Convert CD from unbalanced to balanced output?

aps · 3rd January 2011, 12:40 AM

My pre-amp has a true, balanced, design but my CDP has unbalanced (single ended) outputs. To deal with this difference I've just used some interconnects with XLR on one end and RCA on the other end. Is it possible to convert the unbalanced output of the CDP to a balanced signal prior to input to the pre-amp? And, if so, then how is this best done? I've read some posts about use of Jensen transformers but, having little experience in DIY electronics, I don't fully understand this option as most look to do voltage conversions. Thanks for the assistance and the reason for the interest is that the system into a new room that requires longer interconnects in a much more electrically noisy environment (behind an entertainment unit below a plasma screen).

Regards
APS

nightanole · 3rd January 2011, 02:03 AM

This might get you going:
Neve 1272 Preamp

It would act like a output buffer too which would help in long runs. The opamp he picked is a very good one. The power supply is alittle tricky but the opamp can work at 12 volts so you could use one of several designs such as ambs mini3.

Mind you all this is, is a rca to balanced converter thats happening inside your cd player. Depending on the cd player you might just be able to find a balanced single and just buffer it.

stephensank · 3rd January 2011, 03:14 AM

It would be FAR simpler an MUCH more sonically transparent to simply use an Analog Devices SSM2142 balanced line driver, if you are up to building a simple circuit board. If not, then the best way to go unbalanced to balanced is to go to the Jensen Transformers website & pick out one of their transformer-based converter boxes for the purpose. Pricey, but they make the best transformers currently available.

SoNic_real_one · 3rd January 2011, 04:28 AM

Quote:

Originally Posted by nightanole

This might get you going:
The opamp he picked is a very good one.

Really? The antique NE5532 is a "very good one"? better than other jellybeans, yes. Very good... not.

Steve Eddy · 3rd January 2011, 05:21 AM

Do you know if your preamp's inputs use input transformers?

If so, then there's really not much need to convert your CDP's output to balanced as input transformers will give you good common-mode rejection even when fed from unbalanced sources.

se

Extreme_Boky · 3rd January 2011, 07:39 AM

Quote:

Originally Posted by aps

My pre-amp has a true, balanced, design but my CDP has unbalanced (single ended) outputs. To deal with this difference I've just used some interconnects with XLR on one end and RCA on the other end. Is it possible to convert the unbalanced output of the CDP to a balanced signal prior to input to the pre-amp? And, if so, then how is this best done? I've read some posts about use of Jensen transformers but, having little experience in DIY electronics, I don't fully understand this option as most look to do voltage conversions. Thanks for the assistance and the reason for the interest is that the system into a new room that requires longer interconnects in a much more electrically noisy environment (behind an entertainment unit below a plasma screen).

Regards
APS

Your CD player may have DAC (or 2) with differential outputs...

Boky

nightanole · 3rd January 2011, 02:04 PM

Quote:

Originally Posted by SoNic_real_one

Really? The antique NE5532 is a "very good one"? better than other jellybeans, yes. Very good... not.

Well do you have an opamp hierarchy list? hes fine with stock rca outs but wants a longer run and to take advantage of his balanced ins.

AD8620
LME49720/LM4562

SoNic_real_one · 06:11 PM

LM4562 is my favorite for dual opamps.

Quote:

Originally Posted by Extreme_Boky

Your CD player may have DAC (or 2) with differential outputs...

I was ready to suggest that, but then I saw this in his first post:

Quote:

...having little experience in DIY electronics, I don't fully understand this option...

I don't expect changing the analog stage following the DAC is at his expertise level.

Bill Fuss · 3rd January 2011, 07:21 PM

If your player's output impedance is low enough (<300ohms), an output trafo such as a Jensen JT 11-em would fit the bill. Pretty much plug and play too. Just keep the connections from the player to the trafos as short as possible.

qusp · 5th January 2011, 06:37 AM

I would recommend getting Line transformers from Onetics/Bud purvine (BudP) here on the forum over the comparatively expensive Jensens, not much difference in SQ, but price is quite different and you can get it custom made to suit the gain you need and impedance match your gear.

3rd January 2011, 12:40 AM	#1
aps diyAudio Member Join Date: Jan 2009	Convert CD from unbalanced to balanced output? My pre-amp has a true, balanced, design but my CDP has unbalanced (single ended) outputs. To deal with this difference I've just used some interconnects with XLR on one end and RCA on the other end. Is it possible to convert the unbalanced output of the CDP to a balanced signal prior to input to the pre-amp? And, if so, then how is this best done? I've read some posts about use of Jensen transformers but, having little experience in DIY electronics, I don't fully understand this option as most look to do voltage conversions. Thanks for the assistance and the reason for the interest is that the system into a new room that requires longer interconnects in a much more electrically noisy environment (behind an entertainment unit below a plasma screen). Regards APS

3rd January 2011, 05:21 AM	#5
Steve Eddy diyAudio Member Join Date: Sep 2002 Location: Sacramento, CA	Do you know if your preamp's inputs use input transformers? If so, then there's really not much need to convert your CDP's output to balanced as input transformers will give you good common-mode rejection even when fed from unbalanced sources. se __________________ The Audio Guild

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3rd January 2011, 02:03 AM	#2
nightanole diyAudio Member Join Date: Feb 2009	This might get you going: Neve 1272 Preamp It would act like a output buffer too which would help in long runs. The opamp he picked is a very good one. The power supply is alittle tricky but the opamp can work at 12 volts so you could use one of several designs such as ambs mini3. Mind you all this is, is a rca to balanced converter thats happening inside your cd player. Depending on the cd player you might just be able to find a balanced single and just buffer it.

3rd January 2011, 03:14 AM	#3
stephensank diyAudio Member Join Date: Oct 2006	It would be FAR simpler an MUCH more sonically transparent to simply use an Analog Devices SSM2142 balanced line driver, if you are up to building a simple circuit board. If not, then the best way to go unbalanced to balanced is to go to the Jensen Transformers website & pick out one of their transformer-based converter boxes for the purpose. Pricey, but they make the best transformers currently available.

3rd January 2011, 07:21 PM	#9
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	If your player's output impedance is low enough (<300ohms), an output trafo such as a Jensen JT 11-em would fit the bill. Pretty much plug and play too. Just keep the connections from the player to the trafos as short as possible.

5th January 2011, 06:37 AM	#10
qusp is choosing a less facetious title... diyAudio Member Join Date: Oct 2009 Location: Brisbane, Australia	I would recommend getting Line transformers from Onetics/Bud purvine (BudP) here on the forum over the comparatively expensive Jensens, not much difference in SQ, but price is quite different and you can get it custom made to suit the gain you need and impedance match your gear.