John Sayers' Recording Studio Design Forum

Hi, I've just started building a small home studio with pretty decent equipment. I'm using a Eurorack UB-2442 12 Channel Mixer running through an iMic into an Apple G4 iBook running Pro Tools 5.0 in OS 9.2.2.

I'm monitoring sound after it's been recorded with 2x 7" Speakers through an amplifier, where the humming is only slightly heard. However when listening to the recording in iTunes or from a CD the hum is much more evident.

When recording, I'm only using a standard vocal mic approx. 10-20 cm from the Guitar amplifier's (60 watt) speaker at just above half volume. There is very little EQ being used on the mixer but that doesn't stop the humming. The Guitar amplifier itself has been readjusted many times (ie. Reducing Bass, Volume, Presence, Mids etc) and the hum persists. I'm looking for a cheap way of solving this problem, or the expensive way if it's the only way.

The other problem is recording with the sound being input a split second after it's heard causing a delay and timing errors which must then be corrected manually. When recording over the top of multiple tracks I must mute the tracks being recorded in order to keep time. Remember I'm using Mac OS 9.2.2 for all of this because OS X brings me an error when using Pro Tools LE 6.0 saying the timing is out and I should reset my clock settings.

If anyone can help me solve any or all of these issues, it would be greatly appreciated.

turn your monitor off, i'll bet that'll drop 90% of your hum right there.

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SaM Harrison
Location Engineers
Nashville, TN

I actually don't think that will make much difference since he is using an Ibook which has an LCD screen.

The only way to cure hum is to first understand it's source. More than likely it's 60 cycle hum. Unfortunately, there are too many sources to guess. Flourescent lights and neon lights are both big culprets. Poor grounding in cables and on outlets is another. Failed filter caps in power supplies. I would start with turning off anything electric that is not needed for the recording. If the hum persists, then start turning off (and disconnecting) what's left until the hum is gone. Then fix whatever caused the hum.

As far as the "delay" you describe is concerned, it's called latency and is, unfortunately a by product of computer recording. It simply takes time for the computer to take the data off of the hard drive, convert it to audio, then send it out through the speakers. I'm assuming you are using Protools Free because you don't mention any digidesign hardware.

You can reduce the latency to a manageable time (milliseconds) during recording by lowering the hardware buffer size as low as possible. (Settings>Hardware>H/W Buffer Size) Also disable ALL plugins during recording. (on PC you can hold <CTRL> and right mouse click on the plug in to disable it. You will need to increase the buffer size when you are finished tracking and start mixing.

On Digi001 and Digi002 systems there is a menu selection under the operations menu for Low Latency monitoring which effectively disables the plug in-s for you.

...db

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"It's all about the music"