Audio engineers, pro mixers, and manufacturers have varying definitions for pretty much everything in your audio gear, including all the inputs, knobs, and switches on your sub.
Two of these settings are line level and speaker level. Many people confuse these settings with each other, but they’re distinctly different.
Subwoofer line-level refers to an audio signal that hasn’t yet been amplified. Such a signal would come from a consumer device like a DVD player or professional audio gear (mixer, EQ., or audio interface). On the other hand, speaker level refers to the amplified signal fed directly to your speakers.
This article will guide you through the commonly used signal levels and touch on some of the key differences between your subwoofer line level and speaker level.
Audio equipment runs on varying voltage levels. Each device has its own requirements, so be sure to check what your headphones, television, speakers, or other devices require.
On average, smaller consumer electronics require lower voltage to pass audio signals from one stage to the next. Massive concert speakers, on the other hand, require more energy.
Generally, there are four signal levels you can monitor in your audio output:
As the name implies, mic-level signals are the audio signals captured by your microphone. A condenser microphone captures sound by detecting changes in air pressure. These changes make the mic’s diaphragm vibrate, which converts them into an electronic signal.
The strength of the mic signal can be altered by how far or close the person speaking into the microphone is. Often a mic signal is too weak and needs a boost. That’s what a preamp is for. It boosts the strength of a mic-level signal in preparation for processing.
Instrument-level signals are generated by your musical equipment (e.g. bass, electric guitars). They lie between mic and line levels.
Although an instrument signal is a bit stronger than the mic-level signal, you’ll still need a preamplifier to bump it up to a higher voltage to meet the requirements of most audio systems. Instrument signals aren’t strong enough to drive speakers.
Instrument-level signals can’t even make it past 25 feet (7 meters) without picking up unwanted noise. If you’re using long wires, you might want to switch to shorter ones. You’ll likely need to use a preamp to boost a line-level signal so that it can be safely transported to the amplifier.
Subwoofer line-level signals have a higher voltage than both mic and instrument signals combined. The preamplification that a subwoofer provides boosts the signal of these audio signals so that they can feed into an amplifier, which strengthens the signal into one that speakers can interpret.
A line-level signal without an amplifier doesn’t have enough power to drive most speakers. You might hear some sound with small speakers and subs, but if you’re dealing with larger subwoofers or commercial entertainment, you’ll need an amplifier.
Amplifiers can boost a line-level signal into a powerful signal capable of driving large speakers.
Speaker-level signals refer to the input audio that goes into a speaker. It needs to be at a certain voltage level before reaching the speaker to avoid distorted sound or equipment damage.
Of all the signal levels we’ve talked about, speaker-level signals (sometimes called high-level signals) are the most powerful sound outputs in a system. They also carry the largest voltage.
These signals vary in strength depending on the speaker sizes and the amplifier. You’d need more voltage to drive huge speakers and a smaller voltage to drive smaller speakers. Some amplifiers are much more powerful and better at amplifying signals than others.
Check out the video below for a more detailed explanation of the different voltage levels:
Line-level signals are low voltage signals output by devices, usually about -10 dBV. Speaker-level signals are high-voltage signals output by amplifiers. Line-level signals are fed into amplifiers that turn them into speaker-level signals which a speaker can pick up and output as sound.
Note that you’ll need to learn the exact input and output voltage levels of your equipment, or else you could develop poor quality audio or even damage your equipment.
Hooking up line-level devices to speaker-level outputs can melt the speaker wires and do irreparable damage to your amplifier from the excessive voltage.
Another big difference between line-level and speaker-level signals is the stage of processing. An audio signal from a consumer device such as a DVD player goes through processing, and the output is usually a line-level signal that’s yet to be amplified.
Feed this line-level signal to your subwoofer, and the built-in amplifier will turn it into a speaker-level signal.
As we embrace a digital age, sound systems, subs, and other audio gear continue to evolve. We have line-level signals mostly coming out from low-voltage RCA outputs.
In most cases, you’ll find a line-level signal ranging between 2-5V before amplification. Anything above the maximum threshold may overdrive your amplifiers and speakers and possibly fry them.
Speaker-level signals carry three, four, five, or ten times the voltage of a line-level signal. They could be slightly below or above 10V, depending on the power given off from the amplifier.
Clearly, such an amplified voltage is more than strong enough to drive massive speakers and subwoofer cones.
Note that a subwoofer line level can also refer to the input for incoming CD and DVD player signals, AV receiver, and professional audio equipment signals. From here, the speaker level output feeds the processed and amplified audio signal to the speakers.
Speaker-level and line-level both refer to the output voltage of audio devices, which need to be paired with compatible inputs in order to avoid distorted audio and equipment damage.
Line-level signals refer to the output voltage of an audio device, whereas speaker-level signals refer to the final output that the amplifier feeds into the speakers.
- Sweet Water: What’s the difference between Mic, Instrument, Line, and Speaker level signals?
- Sweet Water: Understanding Signal Levels in Audio Gear
- Audio Technica: Audio Solutions Question of the Week: What is “Line” Level and What is “Mic” Level?
- Black Ghost Studio: Audio Signal Levels Explained: Mic, Instrument, Line, and Speaker
- Sonic Electronix: High-Level V.S. Low-Level Inputs
- Youtube: What is Mic vs. Line Level? Signal Levels Explained
- Mixing Lessons: Mic, Line & Instrument Level Signals: Their Differences And How To Use Them
Jason is a home theater expert with over 10 years of experience in setting up home cinema rooms and systems. What started out as a hobby soon transformed him into an authority in the audio-visual field. He is passionate about providing readers with accurate and up-to-date information on the latest audiovisual technologies and their applications for home theaters. Read more about Jason.