Harvey Gerst
New member
muzeman said:
How does diaphragm size/polar pattern relate to mic applications?
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muzeman
New member
Harvey,
Thanks very much for taking the time to answer,
I appreciate it.
How is the earthworks stuff.
I'm looking at the SR71.
How do they compare to the SM81?
Do you think I can use just one for mono on an acoustic with vocals on another mic,or do you think I would do better with a large diaphram figure 8 on the acoustic?
I record in an unacousticly enhanced room(if you know what I mean)
What brand of figure 8 would you recommend?
I guess it would have to be a multi pattern?
Thanks again,
Pete
Thanks very much for taking the time to answer,
I appreciate it.
How is the earthworks stuff.
I'm looking at the SR71.
How do they compare to the SM81?
Do you think I can use just one for mono on an acoustic with vocals on another mic,or do you think I would do better with a large diaphram figure 8 on the acoustic?
I record in an unacousticly enhanced room(if you know what I mean)
What brand of figure 8 would you recommend?
I guess it would have to be a multi pattern?
Thanks again,
Pete
Harvey Gerst
New member
muzeman said:
Harvey Gerst
New member
Microphone Frequency Response - The Window
Most microphone manufacturers quote frequency response numbers somewhere on their spec page, and it's usually something like "20 - 20 kHz" (or "30 - 15 kHz"), but what does that really mean, and how does it relate to what you hear?
For that you'll need to know how to read a frequency response curve, add in what they "don't tell you", and understand the amount of deviation possible between identical units. But before we can do that, you need to know how microphones are measured.
Even though computer measurements have replaced a lot of the mechanical measurement systems, companies (like B&K) still provide precision microphone test equipment, consisting of a frequency sweep oscillator, synched to a chart recorder, and a ruler flat test microphone.
Basically, you feed the oscillator signal into something that will generate the sound, hook up the mic you want to test, and the calibrated mic, then sweep the entire audible frequency range while you chart the "difference" between the calibrated flat mic and the mic you're testing. The resulting chart is the frequency response of that one microphone.
Calibration mics usually come in two flavors: direct measurement mics (on-axis), and diffused field mics (usually 90° off-axis). Direct measurement mics are used in anechoic chambers where there is no sound bouncing around so the mic can be designed to be absolutely flat on-axis (i.e. pointed straight at the sound source). As you aim the mic away from the sound source, the high end response of the microphone drops off dramatically.
Diffused field microphones are used in normal type rooms where pointing the mic directly at the speaker will pick up unwanted reflections. When making measurements with diffuse field mics, they're usually pointed 90° off-axis (towards the ceiling, the floor, or one of the side walls. Diffuse field microphones are flat 90° off-axis, but they have a large rising frequency response on-axis.
So we now measure our mic, using one of the two methods described above and we look at the chart that was produced, but that only tells us about that one mic. . Here's the mic curve for "our mic":
We'll need to run a batch of the same mics to see how much they'll vary from this one mic we just tested. To make it easy to compare the frequency response, we'll adjust the level so that each mic is set to the same level at 1,000 Hz (although we'll keep track of how much the level needed to be adjusted for each mic). Let's say we test 50 mics. We lay out the 50 charts and we also have a blank piece of chart paper in front of us.
We find the lowest frequency (20 Hz) on each chart, and look for the highest signal level (loudest), and the lowest signal level softest) we measured at 20Hz. We put two marks (shown in red)on our blank piece of chart paper at 20 Hz. We do the same thing at each line, peak or dip on the chart, until we have an upper and lower row of dots that represent the maximum and minimum range of frequency responses from this batch of mics. Here's the curve for "our mic" and the variations we found in testing 50 mics:
We then connect all the upper red dots, and we connect all the lower red dots (with the final curves shown in grey):
We can then draw a line (the blue curve) exactly centered between the upper and lower dots and that's our "typical response curve" that we submit to the marketing department. Understand, at this point, the curve could look fairly flat, but individual mics can vary by 5dB or more from the "average curve", and still be considered "normal". (Remember we also adjusted the output level for a constant 1,000 Hz signal from each mic? That will thow off the results even more and be critical when it comes to finding a matched pair).
