Ever wanted to give a lush stereo effect to a mono track? You can resort to using a stereo imaging plugin but the effect can leave a lot to be desired. There is actually a very simple way to turn a mono track into a rich stereo sound in your home studio. You can create the effect with no plugin at all or use a simple delay. This article is going to cover several ways to achieve the sound. Pick the method that is easiest for you!
Though the effect is quite straight forward it has a formal name, the Haas effect. The Haas effect is named after Helmut Haas who formally researched the effect in a paper that was first translated into english in 1949. I have been unable to find the date of original German publication. The effect works only on a mono track. You could sacrifice the left or right channel of a stereo track and apply it to the remaining mono channel. Pan your audio track hard left or hard right. It doesn’t matter which extent you choose but you must pan the track 100% to that side. The sound will be coming out of only one speaker. You then send a copy of the audio signal to the other speaker but delay it slightly. I don’t have a reference to Haas’ original work and most online sources differ slightly, but it seems this delay should be no longer than 25-40 milliseconds. This sounds a bit complex talking about sending audio to one speaker and delaying a copy in the other speaker. It really is quite simple once you break it down. There are a few ways to do this described in order from most simple to most complex.
Haas effect sound samples
- dry keyboard This is the dry, original keyboard part we were working with. Its timbre is a little drab and doesn’t cut through the mix well.
- keyboard with Haas effect This is the above sample with the Haas effect applied at 18ms. Sounds much cooler and it sits in the mix really well.
Easy Haas effect
Start with your desired track panned center. Copy the sound file to an adjacent track (it doesn’t strictly have to be an adjacent track but it makes things nicer to look at). You should have something similar to Figure 1.
Now we move one of the tracks back no more than 30 milliseconds. Back in this case means “to the right” which would be the audio equivalent of delay in the signal. You don’t have to move a full 30 milliseconds as shown in Figure 2 but you probably won’t hear the effect very well unless you move at least a few. The more you move the more pronounced the stereo effect will be.
Almost done. The last thing to do is pan both tracks in opposite directions. It doesn’t matter which direction you pan them. You can put the original on the left with the Haas track on the right, or the other way around. Pick which sounds best for your mix. The main thing is that you pan them 100% and one on each side as shown in Figure 3.
Have a listen. You should be greeted with a very rich stereo sound similar to my sound samples above. The advantage of this basic way of setting up a Haas effect in your home studio is the simplicity. Most modern DAW programs make this process as easy as: select, copy, paste, drag, pan, done. It can be set up very quickly and you can adjust the amount of the delay by nudging the soundfile back and forth. This way of doing the effect also allows you to easily adjust the delay by very small amounts. Most delay plugins give you resolution in full millisecond steps. By sliding the track manually you can adjust the delay down to the sample (typically one 44-thousandth of a second or more). The main draw to this method is having two copies of the soundfile in your project. If you later decide to edit the part you will not only have to perform the same edit on both tracks, but you will actually have to perform the edit on the Haas track offset from the original edit. This is where the next method comes in…
A better Haas effect set up
Wouldn’t it be nice if both soundfiles could be edited together? This way of setting up the Haas effect allows you to make identical edits in both tracks without worrying about the offset of the delayed track. Start by setting up two tracks with the same soundfile and pan them to opposite sides like we did in the first method (see Figure 1 and Figure 3). The difference in this method is the use of a delay plugin on one track instead of manually sliding it. Most DAW software comes with at least a basic delay plugin and it should be fine for this effect. Your delay plugin needs to be able to do small delay times (1-30ms), and adjust the wet/dry mix ratio with either a wet/dry balance or individual level controls for each.
- Load the delay plugin on either one of the tracks.
- Adjust the delay for 100% wet, 0% dry
- Delay with a wet/dry balance knob: turn the knob all the way to wet
- Delay with individual wet/dry volumes: set the wet volume all the way up and the dry volume all the way down
- Set the delay feedback (number of repeats) to minimum (one repeat)
- Set the delay time to your desired value (1-30ms)
I usually start at about 20 milliseconds and play around from there. This effect makes the delay time very sensitive so you may find a completely different sound at 19ms from the one at 20ms, and yet another new sound at 21ms. Play around. A great advantage of this method is being able to change the sound of the effect by adjusting your delay time up and down without worrying about sliding a soundfile back and forth in the multitrack view of your DAW. It is also easier to remember where you got the cool settings, “It sounded awesome at 18ms” instead of “Now was that cool sound at 235 samples offset or 325 samples offset?” You can also make edits to the soundfile in the same place on both tracks without having to calculate offsets. I can hear you thinking, “What I’d really like is to not duplicate the soundfile at all, and only have to make edits in one place!” Fear not, and read on…
Haas effect advanced routing
Assuming you’ve been following along, lets start where the last example left off. You now have a nice sounding Haas stereo effect happening but you would like to eliminate the duplicate soundfile. Delete the soundfile from the track with the delay plugin on it. Instead, route an auxiliary send from the track with the soundfile to the track with the delay. This send should be pre-fader, pre-pan but is ok to be post effects if you have some other effects on the track (possibly eq or compression). Now you have the Haas effect but you only have one soundfile in your project view. Making edits is no more difficult or involved than for any other non-Haas track (unlike the first two methods we discussed).
The main complexity with this method is how to set up the auxiliary send in your DAW software. Some software like SAWStudio provides a fixed number of sends from which you will need to use one as the delay send for this one track. Software like Sonar offers a bit more flexibility to create new auxiliary send tracks but they still live off on their own section of the mixer. Some software has more advanced routing possibilities to send any track to any other track. Reaper is in this family and allows you to keep your Haas track visibly “next to” the track it is coupled with.
More Haas experimentation
Haas’ original research says the delayed track can differ in volume from the original track by up to 10dB. That means you can adjust the delayed track up to 10dB louder or 10dB softer than the source track. You can get some interesting effects across the stereo field playing with the volume balance of the two tracks. The effect will also generally sound richer through speakers than headphones.
Related article: Creating heavy guitar tracks with haas delay.
Now you know how to turn a boring mono track into a lush stereo sound that jumps out of the speakers. Remember boys and girls, DO try this at home!