The No.1 Website for Pro Audio
Linear phase "pre ringing" audio examples?
Old 5th November 2012
  #1
Gear Addict
 
Pyxis360's Avatar
 

Linear phase "pre ringing" audio examples?

Hi everyone, as I wrap my head around the differences between linear phase eq and minimum phase eq I'm looking for online audio examples of the differences between these two tools.

Can anyone point me to some audio examples of pre-ringing when using a linear eq? I've yet to come across any in my searches.

Thank you in advance.
Old 5th November 2012
  #2
Lives for gear
 
24-96 Mastering's Avatar
Quote:
Originally Posted by Pyxis360 View Post
Can anyone point me to some audio examples of pre-ringing when using a linear eq? I've yet to come across any in my searches.

Thank you in advance.
Here you go. One file uses a minimum phase EQ, the other a linear phase (see file names). I made these very obvious, to create a worst case example, using a strong transient snare sound with fairly low frequency cut at narrow Q.
Attached Files

snare_200hz_q20_minus6db_minimum_phase.wav (635.7 KB, 21179 views)

snare_200hz_q20_minus6db_linear_phase.wav (635.7 KB, 27019 views)

Old 5th November 2012
  #3
Gear Addict
 
Pyxis360's Avatar
 

Hi Robin, that's fantastic, thank you very much. I hear it very clearly.

Do you personally find this to be an issue when working? Do you have a general preference for either type of EQ?
Old 5th November 2012
  #4
Lives for gear
 
24-96 Mastering's Avatar
Quote:
Originally Posted by Pyxis360 View Post
Hi Robin, that's fantastic, thank you very much. I hear it very clearly.

Do you personally find this to be an issue when working? Do you have a general preference for either type of EQ?
The problem of a downbeat creating a "swoosh" leading up to it it is a reasonably rare occurence, but it does happen and is something to watch out for whenever using linear phase EQ. Usually linear phase pre-ringing rather shows itself as a perceived difference in tone, since the pre-ringing is much shorter with higher frequency and broader EQ changes. To me, that different tone, along with a slight perceived softening of transients, is enough to put me off linear phase most of the time.
Old 5th November 2012
  #5
Lives for gear
 
wado1942's Avatar
 

Like 24-96 said, you usually don't get a noticeable RINGING so much as the perception of softened transients. Sometimes a linear phase EQ is just the ticket for a certain problem, particularly in the high end. Most of the time, I stick to minimum phase.
Old 5th November 2012
  #6
Lives for gear
 
huejahfink's Avatar
 

Verified Member
For the exact same reasons above, LP in the higher end of the spectrum can be great for bringing out 'inner details' and harmonic textures etc without pushing the main transients in that area so much.
Old 5th November 2012
  #7
Lives for gear
 
Red Mastering's Avatar
 

Verified Member
Quote:
Originally Posted by huejahfink View Post
For the exact same reasons above, LP in the higher end of the spectrum can be great for bringing out 'inner details' and harmonic textures etc without pushing the main transients in that area so much.
good point!
you can also benefit in low end, when LP 'distortions' actually can sound good
Old 8th November 2012
  #8
Lives for gear
 

The temporal distortion of the transient is more significant the lower the frequency. It has a relationship to the Secant function of the unit circle, where time is delayed almost exponentially as a function of frequency. It is best to use as wide Q as possible, and combine with minimum phase EQ for sharper moves.

The LP10 EQ by DDMF has the function to adjust the resonance from minimum to linear to maximum phase, with maximum being equivalent to a TIIR or IIR in reverse. It can set an inbetween, where resonance is biased to either side of the impulse. While I am not fond of FFT processes in general (except analysis), YMMV.

I do agree that it really brings out the details in a very transparent and silky smooth way. In some situations this is exactly what is called for.
Old 8th November 2012
  #9
Deleted User #106149
Guest
Just writing so it is in my history.

Sent from my HTC Desire
Old 8th November 2012
  #10
Lives for gear
 
dcollins's Avatar
 

Verified Member
Quote:
Originally Posted by OpusOfTrolls View Post
The temporal distortion of the transient is more significant the lower the frequency. It has a relationship to the Secant function of the unit circle, where time is delayed almost exponentially as a function of frequency. It is best to use as wide Q as possible, and combine with minimum phase EQ for sharper moves.
Which makes sharp linear-phase HPF's the worst possible place to apply it.


DC
Old 12th November 2012
  #11
Lives for gear
 

Quote:
Originally Posted by dcollins View Post
Which makes sharp linear-phase HPF's the worst possible place to apply it.


DC
For mastering, yes. There is no benefit to LP lowcutting unless the material is already loose. Using a sharp LP lowcut on the master is just bad practice.

