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The test you refer was done with headphones so if was incompetent for evaluating all effects and significance of group delay at L.F.

View attachment 422799
Regarding the suitability of the test method to loudspeakers, you can post that question to Aki Mäkivirta, who is the second author listed on the paper.
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Regarding the suitability of the test method to loudspeakers, you can post that question...
Probably not. That study is really important and useful, and could be one of the reasons why Genelec has improved significantly especially in midrange GD since the first Ones and last analogue Masters. Much cannot be done anymore with their existing speaker concepts, latency limits and reliability/durability policy for pro audio.

Ears and auditory weighting has been almost standard in group delay testing. For example ref [8] Krauss, G. J., “On the audibility of group distortion at low frequencies,” in Proc. Audio Eng. Soc. 88th Conv., Montreux, Switzerland, Mar. 1990 was using Stax headphones: Stax Lambda Pro and Stax Monitor SRM.
Older study ref [7] Greenfield, R. and Hawksford, M. J., “The audibility of loudspeaker phase distortion,” in Proc. Audio Eng. Soc. 88th Conv., Montreux, Switzerland, Mar. 1990 was using Celestion SL700 loudspeakers. That wasn't very "deep" science with L.F. either.

Fortunately we can make our own applications and conclusions so possible poorness of audio science does not prevent anything.
 
One thing I have not seen discussed much is whether we can sense group delay distortion in low frequencies not by hearing the delay but by feeling it via a delay in the tactile sensation. I have read numerous reports over the years that we can sense bass directionality via tactile sensation, even at low frequencies where we would not be able to do this with our ears by interpreting the relative levels and phases between each ear (i.e. we can sense the chest slam from bass drums or nearby fireworks hitting the front of our bodies first and as such perceive the sound as coming from the front).

As such, one would think that there is a point where an appreciable delay between the physical sensation of the base for short impulses and the higher frequencies would be perceived.

The folks who setup tactile transducers in their setups have known for some time that getting the delay right between the tactile transducers and the audio is very important for the experience to feel seamless and natural. I have a sneaking suspicion that we might be more sensitive to group delay distortion a low frequencies than these headphone only studies would suggest - would be interested to know if anyone has come across any literature along these lines?
 
Hey community,

I’m resetting my strategy for deploying multiple subwoofers in my setup. Information sources include fellow members' testing (@Nuyes I measured 10 Subwoofers) and spreadsheets (@sweetchaos Subwoofer Comparison). Also using Audioholics, Buttersworth, and Erin’s to identify those in my price and output ranges. Nuyes testing brought to my attention group delay and how varied it can be below 80hz. I really don't know anything about it and will certainly not be attempting to explain its significance. But it got me wondering at what point would measurements show "this is now a problem"? I have (tried) to understand posts and papers group delay that have been linked on other threads and I simply confidence in drawing my own conclusions. I did see one post on DIYAudio stating the ‘ideal’ is sub-one cycle at a given frequency. If true, the ideal group delays should measure less than:

20hz — 50ms
30hz — 33.33ms
40hz — 25ms
50hz — 20ms
60hz — 16.67ms
70hz — 14.29
80hz — 12.5ms

Ok, this is may not be the best rule of thumb and responders may quickly call out a 'general rule' error. If so, let's find something agreed upon to the best of our ability. Right now it's what I have found that I can run with. I want to learn more.

So why am I asking for help with this subject and possibly making knowledgable people on the forum tired of beating a dead horse? I want to sell my current subwoofer to find a more affordable unit to be able to scale up (2-4 subs). My current SVS 3000 micro nails the form factor, but there are less expensive options - namely the Kali WS-6.2. If I could afford them, I would be looking at the Paradigm MilleniaSub, Sigberg Inkognito, or continue with more 3000 micros. I'm not looking for crazy output or sub-20hz output. I just want to get the most for my money and be done with it with as much peace of mind as I can knowing I made the most educated decision I could.

