Unbalanced Polarity Flip

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Drone
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Unbalanced Polarity Flip

Post by Drone » Wed Aug 08, 2018 2:45 pm

I have a little mixer without a polarity / phase invert switch, I'd like to make something that will flip the polarity of an unbalanced signal (coming in on a 1/4") without running the risk of shorting something, can I do it with a transformer or a couple of caps or something? :mrgreen:

Thanks in advance.
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Re: Unbalanced Polarity Flip

Post by vvv » Wed Aug 08, 2018 3:56 pm

Can't you just do that by rewiring a cable or extension jack?
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Re: Unbalanced Polarity Flip

Post by MoreSpaceEcho » Wed Aug 08, 2018 5:26 pm

if it were balanced, yes, but if it's unbalanced it's just the signal and ground wires, innit?

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Re: Unbalanced Polarity Flip

Post by I'm Painting Again » Wed Aug 08, 2018 7:46 pm

ya seems like you don't have multiple phases to flip - just the one phase plus ground coming in on the unbalanced line

what are you hoping to achieve ?

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Re: Unbalanced Polarity Flip

Post by emrr » Thu Aug 09, 2018 5:56 am

Yes, a transformer will do this.
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Re: Unbalanced Polarity Flip

Post by I'm Painting Again » Thu Aug 09, 2018 6:59 am

I'm assuming drone wants a way to flip polarity to A-B for what sounds better with multi mic recording or since it's coming in on an unbalanced line maybe an unbalanced analog mix

???

seems like you could buy a different mixer for the less than cost of all the transformers and components needed to build a switch and distribute the signal in order to do so - i dunno

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Re: Unbalanced Polarity Flip

Post by vvv » Thu Aug 09, 2018 5:34 pm

You could do it with software ...


... by what I mean, invert the track after it's recorded.
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Re: Unbalanced Polarity Flip

Post by Drone » Tue Sep 04, 2018 7:26 am

emrr wrote:
Thu Aug 09, 2018 5:56 am
Yes, a transformer will do this.
How would I wire it? Would I effectively be lifting the ground?

I'm guessing feed the signal in one side of the primary, and ground the other, and then on the opposing side take the signal of the opposing end of the secondary and use the other end of the secondary as signal ground?

If I feed the signal into a passive DI, would I be able to use the output of that and just use the +ve or -ve signal pin to get the desired signal? Hmm, dang it, Weber used to have little transformers for making a balanced output from a line level, but they seem to have gone. :cry:
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Re: Unbalanced Polarity Flip

Post by Drone » Tue Sep 04, 2018 7:27 am

vvv wrote:
Thu Aug 09, 2018 5:34 pm
You could do it with software ...


... by what I mean, invert the track after it's recorded.
Unfortunately the mixer is a submixer, as in it's mixing stuff before it's recorded :(
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Re: Unbalanced Polarity Flip

Post by Drone » Tue Sep 04, 2018 7:40 am

I'm Painting Again wrote:
Wed Aug 08, 2018 7:46 pm
ya seems like you don't have multiple phases to flip - just the one phase plus ground coming in on the unbalanced line

what are you hoping to achieve ?
I try not to say phases, isn't that a bunch of peoples pet peeve when you confuse polarity and phase? But yeah, I'm looking for 180 degree phase shift, so that when the wave goes up, the signal goes down, kind of thing.

The problem is, I have a signal split into multiple signal chains, and then mixed back together, but one particular chain seems to cause the low end to disappear when added in, so I wanted to try inverting the polarity to see if that improved things. I don't have a fancy phase adjustment tool, and I can't do it in the box.
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Re: Unbalanced Polarity Flip

Post by floid » Tue Sep 04, 2018 9:12 am

I think what Beard of Bees is saying is that a balanced signal has two opposite polarity phases with respect to ground, while an unbalanced signal only has one phase with respect to ground.
If you tie your single phase and ground to a transformer primary, the secondary can have a simple dpdt polarity switch. Any D.I. or isolation box that is transformer based could be modded this way if it does not already have the feature.
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Re: Unbalanced Polarity Flip

Post by emrr » Tue Sep 04, 2018 11:53 am

Drone wrote:
Tue Sep 04, 2018 7:26 am
emrr wrote:
Thu Aug 09, 2018 5:56 am
Yes, a transformer will do this.
How would I wire it? Would I effectively be lifting the ground?

