#### melowman

##### Member
It is, see here. Any signal between 0 and 22.05 kHz is mirrored at 22.05 kHz. That's why you need a filter to get rid of the mirrored signals.
You need a LPF in order to band-limit a signal below fs/2, because it’s the frequencies above fs/2 that get mirrored. A 20kHz pure sine wave isn’t mirrored, because it’s <= fs/2 when fs=44.1kHz.
f=24.1kHz gets folded back to 20kHz, but not the opposite.
That’s the basic sampling theorem and the basics of DACs.

most are down 3 dB at 22.05 kHz and below 90 dB at 24 kHz, for whatever reason
Well, precisely because 24.1kHz gets folded back to 20kHz! Anything between 22.05kHz and 24.1kHz gets folded back in the “reserve band” (20-22.05kHz) which is supposed not to be audible.

#### melowman

##### Member
The ideal filter would be down by 96 dB (for 16 bit samples)
Lots of people mess this up. 16 bits LPCM samples have a dynamic range of about 90,3 dB, not 96 ; )

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#### LTig

##### Major Contributor
Forum Donor
You need a LPF in order to band-limit a signal below fs/2, because it’s the frequencies above fs/2 that get mirrored. A 20kHz pure sine wave isn’t mirrored, because it’s <= fs/2 when fs=44.1kHz.
f=24.1kHz gets folded back to 20kHz, but not the opposite.
That’s the basic sampling theorem and the basics of DACs.
Your explanation is correct for the ADC. Signals above fs/2 will be folded back below fs/2 if there is no AA filter to suppress them. A 24.1 kHz signal would be folded back as a 20 kHz signal.

This is somewhat different for the DAC. On the digital side all signals below fs/2 are mirrored above fs/2. Therefore if the digital audio data contain a 20 kHz signal they also implicit carry the corresponding 24.1 kHz signal. If the 20 kHz signal would not exist neither would the 24.1 kHz signal. A DAC outputs both frequencies on its analog side and the reconstruction filter must remove frequencies above fs/2. See the screenshot of the scope and my plot which are very similar.

#### melowman

##### Member
Maybe you’ve missed the theory.
Any `f` between 0 and fs/2 at the output of a converter can be a mirror of `n x fs ± f` at the input. “Converter” here means ADC or DAC.
So, in the case of a DAC @ 44.1kHz for example, 20kHz in analog can indeed be 24.1kHz in digital if that has not been properly filtered in the digital domain — but you don’t retrieve 24.1kHz in the analog domain. But that 20kHz in the analog domain could also be 64.1kHz (44.1 + 20), 68,2kHz (2x44.1 - 20), 108,2kHz, etc. etc. in the digital domain.

Coming back to the RME DAC, not only did you only feed the DAC with a 20kHz pure wave (so no 24.1kHz was present at the input, thus no aliasing could theoretically happen), but also you cannot retrieve any 24.1kHz at the output (which means the analog oscilloscope graph cannot be that of 20kHz + 24.1kHz).
Your initial second screenshot btw shows f=17.57kHz, as opposed to the first showing f≃20kHz — not sure what that particularly means for your particular DSO.

OP

#### amirm

Staff Member
CFO (Chief Fun Officer)

#### LTig

##### Major Contributor
Forum Donor
I apologize.

New thread is here. Feel free to move the OT postings from this thread to the new one.

#### Maiky76

##### Active Member
Hi,

If anyone is interested.
based on the data from the first page, I did not go through the entire thread to check if the raw data was available...