Well, our sample (in black) isn't too far off the average (in blue), but we might find some mics in that batch that are better in the bottom end. How tight to hold the "deviation from average" window is a judgement call by the company and then carried out by the quality control department. At companies like Neumann, they use a 4dB window, which means that all mics must fit within a +/- 2dB window (4 dB overall) of their published curve. B&K test mics may use a window as small as +/- 1/10th of a dB variation from their published curves.
But our "average curve" may still look "too jagged" for public consumption" from the marketing department's point of view, so the curve can be "smoothed" by averaging some of the jagged peaks, or slowing down the pen speed on the chart recorder (so it doesn't move as fast up and down and makes the curve look smoother by simply ignoring all the little jagged short bursts). These are usually marketing decisions, so that "our curve" look similar to "other companies' curves":
And there we have the final "respectable" frequency response curve that is published in the advertizing literature.
Now, here's another "gotcha" for most pressure gradient mics: the frequency response will change, depending on the distance from the sound source, or the angle to the mic. Some manufacturers will actually show the "proximity effect" on the frequency response chart, showing how the bass is boosted as you get closer. Some will also show the frequency response at different angles (usually 0°, 30°, 60°, 90°, and 180°), like this:
When you look at a number like "Frequency Response: 20 - 20k", look at the published curve to see what the "usable response" really is, and remember that the curve you see is "averaged and smoothed. Unless the deviation is shown (either as a gray area or a line above and below the curve, or a number like +/- 3 dB), you really don't know what your mic is really doing. That's why it's so hard for the average person to tell what a mic might sound like, judging from the frequency response curve, or just reading the specs.
Any questions so far?
Most microphone manufacturers quote frequency response numbers somewhere on their spec page, and it's usually something like "20 - 20 kHz" (or "30 - 15 kHz"), but what does that really mean, and how does it relate to what you hear?
For that you'll need to know how to read a frequency response curve, add in what they "don't tell you", and understand the amount of deviation possible between identical units. But before we can do that, you need to know how microphones are measured.
Even though computer measurements have replaced a lot of the mechanical measurement systems, companies (like B&K) still provide precision microphone test equipment, consisting of a frequency sweep oscillator, synched to a chart recorder, and a ruler flat test microphone.
Basically, you feed the oscillator signal into something that will generate the sound, hook up the mic you want to test, and the calibrated mic, then sweep the entire audible frequency range while you chart the "difference" between the calibrated flat mic and the mic you're testing. The resulting chart is the frequency response of that one microphone.
Calibration mics usually come in two flavors: direct measurement mics (on-axis), and diffused field mics (usually 90° off-axis). Direct measurement mics are used in anechoic chambers where there is no sound bouncing around so the mic can be designed to be absolutely flat on-axis (i.e. pointed straight at the sound source). As you aim the mic away from the sound source, the high end response of the microphone drops off dramatically.
Diffused field microphones are used in normal type rooms where pointing the mic directly at the speaker will pick up unwanted reflections. When making measurements with diffuse field mics, they're usually pointed 90° off-axis (towards the ceiling, the floor, or one of the side walls. Diffuse field microphones are flat 90° off-axis, but they have a large rising frequency response on-axis.
So we now measure our mic, using one of the two methods described above and we look at the chart that was produced, but that only tells us about that one mic. . Here's the mic curve for "our mic":
We'll need to run a batch of the same mics to see how much they'll vary from this one mic we just tested. To make it easy to compare the frequency response, we'll adjust the level so that each mic is set to the same level at 1,000 Hz (although we'll keep track of how much the level needed to be adjusted for each mic). Let's say we test 50 mics. We lay out the 50 charts and we also have a blank piece of chart paper in front of us.
