I’m trying to figure out the best way to protect the outputs on a handful of analog synths. I want to run them straight to the console (through an xlr patch panel) but I’m absolutely certain I will forget to turn off phantom at some point and I would love to not blow up my synths haha. Prefer to not spend the money on xfrmrs and I’ve seen a couple simple designs that seem like they could work but I’m not certain how they may affect the sound. Any thoughts/advice are more than welcome! Thanks!
Phantom power blocker for synth outputs
- Thread starter bmaughan
- Start date
Help Support GroupDIY Audio Forum:
Brian Roth
Well-known member
Ignoring phantom for a moment, how would you otherwise connect the various synths to your console's mic inputs? Compared to a mic or typical musical instrument, synths are neither "fish nor fowl" in terms of signal level, output impedance or ability to drive low(ish) impedance loads.
Many/most(?) desks have a mic input impedance in the 1500-2000 Ohm range, although some mic inputs are way outside that range. The signal level from a synth may exceed the abilities of a mic input. Lotsa variables here...
Bri
Many/most(?) desks have a mic input impedance in the 1500-2000 Ohm range, although some mic inputs are way outside that range. The signal level from a synth may exceed the abilities of a mic input. Lotsa variables here...
Bri
Look at post #44 here
https://groupdiy.com/threads/help-d...line-level-to-balanced-interface.82656/page-3
https://groupdiy.com/threads/help-d...line-level-to-balanced-interface.82656/page-3
Are the outputs from the synths Balanced or Unbalanced?
Are you connecting them to Line inputs or Mic Inputs on the console?
Does you console have Line inputs?
Perhaps add clamp diodes from the outputs to the power supply rails.
JR
JR
k brown
Well-known member
Since the OP didn't answer the question, I'll also ask: why connect the line out from a synth to a mic preamp, rather than a line input?
Brian Roth
Well-known member
Good question....however, in some facilities a line input isn't "handy" in the area where the synths are set up. However, the OP mentioned having a XLR patchbay....so any given wire circuit could be used for mic or line levels into the desk. He was concerned about having a Brain Phart and making a mis-patch from a synth into a mic input with phantom active.
"Well, hell bellz boy....just don't do that!" some would say. I say "Sh!t happens..."
Bri
Yes exactly!
To answer a few of the questions that came up..
I’m fairly certain they’re all unbalanced outs.. perhaps one or two may be balanced.
And the console I’m using is a Yamaha m1516 that has a +4 line input position on the channel gain switch. Although I would probably rather run the synths output down a bit and drive the signal a bit from the channels 80200.
Each channel has two inputs..I use one for line and one for mic.. both have phantom potential. I know I’ll forget someday lol..
Line Inputs shouldn't have any Phantom Power 48V there.
I never ever up to this day seen a console which had 48V on the Line Inputs, only on the Mic Inputs
Did you measure that?
Did you insert a TRS cable on the Line input, turned Phantom Power on and measured DC voltage with the Multimeter (DMM)?
ruffrecords
Well-known member
I just checked the M1516 schematic. It has a pair of switchable mic inputs which are fed phantom power. There is a +4dBu input position on the mic gain switch which bypasses the mic pre but for some unknown reason it does not disable the phantom power. Even in the +4 position, the input impedance is only 1K3 which could be problematic for some synth output. I think you definitely need some form of protection such as that proposed by Bill.
Cheers
Ian
Cheers
Ian
Rob Flinn
Well-known member
Maybe it's only me, but I would be using a DI box to do this ...................
Accelerator
Well-known member
@bmaughan
Most (if not all of…) synths these days have TRS balance outputs, so you can connect them with a pair of TRS balance cables with 1/4” TRS Jacks to the stereo “line”-inputs of your Stereo Channel Strip(s) of you mixing desk.
If your synths also have XLR outputs (like mine Kawai MP11SE stage piano), it is recommended to connect these XLR outputs throw a D.I. box to your XLR microphone inputs of you mixing desk.
Since every microphone channel of you mixing desk have for its own an independent switch for the phantom power, it will be clever enough for you to make deferent arithmetical groupings between the channels that you NEED to use the phantom power (e.c. 1-8 the channels for your condenser microphones) from the channels that you DON’T NEED to use the phantom power (e.c. 9-16 the channels for your ribbon microphones, for your synths, groove-machines etc, etc,…)
k brown
Well-known member
That's about the stupidest design decision I've ever heard of.
Me too I’m just not able to swing 12 channels of quality DIs at the moment.
Since you have looked at the schematic, can you see a way to cut phantom from one set of physical inputs?? If that were possible then I could essentially have dedicated line inputs.
I’m pretty certain I’ve accidentally sent phantom into my apogee converters outputs with this strange setup.. no issues thus far :/
Im assuming some output sections are capable of handling phantom without issue??
