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3 reasons to add infrasound frequencies (below 20 hz) in the parametric equalizer even if you won't hear them: you can still feel them, it gives FULL control over sound, graphic EQ already has them

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Out of all Android equalizers I've tried, Poweramp EQ is the best one. Just like my new headphones, it combines unmatched technical advancement with convenient user experience. Poweramp EQ deserves every cent paid for it.

It could be even better. There is a feature I would like to suggest: control over subsonic frequencies in the parametric EQ.

Why calibrate sub-20 hz frequencies in the parametric EQ even if we don't hear them?

1. You can still feel them and many users would love to have the control over this feeling

Feeling sound is integral part of listener experience. It makes you feel as if it adds some "movement" to the music. Getting a back massage from car's subwoofer, experiencing wind and pressure from acoustics in your local cinema or - if you have ever attended a catholic church - feeling the floor shake in response to organ's lowest notes always produces an unforgettable impression. You have definitely tested your subwoofer with the title theme from The Dark Knight or the legendary bass check from Hoods Run Down, and if you don't have a sub, you would definitely do it when you get it. Everyone loves feeling the music no less than hearing it. Giving users control over these feelings would make Poweramp even better. And also, some people can really hear them.

2. Adding infrasound frequencies would let use low-Q filters on them, which may contol audible frequencies in ways currently not possible in the parametric EQ, which is crucial for fine-grained control over some audio

This is the main reason why I created this post. Many audio systems, especially open-back headphones, are not capable of producing sub-bass at the same volume as the rest of their frequency range. It can be fixed with EQ, but in some cases it is very difficult or even impossible with the parametric EQ of Poweramp, because fine-grained control over these frequencies requires low-Q filters in the infrasound range, where they cannot be placed.

Take my headphones as example. I use Axelvox HD241, which are a clone of Superlux HD688B, which are a replica of some budget AKG model. To my ear, their response in the bass range is absolutely flat down to 30 hz, and then they start to roll off. I can still feel the thump down to 20 hz and below, but the volume difference is still very easy to notice.

Let's fix it with the parametric EQ:



I chose the 12 db because the available measurements of these headphones show 12 db decrease between 20 and 30 hz, and 0.8 q because it achieves the exact +12 db gain at 20 hz.

But, apparently, this config is bad. Why? Take a look at this:



That's right - when equalizing with these settings, the 30 hz frequency (and everything around) gets boosted too, and the volume difference between the 20 and 30 hz remains the same - not to mention that it also elevates volume of frequencies which I would like to have intact.

But maybe it is not that bad and I can just try other settings. Let's try the most extreme filter with Q = 12 to avoid interference with frequencies at 30hz and above:



The knob is only +1.3, but since the Q is extreme, the actual gain is around +12.

Do you think we have solved the problem? Only partly. And we have also introduced other two, one of which is not obvious at all.

First of all, volume of frequencies at 30 hz and above is still influenced by these settings. Although less than by the previous settings, it turns some compositions from my playlist (particularly Maul by Kevin Penkin) into horrendous rumbling, which makes me worried for my aesthetic pleasure, health of my ears and lifespan of my headphones.

Second, extreme filter settings introduce distortion to the sound. Every EQ I've heard introduces some distortion with extreme EQ settings. Poweramp EQ introduces the least of them, but they are still hearable. I can hear this annoying "zzzz" oscillating saw noise when the Q is too high. It is definitely not clipping because it is also present if I try to reduce the bass, and I can hear actual clipping if I make the volume on my phone too high. Maybe this noise is not heard in the vast majority of the music, but it is still annoying and unsatisfying to think that these settings are not perfect.

But okay, we can somehow deal with these two problems if we... simply reduce the volume gain. Why? Because the measurements of these headphones made on reference microphones do not line up with the measurements made with my supreme, objective and unbiased (no) hearing, and, apparently, the +1.3 db with Q = 12 is too high. +0.7 would be enough:




When listening to music with these settings, there is no annoying rumbling at around 30 hz, and the volume of 20 and 30 hz is perceived at around the same level. I believe that I can still hear difference in volume when listening to test tones, but I usually listen to music and not test tones. Also, the extreme Q distortion is more difficult to notice now.

Do you think that it is the solution? No! I said that we have introduced two new problems. The extreme Q distortion was only one of them. The second is not obvious at all, but it will scare away every perfectionist audiophile like me. Take a close look at this:



Do you see what's wrong? The filter that compensates the 20-30 hz roll-off does not sustain the volume of infrasonic frequencies at least at the adjusted volume of 20 hz, and the filter that does it interferes with bass frequencies too much to comfortably listen to music! What if I stump across a recording with infrasonic frequencies and won't be able to feel them (my headphones are apparently capable of reproducing them)? This is just horrible! As a perfectionist audiophile, I feel offended!

