Quality Signal Means Quality Sound

An often overlooked component to the average sound system is the cables associated with connecting everything together. Power and earth cables, both of these can be a road block if not provisioned properly. Without going into it too much, RCA’s and speaker cable too but to a lesser extent. We’ll go into more detail down below.

Cable is cable...right?

You might be aware of this but put simply, there is a difference between cheap cable and the good stuff. CCA (Copper Clad Aluminum) = Bad. Tinned 100% OFC (Oxygen Free Copper) = Good. Here’s why.

OFC is better for your car and your system.

Aside from being made from superior material, OFC cable is a copper base that has to go through a few extra steps before is sheathed and sold. Using chemical processes all the oxygen and other corrosive elements away from the cable and then tinned with a fine non-oxidising layer before adding the protective cover. Because of this and the fact it is copper and not aluminium the OFC cable can transfer current much more effectively meaning less drain on your car’s electrical system and power loss (due to heat) between the battery and the amplifier.

We use tinned 100% OFC cable exclusively. It's just better for everyone.

What's in an RCA?

RCA’s are a tricky subject. Not because they’re so complicated and sophisticated, but because there is so much information about them. I don’t want to pile on much more on top of that so I’ll just say that most of the time in terms of signal quality alone it’s not going to matter too much. Use some coat hangers for audibly identical results if you want. The real reason you want to think about what type of RCA connector to use is for it’s ability to reject electrical magnetic “noise” in a given setup. Knowing when to use which type of RCA is what separates the men from the boys in terms of signal interconnects.

First a quick background

Two types of signal transfer – Type 1: Single Ended (Unbalanced)

Coax RCA’s are made to transfer a single ended, unbalanced signal. The the inner wire carries the signal while the outer shield is earthed at both ends. The amplifier must have unbalanced inputs and will amplify the signal on the center pin relative to the earthed shield. The way noise is rejected in this case is that the shield takes in ALL the noise along the run and it is earthed, sending this noise away from the amplifier. This system is good for electrical noise, not so much magnetic noise and the coax shield generally has limitations of it’s effectiveness.

Type 2: Differential Signal

The signal is sent a little bit different here. The cables made for transferring it is known as a “Twisted Pair” RCA. What happens is the signal is sent through both connectors of each RCA, both the pin AND the “shell” connector. In this case one of the signals is inverted 180 degrees in relation to the other, completely opposite. If you put these signals directly together they would cancel each other out.

The signal is sent to the amplifier and along the way, because we have twisted the wires, all sorts of electrical and magnetic noise is introduced EQUALLY along both wires. So, how is this meant to work then? That’s where the differential inputs of the amplifier come into play. It’s a little complicated but basically the amplifier only amplifies the difference between the two signals, in this case the out of phase signal difference between the two wires. The noise which is common and equal is completely rejected. This process is completely analogue, no computer analysing or processing and very effective at rejecting both electrical and magnetic interference.

What the hell does this mean!? What should I use…twisted pair, right?

First make sure when you are designing your system you choose your equipment to match. No matter what parts you choose, follow these rules.

If the head unit has Single Ended outputs and the amplifier has Single Ended inputs = coax cable

If the head unit has Single Ended outputs and the amplifier has Differential inputs = twisted pair, it just won’t be 100% effective.

If the head unit has Differential outputs and the amplifier has Differential inputs = twister pair

If the head unit has Differential outputs and the amplifier has Single Ended 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 Differential inputs or a converter to convert the head unit’s outputs to Single Ended.

Connected Car Solutions Uses Coax Cable and Twisted Pair Effectively In Our Installations

That was just a taste.

Want to get technical?