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Quarter to quarter is easier and you can get the cable at any guitar shop (or Radio Shack)
Thanks man. I think I saw some posts from you regarding all of this when I was researching the MobilePre. I thought you had to make a -30dB attenuator so the phantom power didn't hose your MobilePre?

Since I already have an XLR to 1/4" cable, can I go ahead and use it? I am assuming that the phantom power should be turned off so power won't go into the 1/4" input.
 

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Elite Shackster , HTS Moderator Emeritus
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Discussion Starter #122
The attenuator was to go between the mic level and the line level of the 1/4" plug. It was in no way a protection circuit. I have no idea what would happen if you turned on phantom power, but it might not be good :yikes:

I don't know enough about your mic to 1/4 adapter cable. Does it attenuate? Is it balanced to balanced (tip-ring-sleeve)? I still think 1/4 to 1/4 is easiest, but if you have the cable you should be able to try it. I would keep the levels and gains VERY low at first to make sure you aren't over-feeding it. It can protect from a serious clip, but only so much.

Good luck.
 

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Elite Shackster , HTS Moderator Emeritus
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Discussion Starter #124
It won't attenuate, but it is unbalanced, so the mic input should know what to do with it (i.e. go unbalanced for the input signal).

It's been a while since I did that experiment so I'll have to refresh my memory on what I did.
 

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It won't attenuate, but it is unbalanced, so the mic input should know what to do with it (i.e. go unbalanced for the input signal).

It's been a while since I did that experiment so I'll have to refresh my memory on what I did.
I appreciate your help.
 

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The attenuator was to go between the mic level and the line level of the 1/4" plug. It was in no way a protection circuit. I have no idea what would happen if you turned on phantom power, but it might not be good :yikes:

I don't know enough about your mic to 1/4 adapter cable. Does it attenuate? Is it balanced to balanced (tip-ring-sleeve)? I still think 1/4 to 1/4 is easiest, but if you have the cable you should be able to try it. I would keep the levels and gains VERY low at first to make sure you aren't over-feeding it. It can protect from a serious clip, but only so much.

Good luck.
I just had to mention that my niece saw your avatar, and now we're watching Ratatouille.
 

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Elite Shackster , HTS Moderator Emeritus
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Discussion Starter #128
Counsil,
I just reread this entire thread (it kinda took off on its own). Now that I remember stuff, I think the worry was that we couldn't get the level down low enough without the attenuator. But with the master volume low and the dial gain all the way down, you can slowly bring it up to see how it looks.

If it goes all over the place, or looks too different from the graphs I posted, you may have to either attenuate or just do the 1/4 to 1/4 calibration when you can get a cable.

Let us know how it goes.
 

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Instead of getting the MobilePre, I am thinking of getting an M-Audio Fast Track Pro from a buddy of mine for really cheap (<$100). The Fast Track Pro has a mixing knob. Below is what the M-Audio website says about the knob. Where should I set it during sound card calibration and where should I set it when taking measurements? I have an XLR to 1/4" TRS cable (balanced to balanced) and an XLR to 1/4" mono (balanced to unbalanced). I would like to use one of them during the sound card calibration as I don't have a 1/4" to 1/4" cable. Thoughts? Same as above? Just turn the gain down really low to avoid clipping?

------ begin of quote --------

Q: What is the function of the Mix knob on my Fast Track USB/Podcast Factory USB/ Fast Track Pro?

A: The Mix knob on these devices controls the audio mix sent to select analog outputs, fading between the input signals from microphones, guitars, or other audio sources plugged into the device and the output signal from your audio application software. When turned fully counter-clockwise (input position), only the input signals from external sources are heard at the affected outputs of your device. When turned fully clockwise (playback position), only the output signal from your DAW software is heard at the device’s affected outputs.

Next to the Mix knob you will find a "stereo/mono" input selection button. If you are monitoring a mono input source (such as a guitar or microphone plugged directly into one input on your Fasttrack) you will need to have this button set to "mono" so that the mono input signal is panned to both your left and right speaker or headphone ear.

The outputs associated with the Mix knob are generally those that would be used to connect to a monitoring system like speakers or headphones. On the Fast Track USB and Podcast Factory USB, the outputs affected by the Mix knob are the red and white “1/L” and “2/R” outputs and the headphone output. On the Fast Track Pro, TRS outputs 1 and 2 (along with RCA/phono outputs 1 and 2) are affected by the Mix knob.

The advantage of having this type of Mix control is that you can create your own monitoring mix between the external input being sent to your computer and the software output coming back from your computer’s recording/DAW software.

For example, if you were recording a live instrument track, and wanted to be able to hear other pre-recorded tracks in your project while you performed, you could set the mix knob halfway between Input and Playback. Setting the Mix knob halfway between Input and Playback would allow you to hear your instrument input (with zero latency) while recording, while allowing you to also listening to the other tracks playing back from your DAW at the same time. In many cases, “directly monitoring” your external input like this is preferable to relying on the signal coming back from your DAW software to provide you with live input monitoring, as the slight delay introduced by having to send the external input signal from your instrument to your computer/DAW then back to your audio interface can make it difficult to perform your music reliably.

Lowering your latency/buffer settings for your hardware (when possible) can reduce the amount of delay inherent in monitoring your live input through your software, but the zero-latency monitoring offered via the Mix knob will always allow you to accurately and comfortably monitor your performance regardless of your hardware latency settings.

