L/R EQ Effect on Bass

A few weeks ago, I asked Lenny how he got such the bass on Into the Fire (especially when it first comes in at 0:13). He jokingly remarked that he did a bit of EQ magic but would have to kill me if he told me specifics.

So that got me thinking, which is a dangerous thing when the person doing the thinking is me. I wondered what would happen if I converted a mono bass line to stereo and then applied different EQ to the left and right side of the stereo channel. My suspicion is that you’d get a real wide sound as a result without having to resorting to tricks like doubling the track, offsetting one by a few milliseconds, and then detuning it by a few cents.

To test out my suspicion, I took a snippet of the bass from New York Blues. Aside from the fact that my crappy playing is now on display for all to see, listen to what happens. The snippet is played 3 times: untreated (mono), routed to a stereo group track with the Stereo Enhancer applied, and finally with the a +9 dB boost (Q setting of 3) applied at 120 Hz on the left and 500 Hz on the right.

Stereo EQ Test

(Interestingly enough, the stereo spread is much more evident when I play the test project in Cubase.)

When this is applied to the original song, the effect is subtle but definitely noticeable. In this snippet of the same song, the bass is untreated in the first four bars and the same L/R EQ “trick” is used in the second four bars.

New York Blues snippet

To allow you to hear the bass better over the cacophony of the other tracks, a 4 dB boost was applied to the original track for the entire 8 bars.

This isn’t meant to be an exhaustive treatment of this test but only a “proof of concept.” I found that the amount of stereo spread is dependent on the distance between the EQ frequencies used in the left and right channels, but I’m 110% sure it’s also dependent on the spectral profile of the base track.

I hope you find this as interesting as I did.

Very cool that you tried something like this to hear it. You have to be careful with altering the low frequency content to large degrees as the amp that is driving the speakers can become unbalanced as bass frequencies take more power to produce than high frequencies. It can affect the perception of the higher frequencies as well and you or your listener may tilt your head in wondering what it is.

“What did I just hear?”

With bass heavy instruments, if they have mid to high frequency content, it is more advantageous to use the mid->higher frequencies for stereo effect/field/stage placement. It is also how we as humans experience sound as well like rumbles, thuds, etc. in our everyday life.

When I am adding explosion sounds to video, if the explosion is coming from off camera or off to one side of the screen, I create an aux that deals with the high frequency content and use that to place the sound in relation to what you are seeing on screen. The low frequency content remains in the centre.

Another real world example is a bass amp in a room: The low frequencies radiate and the higher frequencies reflect (that is law).

All I write here isn’t to discourage your test. Roll with it! You may find a really cool technique! Just wanted to share this tidbit.

I’m totally in agreement with what you said. Like I added, this wasn’t exhaustive by any means. My wife is working at a wedding today, so I was trying to do this with my 5 year old either crawling all over my lap or trying to play her drum set along with the song snippets. :laughing:

I won’t deny that I was quite surprised that a 9 dB boost really didn’t affect my overall perceived loudness. Of course, a more accurate test of this would be to run it through a K-12 meter but, like I said, I had other distractions to deal with.

You note about video is interesting. Lately, I’ve been noticing the use of reverb as a spatial indicator for dialog occurring off screen.

Another thought just came to me that I’ll have to try later: I was using a fairly high Q value, which prevented overlap (at least in the spline curve representation of the EQ line). I wonder what would happen if I used a lower Q value and intentionally introduced overlap between the two. Would it require less of a boost to have an audible effect? i don’t know, but I intend to find out.

I really have no idea since I have never approached bass frequencies this way (to make them stereo). Wide boosts in general need less gain in order to be heard due to having more content vs notches.

You want something like this?

Closest I could get listening to Lenny’s song using my brain and some tools to examine his bass. His has a lower usable frequency range.

Your bass is distorted too. What are you using for a DI?

Very interesting.
I believe this is the technique employed by the PSP PseudoStereo plugin which I use quite a bit.
The extra benefit of this method (EQing vs. phase alteration /delays) is that it appears to collapse to mono in a very transparent way.

More info here->

Well, this wasn’t the raw signal. I exported the track from the song into a WAV file, which I then tinkered with. So you’re getting this:

Fender Jazz > EnVoice MKII > NI Supercharger > EQ trick

The EnVoice was set to enough tube saturation to keep the saturation indicator from going into the red. Since I know you have the dual-channel version of this, you know what I mean. The Supercharger was using the Bass preset, which is about 1/3 compression, 100% wet. But this is a coloring compressor, so I’m sure any distortion you’re hearing is coming from that.

Interesting. I never heard of PSP. :confused:

Maybe the secret trick is …

a stereo bass . :confused:

Like a Rickenbacker or an Epiphone Zenith ( discontinued now , but I’ve got one :wink: )

Interesting point. I’m simply concerned with making the bass cut through the mix a bit more without the listener being able to detect that there’s actually something going on with the bass line. Consider this as an analogy: playing a stereo bass but making the listener think it’s mono. :laughing:

I vote we ban Tom’s avatar… :open_mouth:


Nice experiment. The only thing to consider is the human ears’ " equal loudness contour". 9db in this area for many of us has a lesser perceived loudness than say 1kHz. And even that will vary a bunch even just based on age. Too bad we all weren’t born with the same base line

Hehe… For some reason my logo transformed into a sexy cow! :mrgreen:

Yeah, I realized this at the time. Higher frequency = more energy = smaller dB boost are needed to achieve the same result.

Fool em, foolomon!

Turn that bass to stereo on the sweet parts, and back to mono when it needs to be solid, or vice versa.

No one will know what hit em.

I like to have several basses loaded (as VST) for different character but when I need it to function as a bass, in comes ol’mono.

I don’t follow either of you here. Why would a 9db boost be less perceived in the lower octaves vs higher? I understand the fletcher munson curve. The curve is static at fixed volumes. I just did a test here and a 9db bass boosts is as noticeable as a treble… Ya lost me.

Hi Tom,

Possibly another way to illustrate it is to say that the perceived loudness of a tone at 1kHz would require an increase in spl of a 30Hz for the 30hz tone to be perceived as equally loud as the 1kHz tone to the human ear simply as a limitation of the mechanics and the neuro function of a normal ear.

That’s just 'udder’ly ridiculous! :laughing: