I bought this Sound Level Meter for next to nothing from Taobao, but it is available from the usual places too.
UNI-T Voltage Meter, Multimeter, Oscilloscope | UNI-T
With this it is very easy to calibrate the SPL in REW as it has a the right settings to match the meter. Knowing the absolute level within a few dB or so is good enough for me, the relative levels are more important for most uses.
This is another way to calibrate the level by electrical measurement and comparison to the sensitivity of the microphone. There is also a way to make your own 90 degree calibration file which works very well if a bit fiddly.
Room EQ Wizard SPL Calibration – without an SLM
There's three in the thread already, Cross Spectrum calibrated Dayton EMM6, Isemcon 7101 (and 7150), Sonarworks Xref20.
Earthworks if you want the mic to be flat without needing calibration and have enough spare cash
fwiw, I've come to believe it's not worth spending much on a mic for any kind of home audio work.
Here's some mic comparison measurements to help explain why.
(Just took these from a speaker i'm currently working on.)
Bottom dark green trace is an Isemcon 7150 with its supplied calibration file.
The light green is same mic without the calibration curve.
The blue trace is an ECM8000 without calibration.
Orange trace is another ECM8000 without calibration.
(i bumped them apart and used 1/6th smoothing for easier comparison)
There's just not enough difference between those traces to matter ime/imo.
About a year ago, i was able to compare my Isemcon 7150 to a matched pair of Earthworks M30's via transfer functions, at a measurement workshop.
There were simply no differences worth bothering over.
I should add the Behringer ECM8000's have had 15-20 years of use, often on a boom out in the sun and wind. Seems like they hold up fine.
I got the Isemcon about 6 years ago because it has a very high SPL capability that helps with PA builds, and i wanted a better mic to compare my cheapies to.
Was happy by the comparisons back then (and now).
So I can't see the need for spending money on a reference mic, unless you have some business need or something....or just plain want to..
And imho, knowing what we are measuring to begin with, and the limitations inherent in the measurement.... makes far more difference to the quality of our tuning than how good our mic may or may not be.
Just my 2c....
Here's some mic comparison measurements to help explain why.
(Just took these from a speaker i'm currently working on.)
Bottom dark green trace is an Isemcon 7150 with its supplied calibration file.
The light green is same mic without the calibration curve.
The blue trace is an ECM8000 without calibration.
Orange trace is another ECM8000 without calibration.
(i bumped them apart and used 1/6th smoothing for easier comparison)
There's just not enough difference between those traces to matter ime/imo.
About a year ago, i was able to compare my Isemcon 7150 to a matched pair of Earthworks M30's via transfer functions, at a measurement workshop.
There were simply no differences worth bothering over.
I should add the Behringer ECM8000's have had 15-20 years of use, often on a boom out in the sun and wind. Seems like they hold up fine.
I got the Isemcon about 6 years ago because it has a very high SPL capability that helps with PA builds, and i wanted a better mic to compare my cheapies to.
Was happy by the comparisons back then (and now).
So I can't see the need for spending money on a reference mic, unless you have some business need or something....or just plain want to..
And imho, knowing what we are measuring to begin with, and the limitations inherent in the measurement.... makes far more difference to the quality of our tuning than how good our mic may or may not be.
Just my 2c....
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This at last got me puzzled a bit. But I think you plan to use the onboard sound card of your computer. If that is meeting the specs (full duplex, one clock), you'd be fine with a microphone preamp with +48V. Like a DAP PRE-202. Or even a single phantom power unit, like the Millennium Pocket Phantom. Don't opt for the tube amps from Behringer unless you've checked they measure ruler-flat. They are not designed for that.
Thanks mark100 for your post btw. It's in line with my findings about stability on electret types, but I don't have access to my measurements now.
Hi ScottG,
Actually, it is not. I raised the issue and it has been already answered in the first few responses. Other questions, re phantom power, pre-amplifier, and alternative microphone were not discussed.
Nevertheless, my prompt yielded a result.
