/* ]]> */
Feb 012018

A collection of headphone frequency response graphs, showing how they vary widely and are far from linear.

Here’s a very clever program that digitally compensates for the non-perfect sound coming from your headphones, creating a clearer, smoother, and broader frequency response, with less unwanted sound coloration.

These days, the speakers/headphones are by far the weakest link in any sound reproduction chain.  The storage and playback/amplification is all very close to perfect, it is only when the sound transitions from digital data back to physical sound waveforms that errors creep in.

The problem with any sort of audio speaker is that its attempts to convert an electrical signal to a physical sound pressure wave are never perfect.  There are lots of reasons why this is so, and while speaker designers and manufacturers have steadily improved the quality of their speakers, they still remain imperfect.  Inevitably, after doing the obvious and easy improvements to a speaker, continued improvements start to move far out on the scale of diminishing returns, and while going from poor to good might mean going from $10 to $100, going from good to great means an increase, perhaps from $100 to $1000, and from great to superb probably sees yet another zero added to the price.

Back in analog times, the less ‘treatment’ of the sound being passed through an amplifier, the better.  A bit like photocopying a photocopy of a photocopy of an original, the more analog processing you added to a sound wave as it passes through your analog amplifier, the more you risked harming its quality.

But this all changed when sound storage and reproduction switched from analog to digital.  Nowadays, we get a digital sound source (either a CD or an MP3/FLAC/whatever file), which then goes through a digital amplifier, and it is only at the final stage, before the power amp and output, that the music changes from digital to analog.

The significance of this is that you can do a lot of digital treatments and sound shaping during the digital part of this process, without harming the underlying integrity of the music.  You’re less likely to have non-linear effects, phase shifts, or noise introduced via digital processing than with analog processing.  This, combined with astonishingly powerful but low-priced signal-processing chips, opens up many exciting possibilities and new ways to optimize the music during its amplification.

We see the benefits of these new digital capabilities with many home theatre systems.  You use a calibration microphone that analyses delay times, frequency responses and room coloration as it actually happens in your living room, and then adjusts the digital sound processing to fine tune and compensate so you have something very close to a perfect room and improved speakers.  This has become so simple and commonplace that we seldom pause to even consider the amazing transformation in sound quality this process now gives us.

The $2000 (before accessories) Bruel & Kjaer Artificial Ear is one way of measuring headphone fidelity.

But how to do this with a set of headphones?  The question of how you monitor headphone sound has always been a vexed one, and there are very sophisticated ‘artificial ear’ devices that have been created to try and approximate the sound that actually gets fed into our ears.  It is definitely not a case of ‘try this at home’ – a reference quality artificial ear testing unit costs many thousands of dollars.

I saw a hint of how good sound processing could improve headphone sound with the Solitude XCS2 noise cancelling headphones that I reviewed back in December 2015.  The headphones provided a reasonably decent quality sound with the noise cancelling turned off and no digital sound processing, but when this was turned on, the sound transformed from ordinary to stunningly excellent.  Unfortunately, the extraordinary sound they gave was not matched by high quality noise cancelling.

Venerable Bose also hinted at the potential to improve audio playback with their QC25 noise cancelling headphones.  Their sound quality appreciably approved when the noise cancelling was turned on.  Prior to then, Bose never allowed for ‘pass through’ sound, and it was rumored the reason for it was that the sound quality, unassisted by sound processing, was unsatisfactory and Bose didn’t want to embarrass itself by allowing it to be experienced in its raw unenhanced form.

But, for normal headphones, we all have to make do with whatever the headphones can do, alone, unaided; or try to fine tune them using some sort of multi band equalizer.  For example, if you’re playing digital music on your PC or Android/iOS device with Foobar 2000, you have an equalizer that slices the audio band into 18 chunks, each capable of high-slope narrow-band adjustments.  But in truth, while the enormous versatility of control this gives is tempting, we’re more likely to mess up the sound than improve it when we start subjectively tweaking it!

So, headphones have been an exception to how digital processing can improve audio performance.  Until now.  Enter the exciting True-Fi App from Sonarworks.

True-Fi – the $79 Solution to Improve Your Headphone Sound

Sonarworks is a digital sound correction company based in Riga, Latvia.  They provide tools for audio-engineers to custom-calibrate their studio equipment, and branched out into a consumer type program called True-Fi, released at the end of last year, and which digitally adjusts the playback sound to compensate for the specific weaknesses of various brands of headphones.

