Okay, here's my question that goes down to the nitty-gritty: I've heard it said several times that mics have different frequency responses that "color the sound". If all it is is just boosts/cuts in certain frequencies, couldn't you (theoretically) achieve pretty much the same result if you were to use a mic (same kind/similar model.... lets say they are both dynamic cardoid) with a flatter frequency responses but eqing it with say a 31 band equalizer if you knew the precise numbers? Or are there other variables in how the mics are built that I am unaware of? What makes a mic "sound" good? If the answer is too complex to answer in a few posts, perhaps someone could direct me to a book or something that answers it.
How does a mic 'color the sound'?
- Thread starter asi9
- Start date
In theory, you could try to make one mike sound like another with EQ. In fact, that is the basis for some of the "microphone modelling" sofware and effects boxes.
Sometimes they come pretty close. A lot of people are happy with the results.
In reality there are two thing that make it virtually impossible to really duplicate the sound:
1. You would need A LOT FINER EQ control that given by a 31 band graphic EQ.
2. Frequency response is only one parameter. Transient response, phase relationships between the frequencies,and how they vary in transient response; and how all these responses vary in the directional beam pattern all contribute to the "sound" of a mike. I'm sure there are others.
So your question is something like "Couldn't I recreate the Mona Lisa if I had a paint-by-number set with all the right colors ?" Yes, you could....but you would also have to recreate all the talent of DaVinci to make it really "good".
I should add that I commonly do look at freq. response curves and then try to "compensate" for a flatter sound, or a particular response, so it isn't a bad thing to try. Just don't expect to transform an SM57 into a "great" microphone, for example.
Peace,
Rick
Sometimes they come pretty close. A lot of people are happy with the results.
In reality there are two thing that make it virtually impossible to really duplicate the sound:
1. You would need A LOT FINER EQ control that given by a 31 band graphic EQ.
2. Frequency response is only one parameter. Transient response, phase relationships between the frequencies,and how they vary in transient response; and how all these responses vary in the directional beam pattern all contribute to the "sound" of a mike. I'm sure there are others.
So your question is something like "Couldn't I recreate the Mona Lisa if I had a paint-by-number set with all the right colors ?" Yes, you could....but you would also have to recreate all the talent of DaVinci to make it really "good".
I should add that I commonly do look at freq. response curves and then try to "compensate" for a flatter sound, or a particular response, so it isn't a bad thing to try. Just don't expect to transform an SM57 into a "great" microphone, for example.
Peace,
Rick
skippy
New member
You've just touched on the secret behind "mic modeling", basically.
The problem with trying to model one mic with another is that the published specs are never what you actually need. They pretty graphs in the mic catalogs were usually made with 1/3 octave (or broader) filters, which produce nice, smooth-looking graphs. The realities of the frequency response for a mic (especially the "colored" ones!) is a much different thing, if you use a narrower filter, with resolutions down to a few Hz.
Generally speaking, the "color" created by a mic consists of a number of very narrow spectral peaks, and maybe some general frequency response bumps. The general bumps show up in the prettified 1/3-octave graph- the narrow peaks don't. The mic modeling companies use a technique called "deconvolution" to build a much more accurate picture of a mic's actual impulse response, with resolution down to just a few hertz. They can then digitally build up a filter set that can mimic these very narrow resonances. The math is annoying for anyone other than a serious nerd, but the bottom line is that they are essentially deriving the Fourier transform (ooh, yuk!) of the mic's response, and modeling that: processing the signal in the frequency domain, and not the time domain. More yuk.
To attempt this with a standalone EQ, you would need a multiband parametric that can be tweeked to provide a number of extremely high-Q resonant peaks superimposed over a set of broader, much lower-Q general bumps and valleys. The problem is getting the data to start with, to know which knobs to twist: the mic companies sure won't give them to you, and that's the stock-in-trade of the modelers, so they won't either.
I'm hardly saying that it can't be done. However, it is difficult, if not outright impossible, to mimic the narrow resonances with a 1/3 octave EQ: the Q of each section is too low, so you simply can't achieve the narrow high-Q resonances that are the heart and soul of "color" in the mic sense, and you get unintended phase errors outside the filter passband that sound like dogmeat. It gets ugly. To really do it right, you need several (many!) sections of a very good parametric EQ, and this is best done in the digital domain, not in the analog domain: DSP was _designed_ for doing frequency-domain tweeks of exactly this nature.