The Kali looks viable. But what about group delay for a ported subwoofer like this one? Looks like there is a direct correlation between ported subwoofers and higher group delays. I don't mind the look of the WS-6.2 because my intention is to conceal them. Output looks respectable based on Erin's video review I stumbled upon through thread Anyone Tried Kali Audio WS-6.2 Subwoofer?. True it may not pass CEA-2010 below 25hz, and I'm ok with that.

20hz ≈ 45ms
30hz ≈ 42ms
40hz ≈ 26ms
50hz ≈ 16ms
60hz ≈ 12ms
70hz ≈ 10ms
80hz ≈ 9ms

Good, you just proved your own point, Justin. The Kali should fit the bill, so why post this at all? Glad you asked...

Presuming one cycle is the ideal, at what point would the group delay become audibly unacceptable? This isn't meant to put anything to bed, but to take my next subwoofer search and have a thread people can look back to in layman's terms, see how we got there, and what is reasonable and within an acceptable margin. Go easy on me.

Thanks!


How long are the decay times in your room?
 
How long are the decay times in your room?
I installed a second subwoofer since this thread started. I hope to take some measurements over the weekend if I can. I have never taken post-calibration measurements.

Anyone have a guide I can reference for MLP or MMM?
 
I installed a second subwoofer since this thread started. I hope to take some measurements over the weekend if I can. I have never taken post-calibration measurements.

Anyone have a guide I can reference for MLP or MMM?

Be sure you set up the polarity / time alignment properly with the sub distance settings. REW is a big help with that. Here's a few videos.

 
Be sure you set up the polarity / time alignment properly with the sub distance settings. REW is a big help with that. Here's a few videos.

Thank you. I am hoping that Dirac has correctly phased both subwoofers. I will find out soon enough.
 
This isn't meant to put anything to bed, but to take my next subwoofer search and have a thread people can look back to in layman's terms, see how we got there, and what is reasonable and within an acceptable margin. Go easy on me.
OK...
Just for your possible interest and reference, let me share my rather primitive approach of "using time-shifted multiple-Fq rectangular tune-burst signals", "energy peak matching using single/simultaneous tone-burst consists of multiple -Fq component" and "precise wave shape matching for 0.1 msec precision time-alignment".
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-1_ Precision pulse wave matching method: #493
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-2_ Energy peak matching method: #494
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-3_ Precision single sine wave matching method in 0.1 msec accuracy: #504, #507
- Measurement of transient characteristics of Yamaha 30 cm woofer JA-3058 in sealed cabinet and Yamaha active sub-woofer YST-SW1000: #495, #497, #503,
#507


In case if you would be interested in using/applying the test tone-burst signals I prepared/used in these measurements and tunings, please simply let me know through PM communication writing your wish.

After these measurements and tunings in my listening environments, I have been enjoying really nice tight clear non-distorted bass sound with my multicannel audio rig.
Just for example:
- Reproduction and listening/hearing/feeling sensations to 16 Hz (organ) sound with my DSP-based multichannel multi-SP-driver multi-amplifier fully active stereo audio system having big-heavy active L&R sub-woofers: #782
A nice smooth-jazz album for bass (low Fq) and higher Fq tonality check and tuning: #910, #63(remote thread)
Just for your reference, please find the latest Fq-SPL spectrum (at listening position) of my audio setup under the below spoiler cover.
Fig14_WS00007522 (10) (1).JPG

I dare did-not/do-not go into further precise delay compensation tunings within the L&R subwoofer-covered Fq-zone, in my case ca. 15 - 90 Hz; my L&R heavy large subwoofer YAMAHA YST-SW1000 works in Helmholtz resonator (so-called air woofer) mechanism (ref. here) which cannot be precisely delay-controlled even applying upstream fine multiple DSP filters with group delay settings within 15 - 90 Hz, I believe.

Furthermore, please note, at least for me, I have no interest at all on "absolute group delay", but I have been being only interested in "relative group delay between the multiple SP drivers", i.e. "time-alignment all over the SP drivers", measured at my listening position.
 
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