The program currently is available for Windows and Mac computers.  Sonarworks anticipate releasing versions for iOS and Android devices late in the second quarter this year (ie probably June).  They plan to bundle the iOS and Android apps with the existing desktop versions of the software (and yes, this will be backdated so you can buy the desktop software now and will qualify for the apps when they are subsequently released).  The future inclusion of the iOS/Android apps removes a lot of the sting from the otherwise slightly high $79 purchase price, and makes it a much fairer value, and also makes the program more generally useful.  These days I am more likely to listen to music through an Android or iOS powered portable music player device or phone or tablet than I am through my laptop, and the chances the same applies to you, too.

The program comes with pre-loaded profiles for about 130 different reasonably common models of headphones.  I had two of the headphone models supported – the deservedly popular Sony MDR7506 (about the best quality/value you can get in a set of under-$100 headphones) and the Bose QC25 headphones.  Inevitably, other models were not supported, most regrettably any in the Sennheiser HD 500 series of mid-priced headphones that generally are the best choices in the $100 – $200 range, except for the no longer current HD 598 model.

Overall it seems Sonarworks have focused more on supporting mid and high end headphones.  Perhaps their reasoning is that people who spend $200 and up on a set of headphones are more willing to spend another $80 to improve their sound still further, whereas people who spend less than $100 on headphones are probably not going to double their total cost to improve the sound.

That sort of makes sense, although the other part of that consideration might be that if you have high-end $500+ headphones to start with, you’ll get less value from the small remaining tweak with the True-Fi program than you would if you had middling grade headphones with much more potential to be digitally improved.  To put it another way, perhaps the way to get the best sound quality per money spent is to get a moderately good set of headphones and then super-power them with the True-Fi app.

This shows the enormous improvement in the raw frequency responses in the top chart after applying the True-Fi corrections

How True-Fi Works

The audio engineers at True-Fi created frequency response profiles for each make/model of headphones supported, noting where the peaks and troughs of the frequency response curve existed.  They did this with multiple sets of each headphone model, so as to average out the random variations between one set of headphones and a second set, seemingly identical, but actually with small variations in performance (they say that there can be up to a 3dB variation in curves as between two seemingly identical sets of the same headphone model).

They then added a correction curve that matches each dip in the headphones’ response with a boost in volume, and of course, matches each rise in the response curve with a cut in volume, so as to end up with an almost completely flat frequency response all the way through the audio spectrum.  Indeed, because any speaker or headphones tends to have their sound response fall away at their upper and lower limits (they don’t just ‘switch off’, they merely work less efficiently) this means the boosting of sounds at the outer limits of the headphone’s rated response capabilities will extend their frequency response still further, as well as making the response more flat, linear, and without interfering ‘coloration’.

All of this sound processing is done on the digital soundfile data inside your computer, before it is converted to analog output, so as to be most protective of the underlying sound quality.

Installing and Using True-Fi

It is easy to download the program from the Sonarworks website.  It is a large-sized file (101MB) and it is far from clear why it is so enormous in size, because it doesn’t seem to include high-resolution graphics or high-quality sound files.  To have 101MB of code alone is surprising.

They offer a free ten-day trial, during which the program works perfectly and without restrictions, but at the end of which the program stops working unless you then purchase an activation key and enter it.  It appears that the program can be installed on three computers.

Having installed the software – an easy straightforward process – you simply select the headphones you’ll be using from a drop down menu of all the supported makes/models.  If you have two or more different headphones you’ll be using, you can preselect them and have them on a hot list for easier switching.

That is basically all you need to do.  The program fits into the ‘middle’ of the sound management chain in your computer, intercepting the signal between where it was stored and when it emerges from your sound output jack.  You can switch it on or off, and you can also set a couple of options (bass boost, age loss compensation – see discussion below), and otherwise, you simply forget about it entirely.  It is set to auto-start when you boot the computer each time.

The program is surprisingly CPU intensive.  With my reasonably powerful CPU (an Intel quad-core/eight-thread i7-4810MQ) it tended to be using around 2% of the total CPU resource, all the time, even when not playing sounds, and even when disabled.  On occasion, it went up to 4%, sometimes 6%.  Sure, that still leaves a lot of CPU for everything else, but the downside is that it uses more battery power on my laptop, meaning shorter battery life, plus it gets everything closer to the point where the fans have to start up to cool things down, meaning even less battery life.

To put this in context, currently my computer is using 6% of its total CPU power, sometimes peaking higher.  I have more than ten programs all open, including 20 Chrome browser windows.  Of that 6% CPU, 3% comes from True-Fi, which is doing nothing.  The other 3% is powering everything else.

Testing True-Fi

I tested the True-Fi app two different ways.