Score no EQ: 73.3
Score with Amirm EQ: 77.5
Score with attached EQ: 100.2

Code:
``````Focal APO EQ Score 96000Hz
January122021-155015

Preamp: 0.0 dB

Filter 1: ON PK Fc 214.5 Hz Gain -6 dB Q 0.37
Filter 2: ON PK Fc 1283 Hz Gain -7.3 dB Q 1.18
Filter 3: ON PK Fc 3217 Hz Gain -4 dB Q 3
Filter 4: ON PK Fc 6000 Hz Gain -3.6 dB Q 8
Filter 5: ON PK Fc 11475 Hz Gain -7.2 dB Q 8``````

#### Attachments

• 289 bytes Views: 12

#### bidn

##### Member
For those combining the Clear with the RME DAC (pro or non-pro): which DAC filter do you prefer?
I find the two first SD filters (sharp and slow) not working for me; the phase linear Sharp filter sounds too aggressive to me; NOS ain't working for me, I have a "bizarre" sensation with it; the SD LD, I don't know if I like or not but definitely the one I like is the phase linear Slow: I lose a tiny bit of very top end but overall it's the filter I enjoy listening music on.

What about you fellow sound passionate?
There is a simple solution (If I remember correctly, it is explained in the manual ) which I have been using with satisfaction:
Set the RME application (accessible though the small, yellow - red "flame" in the Windows bottom taskbar) to upsample, by setting the rates e.g. to 24 bits - 96 kHz. Then you can enjoy the slow filter without a decrease of the high frequencies.

#### JIW

##### Active Member
There is a simple solution (If I remember correctly, it is explained in the manual ) which I have been using with satisfaction:
Set the RME application (accessible though the small, yellow - red "flame" in the Windows bottom taskbar) to upsample, by setting the rates e.g. to 24 bits - 96 kHz. Then you can enjoy the slow filter without a decrease of the high frequencies.
There will be a low-pass filter at half the sample rate of the original file regardless. Using the 'slow' filter at the higher sample rate of the upsampled signal thus does not produce the behaviour of the 'slow' filter but one that is dominated by that of the one used during upsampling.

If you want a flat frequency response with the 'slow' filter at 44.1 kHz or 48 kHz sample rate, you can use the EQ filters given by MC in the thread: B5 G +4.0 F 16.5k Q 2.1 Shelf for 44.1 kHz or B5 G +2.5 F 16.3k Q 1.7 Shelf for 48 kHz.

#### Count Arthur

##### Addicted to Fun and Learning
Hi,

If anyone is interested.
based on the data from the first page, I did not go through the entire thread to check if the raw data was available...

Score no EQ: 73.3
Score with Amirm EQ: 77.5
Score with attached EQ: 100.2

Code:
``````Focal APO EQ Score 96000Hz
January122021-155015

Preamp: 0.0 dB

Filter 1: ON PK Fc 214.5 Hz Gain -6 dB Q 0.37
Filter 2: ON PK Fc 1283 Hz Gain -7.3 dB Q 1.18
Filter 3: ON PK Fc 3217 Hz Gain -4 dB Q 3
Filter 4: ON PK Fc 6000 Hz Gain -3.6 dB Q 8
Filter 5: ON PK Fc 11475 Hz Gain -7.2 dB Q 8``````
View attachment 105531
Hmm, I've tried this, Amir's and another random set of EQ settings I found on the web. They all change the sound, but, to my ears in any case, don't necessarily improve it.

I'm using the parametric EQ within JRiver and an RME ADI-2 DAC. When I used REW with my speakers and plumbed in the recommended settings, I found EQ to be very effective, but for headphones it seems I'm just not that fussy. I like the tonal balance of the Focal Clears as they are, I don't really find any part of the frequency to be either lacking or too prominent.

When I use EQ with my speakers a lot of the "improvements" seem to be in the realm of imaging and some extra clarity; it should be said, that if I use my speakers without EQ, I still like them and soon get used to the sound.

I will also say that I've never really experienced much in terms of sound stage with any of the headphones I've tried. I hear separation, and I hear things left and right, but it's always like a little band in my head and things don't really extend much outside my head if at all - it's nothing like listening to speakers or a live performance.

Am I just a cloth-eared philistine?

