# single - ended output to differential - balanced input



## stubbmuffin (Aug 24, 2014)

I have searched tirelessly for an answer to no avail. I have a jl audio xd600/6 amp that has differential - balanced rca inputs. I have learned that those require twisted pair cables. But what I have noticed is that no head unit manufacturers list if their outputs are differential-balanced. I've heard that only super high end ones have those.


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## 2010hummerguy (Oct 7, 2009)

The XD600/6 looks like it has standard RCA single ended input...where are you seeing that it has balanced input?


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## stubbmuffin (Aug 24, 2014)

The manual says it is a differential-balanced input. Also says you can splice some rca to the head unit speaker wires


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## TrickyRicky (Apr 5, 2009)

Differential-Balanced Inputs: The JL Audio amplifier features differential-balanced input architecture to effectively control noise and ensure compatibility with a wide variety of source units, including many OEM systems. Without resorting to line output converters, you can directly connect most OEM source units to the JL Audio amplifier without creating any noise or compatibility issues. *Unlike conventional single-ended inputs, the differential-balanced design does not connect one side of the audio signal to chassis ground.* This eliminates any voltage sensitivity between one input terminal and ground and greatly reduces the incidence of alternator whine in a typical car audio installation.


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## stubbmuffin (Aug 24, 2014)

Yea I read that in the manual. But it doesn't say anywhere if it is compatible with a head unit with single - ended outputs. Which as far as I know all head units are single ended. I guess what I'm trying to ask is that if a standard head unit output compatable with this amp, and if so will it result in lower quality sound? If it isn't compatible then what do I need to do? Also I'm looking into buying a deh-80prs, I'm just waiting on answers before I pull the trigger.


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## stubbmuffin (Aug 24, 2014)

Also trickyricky, I'm not sure if you were just trying to point out the obvious to me. If so then it flew over my head and I apologize.


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## 2010hummerguy (Oct 7, 2009)

TrickyRicky said:


> Differential-Balanced Inputs: The JL Audio amplifier features differential-balanced input architecture to effectively control noise and ensure compatibility with a wide variety of source units, including many OEM systems. Without resorting to line output converters, you can directly connect most OEM source units to the JL Audio amplifier without creating any noise or compatibility issues. *Unlike conventional single-ended inputs, the differential-balanced design does not connect one side of the audio signal to chassis ground.* This eliminates any voltage sensitivity between one input terminal and ground and greatly reduces the incidence of alternator whine in a typical car audio installation.


Does this mean they use the signal and inverse signal? Never heard of this approach in an amp...I wonder if JL makes an adaptor cable for this.


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## minbari (Mar 3, 2011)

With a differential input you can still just connect a single ended Hu to it. You just lose the noise canceling properties of Differential.


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## TrickyRicky (Apr 5, 2009)

What am saying is that the input circuitry of the JL amps convert the single ended signal to differential INSIDE the amp, the differential-balanced design does not connect one side of the *audio signal to chassis ground*.


In other words to the OP, yes you can use the single ended from you HU or aftermarket. Or the speaker outputs as well (just make sure you set the gain right).


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## minbari (Mar 3, 2011)

^^^^ exactly. "ground" is just a zero volt reference.


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## 2010hummerguy (Oct 7, 2009)

Ahaaaaa, that makes sense. Super weird though...


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## stubbmuffin (Aug 24, 2014)

Freakn awesome. I'm relieved I don't have to drop anymore cash than I already have. Since it is perfectly compatable, what cables should be ran in this setup? Twisted pair or coaxial? Also would anyone happen to know if the deh-80prs has differential outputs, so I can get the utmost clarity? Or at least have some suggestions


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## minbari (Mar 3, 2011)

for the most part is wont matter alot, but technically you should run coax, since the source is single-ended.


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## 2010hummerguy (Oct 7, 2009)

stubbmuffin said:


> Freakn awesome. I'm relieved I don't have to drop anymore cash than I already have. Since it is perfectly compatable, what cables should be ran in this setup? Twisted pair or coaxial? Also would anyone happen to know if the deh-80prs has differential outputs, so I can get the utmost clarity? Or at least have some suggestions


80PRS output is single ended. The only units ever made with differential output are a couple Denons, RF 8250ti, and some of the Eclipse flagship units with outboard adaptors.


