On the subject of "ringing"

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An interesting topic, sparkled by one of archimago's blog entries, has been started at PFM on the subject of "ringing":

 

You pre-rang too soon

With all the broo ha ha about hi rez, new formats and digital filters over the last 20 odd years, much of the fuss has boiled down it a single issue: does pre ringing matter?

 

The main objection which could be levelled against 16/44 was that it requires filtering somewhere around the limits of human hearing. Orthodox theory has it that this should be accomplished by an infinitely steep, infinitely long linear phase filter equal to a mathematical sinc function. This filter "rings" before and after the signal for an infinitely long time, albeit at an infinitely narrow bandwidth. To put it another way, every sampling value affects the value of the reconstructed signal at all times (not just at that instant). [but that is not necessarily a bad thing, see below]

 

http://www.pinkfishmedia.net/forum/threads/you-pre-rang-too-soon.211327/

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3 hours ago, Fokus said:

 

That is a demonstration of equalisation with the filter transitions smack in the audible band. It has been known for three decades or so that under these conditions, given sufficiently steep transitions, linear phase pre-ringing can be audible.

 

But if you move the transition frequency up and up the audible effect vanishes.

 

 

What if you can't move the transition frequency higher up i.e. low-passing a mid-woofer with a digital crossover?

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37 minutes ago, mansr said:

Then you need to use a slower roll-off.

How slower is that?

"Hard" cones need steep filters.

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2 minutes ago, buonassi said:

@John_Atkinson, Fiio X5 3rd gen, uses a filter called "super slow rolloff" that produces almost no ringing.  It must be proprietary to them because it's not listed on the AKM data sheet.  But I can clearly hear the high frequencies being attenuated when switching between this setting an a more traditional filter of the 4490.  Admittedly, this device's amp section really isn't up to snuff for the most critical of listening, but still the result of this special filter is very dry sound - eerily precise. But again, at a cost....  HF rolloff.

http://fiio.me/forum.php?mod=viewthread&tid=42106&page=1&extra=#pid117558

 

On a side note, I've somewhat given up on trying to eliminate ringing.  A minimum phase filter that dumps all the ripple energy after the transient is OK by me provided it's not excessive.  I've played around with iZotope SRC at length to find a good compromise between high frequency loss and post ringing - still avoiding aliasing at -96dbfs.  And of course, I never stray from the minimum phase region of the ringing parameter.  

 

Really it's the "pre" ringing that bothers me.  Post ringing has the effect of added harmonics on cymbals, giving them some more zing and sparkle, which can be overwhelming if too much post ringing is present.  A moderate amount really doesn't bother me.

 

 

 

I've spent some time this evening playing with HQPLAYER's poly-sinc-xtr filters and I am having trouble deciding whether to choose minimum phase or linear phase. I don't like mp so much but when I switch back to lp something doesn't sound quite right.

I must try again tomorrow using poly-sinc-short filters but I like the transient "snappiness" of the xtr.

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5 hours ago, buonassi said:

just got caught up.  in reading the last couple pages, I keep seeing attempts to prove ringing doesn't exist or shouldn't matter if it does.  I'm not even going to try and pretend I can follow some of the posts as I'm not a physicist or electrical engineer.   

 

if ringing doesn't exist, or doesn't matter, then why are there different filter designs and why do they sound different to me?  Are the opponents of ringing going to assert that I'm imagining the differences?  That "expectation bias" is to blame?  

 

I'm not going to state that one filter is better than another.  But am I the only one who can admit to hearing a difference among them?  Have all the hours I've scrutinized iZotope upsampling parameters, observing the rolloff steepness in an RTA, and noted sonic differences all been a hard lesson in realizing I'm "drinking the coolaid"?

 

I am generally quite sceptical and wasn't expecting to hear a clear difference but that's what happened when I recently compared linear vs. minimum phase using HQPLAYER poly-sinc-xtr filters. Even thought about running a poll to have an idea of people's preferences.