We find the lowest frequency (20 Hz) on each chart, and look for the highest signal level (loudest), and the lowest signal level softest) we measured at 20Hz. We put two marks (shown in red)on our blank piece of chart paper at 20 Hz. We do the same thing at each line, peak or dip on the chart, until we have an upper and lower row of dots that represent the maximum and minimum range of frequency responses from this batch of mics. Here's the curve for "our mic" and the variations we found in testing 50 mics:
We then connect all the upper red dots, and we connect all the lower red dots (with the final curves shown in grey):
We can then draw a line (the blue curve) exactly centered between the upper and lower dots and that's our "typical response curve" that we submit to the marketing department. Understand, at this point, the curve could look fairly flat, but individual mics can vary by 5dB or more from the "average curve", and still be considered "normal". (Remember we also adjusted the output level for a constant 1,000 Hz signal from each mic? That will thow off the results even more and be critical when it comes to finding a matched pair).
Well, our sample (in black) isn't too far off the average (in blue), but we might find some mics in that batch that are better in the bottom end. How tight to hold the "deviation from average" window is a judgement call by the company and then carried out by the quality control department. At companies like Neumann, they use a 4dB window, which means that all mics must fit within a +/- 2dB window (4 dB overall) of their published curve. B&K test mics may use a window as small as +/- 1/10th of a dB variation from their published curves.
But our "average curve" may still look "too jagged" for public consumption" from the marketing department's point of view, so the curve can be "smoothed" by averaging some of the jagged peaks, or slowing down the pen speed on the chart recorder (so it doesn't move as fast up and down and makes the curve look smoother by simply ignoring all the little jagged short bursts). These are usually marketing decisions, so that "our curve" look similar to "other companies' curves":
And there we have the final "respectable" frequency response curve that is published in the advertizing literature.
Now, here's another "gotcha" for most pressure gradient mics: the frequency response will change, depending on the distance from the sound source, or the angle to the mic. Some manufacturers will actually show the "proximity effect" on the frequency response chart, showing how the bass is boosted as you get closer. Some will also show the frequency response at different angles (usually 0°, 30°, 60°, 90°, and 180°), like this:
When you look at a number like "Frequency Response: 20 - 20k", look at the published curve to see what the "usable response" really is, and remember that the curve you see is "averaged and smoothed. Unless the deviation is shown (either as a gray area or a line above and below the curve, or a number like +/- 3 dB), you really don't know what your mic is really doing. That's why it's so hard for the average person to tell what a mic might sound like, judging from the frequency response curve, or just reading the specs.
Any questions so far?
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dobro
Well-known member
But you can trust a Neumann frequency response chart to be within 4 dB of what they say it is... Hmm. So one thing you're paying for in a Neumann is a mic that is what it claims to be on paper?
You know, I found an EQ preset in Cool Edit Pro that sounds good on my voice tracks - they call it 'Mackie High Band', but it matches the frequency response chart for a TLM 103. I wonder how many of Cool Edit's presets (or those of other editors) are nothing more than the published frequency response of famous mics.
I think I'm going to do some tweaking with my Cool Edit EQ. LOL
You know, I found an EQ preset in Cool Edit Pro that sounds good on my voice tracks - they call it 'Mackie High Band', but it matches the frequency response chart for a TLM 103. I wonder how many of Cool Edit's presets (or those of other editors) are nothing more than the published frequency response of famous mics.
I think I'm going to do some tweaking with my Cool Edit EQ. LOLHarvey Gerst
New member
Bingo, that's what some of the simpler mic modellers do.dobro said:But you can trust a Neumann frequency response chart to be within 4 dB of what they say it is... Hmm. So one thing you're paying for in a Neumann is a mic that is what it claims to be on paper?
You can trust it to be within 2dB of the pubished curve - in each direction. It should never be more than 2 dB louder or softer than the published curve, once you match the levels at 1,000 Hz.
You know, I found an EQ preset in Cool Edit Pro that sounds good on my voice tracks - they call it 'Mackie High Band', but it matches the frequency response chart for a TLM 103. I wonder how many of Cool Edit's presets (or those of other editors) are nothing more than the published frequency response of famous mics.
