# Is this good hardware to go with REW?



## Horacio (Jul 17, 2010)

I'm looking at buying a Dayton EMM-6 and a Shure X2u pre to connect to my laptop with REW in it. Are these good choices? Am I missing something?

The REW tutorial mentioned a Behringer ECM8000, but it seems for the price the EMM-6 provides more. Then Parts Express suggested the X2u, but I get no hits for it when I dig around for it here.

Thank you!


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## JohnM (Apr 11, 2006)

EMM-6 is good value. The Shure X2u looks to have the features required, including playback via the headphone connector (need to set the monitor control all the way to computer) but it might be difficult to make a loopback measurement, depending on how much range the gain control has. The loopback would allow the interface's roll-off to be compensated for, but more importantly let's you see whether any unintentional monitoring is active elsewhere in the chain (e.g. the input not being muted in the playback mixer controls). If you take some extra care to make sure there is no monitoring going on the Shure should work.


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## Horacio (Jul 17, 2010)

Thank you John.

What would you recommend instead of the X2u? Trying to undesrstand if I would need to pay $300 more to get the features you mention or just $50. On the tutorial I noted a presonus pre, but PE don't seem to carry it.

Thanks again!


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## JohnM (Apr 11, 2006)

There are lots of options, see the soundcards forum. The Tascam US-122MKII seems to crop up fairly often, but A Xenyx 502 with a computer's built-in audio interfaces can also do the job.


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## fenis (Oct 13, 2012)

Another noob here! I also have the Shure X2U XLR to USB converter and EMM-6 mic but I'm totally clueless on how to connect it to my laptop to calibrate it. Do I connect the X2u's headphone out to my laptop's mic in to create the loopback? This should bypass the laptop's internal soundcard I imagine as when I plug in the X2u the laptop shuts off all other line outs as it is in "USB speaker mode".

Also the Shure x2u is a high quality product with a +/-1dB 20-20khz response so do I even need to calibrate it given that I just want to measure the freq response of my car?

I'm trying to avoid the need to buy an external USB sound card if the Shure x2u is capable of getting the job done.


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## JohnM (Apr 11, 2006)

As the Shure has an output as well as its XLR input you could calibrate it using an XLR to single-ended adaptor to loop the Shure's headphone output back to its mic input, with the mic gain turned to minimum, but it would be a bit awkward and you can get away without doing it. Overall accuracy will depend on the EMM-6 rather than the Shure (you could get the EMM-6 calibrated by Cross Spectrum) but for car use (where response varies substantially over fairly small distances) the EMM-6 variations are not especially significant so you may as well simply use it uncalibrated. If you are using the Shure's output as the signal source make sure the monitor mix is adjusted all the way to the playback audio end to prevent any of the mic signal being fed back to the output, otherwise your measurements will be wrong.


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## fenis (Oct 13, 2012)

I have an individual calibration file for my EMM-6 from Dayton. I will attempt to calibrate the X2u via loopback as you suggested! Cheers for the prompt reply!


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## Wayne A. Pflughaupt (Apr 13, 2006)

In order to calibrate the soundcard using the headphone output, your best bet will be to use a 3.5 mm stereo-to-RCA splitter. That will allow you to use one channel of the headphone output (a 3.5 mono plug might not work). Then you’ll need a RCA-to-XLR-male cable to complete the loopback connection.

Regards, 
Wayne


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## fenis (Oct 13, 2012)

How come I have to separate the headphone output into 1 channel (L or R) to calibrate the X2u? Can't I simply just get a 3.5mm stereo to XLR cable for the loopback?


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## JohnM (Apr 11, 2006)

The XLR is a mono input, a stereo to XLR cable would likely break out the + and - of the XLR into the two signal connections of the 3.5mm jack, which would mean you would have one channel feeding the XLR + input and the other feeding the XLR - input, not what you need.


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## Wayne A. Pflughaupt (Apr 13, 2006)

fenis said:


> How come I have to separate the headphone output into 1 channel (L or R) to calibrate the X2u? Can't I simply just get a 3.5mm stereo to XLR cable for the loopback?


To expound a bit on what John said, and assuming you're talking about a cable like this:










The signal from the stereo 3.5mm headphone jack carries the L+, R+ and signal [-] (which is shared by both L+ and R+). However, as John noted, an XLR is a mono connector that’s typically wired Pin 2 [+] and Pin 3 [-]. So you can see the problem: Is the headphone’s L+ or R+ going to the XLR’s [+]? Who knows?? 

A better cable would be a 3.5mm to dual XLR male splitter, like the one pictured below. I have no idea why anyone would even make such a cable, but apparently they do – so hopefully you’re in business.










Regards, 
Wayne


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## fenis (Oct 13, 2012)

Thanks that makes perfect sense. I already have a 3.5mm stereo to 2 RCA Y splitter so I will just buy a RCA to XLR (male) cable.


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