I prefer linear phase but if I compare it with minimum phase there's something not quite right about it... I wonder if @Miska has a filter with 1/3 pre-ringing and 2/3 post- (is it even possible?).

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1 minute ago, Miska said:

 

For PCM yes, "asymFIR". And on my TODO-list for SDM outputs too. From my personal listening experience point of view, I feel it is more like "bad of both worlds" instead of "good of both worlds".

 

Ok, thanks. I'll give it a listen.

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On 13/02/2018 at 11:09 AM, Miska said:

 

For PCM yes, "asymFIR". And on my TODO-list for SDM outputs too. From my personal listening experience point of view, I feel it is more like "bad of both worlds" instead of "good of both worlds".

 

 

What is it exactly that you don't like?

I've spent a bit comparing all three FIR filters and I don't dislike the asymFIR, in fact it sounds quite natural to my ears.

I'm using the following tracks: The Peacocks by Bill Evans, Dance With Waves by Anouar Brahem and the 3rd movement of Cassadó's Cello Sonata by Janos Starker.

 

Unfortunately all three FIR filters sound somewhat unrefined when compared to the poly-sinc-xtr/xtr-mp family...

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1 minute ago, Miska said:

 

To me, it didn't really come close enough to minimum-phase sonically, although it is naturally quite far from linear-phase.

 

Those FIR filters are more similar constructs to DAC chip filters, although still better.

 

I already have partial implementation of those asymmetric filters for poly-sinc -family (for almost a year), but encountered a technical problem and moved to other things meanwhile, so the functionality is not complete yet...

 

 

I listen almost exclusively to acoustic music and up to now have preferred poly-sinc-short. It was only after I compared xtr LP with xtr MP that I felt like hearing what something in between would sound like.

Thanks for all the efforts.

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18 hours ago, buonassi said:

What I think at this point is that I prefer minimum phase because I actually like the phase distortion.  It is the phase distortion that is separating the attack "smack" of the drum verses the resonance of the drum.  They are no longer perfectly aligned, and therefore the smack is easier to hear.

 

This is quite interesting because to me it sounds like a (special) "effect", and I don't like it because it sounds less real or natural with the kind of (acoustic) music I listen to. But I found the 'ASYM' filter an "interesting" alternative to 'LP'.

 

@Miska does recommend 'LP' for acoustic music and 'MP' for pop/rock for a reason.

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47 minutes ago, Jud said:

 

Perhaps the composer of such an audio track would just be going through a phase.

 

Rainbow?

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9 hours ago, buonassi said:

 

@MiskaThe ASYM is for asymmetrical , meaning "intermediate" phase right?  I've had pretty good results with this type of a filter as well.

 

 

I think so. At least from my understanding of Miska's description.

@Archimago writes about it here:

 

 

http://archimago.blogspot.co.uk/2018/01/musings-more-fun-with-digital-filters.html

 

9 hours ago, buonassi said:

I started going back and reading some of @Miska's older posts about his filters in hq player.  What I came across confused me even more.  Originally, I believed it to be the case that low frequencies were delayed realtive to the highs in a minimum phase filter-because that's what I was hearing.  Then, I was pointed in other posts that I may have it backward, it's the highs that are delayed relative to the lows.  Now, after reading this I'm back to believing the lows are delayed, which sounds more natural to me (bass kick drum example).

 

"Linear phase filter" is a filter where all frequencies pass with same time delay. "Minimum phase filter" is a filter where all frequencies pass through as fast as possible, higher frequencies faster than lower ones." https://www.computeraudiophile.com/forums/topic/13071-hqplayer-resampling-filter-setup-guide-for-ordinary-person/?do=findComment&comment=175928

 

 

Maybe an expert on the subject can just put this to bed once and for all.  From this statement I'm inclined to believe the lows are being delayed and arrive at the eardrum shortly after the highs do.  So which is it?  Highs or Lows delayed when using minimum phase?