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Connector termination :: loss of bass / wonky sounds
Old 8th May 2019
  #1
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loji's Avatar
Connector termination :: loss of bass / wonky sounds

Curious as to the 'why' of why this happens ..

when my phone is in it's case, and I plug in my headphone (1/8 TRS) .. it doesn't mate all-the-way . . . it sounds 'fine' but there is a loss of 'center' info, most noticeable in the bass.

the bass is still there, doesn't sound 'wrong' per-say .... but if you push on the connector, suddenly the mono/center gets much stronger. the Bass feels more solid, etc ... it's like ' ahha, this is how it's supposed to sound.

I know it's because the TRS isn't mating fully due to the plastic of the case . . . but what exactly is going on?

is it the tip and ring shorting together just slightly ... is it the Sleeve not connecting to ground properly?

Is there any way this could happen with an improperly terminated XLR cable?
Old 9th May 2019
  #2
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Richard Crowley's Avatar
 

It is most likely the case that the sleeve is not making proper contact because the plug is not fully inserted.
That delivers essentially "Left-minus-Right" to both ears resulting in that monophonic, "thin" sound you describe.
Many commercial recordings/broadcasts mix the bass frequencies into the center. (From early days of stereo record cutting.)
So when you hear Left-minus-Right, the low frequencies are the most affected by the cancellation effect.

A similar problem results from people using XLR microphones through an adapter plugged into their camcorder, etc.
That also results in the Left and Right tracks of the video recording getting OPPOSITE phases of the microphone signal.
And when you listen to the video on a computer, etc, it sound (mostly) OK.
But when you play it on something monaural (that combines the Left and Right channels) the audio is almost completely cancelled.
Old 9th May 2019
  #3
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loji's Avatar
Quote:
Originally Posted by Richard Crowley View Post
It is most likely the case that the sleeve is not making proper contact because the plug is not fully inserted.
That delivers essentially "Left-minus-Right" to both ears resulting in that monophonic, "thin" sound you describe.
Thanks Richard,

the Sleeve should be the ground connection, correct?

So a poor ground connection is able to make a L-R mix? . .

I would think that would be the Tip and Ring bridging, with one out-of-phase because of a balanced connector.... just trying to visualize how a poor ground/shield/Sleeve connection would create that effect?

I've been going over the rane white-papers on grounding : https://www.rane.com/note151.html

Is there a scenario where a poor-wired ground/ pin-1 connection can make the 'thin' effect you are describing on an XLR connector? ... like an Unbalanced->balanced maybe?
Old 9th May 2019
  #4
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Richard Crowley's Avatar
 

Quote:
Originally Posted by loji View Post
I would think that would be the Tip and Ring bridging, with one out-of-phase because of a balanced connector.... just trying to visualize how a poor ground/shield/Sleeve connection would create that effect?
Yes. Because if you loose the common ground (sleeve) that goes to Left and Right, you end up with the Left and Right connected in SERIES between the Left hot signal and the Right hot signal. If you listen to some stereo tracks with pronounced separation on headphones or earbuds in L-minus-Right it produces a rather weird sensation of the music coming from INSIDE your head. Of course, the solution is to simply ensure that the ground/common is properly connected.

Quote:
I've been going over the rane white-papers on grounding : https://www.rane.com/note151.html
Is there a scenario where a poor-wired ground/ pin-1 connection can make the 'thin' effect you are describing on an XLR connector? ... like an Unbalanced->balanced maybe?
Yes. There is the "opposite" of the effect I described in my previous response (XLR into TRS stereo camcorder). And it happens even if the Sleeve/XLR Pin 1 connection is intact.

People take the TRS output from their iPod or phone and feed it into an XLR input on professional audio gear. That sends the unbalanced Left signal into the + side of a balanced input, and the Right signal into the -- side of the same balanced input. Again, that results in Left-minus-Right with the same problems as previously described.
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