Dynamics pick up less room than condensers? True or Not?

Discussion in 'Microphones (live or studio)' started by paulears, Aug 13, 2019.

  1. paulears

    paulears Well-Known Member

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    We're having lots of comments that seem to be stating an almost 'rule' that if you have noises in your recording space that you don't want in the recording, then you go dynamic, and not condensers - and it's been said in many topics that this is an established fact.

    I personally don't happen to agree with this, and I've spent some time trying to find examples of the science from respected sources, and I've failed. Loads of unsubstantiated comment, but no facts from any of the popular manufacturers, apart from the obvious ones.

    Things I found mentioned that support the theory are that the mass and size of dynamic mic diaphragms prevent them responding to short high frequency transients. Low frequencies, with more substance, do produce output. HF sources far less so. Handheld mics, which represent far more dynamics than condensers have the body in the path from the rear, which is the quietest direction of their polar pattern too.

    These features are the ones that do mean dynamics can capture less background noise. Condensers, especially side fire ones, have the body out of the way.

    I'm hoping somebody can produce something tangible to support the notion that dynamics are better at reducing noise. It could be true, but what is the physics? What is it that started the 'rule' so often mentioned.

    I cannot find anything of any substance to support it or shoot it down. I'm just one of those people who cannot promote a techniques as solid until it's explained, detailed and corroborated. I cannot just accept it without proof. If we're saying condensers respond better to the noise, then they also respond better to the wanted signal and all we're left with is wanted signal to noise nuisance ratio.

    Fell free to shout the physics that we can then research and digest, but opinion needs a solid foundation, and I can't find this bit!
     
  2. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    Here's a look at the spec sheets for an akg 414xls, and shure sm57. Two standout specs for me are the frequency response, and sensitivity, which both support the commonly experienced case where a condenser is more sensitive to room sounds, noises (hiss & rumbles), and effective at capturing sound from a distance (room mics, overheads, choirs, ect).

    Couple that with lower self noise, and a condenser is less likely to mask room sound and external hiss.

    Also a consideration is that off axis rejection is not perfectly uniform, it is frequency dependent, so a more sensitive, full range mic can be more likely to pick undesirable hiss and rumble. These specs can be found in the mics manual usually, and vary per model.

    Screenshot_2019-08-13-15-54-01.png


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  3. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    Both mics exibit sensitivity some at 125hz from the rear with the cardiod pattern. Its also relavant how the sm57 rolls off 12db from 2k to 40hz.

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    414xls pickup pattern frequency response.

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    Sm57-

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  4. paulears

    paulears Well-Known Member

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    So the microphone with the poorer frequency response wins Bec cause it isn't so good? If so, we could simply replicate the roll off top and bottom with Eq and remove the hiss at the top and the rumble at the bottom. If the mic is not sensitive and receptive to certain sounds then surely it's just an example of a less good mic?

    This is the problem - what appears to make the mic great for reducing room sound makes the microphone less transparent and compromised.

    We 'think' dynamics are better at reducing noise, because they do so naturally by being a less accurate mic. I can't subscribe to that. I'm very comfy with the concept that a condenser reveals room noises, but that surely is because they are better - and shelving off the bottom end removes rumble and air con noise. EQ seems to do this too?
     
  5. Kurt Foster

    Kurt Foster Distinguished Member

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    i can only speak to anecdotal observation. a U87 will pick up more ambiance in a room than an SM 57 on the same source and placed in the same proximity and gain matched. try it.
     
  6. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    These statements are subjectively judgemental "condenser mics reveal room noises because they are better" "if a mic is not receptive to certain sounds then surely its a sign of a mic being less good". These are not only off, they are only relevant circumstantially. I also missed the physics and supporting data...

    If a condenser is better at picking up unwanted room noises, what good is that? Its about the right tool for the job.

    Its important to take into account the logarithmic nature of the db scale, and the sensitivity. If a mic is 6db less sensitive to 500hz from the rear than another, thats a big difference especially as you move further away like from a window or ac.