All the problems listed above can probably be fixed with some eq-jutsu in cascade mode, but doing it is absolutely annoying and time-wasting. The best solution to these problems would be to allow the control over infrasonics in the parametric EQ to use the no-distortion low-Q filters to adjust audible frequencies. It will solve so many problems, holy cow, I can't imagine how happy I will be when the Poweramp developers add this feature. I can't imagine how many users of budget audio would be happy to get this to achieve that perfect sound they could only dream of. And the solution is to implement just one feature.

3. The parametric EQ simply should have subsonic frequencies just because the graphic EQ already has them, and their lack in the parametric EQ makes the app feel incomplete

The graphic EQ already has knobs for frequencies below 20 hz. It is just absurd that, for some unbelievable reason, the parametric EQ can't have them too! If you have implemented them in the graphic EQ, why don't implement them in the parametric one? Even if I can't hear any difference between identical settings of graphic and parametric EQ in a blind test, there are at least four problems with the graphic EQ compared to the parametric EQ.

  1. Graphic EQ is so less convenient. If I need to add +9 db to everything above 150 hz on a poorly mixed track, the parametric EQ allows to do it with just one knob. If I need to do it in the graphic EQ, I have to adjust each knob 9 db up, and probably have presets made for each corner case. And so on. This adds so much unnecessary overhead.
  2. Adjusting lower frequencies in the graphic EQ also influences frequencies around them, which is simply a catastrophe for fine-grained equalization. If you don't believe me - try to play 50 hz tone (or any other tone that your audio is capable of playing) and adjust frequencies around +-5, 10, 15 and 20 hz. The more the gain, the more interference with other frequencies.
  3. Adjusting lower frequencies in the graphic EQ too much introduces that annoying oscillating zzzz saw sound about which I wrote in the previous paragraph.
  4. Even if I can't distinguish between the graphic and parametric EQ during a blind test, my feelings of a perfectionist audiophile would be still offended. I will never find peace in this world until the parametric EQ will allow users add knobs to control subsonic frequencies.


I believe this feature is what will make the Poweramp EQ the best mobile EQ in the universe. It will solve SO MANY problems, and it must take around zero time to implement (just set the lowest frequency for the parametric EQ at 5 hz instead of 20). I hope that I convinced the developers to implement this feature and everyone else to vote for it. Thanks.

Edited by SuperluxAxelvoxGem4DaPrice
removed unnecessary imgur link
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There are dozens of suggestions how to improve Poweramp on this forum. If this one would be as short as others, nobody will pay attention to this one. If this one won't have clickbait name, nobody will pay attention. If it won't explain why the feature is important, nobody will pay attention. If it won't have three paragraphs of emotional rant about how much the topic starter loves Poweramp and what can be done to make it better, nobody will pay attention.

I believe that the feature I suggest is definitely very important and more important than other features suggested before me, but even if I am wrong and it is not that important, it

  • is very easy to implement, and
  • it will solve many problems for many users when implemented

Therefore, its return-on-investment is high, and it should be implemented in priority the upcoming releases. This is why I try to bait everyone into reading this. Nobody wants to read another generic "uhhm, can we please have this OwO? thank you" topic which will be forgotten by the dinner by every forum user, including the topic starter.

Thank you, mr. moderator, for missing this point, ignoring the fundamentals of advertising 101, and sabotaging my selfless attempt to make the best Android equalizer in the world even better. You can now delete this post or reformat it into the idiotry of your choice so nobody will notice it and this doubtlessly important and necessary feature will never get implemented.

Edited by SuperluxAxelvoxGem4DaPrice
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> and it should be implemented in priority the upcoming releases <

The best part of these requests bordering on techno-babble is when they insist upon jumping the development queue, and then calling into question the 'business acumen' of those not heeding their demand. Every. Time.

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3 hours ago, SuperluxAxelvoxGem4DaPrice said:

Thank you, mr. moderator, for missing this point, ignoring the fundamentals of advertising 101, and sabotaging my selfless attempt to make the best Android equalizer in the world even better. You can now delete this post or reformat it into the idiotry of your choice so nobody will notice it and this doubtlessly important and necessary feature will never get implemented.

Yes, try the "make you feel guilty" approach to get your point across. Never saw that before on any other forum before, ever.

Your ask has been presented. Allow for parametric equalization frequency choices to be lower than the current 20Hz lower limit. SImple.

Keep in mind though for everyone else's consideration - Poweramp's equalizer in both the music player and the stand alone EQ are for use typically on mobile devices. The vast majority of these already struggle to produce enough power to drive most headphones well, assuming they still have a headphone jack. The amount of power draw to get this additional output below 20Hz without distorting is going to severly limit the overall output levels. And most of the dongles are not much better, it just passes the DA conversion outside off the phone.

In a select few cases some users are connected by USB to decent external DACs and/or amplifiers of some kind. But I guarantee in these cases the users are not using extreme subsonic equalization that their systems are already capable of reproducing from the original source files and levels anyhow.

But to each their own. If the developer chooses to implement this ask and adjust the lower threshold - then EQ away!

Edited by MotleyG
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And it's probably only a sub-set of the users that would get anything at all out of this, first of all you need a setup that is able to reproduce "sound" at <20Hz and secondly you need sources that has <20Hz content.

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