When you take REW measurements, there is only the mic at the sweet spot, stand away.
Don’t move the mic between left speaker and right speaker measurements.
I’ve now played through the original test track and the two modified tracks supplied by Thierry. The track is Glass Animals’ ‘Flip’ track which I’ve found a challenging track on every system I’ve ever tried, even my headphone setup. The most challenging is the final 1mins as there is a LOT of overlaid sounds on top of each other most of them in the same region as the vocals. This leads to a flattening wall of sound where everything sounds muddled together.
I noticed that the test tracks are quieter and Thierry confirmed that I should compensate by about +6dB on the test tracks to get them back to the same volume as the original track.
I’ve listened to all three tracks, three times (yes, I’m starting to get fed-up of listening to it). To my ears, the Crosstalk Reduction filter applied to the song is doing a marvellous job in that last 1 minute of the track. The other HAF is also tidying up that section of track but I just prefer the expansiveness of sound with the crosstalk reduction filter - I’ve no idea why that should be but there you go.
So, I’ve asked Thierry to go ahead and bill me for the crosstalk reduction filters. I’m very much looking forward to trying them out with the rest of my library 
Only question I’ve asked Thierry is whether he applies a bit of bass boost to his filters, or leave them neutral and I use the PEQ in Roon (as suggested by Eiffel), or should I just leave it for now and give myself some time to adjust to the filters with a neutral profile?
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We have similar background 
Head geometry and listening position/speakers position geometry are only of relevance and significance for crosstalk reduction. REW/Rephase/DIrac do not address this.
There’s nothing “idiophile” at all about it: cross-talk cancellation DSP have been around for years.
The simple idea is that your left ear should receive what comes from the left channel, and nothing from the right channel (and vice versa)
The trick is to compute a DSP that is preserving the signal from the left speaker and “cancelling” the right speaker at the left ear position, and vice versa. This is done by a matrix filter where data from the right channel is delayed, inverted, reshaped in frequency, and injected into the left channel in order to “cancel” what comes from the right channel to the left ear.
Why delayed: in a typical configuration your left ear is farther from the right speaker than the left. This delay depends on your sitting position relative to the speakers and distance between your ears, that’s why they need to be measured.
Inverted: so that the sound waves cancel and do not add (NB: if you edit your HAF filter you can see the impulse response of the x-talk is actually 180° out of phase with the room correction filter)
Reshaped in frequency: this is more tricky. Most likely your left ear is not directly pointing at the right speaker. It will hear whatever contribution the right speaker has on the reverberated field (this is the core of the HAF room correction) AND what will be diffracted by your head, which is frequency dependent (cf. diffraction sound waves - Yahoo Search Results) . Typically, with my 23cm high head, frequencies below 1700Hz are diffracted (and heard directly by my ear), and the frequencies above are not diffracted and do not reach my hears directly. If you have a shorter head (let’s say 20cm), this transition frequency is 2000Hz. The X-talk cancellation filter has therefore to match the frequency “response” of your head as it is diffracting the sound waves coming from the right speaker. And this response is quite dependant on your head geometry, both vertically and horizontally. That’s why there is a need to measure it to “tune” the filter. With typical head sizes, diffraction occur in the 1.5k-2.5kHz area, this is incidentally where the ear is the most sensitive.
Regarding the size of the sweet spot where the X-talk works well: I’d say in my case it’s a 30cm radius “bubble” around the sweet spot. At greater distance, this is normal stereo listening with room correction (the one you have with the standard HAF filter).
I hope the technicalities above will convince you there is nothing idiophile about the approach of X_talk pushed by HAF. Regarding confirmation bias: if it would be only me to nod and clap hands, I would doubt of myself. Fortunately, there are lots of positive testimonies out there, including some from audiophiles that are far more experienced and critical than me.
Regarding my relationship with Thierry: I’ve said it on another post, but for the record I am not affiliated with him in any way. I paid for my filters. As a DSP-savvy person and audiophile I am enthusiastic about the technology and I am on this forum only to share my experience and explain DRC in general and HAF in particular. Until there is a new solution out there that is outperforming it !
