Effectiveness of peak limiter on mixers?

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ProjectThangsombat

Member
I am new to audio and looking to purchase a field mixer. I am currently looking at the Shure M367 and the SD MixPre. My main concern is how each of these handle very loud car audio. Mic placement is typically under the hood and near the exhuast tip. The audio ends up getting distorted towards the higher RPMs (obviously).

Do ya'll think that either of these two mixers will be able to get rid of the distortion?
 
First of all, you need to determine exactly what is distorting.

It may be your mic, it may be your preamp (input or output stage), it may be your recording device. It may be all three.

You may want to use a high-SPL-spec dynamic mic to start with. Possibly with some built-in or inline pads if the sounds are really extreme.

Depending on your preamping device, you may or may not see indications of preamp input overload or limiting, or output overload and limiting. The MixPre, for example, has clear indicators of all these (and limiter activity); the typical video camera preamp stage does not provide this information explicitly. But if you hear distortion while the meters aren't indicating peaking levels, it's somewhere in the chain before the A/D converter... you can find ways to track it down.

If ever your recording device indicates peaks, you're getting at least some digital distortion. You should be able to attenuate the level into the recording device.

Relying on a limiter is not a plan "A", it's a plan "B" at best.

That said, I've been very impressed with the performance of the limiters in the SD mixers. The MixPre preamps are particularly easy to overload with a hot input, but the limiters do a great job of keeping the sound as nice as possible. Since you're recording engine sounds (rather than, say, classical music), it may be perfectly acceptable to you to let the limiter do some drastic work...
 
And the mic can clip either mechanically (diaphram bottoming out) or the mic electronics might clip. These thing could happen before any padding or limiting can be applied.

Just to clarify.
 
Dynamic mics tend to be the best choice for recording engine and exhaust sounds. Typically that shouldn't distort your inputs but it is always a good idea to have a couple of pads to cover yourself.

BTW, don't let the mic get too near the exhaust. I have gotten a couple comments about the diesel smell of one of my hand mics after placing in too close to exhaust. Ended up putting a "D" label on the mic to remind me not to use with people :)

Cheers
 
if you cant mount dynamics and like to use lavaliers try the dpa 4063 for high spl
lavaliers usially not dinamics but back electret mics which usially cant stand high spl ( dpa is abit exeption ) , there is quit allot of small condencers which can make ajob or small dynamics which could be hooked inside the engen chamber or neer the egsouse pipe with spesial mounts .
the inside of the engine compartment could work with pzms as well mounted over the emgin on the hood ( inside) , some can stand up to 140 db spl .
very nice could be use audix drum mics( small ones ) which are small enouth and could be placed almos every where .
keep in mind that for the outside viacle placement it better place foam and fur to prevent wind bumps . inside the engine there is no need for that .
by the way there is guy on that forum dave fisk which make quit allot of that stuff , you can email him and ask directly.

you will need to check that the maximum spl level and the output of the mics dont screw your preamp stage , if the sound to loud use pads , if it still to load use line ins and power the mics ( if they need power) from external device
sd 744/722 can suply phantom dirrectly on line inputs , so is the **** calls eng 44 mixer ( the problem it also have alwais working limmitters you dont want to use at all or at least use limmiter as high as possible befor total clipping .
for that kind of sfx i will not recomend any limitter tha have slow reliese time .
 
WE have used dynamics on the exhaust and a variety of mics under the hood. On most cars there is quite a bit of room under the hood so even a hand held dynamic will usually fit. One thing to watch out for is the ignition system. The spark plug wires have like 50,000 volts zipping through them and your mic can inductively pick that up if it's close and more often you will get this nasty clicky sound. If you have a second recorder or more tracks you should conceder putting a mic in the wheel well. It's a great boon to post if you can give them sync tire sounds.

THe Mix Pre's limiters have been great for FX work. We have them set as high as they go so it just protect against over loads. THe set up basically was to generate enough signal that the limiters were full on and then setting the recorder so we were just under clipping. Once you know where that is you can just mark it on the recorder. I also flipped on the tone and noted where it sits on the recorders meter. Most of the time it isn't an issue but when you know you could be surprised it's a nice safety net. When we did tests and just hammered the limiter it worked just as one would hope, smoothly crushed the top with out sounding overmodulated.
 
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