Dealing with pin 3 hot on a M-3500.....

[North Alabama]

Hi folks and glad I found this site! I am new to the forum and an ex-musician with some tech back ground getting into recording. Looking at the M-3500 schematics, is there a great and easy way to change the pin 3 hot to pin 2 on the XLR connectors? The cannon connectors looks like they are soldiered into the pc board for noise and structure according to the prints, have not looked into the board yet. One way looks like is to cut the trace and soldier jumper wires and someway swap some of the wires around on the pin J/P-7OO series connectors. I do not know if cutting the leads (or if they can be crossed over) on the cannon plugs would be a good ideal for structure purposes. I did a search and could not find a list or information on this mod.. Plus, any info on this board would be nice to know for I am a sponge right now. Thanks......

 

[diggy_dude]

Wouldn't it be easier to rewire the cable than hack the mixer?

 

[North Alabama]

This is what I am thinking. Others have done mods before but do not know how they did it and how it turned out, need advice or direction or instructions would be nice. If it is not to difficult and works and looks good, I will do a mod to get it behind me and over with so no more thinking about out of phase signals....

 

[diggy_dude]

How about adding phase inversion switches to all the channels then? Think of the engineering challenge, man!

 

[RRuskin]

The simplest thing is to do nothing. Being wired pin 3 hot is no big deal provided that the final polarity is consistent. Your mics will not care one way or the other. Anything coming in line level will not be influenced at all.

 

[North Alabama]

Thanks for the input guys. I am concerned about gear getting fried (me and/or the computer) by hooking up hot #2 pins, or noise, or unknown V floating around. Example, the input to the px for the monitors, that is backwards. The speakers should be going forward and not backwards, am I correct on that? Plus an issue of getting zapped by putting +48 wrong on a mic. I may wind up just resolidering a couple mic cables like everybody does and keep in mind where the + is thru out the chain and not fix the root cause including putting the right +/- to the power supply for the monitors...

 

[RRuskin]

Thanks for the input guys. I am concerned about gear getting fried (me and/or the computer) by hooking up hot #2 pins, or noise, or unknown V floating around. Example, the input to the px for the monitors, that is backwards. The speakers should be going forward and not backwards, am I correct on that? Plus an issue of getting zapped by putting +48 wrong on a mic. I may wind up just resolidering a couple mic cables like everybody does and keep in mind where the + is thru out the chain and not fix the root cause including putting the right +/- to the power supply for the monitors...

You won't hurt a properly wired mic, phantom powered or not, by leaving everything Pin 3 hot. If you are going to make a pin 2/3 swap, do it on all of your mic cables because you most definitely do not want a combination of signals coming in with opposite polarities.

 

[witzendoz]

Our M3700 is pin 3 hot on the mic pres, never had a problem, don't worry about it, a lot of early gear from Japan, Australia and UK had pin 3 hot.

Having pin 3 hot mic pres is like having a console with pin 2 hot and having all the phase reverse buttons pressed (I know that the 3500 does not have them). If every phase reverse button is in all the channels are back in phase. Phantom power works the same pin 2 hot or pin 3 hot.

I would not modify the mic cables either, thats the best way to get out of phase signals in the studio as they will get used with in phase cables at some point.

If you are worried about speakers going backwards (something I don't subscribe too) you can wire the cables on the main stereo outs, and the monitor outs out of phase, these cables should be a permanent connection so there won't be any problem in mixing them up with in phase leads. I would not bother.

Cheers
Alan.