Archive for the ‘Q & A’ Category

I recently dealt with a client that was in need of a 12 channel mixer for use with hybrid live and recording situations. They were looking at either the Soundcraft M12 or the Allen & Heath MixWizard WZ3 12:2. I wasn’t sure what to tell them. I’ve used the 16 channel MixWizard and, as far as smaller format live mixers, I loved it. I’ve never used anything from the M series, but I do know Soundcraft makes solid (and great sounding) gear. So what do I suggest? I had to do a comparison for them, and why not share it with you?

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If you read yesterday’s post, you know that AASG has a new writer, Andrew Levine. He’ll be popping in from time to time with articles regarding recording and otherwise awesome audio stuff.

One of the questions we posed on the AASG Google Wave group was this: Would you, at any time in your production workflow, normalize your audio? The response to the question was good and definitely varied. Andrew decided to weigh in on the subject via this post, so read it and feel free to comment. If you comment with your email, I may just send you a Wave invite!

Regarding the question of when to normalize audio I’d like to put that in perspective with regards to my work-flow.

When I do the final down-mix of a project (mostly in the domain of classical music, jazz or avantgarde), with material at the final sample rate and a dither plug-in in the last slot of the master bus (to reduce to 16 bit for CD-A), I check the peak levels of the loudest passages to make sure they stay below -0.2 dBFS.

You need some headroom when you plan to possibly trans-code the audio, e.g. to an mp3, as peaks can crop up and you definitely don’t want to go above 0 dBFS.

If you plan on sending the file to someone for mastering, or if you are bouncing a file that is to be placed in a compilation of material from other projects, it is useful to preserve headroom in the range of 3 to 6 dB–without clipping the material! Bounce to 24 bit fixed or 32 bit float and don’t maximize levels before you know where this piece of music will fit in.

If I see that there are occasional (and few!) peaks that would either create overs or force me to lower the overall level there are two choices: manually and musically lower the level of the clipping passages (I’ll pick up the topic of “automated gain riding” in a followup) or insert a brick-wall limiter in the processing chain (before the dithering plug-in).

So, when do I personally normalize?

If I have a file that was rendered with some headroom and want to hand it on I normalize it (to -0.2 dBFS) before reducing the bit depth and transcoding it. If I want to send off a small group of similar files I’ll do the same, normalizing all audio to the same level, so that the recipient has an easier job. And that’s about it :-)

Question: How do I get the other outputs on Ultrabeat to work when using the Multichannel version of the plugin?

So Ultrabeat is a monster of a plugin, but there are a few simple tricks to using that save a lot of time and make the plugin really flexible for something that comes bundled with a DAW.

Setting up a multichannel version of Ultrabeat allows you to group your samples and play them out of ultrabeat into different aux tracks.  I chose to have kicks come out of the main track, snares out of another aux, toms a second aux and cymbals out of a third. Basically I can put different compressors and EQ’s on the kicks than I do on the snares.  Then I can tweak the hi-end of the cymbals and gate the toms – all on separate channels.  Pretty cool, right?  Check out the video!

The Question: I have heard that dithering is essential, when changing the sample rate of an audio file. Why?

The Short Answer: Dither is low-level (as in quiet) noise that gets added to a signal to aid in the conversion of “bit-depths.”  Basically you only NEED dither when you’re going from one bit-depth to another. For example you’ll want to include dither when going from 24-bit to 16-bit.

One important note: You do NOT need to add dither when only converting sample rates – like 48 kHz to 44.1kHz sample rate.

One important tip: You’ll get better results if you do sample rate conversions of mixes second-to-last and then bit-depth conversions last.

The Longer Answer: Dithering is a procress by which you can increases the theoretical potential dynamic range of an audio system.  A 16-bit file has potentially about 96dB of potential dynamic range (bit depth * 6). Through more math and physics than I want to get into (because it still confuses me at times) dithering can increase that potential dynamic range significantly – by making resolution clearer in the quieter range of sounds. It basically helps the reduce the distortion inherent in bit-depth reduction – think of the sounds you get when you put a bit-crusher on a track.

(I’ll try to add more to this later, but it’s going to take some delving into my old school notes and a bit of book reading.)

Blue Cat Audio released news today that they’ve added full 3D visualization to two of their plug-ins: FreqAnaylist and StereoScope Pro. This feature is offered as a free upgrade to those who already own the plug-ins and are registered.

Blue Cat is also offering a special promotion for the rest of August. Demos of the plug-ins are available in VST, Audio Unit, and DirectX from Blue Cat’s website.

Here’s a list of new features within the updated plug-ins:

- New 3D waterfall view to monitor the evolution of the spectrum or stereo field over time.
- Drag the rulers to move the curve when zoomed (can keep measurement/selection mode and still drag the curves).
- Output automation is now disabled by default.
- Updated documentation.
- Bug Fix (PC): Cubase freezes when loading a preset using a different skin while the plugin window is open.

So even if you’re not into the whole 3D thing, it looks like Blue Cat still gave you more than one reason to upgrade your plug-ins.

Now and for the rest of August, you can buy FreqAnaylist and StereoScope Pro for $75.65 from their online store. Registered Blue Cat Audio members will recieve an additional discount, as well.