In sound design, there are not such simple rules. As an in between process with particular treatment afterwards, LP lowcut can make very interesting sounds.
Old 12th November 2012
  #12
Lives for gear
 
Alexey Lukin's Avatar
 

Verified Member
Quote:
Originally Posted by dcollins View Post
Which makes sharp linear-phase HPF's the worst possible place to apply it.
The amount of ringing really depends on the signal: whether the signal contains any significant energy at the cutoff frequency of the filter. If the transition band of the filter does not overlap any significant energy in a signal, then a linear-phase HPF is the best choice because it keeps the signal above the cutoff intact. For example, if your signal lies all above 70 Hz and there's a hum at 50 Hz, I would use a linear-phase filter to perfectly separate them, without any phase distortion to the useful signal.
Old 12th November 2012
  #13
Lives for gear
 
dcollins's Avatar
 

Verified Member
Quote:
Originally Posted by Alexey Lukin View Post
The amount of ringing really depends on the signal: whether the signal contains any significant energy at the cutoff frequency of the filter. If the transition band of the filter does not overlap any significant energy in a signal, then a linear-phase HPF is the best choice because it keeps the signal above the cutoff intact. For example, if your signal lies all above 70 Hz and there's a hum at 50 Hz, I would use a linear-phase filter to perfectly separate them, without any phase distortion to the useful signal.
At any rate, when I have audibly compared these filter families minimum-hase always sounds better to me. At every frequency. It actually seems to do less damage.

Although I haven't tried your system that allows for an in-between phase response to be phase response, which does seems interesting.

DC
Old 12th July 2019
  #14
Reviving this thread: Is there an easy way to visualize and quantify FIR pre-ringing in VST plugins?
Old 12th July 2019
  #15
Lives for gear
 

Verified Member
Quote:
Originally Posted by johannburkard View Post
Reviving this thread: Is there an easy way to visualize and quantify FIR pre-ringing in VST plugins?
I wouldn't say easy but if you understand some of the principals you can test plug ins very effectively with this - https://ddmf.eu/plugindoctor/

It's a little buggy and if you don't know a little about how these things work you will get confusing results.
Old 12th July 2019
  #16
Quote:
Originally Posted by Ruairi View Post
I wouldn't say easy but if you understand some of the principals you can test plug ins very effectively with this - https://ddmf.eu/plugindoctor/
What are you using within Plugindoctor to do that? The oscilloscope?
Old 13th July 2019
  #17
Lives for gear
 
Nordenstam's Avatar
 

Verified Member
Quote:
Originally Posted by johannburkard View Post
Reviving this thread: Is there an easy way to visualize and quantify FIR pre-ringing in VST plugins?
Yes. Time behavior of equalizers is well described in impulse response snapshots. Use something like RXs reconstructed waveform view to get an idea of what your DA converter does to represent those sample points.

A perfect impulse is zeroes only with a single sample at max level. Leave enough time around the lone peak to capture the event you’re looking for. Run this through any process and the output will be the IR for that system.

Normal EQs will only show things happening after the excitation impulse. Linear phase will have equal amounts of activity before and after the impulse. Mixed phase will (usually) have more happening after the impulse, and some things happening before the pulse.

The quanta you’re looking for is the RMS value for the before/after parts. Linear phase have the same area under curve before/after the impulse. Normal equalizers / minimum phase will have infinite difference as there is nothing happening before the impulse arrives. Mixed phase systems will typically give some lesser RMS numbers for the before parts and larger RMS figures for the after part. The difference between the before/after can then again be used as a ratio for dB figure if you so pleases.
Old 13th July 2019
  #18
Lives for gear
 
GJ999x's Avatar
Awesome, thanks for this
Old 13th July 2019
  #19
Quote:
Originally Posted by Nordenstam View Post
Yes. Time behavior of equalizers is well described in impulse response snapshots.
Well, I tried to test Waves LinEQ with a Dirac pulse but for some reason the pulse was perfectly preserved with no ringing -- is Waves LinEQ smarter than me?

Quote:
Originally Posted by Nordenstam View Post
The quanta you’re looking for is the RMS value for the before/after parts.
That's what I was expecting, thanks for confirming it.
Old 14th July 2019
  #20
Lives for gear
 
stinkyfingers's Avatar
 

You could try using a “pulse” of DC. (That’s what I do fwiw)
(ie...step response)
This guy shows example in his blog > https://cravedsp.com/blog/linear-phase-eq-explained
Old 14th July 2019
  #21
Quote:
Originally Posted by stinkyfingers View Post
You could try using a “pulse” of DC. (That’s what I do fwiw)
Thanks. For those that need one, I'm attaching a half-square wave impulse.
Attached Files

square-impulse.wav (26.0 KB, 1879 views)

Old 17th July 2019
  #22
Lives for gear
 

Verified Member
Quote:
Originally Posted by johannburkard View Post
Reviving this thread: Is there an easy way to visualize and quantify FIR pre-ringing in VST plugins?
There are some excellent examples in the RME ADI2 pro FS manual when discussing their different AD/DA filters

https://www.rme-audio.de/download/adi2profs_e.pdf

Page 77

Short Delay = Minimum Phase
Slow = long roll off
Sharp = sharp roll of

They use some confusing terms but take a look at that and will explain how different filters in LP and MF effect the transient response as well making cuts within the pass band.
Topic:
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump