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Mic for REW

post #1 of 24
Thread Starter 
I was recommended the Behringer ECM8000. It looks good, but finding a xlr to trs adapter is proving to be a pain ( I want more than 3 ft of cable) and I'm not quite understanding the power requirements.

I've been looking online for an hour.

Would someone help me out on the power supply and where I can find a simple XLR to TRS adapter?

Gear mentioned in this thread:

post #2 of 24
Quote:
Originally Posted by pdxrealtor View Post

I was recommended the Behringer ECM8000. It looks good, but finding a xlr to trs adapter is proving to be a pain ( I want more than 3 ft of cable) and I'm not quite understanding the power requirements.

I've been looking online for an hour.

Would someone help me out on the power supply and where I can find a simple XLR to TRS adapter?

Normally we use short TRS to XLR cables as adaptors and then use XLR - XL:R cables to get the length.

There is similarly no mystery to power - it is handled using standard phantom power standards.

I get this feeling that you have a very non-standard mic preamp, and maybe you should obtain something more standard.
post #3 of 24
Thread Starter 
Yes I was looking for the right xlr to trs short adapter to go with a 15' xlr cable. I'm not coming up with any options online. Maybe I'm not looking correctly.

Phantom power? Mic pre-amp? Ummmmm.... I'm lost. Doesn't someone make a simple kit?
post #4 of 24
Thread Starter 
Bump-- Just need a simple 'package deal' recommendation.

Thanks
post #5 of 24
My suggestion is to get a UBS Mic instead. Much less parts to connect every time you want to measure. They do have higher distortion/noise floor but for room measurements, it doesn't matter. UMM-6 is what I have and it works very well. I have discrete Mic and pre-amp but I don't use anymore due to hassle of connecting it and disconnecting all the parts and all the cables and such. Price is also insanely good.

You can get them with better calibration from Cross Spectrum: http://cross-spectrum.com/measurement/calibrated_umm6.html. I bought mine with stock calibration from Parts Express: http://www.parts-express.com/pe/showdetl.cfm?partnumber=390-808
post #6 of 24
I might consider this USB mic instead though:
http://cross-spectrum.com/measurement/calibrated_umik.html
(currently sold out but pre-ordering for July)

Having the validated calibration file from Cross Spectrum is "worth it" from what I've understood.

If you have a laptop with an HDMI connection, then use HDMI to connect you laptop to your AV receiver. Then buy the UMIK-1 USB mic and connect it to the USB port on the laptop - and you are ready. No phantom power or anything else. The REW Guide on this site has the best explanation of the HDMI connection around (that I've found).

So, that is the most basic kit:

Use this guide:
http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/270#post_22823228

Have this hardware:
Laptop with USB and HDMI
The UMIK-1 or other USB mic
USB Cord (if you need extra length)
HDMI Cord of desired length
post #7 of 24
Quote:
Originally Posted by CubicleCrusher View Post

I might consider this USB mic instead though:
http://cross-spectrum.com/measurement/calibrated_umik.html

If you have a laptop with an HDMI connection, then use HDMI to connect you laptop to your AV receiver. Then buy a USB mic and connect it to the USB port on the laptop - and you are ready. The REW Guide on this site has the best explanation of the HDMI connection around (that I've found).

So, that is the most basic kit:

Laptop with USB and HDMI
The UMIK-1 or other USB mic
USB Cord (if you need extra length)
HDMI Cord of desired length
Good post smile.gif. The UMIK-1 seems to be the replacement favorite for UMM-6 although the last time I tried to read the very long threads as to why, it didn't converge to any good reason other than better bass calibration < 20 Hz or some such thing.
post #8 of 24
Thread Starter 
Thank you very much for that suggestion. I will order one of the USB mics.
post #9 of 24
Thread Starter 
Quote:
Originally Posted by CubicleCrusher View Post

I might consider this USB mic instead though:
http://cross-spectrum.com/measurement/calibrated_umik.html
(currently sold out but pre-ordering for July)

Having the validated calibration file from Cross Spectrum is "worth it" from what I've understood.

If you have a laptop with an HDMI connection, then use HDMI to connect you laptop to your AV receiver. Then buy the UMIK-1 USB mic and connect it to the USB port on the laptop - and you are ready. No phantom power or anything else. The REW Guide on this site has the best explanation of the HDMI connection around (that I've found).