With deconvolution-convolution techniques, theoretically you can take an SM-57, mic a source, deconvolve out the SM-57's many peculiarities (leaving a "perfect" representation of the uncolored input), and then convolve that "perfect" input with the impulse response of say a Neumann U47- and get something that sounds like it was recorded with a U47.
Right. That's the theory, and that's what Antares and whoever else is selling. In practice, this falls a little short, because you can't ever completely work around the really gross characteristics of the input mic (like there not being any signal below 30Hz or above 15kHz to work with, or really huge phase response errors due to the mass of the diaphragm, or whatnot). Unsurprisingly, for modeling, the better the input mic, the better the output results... It's your call as to whether this works well enough for your application.
Anyway, it's not so much differences in how the mics are made as it is individual frequencey characteristics that are well beyond the resolution of the marketing-driven graphs you can get. The big-dollar vintage condensers will have 4 or 5 resonant peaks of +6-8dB (or more!) that are only a few hz wide, up in the 7-12kHz range. You and I hear it, and call it "air"... and marvel at the fact that two mics with "flat" 1/3-octave response curves can sound so different...
What makes a mic sound "good"? The two pints of gray soup between the ears of the listener! Your mileage may vary.
Hope that helps...
The problem with trying to model one mic with another is that the published specs are never what you actually need. They pretty graphs in the mic catalogs were usually made with 1/3 octave (or broader) filters, which produce nice, smooth-looking graphs. The realities of the frequency response for a mic (especially the "colored" ones!) is a much different thing, if you use a narrower filter, with resolutions down to a few Hz.
Generally speaking, the "color" created by a mic consists of a number of very narrow spectral peaks, and maybe some general frequency response bumps. The general bumps show up in the prettified 1/3-octave graph- the narrow peaks don't. The mic modeling companies use a technique called "deconvolution" to build a much more accurate picture of a mic's actual impulse response, with resolution down to just a few hertz. They can then digitally build up a filter set that can mimic these very narrow resonances. The math is annoying for anyone other than a serious nerd, but the bottom line is that they are essentially deriving the Fourier transform (ooh, yuk!) of the mic's response, and modeling that: processing the signal in the frequency domain, and not the time domain. More yuk.
To attempt this with a standalone EQ, you would need a multiband parametric that can be tweeked to provide a number of extremely high-Q resonant peaks superimposed over a set of broader, much lower-Q general bumps and valleys. The problem is getting the data to start with, to know which knobs to twist: the mic companies sure won't give them to you, and that's the stock-in-trade of the modelers, so they won't either.
I'm hardly saying that it can't be done. However, it is difficult, if not outright impossible, to mimic the narrow resonances with a 1/3 octave EQ: the Q of each section is too low, so you simply can't achieve the narrow high-Q resonances that are the heart and soul of "color" in the mic sense, and you get unintended phase errors outside the filter passband that sound like dogmeat. It gets ugly. To really do it right, you need several (many!) sections of a very good parametric EQ, and this is best done in the digital domain, not in the analog domain: DSP was _designed_ for doing frequency-domain tweeks of exactly this nature.
With deconvolution-convolution techniques, theoretically you can take an SM-57, mic a source, deconvolve out the SM-57's many peculiarities (leaving a "perfect" representation of the uncolored input), and then convolve that "perfect" input with the impulse response of say a Neumann U47- and get something that sounds like it was recorded with a U47.
Right. That's the theory, and that's what Antares and whoever else is selling. In practice, this falls a little short, because you can't ever completely work around the really gross characteristics of the input mic (like there not being any signal below 30Hz or above 15kHz to work with, or really huge phase response errors due to the mass of the diaphragm, or whatnot). Unsurprisingly, for modeling, the better the input mic, the better the output results... It's your call as to whether this works well enough for your application.