Harvey Gerst
New member
Three more things I forgot to point out.
1. There is no mic (in any batch you test) that will match the advertised blue curve.
2. If you happen to get a worst case mic that has the horrible peak at 200Hz and at 7,000Hz, it might sound very bloated and screechy if you have a singer with a lot of energy in those ranges, or it could sound "full and detailed" if the singer doesn't have a lot of energy in those areas.
3. Even though the response takes a nose dive after 10kHz, and starts to rolloff below 100Hz, it is still capable of responding to energy from 20Hz - 20kHz, and the manufacturer can advertise it as such (and not bother to publish a curve).
BTW, the first 5 mic graphs shown in the above example were all hand-created by me; no microphones were actually harmed or used during the making of these curves. The very bottom curve (showing off-axis responses) is a real curve of a real DPA mic.
1. There is no mic (in any batch you test) that will match the advertised blue curve.
2. If you happen to get a worst case mic that has the horrible peak at 200Hz and at 7,000Hz, it might sound very bloated and screechy if you have a singer with a lot of energy in those ranges, or it could sound "full and detailed" if the singer doesn't have a lot of energy in those areas.
3. Even though the response takes a nose dive after 10kHz, and starts to rolloff below 100Hz, it is still capable of responding to energy from 20Hz - 20kHz, and the manufacturer can advertise it as such (and not bother to publish a curve).
BTW, the first 5 mic graphs shown in the above example were all hand-created by me; no microphones were actually harmed or used during the making of these curves. The very bottom curve (showing off-axis responses) is a real curve of a real DPA mic.
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Henrik
Member
Yeah, I have a question, or rather a clarification so I'm sure I understand this properly:
Assume you're comparing some mics of the same model, as in your second jpeg, with the red dots. At 200 hz for example, one mic reaches 10 dB and another mic reaches 18 dB.
Now suppose that apart from the 200 hz deviation, these two mics have similar response curves (a very theoretical assumption no doubt). Would you then be able to make a recording with the mic with the 10 dB response, and on your EQ boost the recording 200 hz 8 dB, and as a result have the sound you would have obtained if you had recorded with the other mic?
If so, then I can understand that's a helluva difference! I mean boosting any recording 8 dB really alters it A LOT. Are there any real mics out there that show these big differences between the individual mics? Even Neumann's guaranteed +/- 2dB could really make a noticeable difference (if you were unlucky enough to get hold of two mics on each end of the spectre).
Can we trust manufacturers that sell what they claim are matched pairs of their mics?
And again...thanks Harvey, for the best thread ever.
Cheers
/Henrik
Assume you're comparing some mics of the same model, as in your second jpeg, with the red dots. At 200 hz for example, one mic reaches 10 dB and another mic reaches 18 dB.
Now suppose that apart from the 200 hz deviation, these two mics have similar response curves (a very theoretical assumption no doubt). Would you then be able to make a recording with the mic with the 10 dB response, and on your EQ boost the recording 200 hz 8 dB, and as a result have the sound you would have obtained if you had recorded with the other mic?
If so, then I can understand that's a helluva difference! I mean boosting any recording 8 dB really alters it A LOT. Are there any real mics out there that show these big differences between the individual mics? Even Neumann's guaranteed +/- 2dB could really make a noticeable difference (if you were unlucky enough to get hold of two mics on each end of the spectre).
Can we trust manufacturers that sell what they claim are matched pairs of their mics?
And again...thanks Harvey, for the best thread ever.
Cheers
/Henrik
Harvey Gerst
New member
Henrik said:
Last edited:
dobro
Well-known member
A comment, a question.
So, in the end, forget the published graphs and trust your ears.
However, the Neumann published graphs are pretty trustworthy, from what you say. Any other companies you know about Harvey, that put out more or less reliable frequency response charts, 'smoothing' notwithstanding?
So, in the end, forget the published graphs and trust your ears.
However, the Neumann published graphs are pretty trustworthy, from what you say. Any other companies you know about Harvey, that put out more or less reliable frequency response charts, 'smoothing' notwithstanding?
