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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: MIQ on July 01, 2015, 11:19:53 AM
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I saw this the other day and thought it was interesting. http://www.radialeng.com/decoder.php (http://www.radialeng.com/decoder.php) It has 3 mic/line pres and a Mid Side matrix circuit. Anyone seen or played with one yet?
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I just took a look at it. Physically it resembles the Healy box he made when he started doing M/S for the GD audience inputs. What you need next is for one of the electronics gurus to tell you which op Amp this box is using, that would be the best way to understand it's audio quality as compared to other electronics in your chain.
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I personally never decoded M/S in the field and point out that this one of it's stong points - i.e. you decode after the fact and can adjust the sound stage instead of being stuck with what you mixed in the field.
Maybe you could use it to run to a headphone amp if you want to hear what it sounds like but I would suggest mixing you recording after the fact.
Also I wouldn't suggest running two cards to represent a figure 8 as this product suggests - I think the results would be less than great.
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You would never be stuck with a decoded field mix as you can always re-encode and process as desired.
Sure but couldn't you just do this with any stereo recording and skip the M/S setup during record in the first point?
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Sure but couldn't you just do this with any stereo recording and skip the M/S setup during record in the first point?
Sure you can. This box works with mic input or line in so it could be used to capture MS with mics or process a stereo signal.
I like that it's analog and outside a computer with real knobs etc. I also realize I can do all the same stuff with a small mixer, but this box makes it pretty easy.
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H2, with any _coincident, two-microphone_ stereo recording you can sum the channels to derive an "M" signal and take their difference to derive an "S" signal, then equalize M and S separately if you want (I often boost the bass in the "S" channel), and recombine them in any desired proportion, and there shouldn't be much destructive interference between channels to speak of.
With spaced-microphone recordings you could derive "M" and "S" signals and then immediately recombine them 1:1, and you'd get your original L and R signals back. But I'm not sure what benefit that would give you, other than the satisfaction of knowing that you can do it. You don't have nearly as much freedom to process the "M" or "S" signals in that situation (although this approach has been used to reduce noise in fringe FM reception, since the "S" channel in that particular situation is generally the main source of audible noise).
--best regards
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With spaced-microphone recordings you could derive "M" and "S" signals and then immediately recombine them 1:1, and you'd get your original L and R signals back. But I'm not sure what benefit that would give you, other than the satisfaction of knowing that you can do it. You don't have nearly as much freedom to process the "M" or "S" signals in that situation (although this approach has been used to reduce noise in fringe FM reception, since the "S" channel in that particular situation is generally the main source of audible noise).
Hi David,
I'm not sure I understand why you would have "less freedom" MS processing stereo signals created by processes other than coincidently derived mic signals. One common application I can think of is directing more "Mid" signal to a center channel in systems with LCR front reproduction. It is not uncommon to direct more or only the information that is common to both L&R (ie. L+R) to the center channel.
There are many other applications for mastering the mid and side components of the mix differently. Certainly this box is targeted for folks that want to try MS processing in all sorts of ways and Radial is not the only company proposing this as a useful tool.
How useful/pleasing this technique really is may be a different conversation. The times I've played with MS processing studio derived stereo material, the results could be more than subtle. It is another tool that can be used to shape the sound, for "good" or bad" depending on your subjective evaluation.
The collapsing of FM to mono in poor reception areas is an interesting application and I've encountered this many times when traveling state to state in a car. Thanks for pointing it out. :)
Regards.
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MIQ, it's because when you combine the L and R signals from a spaced pair of microphones, you immediately get destructive interference because any sound source that was not equidistant from the two microphones will arrive at those microphones at different times, and thus for any given frequency, the phase of the wave at the moments of arrival will be unequal.
This causes "comb filtering"--a frequency response characteristic with wild deviations from one note to the next. It's the same reason that spaced-microphone stereo recordings don't make good mono when you sum the channels.
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Hi David
I did a poor job explaining my confusion. Of course you're right that combining spaced microphone signals will create comb filtering. This combing will create notches starting at lower and lower frequencies as the time difference between the mics signals increases. So the notches move in frequency as the angle of the sound source in front of the mics changes. The depth of these notches is dependent on the size of the two signals being combined, with equal signals being able to completely cancell eachother. So the worst case is the combination of spaced omnis' signals. With directional mics the levels will be different for signals arriving from directions not directly in front of the mics. The combing would be less severe for directional mics but clearly not a desireable thing.
But I was thinking about MS processing stereo music recorded using level panned close mic'd signals that have likely been processed with reverb. There is no issue with that. I guess studio derived signals are outside the normal discussion here but MS processing line level stereo signals is part of what this Radial box appears to be about.
Regards.