Is it possible to create a balanced RCA to XLR cable?

[WhoaNotWoah]

And if so, is there anything "less" balanced about such a cable than a mini-XLR to XLR cable?

I'm asking in the context of Pro-Ject turntables, as I decide between two different models, one with and one without a mini-XLR output.

Finally, if such a cable is possible, is there anything I specifically need to ask for from a custom cable maker to ensure that it's a balanced cable and not simply a common unbalanced RCA to XLR cable? And I have the same question for a custom mini-XLR to XLR cable, I suppose, in the event that I'm ordering one of those instead.

 

[Moonbase]

You are correct in think converting rca to xlr is not just totally a case of different connects. It quite easy to create an earth loop or impedance miss match. Ideally a clean box would be used to ensure signal levels and impedance matching.

 

[staticV3]

It's possible to create a balanced RCA to XLR cable.

When constructed correctly, the resulting connection is just as balanced as regular XLR->XLR.

Finally, if such a cable is possible, is there anything I specifically need to ask for from a custom cable maker to ensure that it's a balanced cable and not simply a common unbalanced RCA to XLR cable?

Here are two proposed schematics for balanced RCA->XLR:


Search for "Bruno Putzeys The G Word" for a deep dive on balanced audio.

And I have the same question for a custom mini-XLR to XLR cable

No special construction is required for mini XLR.

 

[gberchin]

The diagram here is the same as the one on the left in @staticV3's post, but is perhaps a bit more intuitive.

 

[Moonbase]

Although these cables can work maybe only use for a short distance. Ideally an adapter like this would be more technically correct.

 

[Speedskater]

The thread title is sort of a typo.
But it's easy to create a unbalanced RCA to balanced XLR cable (or adapter).

 

[DVDdoug]

An RCA connection from a phono cartridge can be balanced because the phono cartridge is "naturally balanced" with no "automatic" ground connection... It puts-out two opposite-phase signals (per channel).

However, there should be a separate ground-shield and that can come from a preamp with a proper balanced input. For it to be truly balanced, the RCA connections should not be "shorted" to ground. That means the adapter/conversion should be done at the turntable-end so that a 3-conductor balanced-shielded cable is used between the turntable and preamp. And the turntable itself may need a separate ground wire.



...I built something recently with a regular unbalanced RCA output (existing) going into a differential amplifier (that I built) with no ground on the RCA inputs - Just two differential inputs. (It solved a ground-loop noise problem.)

I'm asking in the context of Pro-Ject turntables, as I decide between two different models, one with and one without a mini-XLR output.

I assume you have a phono preamp with balanced inputs? It would obviously be more straightforward and more foolproof to get the one with balanced outputs.

It SEEMS like a good idea but in the real world I'm not sure if balanced phono connections have any advantage. I think any hum usually comes from the cartridge itself (which is a coil) so the noise is differential just like the signal and it's not killed with a balanced connection.

But hopefully you don't have audible hum, and you're never going to get "digital quality" anyway.

 

[Speedskater]

Well the raw output of a phono cartridge is often balanced. But a RCA connector or coax cable is a bad choice for connecting it to a balanced input phono pre-amp.

 

[WhoaNotWoah]

It's possible to create a balanced RCA to XLR cable.

When constructed correctly, the resulting connection is just as balanced as regular XLR->XLR.



Here are two proposed schematics for balanced RCA->XLR:
View attachment 380736 View attachment 380737

Search for "Bruno Putzeys The G Word" for a deep dive on balanced audio.


No special construction is required for mini XLR.

Thanks.

So, in your opinion, would a turntable with a mini-XLR output not offer me any advantage over a turntable without one (speaking of two Pro-Ject turntables if there's anything unique about them that makes them balanced at the RCA output, as I believe they claim, when using a MC cartridge)--specifically in the case where the phono amp I choose has no mini-XLR input and thus seems to require a custom cable either way, whether it's RCA to XLR or mini-XLR to XLR?

 

[DVDdoug]

So, in your opinion, would a turntable with a mini-XLR output not offer me any advantage over a turntable without one (speaking of two Pro-Ject turntables

If I wanted to go balanced I'd go with the balanced turntable or I'd re-wire it myself.

The RCA connections MIGHT be connected to the turntable's ground and any internal shielding. In that case, one of the signal wires is still "grounded" and you don't have a proper balanced connection.

But personally, I wouldn't bother with going balanced... I'm not sure it makes any difference and I gave-up trying to perfect/improve vinyl almost 40 years ago when I got my 1st CD player. Eventually, I replaced my vinyl and gave-up on vinyl altogether. (I still occasionally digitize a record that's not available digitally.)

...If I were buying a turntable today, I'd get one with USB and a built-in preamp.

 

[staticV3]

Thanks.

So, in your opinion, would a turntable with a mini-XLR output not offer me any advantage over a turntable without one (speaking of two Pro-Ject turntables if there's anything unique about them that makes them balanced at the RCA output, as I believe they claim, when using a MC cartridge)--specifically in the case where the phono amp I choose has no mini-XLR input and thus seems to require a custom cable either way, whether it's RCA to XLR or mini-XLR to XLR?