Harvey Gerst
New member
Shure is pretty accurate, and so are many of the good quality mics (like Schoeps and Earthworks and DPA and B.L.U.E., just to name a few). I'm sure Soundelux and Brauner and Soundfield are also pretty honest. All the Oktavas I bought from the sound room had curves with them that matched very well with what I heard.dobro said:
Harvey Gerst
New member
Sensitivity - What's that all about?
Sensitivity is the measurement that tells you how hard your preamp is going to have to work to get the signal up to a useful level. It's found by feeding a specific sound level into the microphone and measuring the output level of the mic.
The older standard was µbars (where 1 µbar equaled a 74dB SPL). The new standard is Pascals (where 1Pa equals a 94dB SPL). If the measurement is shown in µbars, simply add 20 dB to the ouput level to convert it to Pascals. Here are some typical microphone ouput levels:
1.1 mV/1Pa = -59dB (very low output - requires almost 60dB of gain to hit 0 on the meters - typical ribbon mic output)
1.2 mV/1Pa = -57dB
2 mV/1Pa = -54dB (typical dynamic mic output)
2.3 mV/1Pa = -53dB
5.6 mV/1Pa = -45dB
10 mV/1Pa = -40dB (typical condenser mic output)
20 mV/1Pa = -34dB
25 mV/1Pa = -32dB (very hot condenser mic output)
If your preamp gets noisey at high gain, avoid using mics with a big negative dB number. All that -dB number is showing is how much preamp gain you're going to need to bring the signal up to a useful level.
Finally, you may see a number thrown into the sensitivity measurement that says "+/- 1.5dB" or "+/- 2dB" - that's how much variation in output is allowed by the manufacturer between units of the same model of mic. "+/- 1.5dB" means that one mic may have 3 dB more output (or 3 dB less output) than another mic of the same exact model.
Sensitivity is the measurement that tells you how hard your preamp is going to have to work to get the signal up to a useful level. It's found by feeding a specific sound level into the microphone and measuring the output level of the mic.
The older standard was µbars (where 1 µbar equaled a 74dB SPL). The new standard is Pascals (where 1Pa equals a 94dB SPL). If the measurement is shown in µbars, simply add 20 dB to the ouput level to convert it to Pascals. Here are some typical microphone ouput levels:
1.1 mV/1Pa = -59dB (very low output - requires almost 60dB of gain to hit 0 on the meters - typical ribbon mic output)
1.2 mV/1Pa = -57dB
2 mV/1Pa = -54dB (typical dynamic mic output)
2.3 mV/1Pa = -53dB
5.6 mV/1Pa = -45dB
10 mV/1Pa = -40dB (typical condenser mic output)
20 mV/1Pa = -34dB
25 mV/1Pa = -32dB (very hot condenser mic output)
If your preamp gets noisey at high gain, avoid using mics with a big negative dB number. All that -dB number is showing is how much preamp gain you're going to need to bring the signal up to a useful level.
Finally, you may see a number thrown into the sensitivity measurement that says "+/- 1.5dB" or "+/- 2dB" - that's how much variation in output is allowed by the manufacturer between units of the same model of mic. "+/- 1.5dB" means that one mic may have 3 dB more output (or 3 dB less output) than another mic of the same exact model.
chessparov
New member
Re: SPL
Harvey, what do you consider a good SPL rating for vocal mikes,
and have you had any singers "blow out" any?
Harvey, what do you consider a good SPL rating for vocal mikes,
and have you had any singers "blow out" any?
Harvey Gerst
New member
Harvey Gerst
New member
Maximum SPL - How Loud Can You Go?
Since chessparov just brought it up, let's discuss "Maximum SPL"and what that specification means.
"Maximum SPL" is the maximum Sound Pressure Level a microphone can take, at a specified level of permissable distortion.
The problem with this spec is that some microphone manufacturers don't tell you what the distortion level is, or whether it's the capsule or the mic preamp (inside the mic body) that's distorting, or they calculate the level at a distortion level that's different from other manufacturers. If the distortion isn't mentioned, figure it's either 1/2% to 1% (tolerable), or 5% (starting to get gross).