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## minbari (Mar 3, 2011)

FYI

Dont confuse "balanced" and "differential" they do get used interchangeably, but they are not the same. you can have a balanced singled ended output. balanced just refers to the matching of impedance between two components.

differential is the use of inverted and non-inverted signals to cancel common-mode noise. You can also have differential and not have them balanced. ( I would guess that alot more are not balanced than are)


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## rton20s (Feb 14, 2011)

I know this has been posted before, but it is a pretty good explanation of the two types of RCA cables. 

https://www.youtube.com/watch?v=QOagVDZLQnA

Tony D'Amore also gives a quick breakdown on which type of RCA to use under specific circumstances in the comments...

If the head unit has SE outputs and the amplifier has SE inputs = coax cable 
If the head unit has SE outputs and the amplifier has Diff inputs = twisted pair 
If the head unit has Diff outputs and the amplifier has Diff inputs = twister pair 
If the head unit has Diff outputs and the amplifier has SE inputs = bad no matter what as you will shorting out half of the head unit's outputs. In this case you would need an amplifier with Diff inputs or a converter to convert the head unit's outputs to SE


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## minbari (Mar 3, 2011)

ya, but making a diff output single ended is as simple as using the non-inv or inv output ONLY (one or the other) and signal ground. no convertor is required.


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## RocketBoots (Apr 16, 2011)

I think you've basically had you question answered OP, but just to clarify and consolidate:

Yes, the JL can take single ended RCA's. The nice thing is it can handle balanced diff RCA's as well. If you were to connect directly to an OEM HU, some of them use balanced differential outputs; most amps cannot accept that type of signal.

The Pioneer's outputs are single ended. Most aftermarket HU's are single ended. You do not need any adapters, converters, etc.


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## 14642 (May 19, 2008)

The reason for "balanced differential" is that it doesn't tie the shield to ground, thereby preventing ground loops. They can also be made to have high common mode noise rejection--that's essentially what "differential" means. They amplify only what's different between the + and - and reject everything that's common. Ideally that would be without reference to an attachment to ground, as in a real balanced output, but the head unit's output is usually tied to ground. In practice, inside the amp, low frequencies are tied to ground, but higher frequencies are not and this is done through an RC circuit in the input. Tuning that circuit is how you optimize the CMMR at higher frequencies where ground loop noise is a problem. In a true balanced input, that connection to ground doesn't exist. 

the speaker level outputs of the radio are balanced out and are completely isolated from ground (by 6V). You can hook those up to the "balanced differential" inputs and be 100% ground loop noise free. 

Basically, "balanced differential" means you can hook up just about any input.


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## ATOMICTECH62 (Jan 24, 2009)

The only HU's I know of that had balanced outputs were some of the older Kenwood Excelon's from about 15 years ago.I believe they were they were the 8xx and 9xx series that had the flip around MASK feature.They offered a few amps that had balanced inputs but it didnt catch on so they stopped making them.

I think there were a few other HU's like RF that had them but Im not positive.


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## Jepalan (Jun 27, 2013)

ATOMICTECH62 said:


> The only HU's I know of that had balanced outputs were some of the older Kenwood Excelon's from about 15 years ago.I believe they were they were the 8xx and 9xx series that had the flip around MASK feature.They offered a few amps that had balanced inputs but it didnt catch on so they stopped making them.
> 
> I think there were a few other HU's like RF that had them but Im not positive.


FWIW - Quite a few modern OEM "premium" sound systems with a separate factory amplifier use balanced-differential connections between the head unit and the OEM amp. Honda's "premium" sound systems are just one example.


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## stubbmuffin (Aug 24, 2014)

On that last note, if differential input is superior clarity wise, then why do no high end aftermarket head unit come equipped, and some oem ones do? I always thought that putting in a high end headunit wad one of the most important steps to a quality sound system?


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## Jepalan (Jun 27, 2013)

stubbmuffin said:


> On that last note, if differential input is superior clarity wise, then why do no high end aftermarket head unit come equipped, and some oem ones do? I always thought that putting in a high end headunit wad one of the most important steps to a quality sound system?


Because aftermarket HU manufacturers have to cater to the lowest common denominator, and they are always struggling to keep costs down. OEM's have advantage of designing a 'closed system' (i.e. they have control over both the HU and amp). BUT don't be fooled - IMO, OEM designs probably use balanced differential outputs for two main reasons: 1) they are re-using the same high-level output circuits in the 'premium' HUs that are used in the non-premium version of the HU that drives speakers directly, and wiring harnesses are cheaper to manufacture than shielded coax + RCAs. I'm not sure they are doing it strictly for SQ reasons.


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