    Besides the frequency response its the sensitivity.

    Its also the higher self noise which can mask hiss and rumble.

    So yeah, id say at matched recording levels, a mic that is 12db lower at 40hz and 15-20khz, is gonna pickup less rumble and hiss than a flat mic, even with identical noise, sensitivity, impedence ect. Now add in a huge difference in sensitivity, and the effect gets further exaggerated.

    Part of what makes classic peices of gear desireable or good, is their technical defficincies.

    There is nothing about the data that would indicate the 414 is better at rejecting room noises. If that's the goal, the dynamic wins. If the subtle nuances of a delicat vocal performance, strings, or a nice clear far mic is what the job calls for, then the 414 would excel.

    In all my experiences with dozens of mics of primarily condenser and dynamic, from nady to senny 441, from at3035 to akg c12, the dynamics always pickup less ambience.

    If your experiences differ, a demonstration, data, or logical/physics based statement would seem to be necessary, as it seems contrary to most others experience, and what the data sheets would imply (at least to my non electrical engineering self). You asked for data, then denied it. The technical data and performance of the shure 57 show its less prone to picking up ambient noise.
     
  7. paulears

    paulears Well-Known Member

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    The dynamic reduces room noise because it’s a worse mic - seems to be a poor reason to use it. If we restrict the Condenser’s frequency response to make it behave the same, is this better? If it’s also the dynamics ability to respond to weak sound pressure for momentum and physical reasons then those deficiencies also MUST have an impact on the mics ability to be truthful?

    I can hear the condensers picking up room noise dynamics don’t but my question is why none of the respected sources, like DPA for example list lots of differences but not this one. Seems odd. Is eq on a condenser the same thing, or not?
     
  8. Makzimia

    Makzimia The Minstrel Well-Known Member

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    As someone who, among august company, used a SM58 live, I can attest to its superior use in at the very least live setting due to lack of clear pickup outside a small area of its cartridge. This was a more original version of course.

    Current mics I use in the studio are certainly better for my purposes of picking up the more subtle nuisances required in recording. It’s why it behooves us to create a good recording environment if possible. Anything else is doctoring after the fact. Possible but less than perfectly desirable to the perfectionist of our trade/pass times.

    As I have pointed out before though, if your noise issue is low but noticeable with absence of the performance, simply gate it out ( if mic related) and adjust performance to always be above that threshold. Only an issue then with very low performance volumes.

    That’s my .02 for what it’s worth :).

    Tony
     
  9. miyaru

    miyaru Active Member

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    I hardly use dynamic mics, mostly Large Membrane Condensers, and take a little noise for what it is. The overall feeling of open sound a LDC brings is not replacable with a dynamic mic. That said for rejecting noise during my weekly broadcast on the local radio station, I always use a Shure SM7B........ Would that one get use in the studio for recording instruments or vocals: no!!!

    Use whatever you feel good about, it's the joy, not the toy in the end. Mic's are tools, and one should use the best fitted. I even record my wet bass signal with a LDC, and also my Fender amp for guitar. I have a SM 57, but use that mainly if I have to sing (Backing Vocals) in a band setup and live.

    But then again some guys get wonderful results using dynamics, so no big deal use whatever you like!!!!!
     
  10. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    I think there is something else to it. I don't like to assume only by going through specs.
    Is it possible that the beaviour of the capsules react differently to the sound waves ?
    Or is there a difference for capsules with open backs and filed ones..

    The real test would be to measure how much the signal force go down when moving the source away from both types of mic and see if the dynamic mic drop faster..
    This is something I could do. If both mics loose 10db per feet, they should be consider equal.

    I'm curious to read what @Boswell has to say about this !
     