If they show only one distortion vs. SPL figure, it's easy to convert that number to distortion figures other manufacturers use, to help make a fair comparison. Here's how:
For a round diaphragm mic, distortion will usually double for every 6dB increase in SPL. So, if someone shows a max SPL of 1/2% @ 128dB, it's gonna be around 1% @ 134dB, 2% @ 140dB, and around 5% @ about 148dB.
You can control too much output level by two methods: by placing the artist further back from the mic (which will also help reduce wild variations in level due to movement), or by using compression to smooth out level inconsistancies, but with the liability of a possible increase in room noise.
As you move the person back, the inconsistancies from note to note smooth out, but you pay the price of added room noise.
Usually, you'll want to strike a balance by moving the artist back just a little (to control levels, but not so much that you pick up a lot of room sound). For condenser mics, I like somewhere between 1 and 2" away (for ballads and very soft singers), and 6 to 12" back (for the "belters"). I might also add some compression if their levels get really wild (anywhere from 2:1 to 10:1 ratios, but only triggered on the VERY LOUDEST peaks).
The final section (on polar patterns) is coming up next, and that should wrap this whole thread up.
I'm sure they'll be some questions, and I'll try to answer them all, if I can. Thanks to everybody for hanging around this long.
Since chessparov just brought it up, let's discuss "Maximum SPL"and what that specification means.
"Maximum SPL" is the maximum Sound Pressure Level a microphone can take, at a specified level of permissable distortion.
The problem with this spec is that some microphone manufacturers don't tell you what the distortion level is, or whether it's the capsule or the mic preamp (inside the mic body) that's distorting, or they calculate the level at a distortion level that's different from other manufacturers. If the distortion isn't mentioned, figure it's either 1/2% to 1% (tolerable), or 5% (starting to get gross).
If they show only one distortion vs. SPL figure, it's easy to convert that number to distortion figures other manufacturers use, to help make a fair comparison. Here's how:
For a round diaphragm mic, distortion will usually double for every 6dB increase in SPL. So, if someone shows a max SPL of 1/2% @ 128dB, it's gonna be around 1% @ 134dB, 2% @ 140dB, and around 5% @ about 148dB.
You can control too much output level by two methods: by placing the artist further back from the mic (which will also help reduce wild variations in level due to movement), or by using compression to smooth out level inconsistancies, but with the liability of a possible increase in room noise.
As you move the person back, the inconsistancies from note to note smooth out, but you pay the price of added room noise.
Usually, you'll want to strike a balance by moving the artist back just a little (to control levels, but not so much that you pick up a lot of room sound). For condenser mics, I like somewhere between 1 and 2" away (for ballads and very soft singers), and 6 to 12" back (for the "belters"). I might also add some compression if their levels get really wild (anywhere from 2:1 to 10:1 ratios, but only triggered on the VERY LOUDEST peaks).
The final section (on polar patterns) is coming up next, and that should wrap this whole thread up.
I'm sure they'll be some questions, and I'll try to answer them all, if I can. Thanks to everybody for hanging around this long.
Harvey Gerst
New member
Polar Response - Turn, Turn, Turn
Ok, I noticed my last post was #299 in this thread, so I might as well finish this whole thread off at post #300, so here's the last section, on polar response. I'm gonna use the sheet for the Shure SM-57 as the example, so download this and follow along:
http://www.shure.com/pdf/userguides/guides_wiredmics/sm57_en.pdf
Notice the polar response looks very smooth and you can almost visualize what it would sound like if you moved 30° off to the side of the mic, but what "you see" isn't exactly what "you get". Look at the frequency response curve to see why. Notice that the response of the mic is down a couple of dB at 125 Hz and it's got a 7 dB peak at around 5kHz or so?