#### Chuckv

##### Member
Forum Donor
Sorry that wasn't meant to criticise you or the review, should have made that clearer. Of course if it happens during normal listening for a specific person it's a deal breaker for that person. If that is a reviewer he should also call that out. What I don't understand is how many people here and on reddit seem to instantly dismiss the headphone because it "clips at normal listening volumes" or with any bass EQ applied. Both are not the case for me and for the 2 Focal Clear Pro I have, so I just want to add that as a different view on it. Also still not 100% sure if your Focal Clear maybe was worse than average. My 2 samples clip exactly at the same volume as far as I can tell.

No measurements on a science forum means being ignored as noise dude. Sorry. If we try to justify our position without measurements then we are looking to get banned. That's how it is around here. We NEED TO KNOW what science can share that our "trusted vendors" sometimes will and sometimes won't. For \$1500 it better be scientifically sound. Period. Focal is trying to STOP A STORM and I can't prove it.. I repeat... I can't prove it.. but the FACT that a BUNCH of Clears started being sold as "seconds" for \$500 less in batches around the end of last year and a LOT of people stopped hearing the problem proves that science FORCES COMPANIES TO BE HONEST. I can't prove it but I bet my cat they dumped the ones that sucked and fixed the problem. @amirm is late to the party but fortunately got an older version that was smack dab in the middle of the flawed fray is my hunch. My take is also that Focal engineering "tapped out" but the profit margins DID NOT REFLECT THE ENGINEERING LIMITATION. So who is left paying for less?????? The hard working music loving dude in the mirror. You and I got an "improved batch" but that is not the point. Gimme ASR all day. For 1 reason. Kick these companies where the sun don't shine when they mess up and are not transparent. I can't do it. You can't do it. Finally someone can and more importantly IS. Do it better @amirm. Just because of your post I'm donating now instead of lurking. Enjoy the music???? Absolutely. Not get pissed on while I enjoy the music?????? Much better music!

@ FOCAL CORPORATE - Show some integrity. Recall the lot or send out new drivers for the serial numbers affected. Do it now. This will not go away. The fire will only spread. Its a great product, but your engineers made a compromise. We get that. You were not transparent though and now the cat is out the bag. Do the right thing. You sold your bad stock at a discount. Wrong thing. You didn't tell us what happened. Wrong thing. You are silent on this thread. Wrong thing. You limited your official response to a French Forum but sell millions in other language markets. Wrong thing. Isn't it time you did the right thing?

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#### melowman

##### Member
Dude, that was intense lol
The good news is that the info is spread out all over the world including other language parts of the world, and people and reviewers won't give any chance to Focal's next release if they f it up; clipping will be the very first tested thing
Chill out man, keep calm and enjoy your Clear!