  11. Kurt Foster

    Kurt Foster Distinguished Member

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    therein lies a nugget. the best way to choose the worst sounding piece of gear is to make your decision by the spec sheet. i've seen lots of stuff that had great specs but still sounded like ass.

    sometimes you might not want to capture everything. who needs a 20 to 20k response to record a vocal? no human voice has any information anywhere near 20k, so what's the point? well, to capture all the detail and ambience in a concert hall or well designed room. but often in a crowded studio setting or perhaps in a small venue there isn't all that wonderful detail and ambience to capture. instead what's usually there is muck, sludge and cacophony. that's why gawd made dynamic and ribbon mics (it would be egregious not to mention ribbon mics. that's another whole ball of wax).

    the one thing to know is dynamics, ribbons and capacitor mics all function in a different manner. it stands to reason they would display different characteristics.

    it's all about choosing the right tool for the job. the only way to learn this skill is trial by error.
     
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  12. dvdhawk

    dvdhawk Well-Known Member

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    Like Kurt said, choose the right tool for the job.
    Apples and oranges... different flavors. Both good, unless you're trying to make lemonade.

    Some things (me, for instance) will look a lot more presentable photographed in soft focus than they will in razor sharp high resolution. In softer focus it's still definitely me, but many of the imperfections are glossed over. In my case, there would be such a thing as too much fine detail.

    A lot of novices seem to assume an LDC is the only way to get professional results and that's simply not true. For one thing, there are some nasty sounding LDC mics out there (that probably fabricated some lovely spec sheets) that look really nice. There are also some silky smooth, highly-detailed dynamics out that are stunningly good. And for another thing, that assumption is often based on staged photographs and videos that chose the exotic looking LDC mic for it's visual appeal for the photo, even when they used a less glamorous dynamic to cut the actual tracks.

    I think the mic discussion here is about sensitivity. Generally speaking, dynamic mics are less sensitive than condenser mics, and that's not necessarily a bad thing. Dynamics use a thicker, more robust material for their diaphragm. They cannot react quickly enough to capture fine detail. They tradeoff an acceptable level of detailed response for durability. The Shure SM57 and 58 have been a defacto standard on stage and in studio for a long time. Nobody said they're laboratory accurate, they're just familiar sounding and crazy durable. However, if you've ever taken an SM57/58 through a high-end preamp and given it a ton of clean gain you know how much that opens up a garden-variety dynamic mic. But again, now you're hearing more of the room and its reflections, and the neighbor's dog, and traffic outside... If you want more detail, subtlety, nuance an SM57/58 may not be your best bet. If you get a good LDC it can certainly expose a lot more detail in the performance (good and bad) - along with the boundaries of the space you're recording in. There is often a tipping point where too much sensitivity / detail can have unintended consequences in home recording. It is a game of signal to noise ratio. How will I capture the purest version of the source - without excessive background noise? If dynamic mics strongly favor the voice directly in front of them over reflections from the boundaries of the room, use that to your advantage when you don't have a room with great acoustics. If you're in a small room and want to use an LDC for more nuance, luckily there are ways to mitigate those unwanted boxy / phasey room reflections.

    Again, everyone should use the right tool for the job. I'm sure if they were desperate, someone could cut down a small tree with a scalpel or remove your gall bladder with an axe.
     
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  13. paulears

    paulears Well-Known Member

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    This is the interesting stuff - the how and why of the topic. I think we all have discovered the differences, but nobody on the net or in any of the books I still have seems to discuss it. We're comfy with pressure operation and pressure gradient, but is there some other mechanism at play here that we don't understand. We know the result is fact, but how the heck does it work!
     
  14. dvdhawk

    dvdhawk Well-Known Member

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    How quickly, accurately, and efficiently does any mic convert those fluctuations in air pressure into (milli)voltage?

    Neumann: What is Sensitivity?

    Earthworks Impulse Response
     
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  15. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    The title of the thread is "dynamics pick up less room noise, true or not?"

    So with respect to rejecting room noise it is the "better" mic. Wether or not its ideal for micing the source is up to the ears. Its part of the endless series of compromise we have to make.
     
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  16. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    Yeah, everyday I compromise not having Focal monitors, a few Millennia channel strip, a Manley slam and a series of grace audio preamps !! ;) ha ha ha !!
     
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