John Darko
Best? When I say best, I mean favourite. My favourite hi-fi products for 2024 were chosen on merit and my predilection for (what I call) Future-Fi. Part one can be found here. Part two is here. This is part three…
OPRA (and not Winfrey). That’s the name of the new headphone EQ functionality recently folded into Roon. OPRA’s control panel can be found in Roon’s desktop app: press the little speaker icon at the bottom right of the screen followed by the squiggly wave symbol. Me? I’ve not been using OPRA that way. I’ve been using it inside Roon ARC running on the Asus Zenfone 10 and – another 2024 favourite – the Moondrop MIAD-01.
Roon’s headphone EQ isn’t just a new feature but a front-end to a community-driven project whose behind-the-scenes thinking is twofold:
- Headphone manufacturers can only take their designs so far before incremental improvements become prohibitively expensive. DSP-powered EQ can pick up where that expense prohibition leaves off
- Instead of users manually applying EQ settings to their favourite headphones – often one frequency band at a time – OPRA lets us apply headphone EQ with just two clicks: we choose our headphone model and then our preferred EQ profile, which often comes from a long-time respected source.
I began my OPRA testing some weeks ago with Sony’s MDR-7506: the ‘oratory1990’ preset gave me a smoother, better-balanced sound with fewer noticeable bumps and dips. The drop in volume is an EQ side effect that dents the reliability of any quick-fire on/off side-by-side comparisons. We must listen for longer – but also, in the MDR-7506’s case, to the three other OPRA profiles. The ‘Headphone.com Legacy’ preset is too bass-heavy for my taste. An abrupt reminder that we all have different preferences.
We often find more than one EQ profile in a headphone model’s submenu, which reminds us that the headphone measurement process is not ‘100% objective’. To say so would be to gloss over its numerous subjective considerations.
Before measuring a headphone, people like ‘oratory1990’ must choose a dummy head simulator, an ear simulator and a microphone. All three pieces of hardware vary in quality to produce different results. That makes them subjective choices.
If you’re thinking that a $500 measurement rig in experienced hands would produce more reliable results than a $5000 measurement rig in inexperienced hands, you’d be right. This thinking underscores my next point: the measurer chooses the microphone’s position and positions the headphone (or earphone) on the head/ear simulator. Different microphone/headphone positions produce different results. This folds two more subjective calls into the headphone measurement process.
I’m not suggesting that anything goes in the headphone measurement space – and I have no doubt that everyone involved is doing their best – but it’s probable that no two headphone measurement people have the same measurement hardware and/or use the same measurement process. Results will vary.
Muddying these already muddy waters, measurement people have zero control over unit variation: one headphone sample might not measure the same as another sample on the same measurement rig.
These are just some of the reasons why a) OPRA serves up more than one EQ profile for the Sony over-ears and b) why all four of those profiles sound different. If measurements were 100% objective, we’d see only one EQ profile.
Two related questions for you to ponder: if the measurement process isn’t 100% objective, what percentage is it? And, more importantly, who decides?
It goes further. The measurer must then interpret his/her measurements for his/her audience. That’s a subjective process that doesn’t impact OPRA but the compensation reference target curve does.
Each EQ profile found inside OPRA is built around two or three elements: 1) the headphone’s frequency response curve, as measured by a (pre-vetted) community member; 2) a compensation reference target curve; and 3) the profile creator’s slight preference ‘nudges’. At the time of writing, OPRA working inside Roon pulls profiles from oratory1990 as well as something called the ‘AutoEQ’ repository which lets us see the frequency response measurement but not the compensation curve applied or, indeed, how it was applied.
Which compensation curve should our headphone measurer choose? Harman’s remains popular but isn’t the only game in town. Case in point: my Roon contact tells me oratory1990 is a significant contributor to the OPRA project but that outside of it, he publishes .pdfs on Reddit with his preferred non-Harman compensation curve alongside his headphone measurements. OPRA – and, in turn, Roon’s OPRA implementation – is on the cusp of warehousing all of the profiles created by oratory1990 and in the case of the AutoEQ versions, it doesn’t yet concern itself with whether AutoEQ is using oratory1990’s correction curve or one of the many alternatives. Reference target curve selection could theoretically become an OPRA-in-Roon feature but we’re not there yet.
I am not pouring cold water on headphone measurements and their compensation curves. Listening to music inside Roon ARC and with OPRA activated shows us how their combined utility impacts what we hear from our music. I prefer the sound of the Sony MDR-7506 with oratory1990’s OPRA profile activated but other MDR-7506 owners might prefer a different profile (or no profile at all).
With other headphones, the improvements are more subtle. Sennheiser’s IE 300 in-ear monitors are already a terrific match for the Asus Zenfone 10’s 3.5mm headphone socket. With Roon ARC handling playback, I like ’em best with crinacle’s IE 300 EQ profile activated. It sounds slightly livelier in the upper-most treble than superreview’s profile (which also sounds quite nice). If we see the IE 300 as a meal and OPRA (in this case) as salt and pepper, we’re not radically changing the meal’s ingredients or its fundamental flavour. We are adding seasoning.
Bluetooth headphones are also part of the OPRA project. We find EQ profiles for most major models (if not the very latest). Pull up Kazi’s EQ profile if you want more zip and zing from the Sony WF-1000XM5. Choose oratory1990’s EQ profile for a less energetic sound. The choice is yours.
On the one hand, I am concerned that OPRA further cements the idea that a headphone’s frequency response is the only measurement that matters. Any headphones that internalise more than one driver will have a time domain behaviour that isn’t being considered – or measured. Is this why we can’t EQ the Sennheiser IE 300 to sound anything like the Campfire Audio Clara? Or the Sony WF-1000XM5 to sound like the Sennheiser Momentum TW4? That’s for those more clued-up in these matters to tell us, especially professional audio engineers designing headphones at the commercial level. Sennheiser’s Audiophile Product Manager Jermo Köhnke offered up numerous valuable insights in an episode of the Darko.Audio podcast last year.
On the other hand, my concerns about frequency response-induced tunnel vision are overridden by OPRA being bigger than Roon playback. Roon Labs set up the OPRA project but does not own it. It has been designed as a distribution point for headphone EQ profiles for anyone to use. EQ profiles whose component data would otherwise remain scattered across Reddit, forums and miscellaneous headphone enthusiast websites.
OPRA distributes its EQ profiles under a Creative Commons licence via GitHub. There is no licensing fee. Plex could put OPRA inside Plexamp without dropping a dime beyond software development costs. Ditto JPlay, Audirvana and Foobar. The only requirements for OPRA’s usage are 1) to display the OPRA logo, 2) add a brief description of what the project is about and 3) credit the community member behind each EQ profile. That’s my summary. The specifics can be found here.
With OPRA’s community focus and the headphone measurement process’s numerous subjective calls, I foresee a time when headphone users will enjoy, trust and gravitate toward the work of one headphone measurer over another. The age of personality-led headphone measurements is upon us. And it comes to us free of charge. Who wouldn’t want to try to improve the sound of their favourite headphones with a couple of clicks inside an app? It’s a question whose simplicity tells you why OPRA inside Roon is my third (and final) favourite hi-fi (nay, head-fi) product of 2024.
Further information: The OPRA Project on GitHub
