One of the crucial moments of experience in an audio system is to have a punchy bass with excellent audio. While some people like their bass to be moderately deep, others love room-shaking, chest-pounding bass. If you are a bass-head, then you should definitely get a subwoofer no matter how high-end your speakers are.
Tuning the subwoofer frequency can be a bit tricky because to have the perfect sweet spot for a smooth transition between the subwoofer and the speaker, you have to go by your ear. Although modern AV receivers come with an auto-calibration method with mic, the settings might still need some manual adjustments.
The ultimate purpose is to make sure the subwoofer creates harmony and blends in with your sound system. If the crossover frequency is adjusted at a perfect level, then you will not notice a subwoofer seperately in the system and that’s what we want.
This is the ultimate guide of bass management and once you read it, you will know about the connections and methods of setting up the frequency of a sub.
How does a subwoofer work?
The main purpose of a subwoofer is to enhance the low-frequency range or the bass section which your speakers are unable to reproduce. They deal with the lowest two octaves, 20Hz to 80Hz. The problem is, simply placing a subwoofer in the room will not generate punchy bass, you have to tune it or tweak it, but most modern systems have auto-calibration saving you from doing the legwork.
Along with tuning with frequency, gain (volume), or phase, you also have to work with the placement of the subwoofer for the optimum audio experience. Room acoustics also plays a vital role here.
The sub also deals with bass responsible for having the highest energy. As the subwoofer handles the power of the low-frequency audio, it relives the speakers from this power while delivering punchy and tight bass.
Why do you need one?
Subwoofers are the heart of an audio system that takes your experience with movies and music to a whole new level. If you think you have a large woofer in your speakers that produce deep bass for a small room, then maybe you don’t need it.
However, if you have a large room, chances are that so matter how low the speakers say they can get, they can’t do the job of the sub. Once you decide to get the sub, the next important task is to set the correct crossover.
Define the subwoofer crossover:
The following glossary terms will help us to have a better understanding of the context:
- LFE or Low-Frequency Effect: this is the section of the sound that delivers immense sound effects while watching movies. When we see a home theater system like 5.1 or 7.1, the LFE is the ‘.1’.
- LFE + Main: this crossover mode in the audio system sends audio below the crossover point to the speaker and sub. You can configure it if you want; however, it is recommended to not make any changes to it.
- Low-Pass Crossover: this is where the subwoofer kicks in to generate audio from 40Hz to 60Hz or 100Hz. The speakers aren’t capable of dealing with such low-frequency and this is where we need a sub.
- High-Pass Crossover: this is the opposite of the Low-pass crossover. The speaker kicks in and the sub rolls off. It works with a frequency higher than the low-pass crossover. Usually, you don’t need to tune it.
- Large vs small speakers: although large speakers can go as low as 20Hz you will need a subwoofer to play that low end. Small speakers deal with frequencies that are higher than the sub but lower than the main speakers.
Now that you know the technical terms, let’s focus on our topic, what is a subwoofer crossover?
The subwoofer crossover frequency is the frequency when the subwoofer plays its role while the speaker steps back. At this frequency, the sub deals with LFE and bass and the THX standard value for the frequency is 80Hz.
An ideal crossover setting will allow seamless transition from a low-pass crossover to the high-pass crossover. One of the best ways to check the subwoofer crossover is to invite a friend for listening.
If the person enters the room and praises about the sub, the system is wrong. However if the person claims the audio has a tight and punchy bass without noticing the sub, the setting is accurate.
How to set-up the subwoofer frequency?
As technology rises at its peak, things are more user-friendly and convenient. The modern-day receivers come with an equalization option that analyzes our surroundings and automatically tunes an accurate crossover for the setting.
However, all these advanced settings might not be enough to bring that ultimate desired frequency you seek for crossover. For that, some effort into manual tuning is needed. Some of the examples of auto-calibration in the receiver are:
- Audyssey — Denon and Marantz
- AccuEQ – Onkyo
- YPAO (Yamaha Parametric Room Acoustic Optimizer) — Yamaha
Most of the subwoofer comes with a manual that tells you details and setup procedure of it.
Connect the subwoofer with the receiver:
Connect the LFE in your subwoofer with a single RCA cable and insert the other end of the receiver into LFE out or subwoofer out port. If you connect it this way, it will bypass the internal crossover of the subwoofer. Subwoofers like Rsl speedwoofer 10s offer this type of connection.
- The purpose of bypassing the crossover frequency is to avoid cascading of the crossover frequencies of the subwoofer and the receiver which might lead to muddy or bad bass.
- The crossover helps to direct the high frequency to the main speaker and the low frequencies to the subwoofer.
