Thursday, June 18, 2015

XLR Shielding

About 10 days ago I had an opportunity to record a young girl singer.  She sounded fabulous and I will eventually be releasing the recordings in various formats.  When gathering my gear together, I could not find the required TRS to XLR cable I need to connect my microphone preamp (an M-Audio DMP3) and the recorder (an Alesis Masterlink).  I quickly brewed up a cable.  Actually it wasn't so quick.  First I had to research the TRS and XLR pin connections (TRS is as intuitive as it seems--the tip is hot).  This was the first and only soldering job I've done all year, and I didn't do many last year.  I've never settled in with a good temperature on the RadioShack digital soldering station I now use, it's only a few years since I ditched my old Weller station with broken thermostat, so I even looked online for what temperatures other people use for Eutectic solder.  Just under 700F seems about right, or it could be over 700 if you have "confidence."  Actually it takes less than 400F to melt the solder, but the higher temps let you work quicker--which is better (better fast and hot than less hot and slow).  This was all being done in the wee hours of the morning, 2-4am, with the recording scheduled for the next day at 1pm (an early hour for me).  I made the cable, and then found I had done it completely backwards so I had to take it all apart and put it back the right way.  Finishing just before 4 am.  Whew!

Actually what I did was to cut a 6ft TRS to TRS, and solder in an XLR.  But if you look at the official AES recommendation (as written up by Rane), it appears that a TRS to XLR should be wired lifting the shield at the XLR end.  (This is very strange and seems to deviate from all their other recommendations.)  I wired pin 1 to the shield, which I measured at being connected to the TRS sleeve.

I just ordered a new TRS to XLR cable from Sescom through Markertek…it will be interesting to see how they do it.

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