unbalanced to balanced connection

Speedskater

Speedskater

Audioholic General
The wiring seems like it is wrong from the start.
There is no negative connection in an unbalanced signal. There is signal (+) and ground. ........................................
Any signal has a Send and Return (or High & Low). In this case the Return is also the Shield and is connected to audio circuit common and the chassis.

But I don't think this is what the remainder of your post is about.
 
Johnny2Bad

Johnny2Bad

Audioholic Chief
The wiring seems like it is wrong from the start.

There is no negative connection in an unbalanced signal. There is signal (+) and ground. If an amplifier is wired with left on positive and right on negative, then the audio will cancel itself out as the amp flips the signal and sums the two. This often can eliminate vocals and mess significantly with the audio output levels.

I wouldn't expect anything more serious in terms of signal degradation.

If the incoming audio is mono, then the signal should be signal (center conductor) to + and ground (outer wire) to the ground connection. I would expect if this is for LFE, then it is a mono output from the source.

I assume that the two RCA jacks are connected to the LFE outputs of the Marantz, and that the amplifier then has the signal (center) on the two + connections on the amp. One RCA on one input, then the second RCA on the other input. Either move the ground to the ground connection, or jumper the ground connection to the two negative connections to get a solid signal.

I wouldn't expect a huge jump by putting a unbalanced to balanced converter in line with the amplifier as we aren't dealing with a mic level signal here.
Maybe you are thinking of a balanced 2-wire output (both conductors have the same impedance to ground).
With such a connection if 1V is present on the hot pin and 0V is present on the negative pin, the difference between them ... 1V ... will be the signal level.

If you connect the amplifier L ch Hot to the speaker and the amplifier R ch Hot to the speaker, you will get the phase-altered signal that was used to create pseudo 4-channel sound (as in the Dynaquad system).

I have not heard of a system connecting the L ch Hot and the R ch Ground, but I suppose it would work the same way, just 180deg out of phase.* That phase difference should not matter, however, because the information you will get with either wiring is out-of-phase information in the first place.

With a single-ended output 2-wire system (which describes the AV preamp outs he has) you cannot have 1V on the hot (+) conductor and 0V on the negative (-) conductor. The (-) has a lower impedance to ground than the (+) conductor does, thus it does not meet the criteria for balanced output.

Most balanced outs are 3-conductor, but they do not have to be. However they do have to have the same impedance to ground: (+) to ground and (-) to ground.

Finally, although it does not apply here, you can only have Balanced outputs. What are colloquially (and incorrectly) referred to as balanced inputs are technically not balanced but are differential inputs.

So this discussion has nothing to do with balanced anything; it's a single-ended output into a differential input.

Now, someone could say "well, you know what I mean when I say 'balanced input' " and you would be right, I do know what you mean. But that's not what some posters said; instead they said 'differential input' is incorrect. But that is not true; it is perfectly correct.

* Correction: on second thought it would not be the same. In a single-ended output, the (-) L and R are connected together. It would be as if you were connected only to the L channel, with no R channel information.
 
Last edited:
TLS Guy

TLS Guy

Seriously, I have no life.

The Crown only requires 1.4 volts to drive it to maximum output. I’m sure the Marantz pre-outs do much more than that. Bottom line, there’s not much chance that you actually need the Rolls.

There is no issue blending balanced and unbalanced equipment, despite what you’ve been told. I have balanced equalizers and amps in my systems and it all works fine with no issues.

BTW, you can find an article about gain structure when using pro gear in a HT system in my signature.

Regards,
Wayne A. Pflughaupt
I actually don't float lines like that. It is second best, with impedance and level problems. When going from or to balanced to unbalanced I always use either a transformer or now, more often a buffer amp. That is a better way to go. In his high end system he should be using a buffer amp like I recommended. That is the high road.

The pre out receiver voltage is almost never over a volt, Yamaha are only 0.75 volt out.
 
lovinthehd

lovinthehd

Audioholic Jedi
The pre out receiver voltage is almost never over a volt, Yamaha are only 0.75 volt out.
Not in my experience. Maybe Yamaha, haven't had one, but have seen better measurements for several of those in any case.
 
WaynePflughaupt

WaynePflughaupt

Audioholic Samurai


In his high end system he should be using a buffer amp like I recommended. That is the high road.
Unlikely to make an audible difference in SQ.

The pre out receiver voltage is almost never over a volt, Yamaha are only 0.75 volt out.
Most receivers these days put out well over 1 volt, except perhaps at the lower end of the model lines. You can’t rely on manufacturer’s specs - my receiver is rated for only 1 volt, but puts out 4.



What you need is an active RCA to balanced line out with gain. This unit will provide 4 db of gain which should be enough to boost consumer unbalanced out to pro balanced input.
There’s no free lunch. Boosting a receiver’s output is going to increase the noise floor by the same amount as the boost.

And you’re really recommending a device for a high-end system with a mere 88 dB noise spec, with unknown weighting at that?

Regards,
Wayne A. Pflughaupt
 
Last edited:
BMXTRIX

BMXTRIX

Audioholic Warlord
So this discussion has nothing to do with balanced anything; it's a single-ended output into a differential input.

* Correction: on second thought it would not be the same. In a single-ended output, the (-) L and R are connected together. It would be as if you were connected only to the L channel, with no R channel information.
I thought the discussion was about his wiring and if it is correct and if he can fix it himself or not?

