ruckus328
Well-known member
Shead: Number of things.
1) I can't really make anything out from the pics as it's too big a shot and too low resolution. If you can take some close up shots of all your wiring areas that will help. Since you have hum you have a ground issue somewhere and only so many places that can be cousing it. One thing I can notice in the pic is it looks like all of your Pin 1's are daisy chained and going to start ground - this would be my first suspect on your hum. Each of the XLR's Pin 1 should go to star ground. You could chain the inputs together and run that to star ground, and do the same with the outputs, and send/rtn, but tying them all together how you haved it now could effectively be creating a ground loop with your adjacent piece of gear.
2) If you haven't done so already, make sure you have scraped off the paint/alodine/powder coat/whatever coat from the chassis at your star ground location so you have a solid metal to metal ground contact between your ground stud and chassis. Also be sure to do this at every mounting hole on the individual pieces of your enclosure (top/bottom/sides, etc). Paint and alodine are not conductive, if you don't do this you'll have a bunch of pieces of enclosure that are floating and not grounded to each other (or very poorly grounded). If you use a multimeter and do a continuity check between ground locations it should read little to no resistance (0-1ohm).
3) Lorlin switchs have a metal stopper washer that sets the number of turns. Make sure you switch is turned completely counterclockwise before putting the stopper in. If you switch isn't stopping, than you stopper washer is either not installed or has fallen out, simple as that.
4) SSL threshold knob is often misunderstood:
fully clockwise=no compression, fully counterclockwise=full compression. As you turn it counterclockwise it lowers the threshold point (threshold point=point where compression begins)
The threshold knob centered at "0" DOES NOT MEAN no compression. Again, fully clockwise means no compression. The historical labels on this knob are really misleading. It's dependant on how hot a signal you have going into the unit (ie: if you don't have a loud signal going in you'll have to turn the threshold counterclockwise more to get it to compress. If you have a louder signal going in you won't have to turn it so much)
Even with no meter, if you give it a reasonably good signal (+4dbu or so) and turn the threshold fully counterclockwise you should have VERY audible compression, unless you're Heller Keller, you won't be able to miss it (and even she might utter the words....cam-peths-in). In fact it'll likely sound like utter garbage as you'll be compressing the piss, lint, and shit out of it at that point.
If you're not getting any compression, first thing I would check is that your "external in" switch isn't switched on. Just disconnect the wires from it and the main board. This switch (if engaged) severs the audio going to the internal sidechain, which would result in no compression possible. It's effectively a soft bypass switch (cool little hidden bonus).
Good luck.
1) I can't really make anything out from the pics as it's too big a shot and too low resolution. If you can take some close up shots of all your wiring areas that will help. Since you have hum you have a ground issue somewhere and only so many places that can be cousing it. One thing I can notice in the pic is it looks like all of your Pin 1's are daisy chained and going to start ground - this would be my first suspect on your hum. Each of the XLR's Pin 1 should go to star ground. You could chain the inputs together and run that to star ground, and do the same with the outputs, and send/rtn, but tying them all together how you haved it now could effectively be creating a ground loop with your adjacent piece of gear.
2) If you haven't done so already, make sure you have scraped off the paint/alodine/powder coat/whatever coat from the chassis at your star ground location so you have a solid metal to metal ground contact between your ground stud and chassis. Also be sure to do this at every mounting hole on the individual pieces of your enclosure (top/bottom/sides, etc). Paint and alodine are not conductive, if you don't do this you'll have a bunch of pieces of enclosure that are floating and not grounded to each other (or very poorly grounded). If you use a multimeter and do a continuity check between ground locations it should read little to no resistance (0-1ohm).
3) Lorlin switchs have a metal stopper washer that sets the number of turns. Make sure you switch is turned completely counterclockwise before putting the stopper in. If you switch isn't stopping, than you stopper washer is either not installed or has fallen out, simple as that.
4) SSL threshold knob is often misunderstood:
fully clockwise=no compression, fully counterclockwise=full compression. As you turn it counterclockwise it lowers the threshold point (threshold point=point where compression begins)
The threshold knob centered at "0" DOES NOT MEAN no compression. Again, fully clockwise means no compression. The historical labels on this knob are really misleading. It's dependant on how hot a signal you have going into the unit (ie: if you don't have a loud signal going in you'll have to turn the threshold counterclockwise more to get it to compress. If you have a louder signal going in you won't have to turn it so much)
Even with no meter, if you give it a reasonably good signal (+4dbu or so) and turn the threshold fully counterclockwise you should have VERY audible compression, unless you're Heller Keller, you won't be able to miss it (and even she might utter the words....cam-peths-in). In fact it'll likely sound like utter garbage as you'll be compressing the piss, lint, and shit out of it at that point.
If you're not getting any compression, first thing I would check is that your "external in" switch isn't switched on. Just disconnect the wires from it and the main board. This switch (if engaged) severs the audio going to the internal sidechain, which would result in no compression possible. It's effectively a soft bypass switch (cool little hidden bonus).
Good luck.
You could use shielded twisted pair cable (microphone cable). Solder the shield Only to pin 1 on xlr.
