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Technical question:Unable to dim the LH channel via headphones--> Is this normal?

post #1 of 7
Thread Starter 

Hi all,

 

Im strugling with the following;

 

I have build a Twisted Pear Audio Dual mono Balanced Pre-Amp.

I also have 2 TPA Ventus-EZ headphone amplifiers connected. These convert the balanced signal to Single Ended.

 

The setup is somewhat like this:

 

file.php?id=63050&sid=71f0677a5513d3e1d40f60f5c2a3156f&mode=view

 

I use one shielded twisted pair for the signal of the LH Ventus channel and one Shielded Twisted Pair for the RH Ventus channel.

The Red (hot) wire is used for the signal and I tightened the other wire together with the shielding for the signal ground and protection.

 

Both channels share a common ground just like on the picture above.

 

If I hook up the LH channel from the LH Ventus only the LH channel can be heard via the headphones. The same go's for the RH channel. Logically indeed.

But now when I have them both connected  and I dim the RH channel via the soundcard of the PC only the LH channel can be heard again. Logically again indeed :)

When I dim the the LH channel sound can be heard equally loud, and ik think also mono, trough both speakers.

 

I am starting to think this is normal behaviour. If I open the soundcards both channels stereo can be heard trough both speakers. It might be that the LH channel is a bit louder.

 

Is this normal? Ore is it inevitable since they share a common ground point?

 

The XLR connectors for the power-amp are parralel wired and here the diversion can be clearly made so that part works.

 

Many thanks in advance!

 

Jordo

post #2 of 7
Thread Starter 

No one here who can explain me about headphone plugs and common grounds?

post #3 of 7
Thread Starter 

A more detailed hookup sceme:

 

 

 

 

hookup sceme.png 252k .png file
post #4 of 7
Thread Starter 

Maybe a headphone with a higher Ohm value will help?

post #5 of 7

On the more detailed picture, the tip and sleeve are swapped. That would result in an effect like what you described.

post #6 of 7
Thread Starter 

Hi, thanks for your reply!!

 

Ah I see what you mean! :D   Wrong side around!

 

But in real it is connected correctly.... 

 

So is it more alike :)

 

 

 

 

hookup sceme.png 283k .png file
Edited by jordi81 - 11/9/12 at 6:11am
post #7 of 7
Thread Starter 

I now have a Beyerdynamic T70 250 Ohm.

But it makes no difference.... 

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