadcast. Here are some tips on connecting those systems without creating ground loops and hum.

Consider using a single power distro system, and connect all three systems’ power cables to that distro. Make sure the distro can handle the total current requirements of the three systems.

If you hear hum or buzz when the systems are connected, first make sure that the signal source is clean. You might be hearing a broken snake shield or an unused bass guitar input.

If hum persists, experiment with flipping the ground-lift switches on the splitter and on the direct boxes. If there is no ground-lift switch, insert an adapter that lifts the cable shield at the input of the system you’re feeding. On some jobs you need to lift almost every ground. On others you need to tie all the grounds. The correct ground-lift setting can change from day to day due to a change in the lighting. Expect to do some trial and error adjustments.

Often, a radio station or video crew will take an audio feed from your mixing console. In this case, you can prevent a hum problem by using a console with transformer-isolated inputs and outputs. Or you can use a 1:1 audio isolation transformer between the console and the feeds. Some excellent isolation transformers are made by Jensen (phone (818) 374-5857, (www.jensen-transformers.com). Finally, try a distribution amp with several transformer-isolated feeds.

Bruce Bartlett is the Senior Microphone Design Engineer at Crown International.

Helping The Master by Nick Blagona

Monday, 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 s econds 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.

Recording Vocals Without Headphones by Doug McClement

Monday, 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 per cent, but improve the performance by 30 per cent, it’s a no-brainer. Always let the technology serve the art!

Doug McClement owns LiveWire Remote Recorders in Toronto.

Digital Reverb… by John Klepko

Monday, November 18th, 2002

Close-miked vocal tracks can often produce strange splatters of high-frequency noise when fed through a digital reverb algorithm. If your goal is a smooth and natural reverberation, then this effect can be distracting. This effect doesn’t really happen in natural reverberant environments like the concert halls and cathedrals that these algorithms are modelled after, unless you are feeding a close-miked vocal through a loud PA system in such an acoustical space. The problem lies in the “s” and “t” sibilant consonants that are aggravated into a type of high-frequency overload distortion by the microphone itself. The simple solution here is to insert a de-esser into the aux send signal path. This will suppress the sibilants that would over-excite the reverb.

In a recording situation, another solution is to place an additional microphone to the side or behind the singer, with the signal acting as a reverb feed only. The sound from these microphone positions will not have any sibilants.

Close-miked acoustic guitar signals can also play havoc with digital reverbs: they exaggerate the squeaks produced by the fret board hand movement. Here again, you could use a spare microphone (or two) placed behind the player as a reverb send signal. The sound, as picked up from behind, will be less detailed but fuller and rounder. This will provide a more indirect “average” feed to the reverb that will be void of those extraneous hand noises.

Another solution I have often used is to place a (cheap) transducer-pickup on the guitar. In this application the pickup signal again lacks the highs and squeaks present in a front placed main microphone. This smoother, more average sound is better suited as a reverb feed.

John Klepko is a sound engineer/producer and musician based in Montreal, PQ. He is currently in the final throes of his Ph.D. music degree (from McGill University) in the area of surround-sound. John also teaches courses in sound recording at McGill University and Concordia University.

Don’t Let The Software Push You Around! by David Green

Monday, November 18th, 2002

There are many well known postulates to Murphy’s Law, but none so thoroughly corroborated as ‘Interchangeable Parts Won’t’ in the wonderful world of digital audio. We are all aware of the attributes of DAW’s (Digital Audio Workstations) and the virtually (an interesting choice of word) exponential growth in their functionality, but what happens when you want to interface with someone or utilize a feature on a different platform? Welcome to the world of file exchange.

This has been a major problem particularly for those of us who regularly collaborate on projects and finally there is a light, actually several lights at the end of the tunnel. The voice that has caught the attention of the manufactures is H-TAC (Hollywood Technical Audio Committee). Their group has come up with a proposal for a universal rendered file format that they call ProWave. In addition, the AES (Audio Engineering Society) has formed a committee to develop a recommended standard that they are calling AES-31, and Microsoft (Microsoft) and Avid (Avid) are working together on a AAF (Advanced Authoring Format).

All of that is down the road apiece as the song goes, but in the short term TimeLine recently introduced TransAudio PipeLine, a Windows or NT-based utility program to provide file backup, export and TapeMode conversion. The initial release will read ProTools, Akai, WaveFrame, OMF/SDII, DEVA and Sonic Solutions. Export formats include WaveFrame, OMF/SDII and ProTools.

All TLA’s aside (Three Letter Acronyms), this is an area that is finally receiving the attention it requires. The ability to exchange file data will become increasingly important as our industry grows. If you’re considering upgrades or changes that involve digital audio, it would be worthwhile to check where each of these initiatives are, and/or ask the manufacturer some pointed questions on the subject.

David Green is Vice-President of Audio at Magnetic North, a Toronto post-production facility.

Using a DAW to Remix an Analog Multitrack Tape by Bruce Bartlett

Monday, November 18th, 2002

A rap group recently gave me a multitrack analog tape that they wanted to remix. On two tracks of the tape was a synthesizer playing a stereo mix of MIDI sequencer tracks. On three other tracks were the lead vocal and backup vocals. The group wanted to change the mix of the synth tracks and re-do the mix with the vocals. That was going to be difficult since the MIDI instruments were already mixed to two tracks.

I asked the group if they still had the original MIDI sequencer file. Fortunately, they did. We were able to remix the synth tracks after recording them one at a time onto a hard drive through a 2-channel sound card. The procedure went like this:

1. In the synth, turn on only the bass voice in the sequencer.
2. Record the bass onto one track of a digital audio workstation.
3. In the synth, turn on only the drum’s voice in the sequencer.
4. Record the drums onto another track of the workstation.
5. Repeat these steps for each voice or instrument in the sequence.
6. Copy the vocals, one track at a time, onto tracks in the workstation.
7. In the workstation, slide each track in time to align all the tracks.
8. Using the workstation’s mixing facility, remix the tracks.

Bruce Bartlett is the Senior Microphone Design Engineer at Crown International.

Contact

4056 Dorchester Rd., #202,Niagara Falls, ON
Canada L2E 6M9 Phone: 905-374-8878
FAX: 888-665-1307 mail@nor.com
Web Site Produced by NWC

"