#### Chuckv

##### Member
Forum Donor
Dude, that was intense lol
The good news is that the info is spread out all over the world including other language parts of the world, and people and reviewers won't give any chance to Focal's next release if they f it up; clipping will be the very first tested thing
Chill out man, keep calm and enjoy your Clear!
Good news? That they can't sneak a problem past us? You betcha. Let that be a lesson for ALL of these audio vendors. I added a couple of table spoons of chill to the post for the poster. Thanks Melowman. No chill we be outed for Focal however. A multi-million dollar global high end dealer who promotes cutting edge engineering in their marketing? I work too hard and research too thorough to forgive the way this was handled. The user base here alone shows I'm not alone. Going forward I'm sure they fired the engineering and customer service personnel who got them into this and confirmed it; while they hurriedly improved the drivers. The crime was not owning it for what it is. This is a flaw in a \$1500 audio device; not a engineering compromise for a \$500 - \$650 product. Did they lower the price? Yes. On the second hand market though. Never through an approved dealer. Did they contact owners to alert them? No. Did they do like Schiit and launch the fix as version 2.0 and up the price? No. To their credit they are not a scum company. But they skiffed many conscientious customers by not informing them of the flaw/fix/resolution. I wasn't one of them apparently, but I missed it by I don't know how many serial numbers. Plus I'm ticked off that a few volunteer engineers and hobbyist with strong science leanings got this thing cornered and exposed the flaw when Focal's lab and corporate knew it all along and tried to shovel it under the "second market" rug. Its been 2 months and not a peep...I mean not a PEEP from focal since this thread started. (Unless @amirm is not telling us) Guess their can line of products isn't as large a profit center for them to care. They just let their dealers take the beating when an honest customer demands an answer. I feel real sorry for Focal Clear approved dealers right now. Its going to be a rough year unless Focal backs them up like they should. Hear that Focal????? Back up your dealers who are your front line out here. Where are the Focal dealers by the way? Silent too. Don't bite the hand that feeds and slaps you if you get out of line. We get it. *rant over*. But thank you I'm enjoying my Clears very much. I just wish ALL of my fellow Clear owners were having the same experience after the \$1000 + they shelled out like I did. Only thing I did right is wait until 2020 to buy mine. I'm not gonna lose sleep over it, but I am gonna post my thoughts on a public forum to help evoke change in the industry. Especially because after 40 years of this garbage, change is actually starting to happen. I'm old enough to know. And yes .... I feel even calmer now after writing this. Thanks for the well wishes. May ASR live long and prosper and STICK TO SCIENCE. It helps.

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#### Helicopter

##### Addicted to Fun and Learning
Forum Donor
Good news? That they can't sneak a problem past us? You betcha. Let that be a lesson for ALL of these audio vendors. I added a couple of table spoons of chill to the post for the poster. Thanks Melowman. No chill we be outed for Focal however. A multi-million dollar global high end dealer who promotes cutting edge engineering in their marketing? I work too hard and research too thorough to forgive the way this was handled. The user base here alone shows I'm not alone. Going forward I'm sure they fired the engineering and customer service personnel who got them into this and confirmed it; while they hurriedly improved the drivers. The crime was not owning it for what it is. This is a flaw in a \$1500 audio device; not a engineering compromise for a \$500 - \$650 product. Did they lower the price? Yes. On the second hand market though. Never through an approved dealer. Did they contact owners to alert them? No. Did they do like Schiit and launch the fix as version 2.0 and up the price? No. To their credit they are not a scum company. But they skiffed many conscientious customers by not informing them of the flaw/fix/resolution. I wasn't one of them apparently, but I missed it by I don't know how many serial numbers. Plus I'm ticked off that a few volunteer engineers and hobbyist with strong science leanings got this thing cornered and exposed the flaw when Focal's lab and corporate knew it all along and tried to shovel it under the "second market" rug. Its been 2 months and not a peep...I mean not a PEEP from focal since this thread started. (Unless @amirm is not telling us) Guess their can line of products isn't as large a profit center for them to care. They just let their dealers take the beating when an honest customer demands an answer. I feel real sorry for Focal Clear approved dealers right now. Its going to be a rough year unless Focal backs them up like they should. Hear that Focal????? Back up your dealers who are your front line out here. Where are the Focal dealers by the way? Silent too. Don't bite the hand that feeds and slaps you if you get out of line. We get it. *rant over*. But thank you I'm enjoying by Clears very much. I just wish ALL of my fellow Clear owners were having the same experience after the \$1000 + they shelled out like I did. Only thing I did right is wait until 2020 to buy mine. I'm not gonna lose sleep over it, but I am gonna post my thoughts on a public forum to help evoke change in the industry. Especially because after 40 years of this garbage, change is actually starting to happen. I'm old enough to know. And yes .... I feel even calmer now after writing this. Thanks for the well wishes. May ASR live long and prosper and STICK TO SCIENCE. It helps.
I am quite happy with ASR and my Focal Clears.

#### Chuckv

##### Member
Forum Donor
I am quite happy with ASR and my Focal Clears.
Happy you are happy. ASR is great. Focal Clears post fix are great. How do you feel about the Clears that have the flaw? and the owners of the flawed product that paid a high price for them?

