[pepar]

Does anybody have any recommendations on what to use to convert the balanced pre/pro outputs to unbalanced when they reach my amps?


TIA!

 

[Matt_Doug]

 Jensen Transformers

 

[rich wu]

You can just tie the negative of the balanced output to ground. Connect the positive (pin 2) of XLR to + of RCA and - & ground of XLR to ground of RCA. There are also XLR to RCA adapters from BAT and others that will do the same.

Rich

 

[pepar]

Quote:

Originally posted by Matt_Doug Jensen Transformers

Thanks, I found them as well. Is $100 per line the going rate? That's over $800 for my 7.1 system. Any idea how they compare to Rane's xfmrs?

 

[pepar]

Quote:

Originally posted by rich wu You can just tie the negative of the balanced output to ground. Connect the positive (pin 2) of XLR to + of RCA and - & ground of XLR to ground of RCA. There are also XLR to RCA adapters from BAT and others that will do the same. Rich

Really? That seems like a shortcut. Wouldn't that "unbalance" the whole line?

 

[macboy]

Quote:

You can just tie the negative of the balanced output to ground. Connect the positive (pin 2) of XLR to + of RCA and - & ground of XLR to ground of RCA. There are also XLR to RCA adapters from BAT and others that will do the same. Rich

You definitely do not want to do that.

The best solution is not a transformer either, it is a differential line receiver. This is a fully electronic device that will convert the balanced (a.k.a. differential) output back to single-ended. No electro-magnetics involved.

If you are handy with electronics, they can be easily built using a high-quality op-amp, or you can use dedicated devices, such as these or these from Burr-Brown.

 

[Matt_Doug]

Do not equate differential with balanced. A line with 2 possible signal paths and a separate path for ground is by definition differential but not necessarily balanced. a differential circuit resolves the difference between the 2 signal paths that may or may not be balanced. By balanced I mean that the the voltage on each signal path is of equivalent charge and opposite polarity. Your pre-amp maybe differential or have differential outputs but that does not mean its balanced. To actively balance a singal requires expensive transformers like Jensen's that many components with XLR's do not have. If the output from your pre-amp is not balanced then an xlr to rca adapter is fine. If it is a truly balanced pre-amp (like BAT's $$$$$) then transformers or what macboy suggested are appropriate.


Hopefully I got this right.


Thanks.

 

[scooter_29]

Quote:

Originally posted by pepar Thanks, I found them as well. Is $100 per line the going rate? That's over $800 for my 7.1 system. Any idea how they compare to Rane's xfmrs?

Jensen makes some of the best out there... The Rane transformers are going to be relatively cheap and of a much lower quality (they probably spent a few dollars for the raw transformer). The raw Jensen transformer alone can cost anywhere from $35-120 depending on the application.

 

[millwood]

I am not sure how you guys comfortable you guys are with solding. But get a quality OP amp and you can pretty much make a solid state balance->unbalanced transformer yourself.


I would put the parts to be within $10 (buying from Radio shack).

 

[pepar]

Quote:

Originally posted by Matt_Doug Do not equate differential with balanced. A line with 2 possible signal paths and a separate path for ground is by definition differential but not necessarily balanced. a differential circuit resolves the difference between the 2 signal paths that may or may not be balanced. By balanced I mean that the the voltage on each signal path is of equivalent charge and opposite polarity. Your pre-amp maybe differential or have differential outputs but that does not mean its balanced. To actively balance a singal requires expensive transformers like Jensen's that many components with XLR's do not have. If the output from your pre-amp is not balanced then an xlr to rca adapter is fine. If it is a truly balanced pre-amp (like BAT's $$$$$) then transformers or what macboy suggested are appropriate. Hopefully I got this right. Thanks.

The pre/pro is an Integra Research RDC-7 with AES balanced XLR outputs. Considering the quality of this unit, I'd bet that they're what they say they are.

 

[pepar]

Quote:

Originally posted by scooter_29 Jensen makes some of the best out there... The Rane transformers are going to be relatively cheap and of a much lower quality (they probably spent a few dollars for the raw transformer). The raw Jensen transformer alone can cost anywhere from $35-120 depending on the application.

I can see the higher specs of the Jensen and maybe that's the way to go. Considering all the money I've spent on everything else, I'd hate to choke the sound quality just before it hits the amp. But now I'm a bit confused about the active/passive (OPAMP/transformer) issue.

 

[tszfung]

Why transformer? You can just use the +ve leg of the balanced signal going to your single ended amp. I believe most of the cable companies can custom made these cables for you.

 

[millwood]

Mike:


the purpose of having a balance input is so that you can get rid of any common interference on the signal lines. What you proposed to do will not achieve that.


A transformer will, on the other hand, eliminate the common interference.

 

[pepar]

Quote:

Originally posted by tszfung Why transformer? You can just use the +ve leg of the balanced signal going to your single ended amp. I believe most of the cable companies can custom made these cables for you.

OK everybody, let's stop with this "just wire it unbalanced at the other end" stuff.

 

[Matt_Doug]

Pepar.

Do an internet search for xlr rca and baluns (short for balanced unbalanced.) You’ll learn a lot and maybe you might get lucky. XLR has a characteristic 110ohm Impedance and RCA cinch ranges from 25 to 55 ohm impedance. It appears not many (Jensen not included) consider this impedance mismatch great enough to warrant transformers and most just recommend adapters.


good luck

 

[millwood]

most line-level outputs use a buffer that is essentially an emitter follower (a 0db gain current amplifier). I would be surprised if their output impedance is > 10Kohm, vs. 45Kohm input impedance for a standard bjt line-level stage (and easily every Mohm for JET input stage).


so 25-55ohm vs. 110ohm on the interconnects isn't going to make a notiecable difference.

 

[Matt_Doug]

 Ebtech Audio's 8 channel Hum Eliminator ($290) also converts unbalanced signals to balanced signals and back. It only has 1/4 inch trs (tip ring sleeve mic & guitar ) inputs and outputs so you'll need to get separate rca(cinch) to ts and xlr to trs adapters very cheap at Radio Shack

Hope this helps.

 

[pepar]

Quote:

Originally posted by Matt_Doug Ebtech Audio's 8 channel Hum Eliminator ($290) also converts unbalanced signals to balanced signals and back. It only has 1/4 inch trs (tip ring sleeve mic & guitar ) inputs and outputs so you'll need to get separate rca(cinch) to ts and xlr to trs adapters very cheap at Radio Shack Hope this helps.

Thanks for the link. I'll check it out. Rather than adapters, I'd probably have my cables made with the 1/4" phone connectors.

 

[Matt_Doug]

Some time way, way in the future I plan to upgrade to dual differential fully balanced amps. But my pre/pro will probably only have single-ended outputs. I realize you're converting in the opposite direction but I would still love to know your impressions of the sound quality of the Ebtech unit if you get one. So please let us know- thanks.

 

[pepar]

Quote:

Originally posted by Matt_Doug Some time way, way in the future I plan to upgrade to dual differential fully balanced amps. But my pre/pro will probably only have single-ended outputs. I realize you're converting in the opposite direction but I would still love to know your impressions of the sound quality of the Ebtech unit if you get one. So please let us know- thanks.

I'm now leaning toward selling my ATI 1505 and 1502 amps and replacing them with one of their "Pure Balance" amps (with balanced inputs) eliminating the need for this extra circuitry altogether.