Greetings all,
thank you all for the recommendations.
I am still not sure about two issues:
1. Does the microphones, e.g., the EMM-6 that I mentioned not have a built-in pre-amplifier? From what I read, the pre-amplifier needs to be close to the capsule.
2. If, the microphone does have a built-in pre-amplifier, why do you recommend an interface?
Kindest regards,
M
Actually, it is not. I raised the issue and it has been already answered in the first few responses. Other questions, re phantom power, pre-amplifier, and alternative microphone were not discussed.
Nevertheless, my prompt yielded a result.
Greetings all,
thank you all for the recommendations.
I am still not sure about two issues:
1. Does the microphones, e.g., the EMM-6 that I mentioned not have a built-in pre-amplifier? From what I read, the pre-amplifier needs to be close to the capsule.
2. If, the microphone does have a built-in pre-amplifier, why do you recommend an interface?
Kindest regards,
M
There is a tiny amplifier in the mic, maybe think of it as a pre-preamplifier.
It needs phantom power to amplify the capsule's tiny output, up to a voltage level the interface (sound card) needs, which further amplifies the signal to line level.
So think of the soundcard as the mic preamp, and also as the source of the phantom power.
Make sense?
It needs phantom power to amplify the capsule's tiny output, up to a voltage level the interface (sound card) needs, which further amplifies the signal to line level.
So think of the soundcard as the mic preamp, and also as the source of the phantom power.
Make sense?
The EMM-6 does not contain any kind of "pre-amp". It's a condenser mic, and as such requires a polarizing voltage to operate, which is the "phantom power" that you may be familiar with. It must be connected to a mic preamplifier to increase the voltage from the diaphragm up to the millivolt to tens of millivolt range, and typically that hardware will also include the phantom power you will need. Even a very inexpensive unit like a Behringer UMC202HD will be more than adequate. I advise you to get one with 2 (or more) input channels so that you can do a dual-channel measurements if/when you want one. Look for combo input jacks like are featured on the UMC202HD - they can accept an XLR or TRS plug. The XLR is used for microphones, and the TRS is a 1/4" jack and there are cheap adapters to unbalanced RCA jacks so you can connect a line level signal on the second channel when performing dual-channel measurements. Always carefully read how to engage/disengage the +48V phantom power and whether it can be enabled when you have a TRS jack inserted, since you do not want to send 48V DC back up the line to your consumer gear!
The EMM-6 is basically Dayton's "copy" of the Behringer ECM8000, and it is IIRC a little bit less expensive. But they are more or less the exact same product.
There is another microphone product from Dayton called the "UMIK-1" that looks similar and has a USB connection. That product includes some sort of preamplifier. I would put it a tier below the EMM-6 and ECM8000 mics. It's convenient to use I guess. But one limitation is that you typically will want to position your microphone away from any boundary (floor, desktop, etc.) and this usually means up on a stand. The UMIK-1 encourages people to use the mic only as far away from their computer as the USB cable will reach. It's not ideal and not how you would want to conduct any kind of sensible acoustic measurement e.g. of your loudspeaker and its drivers.
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Hi M,
I still am not sure if I understand what you want. Maybe if you read this Gainphile: Cheap and accurate speaker measurement or even follow the link to siegfried linkwitz' microphone build, you find the answers you are searching.
Generally speaking, these microphone capsules need a voltage to work. It can be supplied from battery source as gainphile did and is also sometimes the case with mobile microfons when the recording device is not professional or non-classic AV tool.
Phantom voltage is not amplification and you may not need amplification. And interface is useful because it combines a proper Analogue-Digital-Converter ADC with standardized connectibility to use any mic and also phantom voltage is a standard feature. If you find out that your regular soundcard can deliver technically, you can DIY a cheap mic as was done in the provided link. If you find this to be an advantage.
I still am not sure if I understand what you want. Maybe if you read this Gainphile: Cheap and accurate speaker measurement or even follow the link to siegfried linkwitz' microphone build, you find the answers you are searching.