I'm guessing feed the signal in one side of the primary, and ground the other, and then on the opposing side take the signal of the opposing end of the secondary and use the other end of the secondary as signal ground?
Yes, if I'm reading you right.
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Re: Unbalanced Polarity Flip

Post by drumsound » Tue Sep 04, 2018 3:53 pm

Drone wrote:
Tue Sep 04, 2018 7:40 am
I'm Painting Again wrote:
Wed Aug 08, 2018 7:46 pm
ya seems like you don't have multiple phases to flip - just the one phase plus ground coming in on the unbalanced line

what are you hoping to achieve ?
I try not to say phases, isn't that a bunch of peoples pet peeve when you confuse polarity and phase? But yeah, I'm looking for 180 degree phase shift, so that when the wave goes up, the signal goes down, kind of thing.

The problem is, I have a signal split into multiple signal chains, and then mixed back together, but one particular chain seems to cause the low end to disappear when added in, so I wanted to try inverting the polarity to see if that improved things. I don't have a fancy phase adjustment tool, and I can't do it in the box.
Is the source a microphone? Can it be moved to correct for phase coherence instead of reversing the polarity electronically? Maybe we're talking about a line level source?

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Re: Unbalanced Polarity Flip

Post by vvv » Tue Sep 04, 2018 5:27 pm

Otherwise, mebbe get an XLR coupler, open it and rewire the phase on one side. Just be sure to label the coupler for what it is!

See here: https://www.amazon.com/Hosa-GXX-195-XLR ... B000068O4L

https://www.musson.com/3-pin-xlr-phase-reverse.html (expensive version, but good description)
"The phase reverse offers a temporary solution to fix a miswired mic or cable. This female-to-male XLR 3-pin inline device reverses the connection of Pins 2 and 3 between the connectors, which flips the polarity of a balanced audio signal."

EDIT: OOPS! :oops: Just realized you said, "unbalanced signal".

I'll leave this up anyway because:
1. it might be helpful;
2. it makes me look dumb.

But see:
https://www.sweetwater.com/store/detail ... ent-device
https://www.sweetwater.com/store/detail ... nment-tool (XLR + reamp)

Or there's the out-of-production SM Pro Audio P-Control ...
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Re: Unbalanced Polarity Flip

Post by I'm Painting Again » Wed Sep 05, 2018 10:05 am

Drone wrote:
Tue Sep 04, 2018 7:40 am
I'm Painting Again wrote:
Wed Aug 08, 2018 7:46 pm
ya seems like you don't have multiple phases to flip - just the one phase plus ground coming in on the unbalanced line

what are you hoping to achieve ?
I try not to say phases, isn't that a bunch of peoples pet peeve when you confuse polarity and phase? But yeah, I'm looking for 180 degree phase shift, so that when the wave goes up, the signal goes down, kind of thing.

The problem is, I have a signal split into multiple signal chains, and then mixed back together, but one particular chain seems to cause the low end to disappear when added in, so I wanted to try inverting the polarity to see if that improved things. I don't have a fancy phase adjustment tool, and I can't do it in the box.
phases is appropriate here - phases don't exist to flip on unbalanced lines - - you have two phases in relation to ground on a balanced line

first thing I'd do is go over how everything is wired and the types of inputs and outputs on the devices in your signal path - are you mixing unbal and bal devices ? wrong wiring could be causing your problem in that case

if you know everything is connected correctly - try a simple delay in the path first and see if you can get a change in your low end by delaying it against the rest

might give you a clue that it's actually a polarity or phase issue

as for a polarity flipper in that situation and
I dunno if this will work but maybe try this …

the ebtech line level shifter will balance an unbalanced line (also change its operating level - so watch overloading your next piece of gear) the output can be wired to a switch (like the Shure A15PRS) to swap pins 2 and 3 to another line that's carrying ground or one of the polarities off the switch to the next unbalanced input



so it'd be like unbalanced cable (TS) from unbalanced output to the -10 in on ebtech then +4 output on ebtech to a balanced cable TRS wired to XLR -to the [Shure switch] - then - XLR out of Shure switch to cable wired XLR pin 1 to Sleeve / XLR pin 2 to Tip

if this works its probably possible to DIY with parts more inexpensively









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