The Mix knob does not affect the signal being sent to your computer for recording in any way.

------ end of quote --------
 

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The Fast Track Pro has a mixing knob. Below is what the M-Audio website says about the knob. Where should I set it during sound card calibration and where should I set it when taking measurements?
Sounds like a monitoring function. I believe the full-clockwise position is what you want (input sources off).

Regards,
Wayne
 

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Great dialog, but not clear to me if there is a conclusion wrt microphone angle, the original topic of discussion.

Is it fair to say the conclusion is now that ECM8000 microphone should be best pointed at speaker for full range measurements UNLESS you only have a calibration that was done otherwise? It sounded like Anechoic does calibrations at both 0 and 90 degrees. Does 0 degrees means pointed at speaker? 0 degrees seemed to show HF peak between 10k and 20k (2-10 dB, average around 5) but extended response to 20khz. 90 degrees (vertical) gives flatter response at first, then drops 10dB or so at 20khz.

But even if it is "best" it may not be worth the trouble, given you have vertical calibration it's far easier to do vertical orientation measurements (and particularly if you need to do several).

One problem might be if microphone becomes more orientation/position sensitive when pointed at speaker. Perhaps vertical orientation would reduce that, for one thing, there would be less issue regarding how exactly you are aiming it, and therefore more repeatable results. Plus, it would be a whole lot easier for measuring multiple channels to use vertical orientation.

Another question in my mind is "what does vertical mean"? Is vertical pointing at ceiling or pointing at floor?

Now a question no one has mentioned here. Is it better to measure with listening chair in position? It would seem to me better to remove listening chair from room, otherwise gating will be ineffective, lots of early reflections. Human listeners, from what little I understand, can to some degree compensate for the early reflections from something like chair.

And how about this question: if you choose to use just one capsule position or vertical orientation, what part of listener's head should microphone capsule be positioned at? It would seem to me that for best accuracy, left-side channels should have microphone capsule positioned at left ear (where it would be during listening), and vice versa. I don't think I've ever seen anyone do this. If you choose not to take the trouble to do it, would it be better to position capsule at nose position or midway between the ears?
 

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Welcome to the Forum, Charles! These links should answer most of your mic orientation questions.

http://www.hometheatershack.com/forums/rew-forum/20293-full-range-eq-no-go-4.html#post184039
http://www.hometheatershack.com/forums/rew-forum/28299-first-time-rew-plot-3.html#post263849

There’s no good reason to get worked up about the listening-position furniture being in the room. The main thing is to keep the mic away from adjacent surfaces, especially the front and sides of the capsule. Just position the mic about a foot or so in front of where your head would be (i.e., giving it some distance from the back of the seat, especially if it’s high) and you’ll get good results.

Regards,
Wayne
 

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Hey i dont speak english so much as you do.. But i have a question im new in this thing i cant get working the rew program.. Mi question is doews this program works with my mini laptop microphone? Because non sistem goes higher than 94 db or 98 db please help..
 

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Just got a new, calibrated ECM8000 from Spectrum. I thought I'd ask a few, probably redundant, questions before taking some readings.

In particular, I wish to measure the performance of each of my drivers in my room, hence the problem. I don't have an anechoic chamber and taking the speakers outside is a no go due to their size.

I understand the best way to get a reasonable reading is to use the gating function to exclude room interaction. If that is correct, what are the recommendations for the gates? How far from the driver should the mic be placed? My speakers are two way DIY products with 15" ported bass bins and Tractrix horn HF.

If this has been covered in another thread, my apologies and could you post a link? I'm still searching.
 

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Elite Shackster , HTS Moderator Emeritus
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Discussion Starter #136
I used to do "Distance to first reflection point"/1100ft/s = Time to First reflection.

This is from memory, but I think that's right. Set the first gate to a few ms before the wave would even arrive (to minimize noise) and then the second gate after the first reflection.

For me, that was usually the floor and was really close, so I couldn't get any bass measurements. I would cover the floor with pillows and fluffy blankets and then use the next reflection (ceiling) measurement for the gate. This was for when I was getting measurments from the listening position.

For actual driver tests, I had a stick that was exactly 1m long that used to space the mic on axis at that distance. No early gate, but I set the late gate the same way as above.

If you can see the time/pulse waveform, you can actually see spikes when the first wave arrives plus all the reflections. This can give you a better idea of where to set the gates.

It's been a while, so this may be a bit rusty. Good luck, and let us know how it goes.
 

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Anthony, thank you and I will post results when I get going on this. Likely sometime next week.
 

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I've just purchased a pair of Behringer ECM-8000's that I will eventually have calibrated, but would like to download "Sonny's (Sonnie's?) calibration file" for some immediate measurements.

I've used the search function and can't seem to locate the Behringer ECM-8000 calibration file that I've seen mentioned in several threads here.

Where can I find it?
 

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thnks for your help.. my computer fail ad until ow i got it workimg.. im trying to use the rew program for car audio..:T i don´t know where to find a mic for made my mini lap acer workig:scratch:.. can you please tel me where to uy one ad send it here to mexico?:D im triying to get my self into the spl comp:paddle:..:clap: as you know im new in this.. thnks so much for your :help:..:wave:
 

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