[Harp-L] Mic Hum and wiring

["lprice@midwestmicrophone" <lprice@xxxxxxxxxxxxxxxxxxxxx>]

Hello,
   Larry Price from Midwest Microphone. I am sure you got a hundred replies allready but here is one more.  I think you are looking at a ground problem.  On the cable you should have two conductors maybe three.  either a middle wire and the braided sheath or the two middle wires and the braided sheath depending on the type of cable.  Now on the connector end of the cable you should have a 1/4 male connector the point is called the tip and the body is called the sleeve.  you should be abble to unscrew the sleeve cover from the connector.  What you want to do is identify which color wire (usually red) is connected to the tip.  This is important as this should be attached to the hot lead on your element. More about that later.  Now the next thing you need to do is connect the bradied sheath AND the second wire (usually Black) if there is one, to the sleeve portion of the connector. Usually this is the longer prong part on the backshell of the connector.  That is where a lot of problems occur with mic hum, in the connector, because everything else can be grounded properly and if the connector isn't or wears out (most common) that will screw everything up.  Anyway now you have to hook up the element.  If you have an astaic ceramic or crystal at least on the newer elements you will see that there is a tab that looks like it is rivited into the element.  This is your ground, so you want to connect either the black wire and braided sheath combo to it or just braided sheath if you have that kind of cable.  This is the most important part of killing mic hum. The shell, element and the cable all must be grounded together.  Do not assume that just because something is touching or looks like it would conduct a signal, that it will.  You will have to figure out how to positivly attach the ground wire to these components yourself but I'll give you an example.  On a Jt-30 there is a screw that is in the inside of the shell housing above the standhole.  I use this screw to attach a terminal lug.  On the terminal lug I solder the incoming braided sheath (now twisted into a wire)and black wire if there is one with a second wire that goes to the elements negative end.  This is a daisy chain ground but it insures all components are grounded properly.  All that is left is to connect the Hot wire (red usually) directly to the hot lead on the element again on a newer astatic element it will be a solder lug that is isolated from the element shell. You'll be able to tell the difference.  Put it all back together and viola no more hum unless you have other component problems and then there are other things to troubleshoot.  

This is a generalized account for most mic wiring there may be a myriad of components and configurations so without specific information I can't tell you exactly what you need but this should go a long way to explaning what the proper way is to wire most Hi impedance mics.  When you start to throw in volume controls on/off switches and xlr connectors things get more complicated and I am sure everyone has had enough.  

If you have questions feel free to write or call me at 
lprice@xxxxxxxxxxxxxxxxxxxxx
www.midwestmicrophone.com
800-286-7304

As always information is free and there is no such thing as a stupid question,  so don't be afraid to call.

Also sorry for any typing errors, Dammit Jim I'm a mc doctor not a linguist.