So, that is the most basic kit:

Use this guide:
http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/270#post_22823228

Have this hardware:
Laptop with USB and HDMI
The UMIK-1 or other USB mic
USB Cord (if you need extra length)
HDMI Cord of desired length

I missed this. What if my laptop does not have HDMI?

Thanks for your help, by the way.
post #10 of 24
Quote:
Originally Posted by amirm View Post

Good post smile.gif. The UMIK-1 seems to be the replacement favorite for UMM-6 although the last time I tried to read the very long threads as to why, it didn't converge to any good reason other than better bass calibration < 20 Hz or some such thing.

I'm not 100% sure but isn't one of the benefits of the UMIK-1 is you don't need a separate SPL meter for mic calibration for REW?
post #11 of 24
Quote:
Originally Posted by pdxrealtor View Post

I missed this. What if my laptop does not have HDMI?

Thanks for your help, by the way.

Then you'll need an external sound card/pre-amp.
You'll also need an SPL meter.

This help guide has a specific product list for that kind of calibration:
http://polaraudio.blogspot.com/2012/01/calibration.html
post #12 of 24
Thread Starter 
Will a redmere HDMI cable work?
post #13 of 24
Quote:
Originally Posted by pdxrealtor View Post

Will a redmere HDMI cable work?
Redmere cables are good from the point of the view that they are thin so good in this situation where you need to keep your laptop connected to your system but want to move around. Not so good from the point of view that their silicon (in the cable) draws power from HDMI source and it should not be doing that. So if you are going to buy one, buy it locally so that you can return it if it doesn't work.

Either way, a long flexible HDMI cable is the way to go. You don't want to have heavy weights dangling from your laptop smile.gif.
post #14 of 24
Quote:
Originally Posted by |Tch0rT| View Post

I'm not 100% sure but isn't one of the benefits of the UMIK-1 is you don't need a separate SPL meter for mic calibration for REW?
As far as I know, that is supposed to be true of both mics. That said, I am not sure calibration is working reliably in either as last I checked, there was back and forth between revisions of REW and calibration files for these mics. I have read people saying that UMIK-1 is working that way but the same promise existed for the UMM-6.

Here is the good news though: you do not need to calibrate the levels at all. It doesn't matter if the frequency response graph is at say, 80 dB SPL and it should be 85 db SPL. You are not acting on that numerical level. What you are acting on is the shape of that graph and relative values. If you have a peak that is 20 dB higher at 42 Hz than 100 Hz, that is what you care about. What its absolute level is, is not material. It is like looking at a basket of apples: your goal is to have all of them be the same size. What each one of them weighs, is not important.

Let me know if this is not clear and I will post an example.
post #15 of 24
Thread Starter 
Quote:
Originally Posted by amirm View Post

Redmere cables are good from the point of the view that they are thin so good in this situation where you need to keep your laptop connected to your system but want to move around. Not so good from the point of view that their silicon (in the cable) draws power from HDMI source and it should not be doing that. So if you are going to buy one, buy it locally so that you can return it if it doesn't work.

Either way, a long flexible HDMI cable is the way to go. You don't want to have heavy weights dangling from your laptop smile.gif.

Well.... I ordered some cables from Mono and it turns out you can't couple two redemer cables together without having an active coupler. Since my coupler is wall plates (for my projector run) I can't use a redmere from wall plate to AVR or wall plate to projector. Needless to day I have an extra 15' run of redmere on the way so I'll be able to test it out.

Am I understanding correctly that a the only of HDMI and REW is audio? There is no video. Even still the source end would go to the AVR and the display end to the laptop. This so the redmere is properly supplied with power.

Quote:
Originally Posted by amirm View Post

As far as I know, that is supposed to be true of both mics. That said, I am not sure calibration is working reliably in either as last I checked, there was back and forth between revisions of REW and calibration files for these mics. I have read people saying that UMIK-1 is working that way but the same promise existed for the UMM-6.

Here is the good news though: you do not need to calibrate the levels at all. It doesn't matter if the frequency response graph is at say, 80 dB SPL and it should be 85 db SPL. You are not acting on that numerical level. What you are acting on is the shape of that graph and relative values. If you have a peak that is 20 dB higher at 42 Hz than 100 Hz, that is what you care about. What its absolute level is, is not material. It is like looking at a basket of apples: your goal is to have all of them be the same size. What each one of them weighs, is not important.

Let me know if this is not clear and I will post an example.

I think I understand. In short- all you're looking is the way the graph is formed at any given DB or HZ. The actual real DB does not matter. It's only a reference.
post #16 of 24
Thread Starter 
Here is the response from Herb at Cross Spectrum Acoustics

I don't measure sensitivity of the UMIK-1, but you can use the manufacturer's sensitivity data
post #17 of 24
Quote:
Originally Posted by pdxrealtor View Post

Am I understanding correctly that a the only of HDMI and REW is audio? There is no video.
That's right. You can also do without HDMI and simply use the headphone out jack. You will be limited to stereo output but that will get you a long way. If you have analog multi-channel, you can take the same analog jack and move it between those inputs and test all the channels.

HDMI on PCs can unfortunately be very unreliable. So the above is a nice back up option.
Quote:
I think I understand. In short- all you're looking is the way the graph is formed at any given DB or HZ. The actual real DB does not matter. It's only a reference.
You got it smile.gif.
post #18 of 24
Quote:
Originally Posted by pdxrealtor View Post

Here is the response from Herb at Cross Spectrum Acoustics

I don't measure sensitivity of the UMIK-1, but you can use the manufacturer's sensitivity data
He is saying he is not calibrating he sensitivity. Assuming you cared, you can take that single line in the calibration file from the manufacturer and put it in the one that Cross Spectrum give you. But again, it is not important.
post #19 of 24
Thread Starter 
Quote:
Originally Posted by amirm View Post

He is saying he is not calibrating he sensitivity. Assuming you cared, you can take that single line in the calibration file from the manufacturer and put it in the one that Cross Spectrum give you. But again, it is not important.

Ok. So I don't need a cal file or SPL meter with this mic?
post #20 of 24
Quote:
Originally Posted by pdxrealtor View Post

Ok. So I don't need a cal file or SPL meter with this mic?
The Mics come with calibration files. Cross-spectrum gives you a more accurate calibration but they don't attempt to calibrate the sensitivity. The sensitivity is just an extra line in the calibration file.

As I noted, levels are not important anyway. The frequency response which is governed by the calibration file is somewhat useful. But even there, you could do without if you had to. Since you have it, make sure to give that to REW so that it uses it.
post #21 of 24
Thread Starter 
Thanks. Good info. wink.gif
post #22 of 24
Thread Starter 
The Redmere cable works. I have had some issues with calibrating the spl level.

Im not sure exactly, but i think it has to do with the floor noise. The first night i used the mic i had a floor noise of ~50, and calibrating the spl meter in Rew was not a problem (using the simplified REW instructions). Later that night my floor noise was 99 and i gave up for the night.

Next day floor noise was still 99 so i reset REW preferences and started from the beginning. Now the noise floor is stuck at 30 and i havent been able to get it higher.

Because the noise floor is low, calibrating to 80db on the spl meter in REW is impossible. My system gets far to loud before the SPL meter hits 80db.

No adjustment of the mic input level has solved the problem.

This sounds like a sensitivity issue with mic... Does it not?

For now Im using -10 AVR setting and a 25 mic level setting to keep things consistent. But.... That will only remain consistent until I change speaker levels via AVR, or sub levels via gain knob.

It d be nice to be able to use the mic as an SPL meter too.

If anyone has any suggestions Im listening.

Also if anyone wants any info on the UMIK I can help where possible.
post #23 of 24
I don't know why we are back to wanting to calibrate smile.gif. Are you able to record a proper frequency sweep? If so, then keep going. If you are getting warnings from REW, simply adjust the level until that warning goes away (clipping). Measure the response with the amp in mute vs off. That will indicate if you are just looking at noise or real response of the system.

Post a frequency response graph and let's look at it.
post #24 of 24
Thread Starter 
Quote:
Originally Posted by amirm View Post

I don't know why we are back to wanting to calibrate smile.gif. Are you able to record a proper frequency sweep? If so, then keep going. If you are getting warnings from REW, simply adjust the level until that warning goes away (clipping). Measure the response with the amp in mute vs off. That will indicate if you are just looking at noise or real response of the system.

Post a frequency response graph and let's look at it.

It'd be nice to know the actual DB. Especially since the UMIK is supposed to be capable of putting that number out. I'm going to contact Herb at CS and see what he says. Here's a graph of just my subs. I was testing each location to see where the best fit was.

This is with no smoothing-

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