In a way I’ve been using an equalizer since my earliest music listening. Dad gave me an Advent amplifier with a loudness switch and I always had it turned on. The effect was to boost both bass and treble, but the amount of boost lessened as you increased the volume. So even as a purist, it’s use was acceptable to me. It was just compensating for my need to play music at less than hi-fi volume. 😏
A few years later a high school buddy showed me his equalizer unit that included a microphone so that it could automatically adjust for room acoustics. Reviews at the time dismissed it as a gimmick. Supposedly it could only do so much and improving your speakers or room acoustics were much better places to put your money. Back then all equalizers added a bit of hiss that was audible when music was not playing too, which is a major faux pas in the audiophile community.
And that formed the basis of my opinion on equalizers for quite some time. Sure I used the tone controls in my car to boost the bass and treble a bit, but I always left my home stereo alone. That changed a few years ago when HDMI became a universal standard.
What’s HDMI got to do with equalization? Nothing really but I needed to upgrade my receiver to support HDMI switching. I didn’t have a lot of money so I ended up buying a budget Denon receiver. On paper it was a downgrade since it wasn’t rated for as much power as my old receiver and it weighed about half as much, indicating an inferior power supply. But it did have one thing my old receiver didn’t: Audyssey room correction — the modern day version of my buddy’s equalizer.
Audyssey is a company that licenses its audio processing technology to various equipment makers, like Denon and Marantz. It uses an included calibrated microphone to take measurements at multiple listening positions and then adjusts individual speaker level, subwoofer crossover frequency, frequency response, and timing accordingly. It is particularly useful for bass management, an area notorious for being difficult to manage manually and known for making big differences in perceived sound quality — especially for home theater setups.
Admittedly I was skeptical but MAN did it make an improvement in my sound! I would say no other upgrade I’ve made over the last 10 years has been as significant. Bass was tighter, deeper, and more authoritative. Surround effects more believable. And since it all happens digitally before the audio is converted into analog, there is no perceivable hiss, noise, or other distortion. I was sold. In fact when I upgraded my receiver again last year (for *sigh* 4K HDMI support), I bought another Denon with an improved version of Audyssey.
But I’m supposed to be talking about headphones, not home theater. Well in the meantime I’d played with the equalizer in Apple iTunes but I never found any settings I liked. I also noticed that my perception of the improvement in sound lessened over time. For instance the longer I listened to a bit of bass boost, the less it seemed to make the music sound better. Until I switched it back off. Then what sounded neutral before sounded thin and lifeless. Adding the bass boost back was the only way to bring it back to “neutral”. I consider this effect similar to the effect of altering the white balance in photos.
I’m always looking to make improvements though and I came across an app for my iPhone from Audyssey that had an intriguing function. If your headphones were in its database, it could apply equalization to “correct” those headphones to perfectly neutral (whatever that is). I tried it out with my Oppo PM-3 and they sounded different, but not necessarily better to my ears. I figured it was probably because my Oppo already conformed closely to the Harman target and therefore didn’t really need correction.
What is the Harman target? The best explanation I’ve found outside of the original research papers is from a Reddit user and audio engineer, oratory1990: https://www.reddit.com/r/headphones/comments/dr1jp3/what_exactly_is_the_harman_curvetarget/
Another issue with the Audyssey, or any other equalization app for smartphones, is that it doesn’t work with music that has digital rights management (DRM) including Spotify and Apple Music. Because of this I pretty much forgot about using equalization until a couple of years ago when I discovered MiniDSP EARS.
I was excited by the possibilities and purchased EARS. I used the Room EQ Wizard audio application on my computer to generate a correction curve specific to my headphones, similar to the Audyssey app on my iPhone. And… I got similar results. It sounded different, but not really better and there wasn’t a simple way to apply the correction while listening to iTunes anyway.
These results repeated yet again when I tried out the Sonarworks Reference software that, like the Audyssey app, uses their own measurements to create headphone specific correction equalization. At least this software can apply the equalization easily but it’s too expensive for what sounds to me like a minor improvement at best.
