Introduction

Difficulty level: Easy

Time required: ~30-60 minutes

Result: Way better bass!

Many use subwoofers for movies, but turn them off (or don't have them in the first place) for music. Often they are too loud on some songs, and too soft on others. Some also complain about "one note bass" where it seems like the subwoofer is only droning the same tone whatever is playing, instead of actually staying true to the musical content.

Let's fix that!

This guide is written for our customers who have Sigberg Audio subwoofers, but the general approach is valid for other subwoofers as well, and even full range speakers, as long as your system has a PEQ (Parametric Equalizer) that can be used to adjust the bass response.

Even if you don't have EQ, this can be useful to just measure the response in your room, and also while testing different positions either for the components or your own listening position.

What do you need?

We will keep this old skool, but with a modern twist. All you really need is 

  1. A smartphone or tablet (iPhone/iPad recommended)
  2. Spotify or Tidal connected to your music system, we will be using this playlist: (Spotify) (Tidal)
  3. A simple excel sheet (download link here) that we will use to plot the bass response of your system. The excel document also contains instructions for how to use it.
  4. Finally you will need something in your system that can apply EQ. If you have a Sigberg subwoofer, this is built in. You will need a laptop to connect to it.

Don't worry, it's easier than it sounds!

Additional tips: While not possible for everyone, we strongly recommend dual subwoofers. This will give you a much more even response and a better starting point for this exercise. The excel document supports this as well.

What will we be doing?

This article will guide you through the following steps using a real world example:

  1. Getting our smartphone or tablet ready
  2. Plotting a graph of our current bass response
  3. Evaluating the response and consider how to improve it
  4. Improving the response through subwoofer placement and/or EQ
  5. Plotting a graph of our improved bass response to see what we have achieved
  6. Enjoying our favourite music with tighter and more balanced bass!

Fixing your bass response

Step 1: Get our smartphone or tablet ready

We are going to play a series of test tones through our system from Spotify (playlist here), and then measure their loudness. We recommend using an IOS device (iphone or ipad) for most accurate results, but an Android device may work as well. Recommended software for IOS: Audio tools (19.99$) as this has compensation filters for the microphone and will be the most accurate. Another alternative is Decibel X. Using Decibel X or other apps without compensation filters means the measurements will likely not be accurate (too low) below 30hz, but this isn't important for the EQ exercise.

Start the app, locate the SPL Meter. Select Z weighting.

Start playing the 80hz test tone from the playlist, place your phone / pad where your head would be located when listening, and point the microphone towards the system. Adjust the volume until the maximum SPL level is around 75dB.

Step 2: Plot a graph of your current bass response

Now open the excel (linked above), and simply follow the instructions in the excel document.

Play each sinus tone from the playlist, starting with 20hz, then 25hz, then 30hz etc, all the way up to 99hz. For each tone, check the decibel level with the app on your phone/tablet, and type it into the excel sheet as instructed. A graph will appear, representing how even (or uneven) your current bass response is.

 

Step 3: Evaluate the response and consider how to improve it

The ideal result would be a straight line following the blue target line, but you will never see this in practice. If we can stay within the blue dotted lines, we are quite happy!

The response in the example above is actually pretty good, but it can be improved. The area from 55-70hz is a bit hot, and we also have a peak at 80hz. Finally we seem to have a dip at 70hz. This can be troublesome to fix with EQ (read why at the end). The first thing we should try, is to move the sub(s) if we have the luxury of alternative positions. Let's get to it in step 4!

Step 4: Improve the response by alternate subwoofer placement and/or EQ

In this example we only had a single sub, but by moving it around to a different location and measuring again, we were able to improve our dip. The subwoofer started out in a corner, but is now located close to the middle, to the left of our right speaker. As can be seen below, this fixed our dip at 70-80hz completely!

 

Then on to the slightly hot 55-70hz area, which we will fix with EQ: All Sigberg Audio subwoofers have built-in parametric EQ, accessible via USB. 

Let's connect to our subwoofer now (check our manuals if you are unsure how)

You can also use alternative EQ available in your preamp / streamer or playback software.

To add a PEQ we need to enter three things:

  1. The frequency we want to adjust. In our case this is the center frequency of the peak we want to fix. As we have only measured every 5hz, it's not perfectly precise. Let's put in 60hz. 
  2. The width of the peak we want to adjust. Our peak is somewhat wide. Let's try a width of 10hz (55-65hz). If we insert this into the PEQ area in the excel document, it will calculate Q for us.
  3. How much we want to increase or decrease the level. The area is about 5dB hot, but it often works best to use a light touch, so let's reduce it by 3dB. 

We take the same approach with the peak at 80hz, ending up with Q 16, and reducing it by 4dB. Let's check the combined results of our new sub placement and EQ in step 5!

Step 5: Plot a graph of our improved bass response to see what we have achieved

That is looking way better than our original response! We see that the hot area at 55-70hz is reduced a bit, and the peak at 80hz is also much better. We could try to reduce the 55-70hz area slightly more, and if we are sure we have enough headroom (power) in our subwoofers, we could also try to gently lift the 35-45hz area by maybe 1-2dB. But even without that, we're quite close to +/-3dB, which is really good. Don't feel bad if you're unable to achieve the same in your system, especially if you only have one subwoofer.

While we have identified that we could possibly tweak this even more, it's time to listen to some music and verify the result before doing anything else!

Step 6: Enjoy your favorite music with tighter and more balanced bass!

Wohoo! This sounds way better! Getting rid of that dip at 70 hz really helped getting a fuller sound on some of our favorite rock tracks, and in general the bass now sounds much more consistent across different music and genres. 

You can go back and forth between these steps to test placement and EQ options, and remember to spend some time listening to music along the way to verify the result! 

Final note: With EQ less is often more. In the bass area you often get far with 1-3 EQ points, and try to not dampen peaks fully, as that may take some punch away as well. When it comes to dips, EQ often doesn't work, so try to fix those with moving your subs. 

We hope this little guide was useful, and wish you good luck on your hunt for great bass!

Questions / Want to discuss results or how to use this?

Check out the thread about this tool on ASR

June 21, 2024