Anyway, it's not so much differences in how the mics are made as it is individual frequencey characteristics that are well beyond the resolution of the marketing-driven graphs you can get. The big-dollar vintage condensers will have 4 or 5 resonant peaks of +6-8dB (or more!) that are only a few hz wide, up in the 7-12kHz range. You and I hear it, and call it "air"... and marvel at the fact that two mics with "flat" 1/3-octave response curves can sound so different...
What makes a mic sound "good"? The two pints of gray soup between the ears of the listener! Your mileage may vary.
Hope that helps...
Mmmmmmm.... meaty, detailed information. So therefore, since we can't know exactly what these little boosted frequencies are and where (that's their main secret for the mic 'sounding' a certain way, and they ain't tellin' us), it's up to our ears to decide which mics sound better for what. Enter the whole damn purpose of this forum. Well, I know what I'm looking for, a good dynamic or large diaphragm condenser mic with a boost between 150 to 250hz, and another at 3 to 5khz, preferably with a rolloff curve starting at about 100hz, but not necessarily. Does that sound like any mic you know of?
skippy
New member
Could be any number of them. Is this for vocals, or for instrument use? Could you use the proximity effect of a cardioid to get the LF boost, or is the source gonna move around too much and give you uneven behavior? And do you have a rental place nearby where you can just snag a few mics for a weekend and experiment to your heart's content (the most enjoyable, though expensive, solution...).
It's tough to imagine recommending a mic to anyone else, even with complete knowledge of what they're trying to do, and for what type of music... Mic selection is totally subjective- and large diaphragm condensers tend to vary quite a lot, especially the older ones. I'm not trying to wimp out, but there are one hell of a lot of variables here.
Back on your "can it be done" question: Here's a fun article on rec.audio.pro that came from a long argument between old aquaintances Monte McGuire (Not the HR monty, but another one) and David Butler. I knew both those guys nearly 20 years ago, when I still had my first studio, but it's amusing to see that they haven't changed much- and that they can still work up a good flaming disagreement. Anyway, it features Monte doing a little on-the-hoof modeling using his newfangled DAW EQ to map one mic onto another, and db telling him he's basically full of shit, in his inimitable way... Whee!
Well, screw. The url I originally posted didn't work. But do a Deja News search on "monte mcguire blue b6 ck28", and you'll get basically the whole thread. Monte's post on 11/6 is the one you want.
Gotta love it. Man, _that_ takes me back.
[Edited by skippy on 12-15-2000 at 14:54]
It's tough to imagine recommending a mic to anyone else, even with complete knowledge of what they're trying to do, and for what type of music... Mic selection is totally subjective- and large diaphragm condensers tend to vary quite a lot, especially the older ones. I'm not trying to wimp out, but there are one hell of a lot of variables here.
Back on your "can it be done" question: Here's a fun article on rec.audio.pro that came from a long argument between old aquaintances Monte McGuire (Not the HR monty, but another one) and David Butler. I knew both those guys nearly 20 years ago, when I still had my first studio, but it's amusing to see that they haven't changed much- and that they can still work up a good flaming disagreement. Anyway, it features Monte doing a little on-the-hoof modeling using his newfangled DAW EQ to map one mic onto another, and db telling him he's basically full of shit, in his inimitable way... Whee!
Well, screw. The url I originally posted didn't work. But do a Deja News search on "monte mcguire blue b6 ck28", and you'll get basically the whole thread. Monte's post on 11/6 is the one you want.
Gotta love it. Man, _that_ takes me back.
[Edited by skippy on 12-15-2000 at 14:54]
Ears
ADA
All this info is interesting no doubt/
However an old guy like me explains it like this.
If it isn't there going in you can't make it happen after. Once it's there. Sure you could model this, emulate that, reverse polarity, comb filter, excite, ad harmonics.....(not slighting you guys here), but the bottom line is that a mic with the least amount of eq will sound the best on it's own. I own a VS1680 with COSM, I know. I use it to fix things. However, only if I have to. Mic placement and microphones make pro quality pure recordings.Thats why there are so many for so many sources. Otherwise let's all by one SM58 and go for it....It will never sound exact compared to the real thing. Sorry, had to get my vote for purity in here.
However an old guy like me explains it like this.