Reference is designed for professional audio engineers to mix music recordings, but Sonarworks released software recently that is geared toward music consumers: SoundID. The idea is very cool. It uses a smartphone app to create a custom equalization for you that they call your SoundID. Your SoundID starts with a profile of your headphones to make them neutral, just like Audyssey, EARS w/ REW, and Reference. However it also allows you to tailor the sound to your preference. The way it figures out your preference is that it allows you to choose a music sample, ranging across rock, rap, jazz, classical, etc., and then plays the same sample with different equalizations applied as A and B. You simply choose whether you prefer A or B and then it moves on to the next equalization. After about 30 choices it produced my unique preference which, not surprisingly, was a bass bump and a bit more treble too. Later you can further refine your SoundID completing a number of audio tests to see if there is any correction needed to compensate for your hearing. So your SoundID uses three factors: how your headphones sound, how you perceive sound, and what your sound preference is. Like I said, very cool!
While your SoundID is created using your phone, it is applied through software on your computer. It is pretty easy to turn it on and off as well as switch which headphones you are using, but it does affect every sound that comes from your computer. The resulting sound is noticeably, but subtilely, improved. SoundID is a paid subscription service but it has a free 60 day trial. I got in the habit of combining the SoundID with iTunes Loudness equalization to hit the sweet spot. This was my preferred listening setup with my Sennheiser 58X headphones and I thought I was going to actually pay for the SoundID subscription until…
Remember oratory1990, the audio engineer who explained what the Harman target is? Well it turns out that as a hobby he takes measurements of various headphones and uses the results to create equalizer settings that correct the headphones to the Harman target — at least as closely as possible. Then he publishes those settings on the internet. For free. All you need is the right software and you can create your own equivalent of Sonarworks without paying for a subscription.
https://www.reddit.com/r/oratory1990/wiki/index#wiki_oratory1990.2019s_list_of_eq_presets
But it gets better! He also uses the same equipment that was used to create the Harman target in the first place. Why does this matter? Well different equipment measures headphones differently. Most of this is because they all use different shapes and materials for the artificial ear. This is a big reason why my EARS didn’t produce the correct correction curve: https://imgur.com/2gvAefX
Also I’m not even sure if any of the other options are using the current Harman target like oratory1990 does. I do know that EARS does not.
I was able to find some software to apply oratory1990’s corrections for my Sennheiser 58X and this is now, by far, my favorite way to listen to them. Bass is noticeably more prominent and treble is smoother, without losing any detail, clarity, or punch. It also sounds good to my ears no matter what music I’m listening to. Sometimes I’ll use another equalizer layer to add just a bit more bass, but it’s really not needed and it’s too much for some music. (Aside: Pink Floyd really knew what they were doing as they are one of the few classic rock groups where the bass is just right and adding more sounds like crap.)
So now that I’m correcting my 58X to a reference sound that I know I prefer, I can just stop trying new headphones right? I mean now my $150 Sennheiser 58X should sound the same as the $1400 Sennheiser 800, right? Well, yes. And no. Mostly no.
For example I have switched between my Oppo PM-3 and my Sennheiser 58X and they still sound very different even after applying their respective corrections. There are aspects of headphone sound that is not related to their frequency response. An easy example is the difference in sound between open and closed back headphones. Also the 58X still have noticeably more punch, and since I’m often focusing on the drums that aspect is important to me. I enjoy it. A lot.
But while I definitely prefer the sound when using this equalization and different headphones still sound different, using it as a default does bring up a lot of questions when comparing headphones. Most reviews concentrate on the relative levels of bass, midrange, and treble. Other aspects like soundstage, clarity, punch, and comfort become much more important yet are far more subjective.
So when comparing headphones before purchasing them, should I even consider the unequalized frequency response curve? If a headphone has elevated bass, does that mean that it will have better bass when equalized vs a headphone with weak bass? What about treble? Is there an objective measurement that directly relates to punch? What about when I’m not using my computer as the sound source and can’t apply any equalization?
As usual things are getting complicated! But then that’s what makes it interesting too. 😎