The following table shows a general crossover frequency for different speakers:
|On-wall or Tiny ‘satellite’ speakers||150-200 Hz.|
|Small center, surround, bookshelf:||100-120 Hz.|
|Mid-size center, surround, bookshelf||80-100 Hz.|
|Large center, surround and bookshelf||60-80 Hz.|
|Very large center, surround, bookshelf||40-60 Hz.|
|Tower speakers with 4”-6” woofers||60 Hz.|
|Tower speakers with 8”-10” woofers||40 Hz or Large/Full-Band|
How to connect the sub with amplifier/receiver without any LFE out:
- If the receiver doesn’t have LFE/sub out, then look for ‘no crossover’ option.
- If the receiver/amplifier doesn’t have that option either, then rotate the dial of the crossover of the sub to a maximum which is usually 150-200Hz.
Setting up the crossover:
- Place the mic that comes with the sub on the couch at the ear level then follow the steps below for auto-calibration.
- Go to the setting option of the receiver and under ‘speaker’ select ‘configuration’. Here you have to tell the receiver about the speakers you have whether they are large or small.
If you have floor-standing or large bookshelf speakers select largely. When you are confused about whether your speaker is small or large always go with small. If you choose the ‘small’ option, then that particular speaker will direct lower frequency to the sub.
- Crossover setting: once you set the size of the speaker, the receiver will automatically insert the crossover frequency and distance between the speaker/sub to your couch. But you can also input it manually.
Select the crossover setting from the setup. Generally, you can input 100Hz if the size of the woofer in the speaker is 4” and if the size is more than that choose 100Hz.
Also, if you own bookshelf speakers you can set it to 120Hz and for large floor standing speakers, you can set it to 60Hz. the low-pass crossover found at the rear side of the subwoofer should be 10Hz more than the lowest frequency of your speakers.
Such as, if the speakers have a range from 70Hz-110Hz, then choose the low-pass crossover around 80Hz. So when the frequency will be more than 80Hz the subwoofer will ‘roll off’ whereas when the frequency will be lower than 70Hz the speaker will ‘roll off’.
- If you don’t know the range of your speakers based on which you need to set the crossover, you can use the subwoofer matching tool. There is no fixed value you need to adjust the frequency for a smooth transition and that particular sweet spot.
- Phase switch: most of the subwoofer has a phase switch with two settings like 0 or 180. If you think the sound still needs improvement, then switch it to the other side.
- Level control or volume control: ideally select the volume knob to ‘middle’ then look into the AVR setting which will give a result that shows the subwoofer level. If you see the level at +10/-10db, then adjust the knob such that the level is around 5 or 7dB.
- If you don’t have an AVR then you can buy a Sound pressure level (SPL). Then run pink noise in your speaker and sub to get that sub-level.
- You can also download the SPL app but the microphone on the phones will not give the best results. For best results, you can place a sound-absorbing platform like Auralex SubDude-HT™ under your sub.
How to check the crossover frequency?
Once you setup the frequency, phase, or volume, you need to check whether the system has a smooth transition. The main method is to check the audio by ear by listening to a bass-heavy known track.
As you listen, if you think there were places with peaks then lower the overlap and if you think you hear a discontinuity, then increase the overlap. What should you do if you hear a bass bump? The bass bump indicates that you should adjust the volume of the sub and match it with the speaker.
If you don’t want to do it manually by listening to tracks and trusting your ear, then you can take help from different tools such as the bass frequency sweep. The purpose of this tool is to generate a tone that begins with maximum frequency and ends with minimum frequency.
This app generates a tone just like the bass frequency sweep with which you can detect any peak or discontinuity in the sound. Even after several tweaking with trial and errors, the audio doesn’t sound excellent with deep bass, and then you should think about the placement of the sub.
Placement of a subwoofer:
- For large room use 12” or more woofer size in a sub
- For small rooms, use the compact size of a sub
- Use subwoofer crawl technique: place the sub in your listening position, then walk around the room to detect 3 or 4 places where the sub sounds best.
Then put the sub in those places and listen to a music track again. Finally, find out the best place for the sub.
If you aren’t satisfied with how your speaker sounds, then you must get a subwoofer. Once you have the sub, the next huge task is to tune it correctly. The general rule is to set the crossover such that it is 10Hz higher than the lowest frequency of the speaker.
If you think you are a novice and don’t want the hassle then you can AV receiver with auto-calibration settings. However, it will be best if you still read this article because there is a possibility that you will need some adjustments.
Along with crossover settings, the phase and volume knob might need adjustments too and most of the time you have to do the sound testing by ear. Although the technical terms will leave you confused, this article breaks it up into an easy-to-understand guide.