If it isn't there going in you can't make it happen after. Once it's there. Sure you could model this, emulate that, reverse polarity, comb filter, excite, ad harmonics.....(not slighting you guys here), but the bottom line is that a mic with the least amount of eq will sound the best on it's own. I own a VS1680 with COSM, I know. I use it to fix things. However, only if I have to. Mic placement and microphones make pro quality pure recordings.Thats why there are so many for so many sources. Otherwise let's all by one SM58 and go for it....It will never sound exact compared to the real thing. Sorry, had to get my vote for purity in here.
CyanJaguar
New member
wow,
so much information here. this is probably why some mics work better with some preamps than others.
So how do preamps color the sound? Is it based around the same principle?
so much information here. this is probably why some mics work better with some preamps than others.
So how do preamps color the sound? Is it based around the same principle?
skippy
New member
Ears wrote: "It will never sound exact compared to the real thing. Sorry, had to get my vote for purity in here."
Yup- absolutely correct. Modeling will *never* be able to perfectly reproduce a U47 sound from something tracked with an SM57. There's no way: there is too much variability in SM57s, so deconvolving out the input mic will always achieve something well short of perfection. And then feeding that to the convolver with the impulse response of the U47 is going to produce- well, shall we say, cruft. Model your U47 with something from a U87, and you'll get something perhaps a little closer to the U47, but still not exact. It's like they say: if you add a thimble full of wine into a barrel full of sewage, you get sewage. If you add a thimble full of sewage into a barrel full of wine, you _still_ get sewage... (;-)
However, on any given day, some engineer in some room with some artist may find that that SM47/U47 modeling cruft actually suits them just fine: perhaps even better than hanging the real U47 hidden away in the locker in front of the disease-ridden, rotgut-sodden vocalist that's paying the hourly rate (;-). In that case, it doesn't matter that it actually sounds more like a Rat Shack PZM that's been backed over by a pickup truck than it does a U47: if it sounds good, they use it, and everyone's happy.
Mic modeling is an effect, nothing more. And I'm with you when you vote for purity. I still think that some of my best recordings have been tracked flat and shipped just like that, with the right combination of mic, performer, room, and mood. All the modeling in the world will not approach that. But sometimes, and for some musics, you might need that magic DSP munger. You know, turning the knob up to 11 to really push you over the edge... And it might save having to boil the U47 in Listerine after the bozos go away. (;-)
CyanJaguar wrote: "So how do preamps color the sound? Is it based around the same principle?"
No, not really. I believe that mic pres color the sound by adding controlled levels of harmonic distortion (which produces harmonically-related frequency-response effects: the "peaks" produced by the pre track the input signal). This is created by nonlinearities in the gain stages or input/output transformers. Highly-colored pres may also mung the overall frequency response curve, to help achieve their "color".
Mics, on the other hand, have specific mechanical resonances that do not track the input signal materially (until you get up into the really high SPL levels) Their color is not primarily a distortion as such: it is mostly the result of resonances in the mechanical/acoustic system inherent to the transducer itself. Mics with built in electronics/transformers do some of both, of course, but IMNSHO the dominant effects that create mic colorations are the mechanical/acoustic resonances.
You certainly can do preamp-style distortion and frequency-response modeling in DSP: just look at the Line6 Pod, and all the Roland COSM stuff. But the actual mechanism of "coloration" is different, and it's usually cheaper to just build a preamp with a good quiet, clean input stage and a wierdly-nonlinear analog output stage to get that specific flavor of harmonic wierdness than it is to spend time writing microcode for a DSP engine to model it (and paying for ther extra A/D hardware to slurp the poor signal into the digital domain). Most preamps are one-trick ponies: they do what they do. The only reason you'd want to code up an emulation and do it in the digital domain would be if you wanted to mimic _lots_ of different flavors, viz: COSM and Pod...
ALl this is just my humble opinion, of course. Your mileage may vary.
