[Amarphael]

Hello,
 
I've a pair of headphones that were recabled, They sound just fine but when i test the plug  for continuity i get a short signal between the channels (continous) as oppsed to other headphones where the signal is only momentary, indicationg shared ground. Please see more deatils in the following thread:
 
http://www.diyaudio.com/forums/headphone-systems/269595-shorted-channels-w-o-apparent-effect-sq.html
 
Restitance check turnes out OK according to nominal impedance which is 70 Ohms.
 
Again, Nothing wrong with the sound that i can detect- but continuity test indicates an apparent short. I'd really like to find out why is this happening.

 

[MindsMirror]

On headphones with a TRS connection you should expect there to be continuity between all the points. The ground for both channels is shared, and the signal wire for each channel is connected to the ground via the coil. You should see roughly 70 Ohms impedance from ground to left, and from ground to right, double that impedance from left to right, and no impedance from the ground wire in the left cup to the ground in the right.

 

[Amarphael]

Thanks, i did check the ground wires and it's aok. I wonder however, why do my other cans, Beyer T90 and K240 Sextetts, which are 250R and 600R respectively- When i test for continuity they both give only a momentary beep whereas the thread subject 70R SA5000 produces the continous signal? Is it some threshold of  resistance (or impedance in this case) that my DMM treats it like a short or something?

 

[MindsMirror]

Yes. You could even check your DMM's manual and it will probably tell you what that threshold is. Mine says it beeps under 50 (±10) Ohms.

 

[Amarphael]

Thanks man, That's what i needed to know.