Pre-out is a labeled or unlabeled line-level audio output that can be used as an alternate source for driving external power amplifiers or powered speakers. The term “pre” in pre-out usually means before, so the signal is just before the internal circuits of the AV receiver.
There are two pre-out options on your audio/video receivers: fixed and variable levels. The pre-out voltage tends to be either fixed (i.e., it has a specific nominal value) such as 2 V, 4 V, and 8 V, or variable (i.e., it varies with the volume setting) typically from 0 V to 5 V or more. In either case, a pre-out line-level audio output is always available unless it has been deliberately disabled – often by physically disabling the power connector at the rear of the AV receiver. The use of a pre-out requires an external amplifier, speakers, and speaker wire.
A pre-out system consists of an AV receiver, usually with an amplifier built in, speakers, subwoofer or passive bass speakers known as woofers, speaker wire to connect the powered speakers to the AV receiver’s multi-channeled line-level audio outputs referred to as “pre-outs.”
How does pre-out on AV receivers work?
Pre-out allows you to use the speakers connected to the AV receiver and another separate power amp for more powerful and precise sound.
When using pre-outs, it’s recommended that you use high-quality, shielded cables for connections between components. The use of unshielded or poorly shielded cables may cause noise.
However, there can also be a problem with some amps if they have a poor pre-out voltage, which is insufficient to power your speakers correctly. In this case, you will need an additional amplifier or replace your receiver.
Also, keep in mind that many receivers do not have the option of selecting pre output for each channel and the only option is to use front L/R jacks. It means that you will not be able to send signals from all your speakers, only front ones and, for example, if more of them are bi-amped or you would like to use different power amps for the center and surround – it’s impossible. If this is your case – look for a better amp or replace your receiver.
Is it needed to have pre-out on the AV receiver?
No, it is not needed, but it is a good option. Usually, AV receivers have pre-outs for amplifiers and power amps. They can be used, as was mentioned, to hook up a powered subwoofer or front speakers with an active crossover. They are very helpful when you want high-quality sound and don’t need the extra effort of setting everything up correctly. The better the pre-outs on the receiver, the better quality of sound you’ll have. It is because a pre-out is an amplified line-level output from a source component, so if your pre-out is of good quality, so will be the line level.
How to adjust pre-out on an AV receiver?
Some AV receivers have a built-in amplifier. It has two types of outputs: speaker terminal and pre-out terminal. On the pre-out terminal, you can connect an external power amplifier through a pair of RCA phonos or speaker wires. The volume level from pre-out is adjustable on your receiver. To do that, follow the below steps:
- Connect the speakers to the receiver. Plugin the power to both of them and turn it on (volume at minimum).
- Take a speaker cable (three or two core) and connect one end to “Sub Out” Speaker terminals.
- Connect another end of the same cable with the receiver’s Pre Out 2 Speaker terminals.
- Open the volume on your receiver to mid-level, then turn on the source from which you want to listen to music or watch movies
- Press the “Volume Up” button a few times on your remote control transmitter until you hear a ‘beep’ sound from connected speakers. It indicates that the pre-out connector is now enabled.
- Re-adjust volume to your desired listening level on the receiver.
Please note some AV receivers may have “pre-out” or “sub-out” on the front panel. In this case, you can use either of them to connect with an external amplifier.