Now look at the polar response curve and find those 2 frequencies. Notice at 0°, they show up on the 0dB line? If you were on axis, the 5kHz signal would actually be 7 dB louder than a 1kHz signal, but they're shown as identical levels at 0°. In other words, they've been "normalized" to be the same level at 0° as all the other frequencies. In reality, that 5kHZ line should be 7dB louder on the graph, all the way around.
The only thing the polar pattern shows is the general pattern of the mic at different angles; it does not represent reality with regards to the actual signal levels you may get off axis. For that, you have to use the frequency response curve and extrapolate (i.e., "guess") the actual off axis response from there.
And that's the "last secret" of this whole thread. We started off discussing "diaphagm size", and this last post covers the polar pattern part of the question, although we discussed different polar patterns and their use earlier.
I hope you enjoyed this as much as I did, and I'll try to answer all questions, and clarify anything I din't explain as well as I should of. It's a big subject and I didn't go into it as fully as I maybe should have, but tried to make it as useful as I could to the broadest spectrum of posters here. If it was too simple and basic for some of you, I apologize, but just look at it as a refresher course. For the rest, I hope it's given you some insights into how to improve your own recordings. Whatever - I've enjoyed the hell out of this.
Sincerely,
Harvey Gerst,
Just An "Old Fart" Recording Engineer
Ok, I noticed my last post was #299 in this thread, so I might as well finish this whole thread off at post #300, so here's the last section, on polar response. I'm gonna use the sheet for the Shure SM-57 as the example, so download this and follow along:
http://www.shure.com/pdf/userguides/guides_wiredmics/sm57_en.pdf
Notice the polar response looks very smooth and you can almost visualize what it would sound like if you moved 30° off to the side of the mic, but what "you see" isn't exactly what "you get". Look at the frequency response curve to see why. Notice that the response of the mic is down a couple of dB at 125 Hz and it's got a 7 dB peak at around 5kHz or so?
Now look at the polar response curve and find those 2 frequencies. Notice at 0°, they show up on the 0dB line? If you were on axis, the 5kHz signal would actually be 7 dB louder than a 1kHz signal, but they're shown as identical levels at 0°. In other words, they've been "normalized" to be the same level at 0° as all the other frequencies. In reality, that 5kHZ line should be 7dB louder on the graph, all the way around.
The only thing the polar pattern shows is the general pattern of the mic at different angles; it does not represent reality with regards to the actual signal levels you may get off axis. For that, you have to use the frequency response curve and extrapolate (i.e., "guess") the actual off axis response from there.
And that's the "last secret" of this whole thread. We started off discussing "diaphagm size", and this last post covers the polar pattern part of the question, although we discussed different polar patterns and their use earlier.
I hope you enjoyed this as much as I did, and I'll try to answer all questions, and clarify anything I din't explain as well as I should of. It's a big subject and I didn't go into it as fully as I maybe should have, but tried to make it as useful as I could to the broadest spectrum of posters here. If it was too simple and basic for some of you, I apologize, but just look at it as a refresher course. For the rest, I hope it's given you some insights into how to improve your own recordings. Whatever - I've enjoyed the hell out of this.
Sincerely,
Harvey Gerst,
Just An "Old Fart" Recording Engineer
chesterfield
New member
Harvey......... with regard to close-micing loud sources (guitar amp, snare, trumpet), isn't high SPL the most important factor? I just bought a Shure SM57 because it's universally acclaimed as THE mic for those applications. Is it because this mic has high SPL?
It's been said before, but thanks again for all your time and effort putting this info together. Now I've got to go back and find the link to print out the main text so I can save it and refer to it often.
It's been said before, but thanks again for all your time and effort putting this info together. Now I've got to go back and find the link to print out the main text so I can save it and refer to it often.
Harvey Gerst
New member
Actually, it's the fact that the frequency response of the mic complimemnts the sound of the snare and electric guitar that makes it so desirable. It adds a nice high frequency boost at the top end and has a natural rolloff at the bottom end, just damn near perfect for rock snare and electric guitar.
Kelly Holdridge
New member
Thanks, Harvey. I've learned volumes (print this sucker out, you'll see what I mean)!
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