Since I really don't have a clear picture of how things are wired, I'm guessing that the two mono subwoofer outputs are wired to the amplifier as follows:
LFE Output 1: Signal to channel 1 positive on the amp, ground to channel 1 negative on the amp.
LFE Output 2: Signal to channel 2 positive on the amp, ground to channel 2 negative on the amp.

I would recommend moving those negative connections to the ground, and if there is no improvement, then jumping them to the negative.

I would prefer to see some photos of how things are currently wired so I could make a more informed recommendation. If they wired LFE 1 signal to positive, and LFE 2 signal to negative, and LFE 1&2 ground to ground on the amp, then the signal would cancel itself out inside the amp and sound very poor. But, it's impossible to tell at this point, and the OP seems to have vanished at the moment.

It's about 15 minutes of rewiring to do some testing, which I think would be worthwhile.
 
Verdinut

Verdinut

Audioholic Spartan
The OP should proceed with one of the two connections suggested in the Rane article, as per Post #3 by Speedskater and put the input gain up on the Crown amp if necessary.

It will work without any problem. That is what I followed for connecting the pre-outs of my Marantz SR5010 to a DBX active crossover and all performs flawlessly.
 
BMXTRIX

BMXTRIX

Audioholic Warlord
The problem is that typical RCA cables, are not shielded cables, but just single pair cable, often of a coaxial design, and the Rane article doesn't address that connection method at all. Similarly, it doesn't address a stereo mini 1/8" jack connection to a stereo connection, which we see all the time in commercial installations (but isn't applicable here at all).

The connection on the back of the amplifier is a Phoenix (or Euroblock) type connection, not a XLR, so the closest drawing in the Rane article is #23, but since the RCA cable doesn't have a shield on it, then I would recommend putting the black (shield) on the ground connection first, then try jumping that connection to the negative terminal.

Certainly the gain on the amp should be set to near 0dB, it should not be sitting halfway or less, or anything close to that. Likewise, the sub output of the receiver should be at a reasonable level.
 
Verdinut

Verdinut

Audioholic Spartan
The problem is that typical RCA cables, are not shielded cables, but just single pair cable, often of a coaxial design, and the Rane article doesn't address that connection method at all. Similarly, it doesn't address a stereo mini 1/8" jack connection to a stereo connection, which we see all the time in commercial installations (but isn't applicable here at all).

The connection on the back of the amplifier is a Phoenix (or Euroblock) type connection, not a XLR, so the closest drawing in the Rane article is #23, but since the RCA cable doesn't have a shield on it, then I would recommend putting the black (shield) on the ground connection first, then try jumping that connection to the negative terminal.

Certainly the gain on the amp should be set to near 0dB, it should not be sitting halfway or less, or anything close to that. Likewise, the sub output of the receiver should be at a reasonable level.
If it's a Phoenix connection, then it's a different matter.

But all RCA cables that I have seen and used so far, in the last 60 years + were and have been shielded. To get an unshielded RCA cable, you have to buy a Chinese product from a store that sells crappy stuff.

See Post #31 for the suite.
 
Last edited:
BMXTRIX

BMXTRIX

Audioholic Warlord
Yeah, but that's not how Rane is referring to the RCA unbalanced cable. They aren't calling it 'shield', they are calling it the signal (red) and (black) then they don't have shield connected to anything. Typical RCA cables do indeed have signal and shield, but the way it connects to a balanced (or differential) input is not covered. I'm not sure what difference a phoenix connector with + - and ground matters compared with an XLR with the same connections.

With the original poster MIA, I'm not sure how much it matters at the moment.
 
Verdinut

Verdinut

Audioholic Spartan
Yeah, but that's not how Rane is referring to the RCA unbalanced cable. They aren't calling it 'shield', they are calling it the signal (red) and (black) then they don't have shield connected to anything. Typical RCA cables do indeed have signal and shield, but the way it connects to a balanced (or differential) input is not covered. I'm not sure what difference a phoenix connector with + - and ground matters compared with an XLR with the same connections.

With the original poster MIA, I'm not sure how much it matters at the moment.
With a RCA cable, the shield is always used in replacement of the return signal usually carried by the black wire. There is no reason the Rane recommendation wouldn''t work with the Euroblock input connection on the amplifier. It works with an XLR connection.

To proceed, a 2 conductor shielded cable such as the Canare L-2ES has to be used and connected as balanced to the Euroblock connector (L+, C-, R-shield) but the shield is not connected on the RCA plug end.

If the OP doesn't have the equipment to proceed, he could get the job done by a pro audio shop or order online from Redco Audio (Redco.com). The firm makes custom cables within a period of 2 weeks. As a matter of fact, I orderd three short Canare L-2ES cables with an RCA plug as the source end and balanced XLR male connector for the other end for my three main front channels. They did a good job at a cheaper cost than Blue Jeans Cables. He can call them and ask for Chris Stubbs, whom I believe is the manager and a nice fellow.

The Phoenix connection is as good for the purpose but not as sturdy as the XLR connection. Otherwise, the product would not be used by pro audio equipment manufacturers. For instance, QSC which is one of the pro audio manufacturing leaders, produce some cinema amplifiers which only have the Euro-style blocks as input connectors.

NOTE: My previous post was a bit misleading as I had forgotten about the required 2 conductor cable. I removed the erroneous section.
Cheers,
 
Last edited:
newsletter

  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis
Top