Generally speaking, these microphone capsules need a voltage to work. It can be supplied from battery source as gainphile did and is also sometimes the case with mobile microfons when the recording device is not professional or non-classic AV tool.
Phantom voltage is not amplification and you may not need amplification. And interface is useful because it combines a proper Analogue-Digital-Converter ADC with standardized connectibility to use any mic and also phantom voltage is a standard feature. If you find out that your regular soundcard can deliver technically, you can DIY a cheap mic as was done in the provided link. If you find this to be an advantage.
Hi mark100,
thank you for your reply. That was my understanding. Perhaps the miscommunication is due to terminology; the sources I found referr to the "tiny amplifier" built in the microphone as a "pre-amplifier".
Unfortunately, the understanding appears to be contradicted by CharlieLaub's contention, which I interpret as the microphone containing only a capsule and another device containing the phantom power supply and a mic preamplifier:
So despite everyone's attempts, I am not any further in understanding the issues.
Hi CharlieLaub,
thank you for your reply. Do I interpret the quoted language in response to mark100 correctly?
Hi sheeple,
as I replied to mark100, my current understanding is that the phantom power supplies power to the microphone, either only to polarize the capsule, if, as CharlieLaub suggests, there is no built in "amplifying device", or, to power a built-in amplifier and polarize the capsule, perhaps through the built in "amplifying device".
To perhaps re-phrase what I need to achieve. Provided that I buy one of the microphones mentioned in this thread, e.g., the EMM-6, and provide it with phantom power, will I be able to connect it via, let us say 5-6 yards long, cable to a sound card? Or, will I further need an additional amplification and/or an interface as suggested by several members?
So far I used a class-I microphone wherein I did exactly what I described above, but I will lose an access to it.
Kindest regards,
thank you for your reply. That was my understanding. Perhaps the miscommunication is due to terminology; the sources I found referr to the "tiny amplifier" built in the microphone as a "pre-amplifier".
Unfortunately, the understanding appears to be contradicted by CharlieLaub's contention, which I interpret as the microphone containing only a capsule and another device containing the phantom power supply and a mic preamplifier:
So despite everyone's attempts, I am not any further in understanding the issues.
Hi CharlieLaub,
thank you for your reply. Do I interpret the quoted language in response to mark100 correctly?
Hi sheeple,
as I replied to mark100, my current understanding is that the phantom power supplies power to the microphone, either only to polarize the capsule, if, as CharlieLaub suggests, there is no built in "amplifying device", or, to power a built-in amplifier and polarize the capsule, perhaps through the built in "amplifying device".
To perhaps re-phrase what I need to achieve. Provided that I buy one of the microphones mentioned in this thread, e.g., the EMM-6, and provide it with phantom power, will I be able to connect it via, let us say 5-6 yards long, cable to a sound card? Or, will I further need an additional amplification and/or an interface as suggested by several members?
So far I used a class-I microphone wherein I did exactly what I described above, but I will lose an access to it.
Kindest regards,
The built-in preamplifier usually has very low gain, it isn't much more than a low impedance buffer/line driver. A computer soundcard that has a mic input should have sufficient gain. A line input won't work. Typical output during "normal" measurement conditions is a few millivolts, even for the phantom powered ECM8000 which has an amp inside.
Beware that many computer soundcards provide "plug in power" which is a high impedance bias for a bare electret capsule. This is not going to power a phantom powered mic, you'll still need a phantom power adapter.
I went for the Isemcon because it is properly documented (the Behringer isn't), calibrated, small and it has a high SPL capability, because I also want to use it for measuring the SPL inside enclosures.
Beware that many computer soundcards provide "plug in power" which is a high impedance bias for a bare electret capsule. This is not going to power a phantom powered mic, you'll still need a phantom power adapter.