Firstly, I simply listened to various music sources and turned the True-Fi on and off.  Did it make the sound better or worse?

While it was possible to hear a change in sound coloration, it is very hard to truly evaluate if the change is for the better or for the worse.  Such things of course are subjective, and even a skeptic like myself has a certain tendency to automatically think the True-Fi sound is ‘better’.  To avoid any type of unconscious bias, I randomized the clicks as between when I was turning True-Fi on and off, so I didn’t know if I was turning it on or off with each click, in the hope that while I’d of course hear a sound difference in the two states, I’d not know which state was ‘on’ and which was ‘off’.

I did this in three scenarios – Sony headphones, Bose headphones with noise cancelling on and Bose with noise cancelling off.  (True-Fi has very different correction profiles for the Bose headphone depending on if the noise cancelling is on or off.)

By the end of many clicks, I am fairly certain I ended up with a preference for True-Fi on.  So, using this methodology, it does seem to add value to the sound quality.

The second test took a different approach.  If True-Fi truly does improve any set of headphones to an almost perfect frequency response, doesn’t that mean, then, that the Sony and Bose headphones should end up sounding almost identical with True-Fi enabled on both sets of headphones?

The first part of this test involved carefully setting identical volume levels for both sets of headphones, using a lovely little $25 comparator device (I review it here).  This is necessary because we perceive sound quality differently based on its loudness.

Having got the two headphones balanced, I then tried swapping between them.  First – a reality check.  There were clear differences heard without the True-Fi enabled.

And then, with True-Fi activated, the two units did sound very similar.  Not completely identical, but very similar indeed.  Clearly True-Fi was working its magic.

The manufacturer, Sonarworks, partially explained the remaining difference as due to individual sets of headphones always have some slight individual variation in their sound profile.  In addition, I suspect there are other factors at play – transient performance and damping (ie inertia) for example, and distortion, none of which shows up in a frequency response chart, but definitely do exist and contribute to overall sound quality.  Plus other things such as even the headphone connector cables, all making additional minor impacts.

My conclusion – you truly can hear a difference when you activate the True-Fi sound correction service.  It makes the sound ‘better’, but not perfect.  Which is perhaps why I’ve headed this ‘make your $80 headphones sound almost like $800 headphones’ rather than ‘make them sound perfectly like the real thing’.  That would require a $10,000+ set of headphones.

In case you wondered, the Sennheiser Orpheus headphones, at $55,000, are generally considered the best there are (and, no, True-Fi doesn’t presume to offer any sound correction profile for them!).  You can spend more than that to get diamond encrusting on a fairly ordinary set of Onkyo headphones (costing up to $200,000) but you’re paying for the diamonds, not the sound, in such cases.

The main screen of the True-Fi program, with the age-related hearing loss adjustment enabled.

Bonus Feature – Age Compensation Curves

You probably know that as you age, your hearing deteriorates.  Not only do we become progressively more deaf, but our hearing loss is more marked at higher frequencies.

Women have a slightly different hearing loss profile than men, and each individual person also has their own unique degree of hearing loss (depending on how many rock concerts they attended in their youth, I guess!).

True-Fi offers an interesting extra feature which, if nothing else, offers the potential for lengthy debate with your audiophile friends.  Is it a good or bad thing to shape the sound you hear to compensate for the frequency-selective nature of hearing loss?

On the face of it, you might say ‘of course it is a good thing to compensate for hearing loss’.  But the thing is, for most of us (assuming we have no hearing aids) inevitably all the sounds we hear directly from the outside world and into our ears with nothing inbetween, are experienced through the filtering effect of our hearing loss.  We become used to it, because the loss is so slow and gradual.

Does it actually make sense to then create a sound which is unlike what we’d hear if we were attending a performance, live?  Sure, perhaps it will be more like what we heard at age 20, but if we are now 40, 60, or even 80, is it now realistic to selectively recreate a sound that is different to what we’d hear directly, unassisted.  Isn’t the purpose of highest quality sound recording and reproduction to give us something identical to the sound we’d hear where the sound was originally recorded?

Well, happily, the lengthy debate is optional, because the feature is optional.  You can tell the program your age and gender, and then you can set the recommended profile to be added to the sound stream at any extent from 0% compensation up to 100% compensation.

I suggest you either leave it off, or use a mild level of adjustment.  The other side of the issue is that with this adjustment enabled, you’re going to be stressing your headphones by driving their high frequencies at a much greater level than they normally expect (easily by 10dB at higher frequencies, maybe even by more – in other words, the higher frequencies are being driven at ten times the power they otherwise normally would be driven at).  But even though the higher frequencies are being played very much louder, the sound you will hear will not sound greatly louder.  There is a danger in such cases that you’ll either overload the sound amp board in your computer, or possibly the headphones, causing an overall deterioration in sound.

