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Balanced vs Unbalanced Signals

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=145148
Printed Date: April 25, 2024 at 9:55 AM


Topic: Balanced vs Unbalanced Signals

Posted By: jh1973
Subject: Balanced vs Unbalanced Signals
Date Posted: January 09, 2019 at 5:22 PM

From what I've gathered,many OEM low level signals are balanced.So if you tap those for a signal and send them into amplifiers with unbalanced inputs what are some of the pitfalls or possible issues that can occur?Fade and balance,amp going into protect,etc?

Also,if you send those types of signals into a LOC will they come out unbalanced?Just looking for a discussion about the different signal types because the topic tends to confuse me.I've done a lot of reading on it and I kind of feel a little more educated about it but I definitely want to learn more.

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Rumors of Bob but never Bob......So what is it you tell people you do these days Bob?



Replies:

Posted By: jh1973
Date Posted: January 10, 2019 at 6:40 PM
Is it true that the - wire in car audio signals is the inverted signal?If so that is going to the grounded shield of an unbalanced input which would be the signal getting grounded out.Seems like it should cause serious issues but I have seen time and again where it does nothing bad and the system sounds great.How can that be?

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Rumors of Bob but never Bob......So what is it you tell people you do these days Bob?




Posted By: series vii
Date Posted: January 12, 2019 at 1:01 PM
The question: OEM design using Balanced signal and processing or unbalanced twisted pair wiring? Balanced signals have a the same signal on two wires however one is inverted and the conductors are usually twisted together and shielded. Known as low impedance wiring used on stage rigs, recording studios etc. This arrangement can send signals 800+ feet with little to no artifacts. Rockford, Soundstream, Zapco offered balance systems to increase voltage and reduced noise. The downside was using specialized cables to connect. Wiring is one Hot, one Cold, one shield.

Unbalanced, high impedance wiring uses a single conductor and some type of shield. This type is good for 20feet or so. Subject to interference, ground loops, signal loss. Standard RCA cables. I have seen a few companies using a quasi "balanced" designs using RCA cables.

The OEM hybrid: Unshielded twisted pairs. Used in telephone backbone systems to send signals over longer distances and provided noise rejection without shielding. One wiring will be the "shield" the other is the hot signal.

True Balanced line converted to unbalanced, combine the shield and the Cold wires as the shield and connect the Hot as your signal conductor. Without combining, the signal level will be low.

Many newer vehicles are using integrated systems. My caution here is know what you are cutting/tapping into!!!! Audio/visual signals are now integrated with control and other signals, CAN bus is one example. CAN bus uses unshielded twisted pair, similar to above. The electronics mod your HU is connected to might also turn on the wipers, seat heaters etc. The connectors might look familiar but it doesn't mean you know what language is being spoken.

An example: The Ford Sync system sends a fixed volume signal from the HU to the factory amp/processor. Volume is controlled via control signal to the processor . This means for integration you don't want to tap signal from the HU. This leaves the speaker outputs, the best option for LOC. PAC does offer a convertor but has some issues. Do research before diving into newer systems!





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