I went for the Isemcon because it is properly documented (the Behringer isn't), calibrated, small and it has a high SPL capability, because I also want to use it for measuring the SPL inside enclosures.
mefistofelez:
I often use for speaker measurements:
Behringer EMC8000 calibrated by Cross-Spectrum Labs, or EMM-6 (I have both)
20 foot long microphone cable (this has XLR connectors on both ends)
USB audio interface (I own: Clarett 2Pre, Scarlett Solo, Scarlett 6i6, and others)
I also have:
Earthworks M30BX - mic contains a battery that provides the polarizing voltage. Needs to preamp. Has RCA connector, and so can be used with any interface with "line in". Great mic. Expensive. But I hardly ever use it. When I do I connect to it using a home-made 12 foot long RCA cable.
These mics are both "condenser microphones". That is the type that is used for DIY audio measurements.
Maybe this will help clear up your fog, as an example of what someone uses?
If not, instead of just posting on here that you still don't understand, it might be time to educate yourself about microphones and measurement interfaces for audio work, since you don't seem to understand even the basics. Google, Wikipedia, etc. You can also go to top pro audio sellers sites and they often have tutorials.
I often use for speaker measurements:
Behringer EMC8000 calibrated by Cross-Spectrum Labs, or EMM-6 (I have both)
20 foot long microphone cable (this has XLR connectors on both ends)
USB audio interface (I own: Clarett 2Pre, Scarlett Solo, Scarlett 6i6, and others)
I also have:
Earthworks M30BX - mic contains a battery that provides the polarizing voltage. Needs to preamp. Has RCA connector, and so can be used with any interface with "line in". Great mic. Expensive. But I hardly ever use it. When I do I connect to it using a home-made 12 foot long RCA cable.
These mics are both "condenser microphones". That is the type that is used for DIY audio measurements.
Maybe this will help clear up your fog, as an example of what someone uses?
If not, instead of just posting on here that you still don't understand, it might be time to educate yourself about microphones and measurement interfaces for audio work, since you don't seem to understand even the basics. Google, Wikipedia, etc. You can also go to top pro audio sellers sites and they often have tutorials.
Charlie has it exactly right all these mics are condensers and the phantom power is for the polarizing voltage. There is no preamp electronics inside the mic, at least for the cheap ones.
The preamp is in the soundcard and the quality of it does matter. You can run a 100m XLR cable from a condenser mic to an interface without issue.
If you don't already have a good audio interface it really is worth getting one to supply the phantom power, have a decent mic preamp and good quality A/D converter. It doesn't have to cost very much to get those things.
If all you want is quick and simple SPL measurements, the MiniDSP UMIK works fine, with REW' s acoustic timing chirp you can go make the most important time locked measurements and the 48K resolution isn't that important most of the time.
If you want to take impedance measurements and measure above 48K sampling then investing in the interface and good enough analogue mic is the sensible way to go for me.
Edit Charlie beat me to it.
The preamp is in the soundcard and the quality of it does matter. You can run a 100m XLR cable from a condenser mic to an interface without issue.
If you don't already have a good audio interface it really is worth getting one to supply the phantom power, have a decent mic preamp and good quality A/D converter. It doesn't have to cost very much to get those things.
If all you want is quick and simple SPL measurements, the MiniDSP UMIK works fine, with REW' s acoustic timing chirp you can go make the most important time locked measurements and the 48K resolution isn't that important most of the time.
If you want to take impedance measurements and measure above 48K sampling then investing in the interface and good enough analogue mic is the sensible way to go for me.
Edit Charlie beat me to it.
Hi mefistofelez,
Charlie has more knowledge about how the mic actually works.
I was just trying to paint a perceptual picture of how low voltage the mic output is, and the need for further amplification to get it to line level.
An XLR cable between the mic and soundcard card can be over a hundred meters long, and still work fine with the tiny mic output.
edit : Haha...fluid beat me to it !
double edit: double haha ... didn't see Charlie beat both of us !
Charlie has more knowledge about how the mic actually works.
I was just trying to paint a perceptual picture of how low voltage the mic output is, and the need for further amplification to get it to line level.