[Edited by skippy on 12-21-2000 at 14:48]
Yup- absolutely correct. Modeling will *never* be able to perfectly reproduce a U47 sound from something tracked with an SM57. There's no way: there is too much variability in SM57s, so deconvolving out the input mic will always achieve something well short of perfection. And then feeding that to the convolver with the impulse response of the U47 is going to produce- well, shall we say, cruft. Model your U47 with something from a U87, and you'll get something perhaps a little closer to the U47, but still not exact. It's like they say: if you add a thimble full of wine into a barrel full of sewage, you get sewage. If you add a thimble full of sewage into a barrel full of wine, you _still_ get sewage... (;-)
However, on any given day, some engineer in some room with some artist may find that that SM47/U47 modeling cruft actually suits them just fine: perhaps even better than hanging the real U47 hidden away in the locker in front of the disease-ridden, rotgut-sodden vocalist that's paying the hourly rate (;-). In that case, it doesn't matter that it actually sounds more like a Rat Shack PZM that's been backed over by a pickup truck than it does a U47: if it sounds good, they use it, and everyone's happy.
Mic modeling is an effect, nothing more. And I'm with you when you vote for purity. I still think that some of my best recordings have been tracked flat and shipped just like that, with the right combination of mic, performer, room, and mood. All the modeling in the world will not approach that. But sometimes, and for some musics, you might need that magic DSP munger. You know, turning the knob up to 11 to really push you over the edge... And it might save having to boil the U47 in Listerine after the bozos go away. (;-)
CyanJaguar wrote: "So how do preamps color the sound? Is it based around the same principle?"
No, not really. I believe that mic pres color the sound by adding controlled levels of harmonic distortion (which produces harmonically-related frequency-response effects: the "peaks" produced by the pre track the input signal). This is created by nonlinearities in the gain stages or input/output transformers. Highly-colored pres may also mung the overall frequency response curve, to help achieve their "color".
Mics, on the other hand, have specific mechanical resonances that do not track the input signal materially (until you get up into the really high SPL levels) Their color is not primarily a distortion as such: it is mostly the result of resonances in the mechanical/acoustic system inherent to the transducer itself. Mics with built in electronics/transformers do some of both, of course, but IMNSHO the dominant effects that create mic colorations are the mechanical/acoustic resonances.
You certainly can do preamp-style distortion and frequency-response modeling in DSP: just look at the Line6 Pod, and all the Roland COSM stuff. But the actual mechanism of "coloration" is different, and it's usually cheaper to just build a preamp with a good quiet, clean input stage and a wierdly-nonlinear analog output stage to get that specific flavor of harmonic wierdness than it is to spend time writing microcode for a DSP engine to model it (and paying for ther extra A/D hardware to slurp the poor signal into the digital domain). Most preamps are one-trick ponies: they do what they do. The only reason you'd want to code up an emulation and do it in the digital domain would be if you wanted to mimic _lots_ of different flavors, viz: COSM and Pod...
ALl this is just my humble opinion, of course. Your mileage may vary.
[Edited by skippy on 12-21-2000 at 14:48]
Ears
ADA
Well said....... I think too that a mic pre especially a good pre/mic combo, that is right for the subject (source) with tube even harmonic distortion react with each other. In other words more natural ..the source sound.....the mic sound.....the pre sound. Emulators are variable effects that do not react with the source or microphone in a natural sense. They more so manipulate the signal to sounding like something it is not. Yes I suppose it can be a fix for a low grade vocalist, and it would be genre dependent.In a short note though I think we should all strive for quality naturally first.
Ears
ADA
Wow this is me old post. I have a lot more gear now then I did back then but still follow the same rules. I'm fortunate to have a great selection of mics theses days.
U47,U67, M367(French M269) M49s, U87s, KM84s in Neumann and many other manufactures. I have grown to conclude over the many years I have been recording, the microphone rules above all others. Many mic pres, and compressors tweak but microphones are the most important in any non injected recording.
Ribbons, tube, solidstate condensers, dynamic. I use them all. All have there purpose all do their job. The preamp is an important part of the chain, but the right mic in the right place will always be the most important choice. In my opinion.
U47,U67, M367(French M269) M49s, U87s, KM84s in Neumann and many other manufactures. I have grown to conclude over the many years I have been recording, the microphone rules above all others. Many mic pres, and compressors tweak but microphones are the most important in any non injected recording.
Ribbons, tube, solidstate condensers, dynamic. I use them all. All have there purpose all do their job. The preamp is an important part of the chain, but the right mic in the right place will always be the most important choice. In my opinion.