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Hey @alec_eiffel I can see where @nquery was coming from. Usually when someone is on a forum so enthusiastic about something it’s because they have a vested interest. Heck we live in the age of paid for reviews. From what you’re saying you’re just enthusiastic and keen to share your experiences.
We need more of that - “audiophiles” seem to be a solitary bunch. Listening to music is a personal experience. So we go into our bubble. Room calls this a community - not a forum. Forums are where you go to call other people stupid for having a different brand car / camera / whatever.
Thank you for sharing your experiences and this thread. It’s good community spirit and not selling. We need more sharing and community 
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Do you have some references/white papers on how head height impacts diffraction? Obviously it does at some small empirical level, not arguing that. But to suggest that a 3 cm difference in head height can be consistently controlled for at that level seems dubious to me. Does the specific diffraction frequency change when I move around the room? What if I turn or angle my head 3 cm to the left - won’t that impact the results just as much? If your head remains in the same exact position, +/- a few cms, or better in a head vice grip, then I suppose it might work … but your 30 cm bubble seems generous. I will remain a skeptic for the time being …
edit: I did some searches and did some brief reading on head related frequency transfer and such … I am not skeptical of the science but still skeptical that it would have any audible impact in a non-controlled environment. But I am open to being proven wrong and may even try it once I get things sorted with my setup.
I was in the same situation. Should I choose a linear setting and have the low end of my Phantom Golds ( rise of up to 10dB from 40 to 20 Hz ) corrected by the HAV filters and then use PEQ to set my preferred house curve again or ask Thierry to leave the low end timbre as is? Both options might have a similar result. But I have chosen the option to keep the speaker characteristics since I generally like them and only to have the room modes eliminated. Anyway, I would set the PEQ to the house curve I like most and it would not make much sense to attenuate the original bass to amplify it afterwards. So, in case I really want a neutral setup I add a PEQ that lowers the low bass with a shelf filter and now also know for how much as the room modes are already eliminated.
I’m extremely happy with the HAF filters from Thierry and even more with the x-talk compensation that open even more up the soundstage, maybe too wide, who knows?!
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I’m going to update my filters soon, after some more acoustic treatment. Then I will ask Thierry to make it 100% flat, with everything filled in (including null nodes), and then I will measure in REW, find excess phase and add band-stop filters together with house curve. Yea, I will also measure my head
I tried some band-stop filters, one on my dead 49 Hz, and with Q=20 all boomy bass was gone, while as much as possible of the rest of the bass remained.
Btw, I talked with Thierry and applying PEQ will not mess with phase in any bad way, so this feels like the best way to get good sound but still be able to adjust to your liking.
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Nope, my reasoning is empirical and mostly qualitative, based on what I saw from the filters response (imported in REW), my average knowledge of acoustics and signal processing, and what I heard. I don’t have the time or the will to reverse-engineer HAF filtering, I am sure Thierry will put forward clearer explanations than mine at the time he will decide to officially launch the “personalised” X-Talk filter.
Is room correction valuable with near-field listening?
Yes, although the effect of the room lessens as you get closer to the speakers. Measure and find out, you will probably be surprise how far from perfect it is, even if you sit 50 cm from speakers.
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I have now been using a set of HAF filters with crosstalk reduction for over a week.
Firstly, Thierry is very responsive and helpful and I highly recommend his service.
Secondly, the HAF filters make a noticeable difference to the listening experience. At first I wasn’t sure whether I liked them as they seem to put the sound further back in my room. However, after extending and critical listening with them enabled or disabled I can now see their value. They are providing a more coherent and controlled soundscape i.e. no one aspect of the music dominates which actually makes for better separation of instruments/vocals, etc. as well as a wider soundstage. Without the filters enabled the KEFs are a lot more forward: yes they are definitely livelier and they make their presence felt!! However, I also find that the sound is quite tiring.