But, such philosophical misgivings aside, I decided to ‘hear what I was missing’ and took what I thought to be a good recording of some piano music from the 1970s (it would have been recorded in an AAD system) and listened to it for a bit, then switched on the age hearing-loss compensation.

What an extraordinary difference!

I suddenly realized that the reason I no longer hear tape hiss in older recordings isn’t because it has been somehow digitally filtered out, but because, ahem, my hearing no longer reaches that high.  All of a sudden, the sound stage came alive with glorious tape hiss in the silences!

Well, okay, you can debate just how glorious tape hiss is, but it very definitely showed me that my hearing – which I’d always thought was still excellent – is alas as much a victim of the vicissitudes of increasing decrepitude as is that of anyone (everyone!) else.

The program also allows you to add extra bass to the playback.  For us, while we love to truly feel a solid bass line in our stomachs, particularly in explosions and other special effects in movies (we have a stunning Carver subwoofer which rattles the shelves and just about everything else in the house when it is being used at high power levels – we have to be careful because at max power, we blow the mains power circuit breakers) we never add bass to headphones, because it doesn’t give the same ‘full body effect’ as it does when played over regular speakers.  We’d rather preserve the clarity and musicality in such cases, with a flat bass line.

A Bit Rough Around the Edges

We really like the concept of this app, and the basic core functionality is excellent.  But there are some small annoyances present.

When we first tried installing the app, it refused to accept any email addresses that had a four letter top-level-domain (ie .info) so I couldn’t use my TravelInsider.info email address.  It would accept anything at all with three letters, even nonsense domains, but it wouldn’t accept valid four letter domains.  That used to be an occasional problem twenty years and more ago (four letter domains have been around since the late 1980s), and it is disappointing to see it reappear.

The good news is that the developers quickly published a fix that now allows four letter domains in email addresses.

We had a problem with the program, and noted there is no link from within the program itself to go to the Sonarworks website, and no built-in help information at all.  There’s not even a copyright page.  Tool tips appear alongside the three configuration options – but only if you set the configuration choices on.  If you don’t set them on, you’ve no way of knowing what they are, and the options such as “Captures your device’s sound” are not at all intuitive.  Neither is the matching tooltip once it has been set on – “True-Fi will be disabled if the output device is changed at the settings.”  I’ve still no idea what either the option or its explanation means, and I’m also not sure whether the disabling occurs if the check box is checked or unchecked.

Another support challenge is the result of the developers being in Latvia, variously 7 – 10 hours ahead of US time, and only providing email support.  So pretty much whenever you send in a support request, it is night in Latvia, and you have to wait until the next morning and hope for a reply having come in overnight.  Alas, as was the case when I sent in a support request, the response wasn’t a resolution, but a request for more information (some of which I’d already supplied in the original support request), and so the answer to a question spills over into a second day, and potentially still more days (in my case, my second email to them has been met with silence rather than additional assistance and the problem remains unresolved).  Annoyingly, the software resets my computer sound card’s volume level to maximum every time I reboot the computer, so I have to then dial it back down to the usual setting, only to need to repeat again the next time I reboot the computer.

It would seem not unreasonable to expect a more interactive form of support for a $79 product, and some additional documentation built into the program itself.

Another minor annoyance was when a new version of the software was released, installing it caused the customization settings and selected headphone types all to be lost.  Sure, it is a small thing, but it is a ‘rough edge’ that should be smoothed over.  There was also no explanation about what was new or improved or fixed in the new version, just a request to download it.

All these issues are of course minor blemishes on a fundamentally fine program, which perhaps makes them all the more regrettable.


The True-Fi program from Sonarworks, currently available for both PC and Mac computers, and soon to be released on Android and iOS devices too, is a great way to make the music you hear through headphones appreciably better.

If you have one of the supported makes and models of headphones (here’s the current list on Sonarworks’ website – we’re told the list is steadily growing) then you’ll for sure get much more improvement in sound quality by spending the $79 that the program costs, instead of buying a better set of headphones.  Does it really make your headphones now sound comparable to headphones that are ten times more expensive?  Perhaps not, but it definitely does improve them.

With a ten-day free trial, and a really easy installation process, there seems no reason not to try it out.  Recommended.

Send to Kindle

Leave a Reply

/* ]]> */
%d bloggers like this: