Pre-Out vs Sub-Out: Everything You Need To Know - Vita Audio

Pre-Out vs Sub-Out: Everything You Need To Know

Just got a receiver and don’t know what is going on? You are not alone!

Looking at the back of this piece of kit can feel like a daunting task – especially when you see two output ports. These are the pre out and sub out ports.

Don’t have a clue what that means? You have found the right place! This article will take you through everything you need to know about pre out and sub out ports. Follow this guide to become an audio expert.

Quick Summary

In a hurry? We are here to help!

In short, the most obvious difference between a sub-out and a pre-out is their function. A sub out connects subwoofers to receivers, while a pre-out port connects the receiver to an external power amplifier. 

The rest of this article will take you through sub-outs and pre-outs in more detail.

Pre-Outs

A pre-out is a type of port that will be included in a typical A/V receiver. If you have gone for a high-end receiver, you will have one pre-out port. 

This port allows you to incorporate a power amp into your audio setup. You are no longer bound to the power amp that has been built into your receiver, allowing you to enjoy a greater quality of sound. 

A pre-out port works by passing audio signals without amplification through the receiver so that these signals can be amplified by an external amp. 

To put it into context, think about your audio system when you use a pre-out port. You can now connect your speakers to an external amp directly instead of connecting to the receiver.

You are connecting the external amp to the pre-out port on your receiver so that the audio signal can move through. It will not be amplified by the receiver, just the external amp, so you can enjoy better sound.

So, if you have a pre-out port, you can add an external amp so that your speakers get that bit more power. More power means more sound without potentially harmful strain on your receiver.

This often means that you will be able to dramatically improve your speaker system. If you are an experimental audiophile who likes to get creative, using pre-out ports will open a lot of doors. We recommend that you start using pre outs ASAP!

With this in mind, there are some things that you need to consider next time you are out shopping for a new A/V receiver. One of these is pre-out ports.

Generally, we don’t recommend that you purchase a receiver that doesn’t have pre-out ports. There are so many high-quality receivers that do support pre-out connections at everyone’s price point – there is no excuse!

That said, you will probably find that a receiver with more than one pre-out port is surprisingly expensive. This is because multiple pre-out ports tend to move the product up a price bracket.

But you do get what you pay for – receivers are almost always value for money, especially with multiple connectivity options.

Sub-Outs

Now onto sub-outs. 

A sub-out is a specific type of output from a receiver that is meant to be connected to a subwoofer. A sub out connection is similar to an SFE Channel in that it only transmits bass or low frequency audio to the subwoofer.

It filters out anything that is of a higher frequency so that bass sounds that are usually lost are now detectable and of good quality.

Sub-outs are the most popular way to connect a receiver and a subwoofer. If you have an at-home movie theater set up, you will probably have some sort of sub out connection. 

Confusingly, brands do not always label this port the same. It may be labeled as ‘sub-out,’ but ‘subwoofer’ is becoming an increasingly popular labeling choice.

Remember that these are the same port, regardless of what the manufacturer calls it.

Generally, there is only ever need for one sub-out connection so there tends to just be one port.

You can find receivers with two sub-out ports, but it is unlikely that the second will be used enough to justify the additional cost.

You will only need one port to connect up your subwoofer to your receiver. This can be done with an RCA cable or if you are feeling fancy or want to get those bass sounds pumping, an LFE cable.

Not sure how to connect up your home theater receiver? It’s super simple.

All you need to do is plug in an RCA cable from your receiver’s sub-out to the input port on the subwoofer. You can now enjoy quality sound and richer bass notes.

Are Sub-Outs Pre-Outs The Same Thing?

Hopefully, you are now well versed in pre-outs and sub-outs, but are they the same thing?

No, they are not. A pre-out is not the same as a sub-out, and nor is a sub-out the same as a pre-out. 

Pre-outs are used to connect an external amp to an A/V receiver. A sub-out connection is used to connect powered subwoofers to a receiver.

You also need to remember that a pre-out and a sub out transmit different types of data.

A sub-out will filter away high frequency sounds to relay only bass elements of an audio signal. A pre-out connection will not make that distinction and will transmit all the data from an audio signal. 

As bass sounds have a dedicated transmission with a sub-out connection, they are more prominent in the audio that will eventually leave the speakers.

This creates a more enjoyable music-listening experience for many audiophiles and a more immersive experience for movie buffs.

Differences

If sub-outs and pre-outs are not the same, what are their differences? We have already covered one key difference – what data is transmitted via the connection – but are there more?

The other, most useful difference to understand is their underlying or intended function.

A pre-out port can connect an external amp to a receiver, whereas a sub-out connection can only be used to connect a powered or active subwoofer. 

So, while both types of ports can be used to connect a powered subwoofer to a speaker without the need to include a receiver’s amp, remember that they are different.

Keep in mind that a powered subwoofer that is connected to a receiver using a sub-out or a pre-out will also act as an external amplifier. 

You will need to connect up an external amp if you are not using a powered subwoofer, no matter which connection type you choose.

Pre-Outs For A Subwoofer

If you are in a pinch, you can use a pre-out for your subwoofer connection as long as this subwoofer has an amplifier built-in.

This subwoofer will only relay the bass sounds from the pre out ports – any higher sounds will be filtered out and not played.

Remember that a sub-out port is designed to relay bass to the subwoofer. All audio data will be transmitted through a pre-out connection.

If you do decide to use a pre-out connection for your subwoofer, you won’t get high frequency audio coming out the other end.

This is because the subwoofer essentially can’t cope with higher frequencies, and so they will be ignored. 

You also need to consider the design of your receiver – some are not designed with a subwoofer output at all. However, you may find that you are still able to connect a subwoofer with a pre-out connection.

This is because pre-outs are compatible with subwoofers that have an internal amp.

To do this, you just need an RCA input cable. Simply run this cable from the receiver to your subwoofer.

Sub Pre-Outs

Some integrated amps and receivers will have an output port that is labeled a sub pre-out. You are not alone in wondering what this is and how it works!

A sub pre-out is just a port that transmits all or part of the data from the audio signal. These are typically found on A/V receivers.

You can use a sub pre-out connection for receivers to active or powered subwoofers. This is usually the port’s only function.

From a technical standpoint, there is no difference between a sub pre-out port and a sub-out port. There are no major differences in connectivity either as they are both designed to connect receivers and subwoofers.

You may find that your manufacturer has labeled this connection as either a sub-out or a sub pre-out. Remember that this does not matter because they are the same thing.

This also explains why many manufacturers use the terms interchangeably – it is not just to confuse audio newbies!

Connection is no different with a sub pre-out port – you still need to use an RCA cable, and you still need to use a powered or active subwoofer. Otherwise, you will need to fix up an external amp.

Final Thoughts

Sub-outs and pre-outs are types of connections found in most audio systems. They allow for upgrade potential for your setup to get better sound quality – an absolute must for any audiophile.

A sub-out connection is for connecting up subwoofers. Using a subwoofer will help bass sounds stand out which creates better and more realistic audio.

A pre-out is used for connecting up an external amp. This will then go on to power your speakers.

This is recommended as it will limit the load or stress that you put on your receiver, so your speakers can now work their best.

Jacob Stable
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