An XLR cable between the mic and soundcard card can be over a hundred meters long, and still work fine with the tiny mic output.
edit : Haha...fluid beat me to it !
double edit: double haha ... didn't see Charlie beat both of us !
Even the cheap mics do contain an amplifier, but it is just a unity gain buffer, and with the XLR connected mics, a differential line driver. Otherwise the mic capsule's signal would be snuffed by the mic cable's capacitance. The mics being discussed here do not need polarization voltage (except for the Earthworks one, which uses a battery for that), they are based on electret capsules which have a permanently pre-polarized diaphragm or backplate.
But anyway, yes, further amplification is required, and using a built-in soundcard is not recommended unless it is a really good quality card. Especially on board soundcards tend to suck.
But anyway, yes, further amplification is required, and using a built-in soundcard is not recommended unless it is a really good quality card. Especially on board soundcards tend to suck.
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Hi timpert, CharlieLaub, fluid, mark100,
thank you for all the help, I now have the false impression that I understand the issues.
I freely admit that I do not know much about condenser microphones. However, the problem with "educating myself" via Internet is, that the information is inconsistent and often contradictory.
I could link several sources that explicitly stated that the pre-amplifier must be close to the capsule. Furthermore, the microphone I used must have both the phantom supply and pre-amplifier built in because it had a charging port for a battery and it was able to drive a line-level input of a sound card.
So, how is one not to be confused?
Kindest regards,
M
thank you for all the help, I now have the false impression that I understand the issues.
I freely admit that I do not know much about condenser microphones. However, the problem with "educating myself" via Internet is, that the information is inconsistent and often contradictory.
I could link several sources that explicitly stated that the pre-amplifier must be close to the capsule. Furthermore, the microphone I used must have both the phantom supply and pre-amplifier built in because it had a charging port for a battery and it was able to drive a line-level input of a sound card.
So, how is one not to be confused?
Kindest regards,
M
If you follow the link on gainphile's blog to SL's microphone build you will also find out about the circuits which are build-in in many condensor mics. Your microphone capsule will have comparable company, but it is nothing like a microphone preamp. If you dont want to buy an interface, just try a phantom power adapter, probably works. Costs 15 bucks from china, plus cables, a used 2i2 you may get for 60. Whatever serves your needs best. Some read-up on the working principles of condeser microphones was already suggested.
Here is a great overview of condenser microhpones:
Electret Microphones
@timpert:
I found this online - the circuit inside the ECM8000. It's as you say, to cleanly drive the signal on the lines back to the mic preamp on a balanced line. Pins 2 and 3 (XLR2 and XLR3 in the pic) both carry 48V DC to power the circuit, and return the mic's signal. Thanks for mentioning it.
Electret Microphones
@timpert:
I found this online - the circuit inside the ECM8000. It's as you say, to cleanly drive the signal on the lines back to the mic preamp on a balanced line. Pins 2 and 3 (XLR2 and XLR3 in the pic) both carry 48V DC to power the circuit, and return the mic's signal. Thanks for mentioning it.
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With condenser mics, the first stage of amplification must indeed be very close to the capsule, because a condenser mic has a very high (and capacitive) source impedance. Anything that loads the capsule degrades the signal, and that includes stray capacitance from cables. That's why electret capsules have a jfet built right in as the first amplifier stage, as you can see on the digaram that Charlie posted. XLR connected microphones need a differential line driver in addition. The EMM-6 (which appears to be the same as the ECM8000) has all that built in, and to power that that it needs phantom power. But the sensitivity is still only 10 mV/Pa, so you're looking at 1 to 2 mV of signal during a typical loudspeaker measurement at home. That is not line level by far.
Phantom power (and integrated pre-amplifer) is almost always from the audio interface: and multiple were mentioned - Behringer, Motu, Scarlett (Focusrite)..
Alternative microphones previously mentioned - Behringer, B&K, GRAS, NTI, Earthworks, SWBA, and Line Audio Design.
-so in FACT they were mentioned.
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