[urs]

Dear Colleagues,

I need the help of an electronics expert.

I own a CEC HD 53 R headphone amp, which has two independent amplification sections, each with plugs and volume control (but common inputs)
Due to a slight hearing imbalance, I would like to operate this amp so that the two amp section each supply the left or right channel respectively and hence I can use it to adjust the balance.

I prepared a suitable Y-connector with the appropriate plugs and common socket (according to my checks, it should be OK)

Actually, the whole device works [size=x-small]nearly[/size] as intended---
EXCEPT: The two channels are “out of phase” (as you would experience with reversed speaker cables)
This is quite puzzling, as I would expect that both amp sections are identical, with a common earth and equal L + R output polarity ?

Any idea, why this is apparently NOT the case ?

I checked both the chinch, as well as the XLR inputs, using a test CD that has “In phase” and “out-of-phase” test signals.

Thanks for your suggestion of how I could fix this problem – if at all--!!

Best regards

Urs

 

[Dorder]

it's pretty odd they chose to use a opposite polarity on the sections, but since your amp has xlr inputs, a common xlr phase-inverter adapter on one input should do the trick.

 

[urs]

Thanks Dorder,

interessting approach !
I'll try that, to fix the problem on the input side

Urs

 

[Sovkiller]

Quote:

Originally Posted by urs /img/forum/go_quote.gif Dear Colleagues, I need the help of an electronics expert. I own a CEC HD 53 R headphone amp, which has two independent amplification sections, each with plugs and volume control (but common inputs) Due to a slight hearing imbalance, I would like to operate this amp so that the two amp section each supply the left or right channel respectively and hence I can use it to adjust the balance. I prepared a suitable Y-connector with the appropriate plugs and common socket (according to my checks, it should be OK) Actually, the whole device works [size=x-small]nearly[/size] as intended--- EXCEPT: The two channels are “out of phase” (as you would experience with reversed speaker cables) This is quite puzzling, as I would expect that both amp sections are identical, with a common earth and equal L + R output polarity ? Any idea, why this is apparently NOT the case ? I checked both the chinch, as well as the XLR inputs, using a test CD that has “In phase” and “out-of-phase” test signals. Thanks for your suggestion of how I could fix this problem – if at all--!! Best regards Urs

Just reverse the polarity at input or output, to see if this solve your problem first, I do not think is an out of phase issue, it is very unlikely they use different phase in both channels, have you checked your cables, and your headphones??? There could be a problem in any other place as well...

 

[urs]

To "reverse phases", what I'm worried about is, that I've got to connect "earth" of one amp output to "positive signal " of the other

(of course, it would be easier, if my HP had balanced wiring - but alas - it's standard 3-string cable, with common earth)

Urs

 

[Sovkiller]

Quote:

Originally Posted by urs /img/forum/go_quote.gif To "reverse phases", what I'm worried about is, that I've got to connect "earth" of one amp output to "positive signal " of the other (of course, it would be easier, if my HP had balanced wiring - but alas - it's standard 3-string cable, with common earth) Urs

Reverse the polarity in the input then, it will be easier...