In summary, the HAF filters have helped iron out some of the overly forward nature of my KEFs, they recess the sound a little but at the same time increase separation and soundstage that ultimately just makes my music more listenable (and I have very eclectic tastes so no mean feat!).
Highly recommended!
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@Rik_Carter I’m so glad you are enjoying your new HAF filters. I never realized how good my speakers could sound (very challenging room setup). I’d say Thierry has a hit on his hands. Thanks Roon and Thierry and this great community.
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@Mark_Allen yes. I listened for a solid 2 hours this evening. The best sound I’ve heard in my home environment. My replacement speakers are still settling in and they are starting to open up. Very happy with HAF.
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Has anyone used the HAF filters with open baffle speakers like the Magnepans? Usually their radiation pattern makes them meaningfully more difficult to use this type of software with.
Oh, good question. I have Spatial open baffle speakers and I’ve been looking forward to checking out HAF filters.
Maggies radiation pattern is indeed different than conventional closed or vented box speakers. HAF filter calculation process will work as it segregates direct field from indirect/reverberated field. No risk in trying! Make sure to mention your speaker type to Thierry, in case he can consider it in the fine tuning. Keep us posted!
Guys, some help please. I love Roon and I love this community. I’ve tried ever since @Magnus‘s detailed REW-post to apply room correction — actually, he’s the one who got me inspired. The results were horrible, but I know for sure that’s entirely up to me as I must have done a ton of things wrong. I think it’s safe to say I’m the least technically educated guy in this entire community, but I do like music and believe sound matters, so I’m really struggling how to do correct measurements. And as long as my measurements are imperfect, Thierry or anybody or anything won’t be able to make something decent out of it.
The drawing below (apologies for its “impressionistic” character) represents our living room / my listening room. S1 and S2 are the speakers, the red cross is my “Sweet Spot” (the place I always use to listen to music). It’s a small room (330cm by 360cm) and the couch is placed directly against the wall. I don’t have a laptop to measure with, I plug the mike (UMIK-1) in the Mac Mini, which is in the same cabinet as the stereo and the tv.
I did my measurements by sweeping the mike around my head, but I now understand from this thread that I shouldn’t be there at all. This is just one illustration of my technical non-knowledge: how do I measure in this room and move the mike when I can’t be there? How long should I measure at each point? Do I have to pause, or should it be a fluent movement? Also, I’ve read I shouldn’t move the mike in between measurements of the left and right speaker. But how then do I go to my Mac Mini in the cabinet to change REW to the next speaker? It would be really helpful if REW or Thierry or anybody would make a short film/animation for dummies (real dummies!). Meanwhile, if anybody cares and has time to assist a bit, I would love to do some proper room correction. Thanks a million in advance!
Lots of people say lots of things about how to do proper measurements, some suggest several sweeps and averaging it out, some (like me) prefer the moving-mike technique. However, if you intend to send the measurements to Thierry you should do sweeps, so why not do it like Dirac suggests. One sweep for each speaker on each of the positions below:
I usually do one extra sweep at 1 with both speakers as well, so the total number of sweeps is 19. To do a sweep in REW, use the “Measure” button up to the left in the REW main window.
Point the microphone to the speaker you are measuring, and use the 0 degree calibration file.
You can still follow my guide, just do an average in REW on your measurements for left speakers and your measurements from right speakers, then you will end up with 2 measurements and can continue the guide with the equalizer. Then test and see if it sounds good, and if so you can improve it even further by sending it to HomeAudioFidelity (just tell Thierry you measured according to Dirac single chair).
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@koen your microphone needs to be completely still during each sweep measurements and between Left and Right measurement at every position. The only way is to have a stand like this one, or worst case the small tripod that ships with the UMIK-1 on books/anything rigid (not cushions/pillows).
During a sweep, it’s OK if you’re still in the room as long as you are quiet and not standing between the speakers and the microphone.
I agree a tutorial video would be great!
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I usually just hold the mike while sitting in my listening position. Having said that, maybe using the stand would improve the measurements, I will try next time.
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