AutoEQ: Automatic headphone equalization from frequency responses

AFAIK, every tool that integrates with these things apply a negative boost equal to the peak added to avoid clipping.

> I am not opposed to EQ, but it should be applied judiciously, and at least partially by ear. I don't believe trying to exactly match a target curve will necessarily provide good results compared to a more judicious approach.

Agreed. While matching generalized target curves are really helpful when applying EQ to sound waves in a music production setting, from a listeners perspective EQ is going to rely much more upon personal preference.

I've always struggled balancing the subsonic portion of my mixes with the higher ranges, and often times I've ended up with way too much bass, or not enough making my mix sound very thin and unbalanced. Using Izotope's Ozone 8 Tonal Balance Control, it gives me a visual representation of where my track meets or misses a target curve based on genre. So for instance, I can see that the subsonic region of my mix far exceeds the subs in a target curve for rock music, and then adjust the eq on the instruments that fall within that spectrum accordingly. That's super helpful for getting me into the ballpark of a "recognized tonal range for a specific genre", but I fully expect people to adjust the EQ to their own tastes once I get into that ballpark.

That being said, while I expect people to adjust EQ to taste, I'd also like to point out that EQ choices made in the production phase are often intentional creative decisions. That is to say, sometimes artists may want to intentionally go against accepted norms and try something new with their frequencies. Imagine if 70 years ago someone made an Auto-EQ for the music that was popular at the time and then applied it to dubstep music being produced today - it just wouldn't work. When an artist masters a mix, that's how they want it to sound. Similarly to how a chef might be insulted if you poured a bunch of a salt on the dish they just served you without even tasting it, a producer could be similarly insulted if listeners blindly apply EQ to their work before taking time to appreciate what the artist's original intent was.

As an example of my point for using a judicious approach above, applying either of the sets of Sennheiser HD8XX measurements and resulting AutoEQ curves from the Crinacle and oratory1990 folders in the Roon DSP system collapses the headstage and tilts the perceived tone of the headphones from relatively full and engaging with a dip in the 2-3 kHz region to thin and hollow, with an overly bright, brittle top end.

Also, these are two sets of measurements of theoretically the same headphones, each with 10 adjustment points, some quite broad, some very narrow. The overall shape of the resulting curve for the same target compensation is similar, but they have some significant differences in the specifics, and they sound different. We have to remember that measurement systems and individual measurement setup can vary quite a bit, so settings from this tool will bake all of that in as well.

As a comparison, based on review of the measured curves in more of a a big picture way, applying a much simpler EQ with a broad 1.5 dB bass lift up to about 100 Hz, another broad lift of about 3 dB around 2 kHz, and a slight drop of about 1 dB centered around 8 kHz brings the bass and vocals up a little but keeps headstage and overall tone intact. Maybe it's this particular DSP implementation, but I would be wary about trying to use any of the precompiled results directly. EQ can have real benefits, but is going to be more personal than automated settings will capture.

Phase shifts make no practical difference when you're equalizing headphones. You really shouldn't need to use notch filters there.

EQ phase is relevant if the dry signal has a chance to mix with the EQ output.

Changes in phase is not "distortion". When you end up making large boosts (especially to make sub bass audible), that's when your headphone drivers might start to distort sound. This is fixed with less volume, obviously.

Analog distortion of signals also affects the phase. A digital filter might or might not compensate for it, but it's not always bad.

Also, human ears tend to be more sensitive to amplitude than to the phase. Especially if the same filter is applied on both channels, which leaves the phase difference unchanged.

Depends largely on how it's implemented. There is a big difference between the quality of a well implemented convolution engine and a crappy biquad filter.

The primary measurement is called group delay, which is the derivative of phase with respect to frequency (since a linear phase is just a uniform delay). Fortunately we have studies from the 70s publicly available that establish a group delay audibility threshold.

FIRs add vanishingly small amounts of distortion. Their real drawback is in the added delay. For asynchronous music playback this is nothing to worry about, but for video or anything interactive (communications or gaming) it's going to be a real tough pill to swallow.

At headphone sizes, does your DAC have a good enough clock to even speak about phasing?

This is exactly what Sonarworks is doing, but without a specific software package to implement it (and sell to you).

> a matter of taste

Taste, yes; and individual circumstances. My hearing is so good it might count as a disability, but I know where I have peaks and valleys in my sensitivity and a good EQ can help with the spikes taken by tinnitus ringing from youthful big boom car stereo work and explosives.

I checked their suggestions for my headphones against my EQ profile and theirs is pretty good. I like more lowfreq and much less high freq than the "flat" they're correcting for.

They're offering a great resource for skipping the "what does this set of cans sound like" stage. I probably spent 60hr or more dialing these in when i got them.

I've experimented with this and the results seem to vary depending on the headphones. I have a set of planar magnetic hifimans that don't have enough sub-bass out of the box, but can easily make tons of sub-bass with eq adjustments. On the other hand, some of the other headphones I tried this on sound like they're just distorting more when I try to apply similar levels of eq compensation.

There's also no way to apply a system wide eq to an iPhone, so you'll need an external device.

from my experience, it's absolutely necessary if you listen to a lot of podcasts because every tech-illiterate podcaster dude will see an EQ setting on their microphone/recording software and think "low frequencies are manly and sound good" and boost the hell out of it, and it sounds absolutely awful.

Granted my home speakers might have something to do with it, and headphones/earbuds do tend to have a high-pass filter built in just from their construction, so it probably doesn't affect everyone the same way.

I've been using equalizerAPO for desktop for years. I can only think of a handful of content creators that don't pull that bass-boosting garbage anymore, so the high-pass filter pretty much always stays on unless I'm playing music.

Not really. That's an immediate noise cancellation function, which only works (a) with headphones and (b) by recording the outside noise and adding its inverse to the sound being played.