The mini XLR to XLR cable is much more straightforward to build.

There's no need to match impedances or add capacitors.

Just straight Pin->Pin connections.

 

[WhoaNotWoah]

If I wanted to go balanced I'd go with the balanced turntable or I'd re-wire it myself.

The RCA connections MIGHT be connected to the turntable's ground and any internal shielding. In that case, one of the signal wires is still "grounded" and you don't have a proper balanced connection.

But personally, I wouldn't bother with going balanced... I'm not sure it makes any difference and I gave-up trying to perfect/improve vinyl almost 40 years ago when I got my 1st CD player. Eventually, I replaced my vinyl and gave-up on vinyl altogether. (I still occasionally digitize a record that's not available digitally.)

...If I were buying a turntable today, I'd get one with USB and a built-in preamp.

I'm really not certain I will (go balanced, that is), and I at least won't right away. Mostly, I just want to future-proof myself if I decide to go that way in the future.

RE: vinyl in general, I understand. I grew up with CDs and it's still my preferred format, but my wife grew up with vinyl, so we're doing both. And I'm certainly not opposed to more physical media. Ideally, I'll come to appreciate vinyl in a haptic kind of way, the way I do with manual focus lenses.

 

[WhoaNotWoah]

I assume you have a phono preamp with balanced inputs? It would obviously be more straightforward and more foolproof to get the one with balanced outputs.

I feel like Pro-Ject muddles things with their "true balanced" marketing and what they offer in terms of turntables, cables, and phono amps. They stress that any of their turntables without an internal phono amp can be run balanced through their RCA outputs and offer RCA to mini-XLR cables for that purpose--which as far as I can tell only do you any good with one of their two Pro-Ject branded phono amps, as I'm not aware of any others with mini-XLR inputs. Then they offer at least a couple turntables with mini-XLR outputs, for which they also offer mini-XLR to mini-XLR cables to use with those same two Pro-Ject branded phono amps. One of those two Pro-Ject branded phono amps also includes XLR inputs, for which they theoretically offer one $200 mini-XLR to XLR cable, but only theoretically as far as I can tell, because no online retailer seems to carry it.

The phono amp that I've chosen (for now) is the Schiit Skoll, which, yes, has XLR inputs, but no mini-XLR, naturally--as that choice from Pro-Ject, as far as I can tell, seems specifically designed to keep you within their ecosystem of expensive cables and phono amps.

 

[WhoaNotWoah]

The mini XLR to XLR cable is much more straightforward to build.

There's no need to match impedances or add capacitors.

Just straight Pin->Pin connections.

Got it. Thanks.

 

[Speedskater]

There are very few pre-amps in the world with a balanced phono input.

 

[marcheloka]

Guys what about unbalanced connection - can i make it noise proof by using shielded cable? How much worse would it be than real balanced cable like xlr xlr? I need like 8m from my external 5.1 USB card with small Jack socket to my front speakers (active studio monitors) on another side of the room.

This cable is okay for unbalanced but shielded connection? Pic rel

 

[AnalogSteph]

I'll put it the other way round, an unbalanced cable should never not be shielded. (The archetype of an ideal unbalanced cable is coax.) Speaker cables can get away without because impedance levels, speaker sensitivity and audible frequencies are very low and any source of electrostratic interference would have to mount enormous fieldstrengths to become a problem. There have been instances of mains transformers coupling into crossover inductors magnetically but that's about it.

In your scenario there's basically a 99% chance of running into ground loop issues if you insist on using all-unbalanced connections, so don't do that. You would have to run a substantial wire for ground bonding in parallel, maybe 4 mm² and up would be my guess... a lot more than that bit of shield. Not very practical, especially if you already have balanced inputs at your disposal.

3.5 mm TRS minijacks are electrically equivalent to a pair of RCAs, just more fiddly, so you can apply the same approaches discussed above. (Adapting to RCA first might might things easier.) Your cable basically is a type of twinax; it's probably not twisted but should still be decent for carrying a balanced signal in a pinch when using one per channel. If you have to order something anyway, just get ordinary shielded twisted pair as used for XLR cables.

 

[morphemes]

The signal can't be balanced by a cable, but the noise is collected by the twisted pair.Feels like a waste of wire but youre still gonna need to use STP (shielded twisted pair) running both strands of the twist and wiring the unused conductor to the shield on the unbalanced side at least assures some noise still gets eliminated before amplification. the shield also shields & the twist also gives each antenna's noise floor a distinct +\- phase characteristic. Twists and braids physically balance in actual space. Probably where the idea for differential circuits came from in the first place. The twisted antennas reject more noise passively & the amplifier knows how to cope with this crazy ground loop you've created.

Long story short, use XLR cable & short the circuit on the RCA side of the cable. When you upgrade your source, you won't need New cable just the plugs. Think of if as extending the balanced amplifier's chassis all the way out to the unbalanced source. it's a faraday cage. A wormhole for your signal. Happy birthday!
This is a one way cable:

 

[staticV3]

The signal can't be balanced by a cable

Yes it can.

Differential =/= Balanced.