#### gatucho

##### Member
Hi,

If anyone is interested.
based on the data from the first page, I did not go through the entire thread to check if the raw data was available...

Score no EQ: 73.3
Score with Amirm EQ: 77.5
Score with attached EQ: 100.2

Code:
``````Focal APO EQ Score 96000Hz
January122021-155015

Preamp: 0.0 dB

Filter 1: ON PK Fc 214.5 Hz Gain -6 dB Q 0.37
Filter 2: ON PK Fc 1283 Hz Gain -7.3 dB Q 1.18
Filter 3: ON PK Fc 3217 Hz Gain -4 dB Q 3
Filter 4: ON PK Fc 6000 Hz Gain -3.6 dB Q 8
Filter 5: ON PK Fc 11475 Hz Gain -7.2 dB Q 8``````
View attachment 105531
Will try, but honestly I tend to be doubtful of EQs as agressive as this (i.e. -7 gain and such high Q).
Trying to eliminate those high frequency peaks with inverted peaks is just too messy in most cases.
In my (very amateurish) measuring endeavors I have found those peaks to be very uncertain so that in many cases cancellation does not really occur and you end up with a the peak AND a dip.
A more light touch approach such as the one proposed by @amirm is less ambitious but less risky in that sense. However, one is welcomed to try it and be their own judge.

I may propose an addendum to @amirm suggestion to reduce the low frequency stress, a high pass filter. I find that frequencies lower than 30 are quite hard to hear for me, so no case in introducing such a high distortion and clipping for those. Just a suggestion.

#### Helicopter

##### Addicted to Fun and Learning
Forum Donor
Happy you are happy. ASR is great. Focal Clears post fix are great. How do you feel about the Clears that have the flaw? and the owners of the flawed product that paid a high price for them?
My Clears are fine. If you bought factory seconds, then you got what you got. You can resell them. It is a bit of a mark against Focal, but I remain a fan.

#### Chuckv

##### Member
Forum Donor
My Clears are fine. If you bought factory seconds, then you got what you got. You can resell them. It is a bit of a mark against Focal, but I remain a fan.
and the owners that have the flaw with retail Clears? the ones that have a record 5 or more ship backs to get proper warranty support? how do you feel about them?

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#### Helicopter

##### Addicted to Fun and Learning
Forum Donor
and the owners that have the flaw with retail Clears? the ones that have a record 5 or more ship backs to get proper warranty support? how do you feel about them?
I probably wouldn't feel as strongly as many people. It might have swayed my decision to spend about \$4000 on Focal speakers. I doubt I would be emotional about it though. When my LG washer failed just after the misleading and very short warranty period, I read a couple consumer reports articles and bought another LG washer.

#### Chuckv

##### Member
Forum Donor
@amirm your future is bright as the sun as long as we consumers care less what these companies get away with. After this thread I am HAPPY to donate. Personally I don't know how you do it. All I can do is salute and \$upport you dude. @Helicopter Couldn't disagree more. Principles man. How about the principle of luxury purchasing. Headsets start at \$10. Washing machines start at \$158 for portables. For your analogy to work a \$1500 Focal Clear level washing machine would cost a measly \$23,700 all things being equal, but you wouldn't care if a feature broke and LG wouldn't fix it and tried to cover the fact up by dropping the price 33% to offload the bad stock? After all, its only hard earned money and vendor trust that's lost. Hey Focal. You win. We deserve every bit of the loss of money and vendor trust you stole from us. We are all talk but have no real teeth and are the wallet opening honey ants you think we are. Please milk us. Go on covering your mistakes, we really were dreaming to expect you would do right by the money we paid you. We know you don't care, because we don't care.....enough. But Focal... ASR scares you at least a little bit right? Right? We know that you know that the footsteps you hear will be a lifelong friend now. We also know that you know that we know you will be watched very closely along with the rest of the other Schiit that comes along.