Time alignment

[Dave A]

I see while looking at pro gear setups some truly small distances are accounted for. Now I know every little thing can add up but at what point in time, distance wise, can human senses even perceive the time arrival difference from various drivers? Does .187 milliseconds even matter?

[wuzzzer]

Didn't PWK say something like "not all instruments play from the exact same spot on the stage" ?

[jason str]

2 minutes ago, wuzzzer said:

Didn't PWK say something like "not all instruments play from the exact same spot on the stage" ?

 

 Good sales pitch.

 

Time alignment makes a noticeable difference. Horns suffer in this regard.

 

 

[Chris A]

4 hours ago, Dave A said:

Does .187 milliseconds even matter?

That equates to 180 degrees of phase shift at 2.67 kHz.  That's a lot of phase shift.

 

I've found that the last 0.145 ms of delay on the HF diaphragm of the BMS4592ND (dual diaphragm) relative to the midrange diaphragm produces a big difference in the overall sound quality of the K-402-MEH.

 

Chris

[Dave A]

I have always followed the recommendations of either PEQ's or entered measured distance into the Xilica just in case. I was curious to know how much difference a few inches made and now I know. Thanks guys.

 

  Chris is the MEH more sensitive to this than other speakers or is this pretty universal. Some of my tweeter buyers maintain they can hear a big difference in moving the tweeters around on the top but I have never tried that yet. Also the thought just occured to me. If I measure a straight line from each driver the distance displacement there is greater at times than the displacement driver to driver in the box. So should the distance to theoretical listening spot also be factored in?

[Chris A]

1 hour ago, Dave A said:

Some of my tweeter buyers maintain they can hear a big difference in moving the tweeters around on the top but I have never tried that yet.

This is the sort of thing that you really need to hear for yourself.  I recommend the experience highly.  But you'll need REW to tell you when you're time aligned, otherwise, you can fool yourself into thinking you're time aligned, but you're actually some multiple of 360 degrees out of alignment, i.e., you'd be phase aligned, but not time aligned.  REW will show you phase and group delay (the first derivative of phase) and will tell you when you're time aligned.

 

1 hour ago, Dave A said:

Chris is the MEH more sensitive to this than other speakers or is this pretty universal.

The answer is "yes", but the reason why is because you can hear more with a loudspeaker that doesn't have polar lobing and has full-range directivity.  With loudspeakers not having full-range directivity, the early reflections from around the loudspeaker destroy the phase coherence--even if you place the loudspeakers away from the walls, floor and ceiling.  This is something that I've talked about but I find that very few people pay much attention to that particular conversation.  The better the loudspeaker performance, the more that you can hear the effects and the more difference it makes when you correct them.  MEHs (and even Jubilees) can sound like the best studio monitors you've heard in the best studio acoustics to be found.  It's too bad that so few people have heard the difference because it's pretty spectacular. 

 

Chris

[Dave A]

1 minute ago, Chris A said:

This is the sort of thing that you really need to hear for yourself.  I recommend the experience highly.  But you'll need REW to tell you when you're time aligned, otherwise, you can fool yourself into thinking you're time aligned, but you're actually some multiple of 360 degrees out of alignment, i.e., you'd be phase aligned, but not time aligned.  REW will show you phase and group delay (the first derivative of phase) and will tell you when you're time aligned.

I have all the tools I just need to make the time to learn them. Every time I get started doing so with good intent I get bogged down in other things.

[Edgar]

10 hours ago, Chris A said:

But you'll need REW to tell you when you're time aligned, otherwise, you can fool yourself into thinking you're time aligned, but you're actually some multiple of 360 degrees out of alignment, i.e., you'd be phase aligned, but not time aligned. 

 

That's an important distinction. Decades ago, when there were huge path length differences in 2-way horn-loaded theater systems, it was discovered that several feet of misalignment were required before multiple transient "events" were heard due to the difference in delay. But the effect of even small amounts of time misalignment upon frequency response is significant -- it causes comb filtering, meaning that peaks and dips appear in the frequency response. And the effect upon polar response is also significant -- it causes lobing, or corruption of the frequency response off-axis.

[Chris A]

I've also found that dialed-in Jubs and K-402-MEH exhibit a subconscious listening effect once time-aligned, besides the measured differences in performance. [Note again that these have full-range directivity control down to the Schroeder frequency of the room.]  They're dialed-in such that polar lobing is minimized via DSP crossover tweaking and moving the K-402s down toward the bass bins in the Jubs--something that I'm pretty sure you didn't hear in Hope during Roy's class. The MEH doesn't require anything but perhaps first-order crossover filters to achieve time alignment of all drivers and effectively drive the effects of polar lobing to inaudible levels. 

 

Those listening effects of time-aligning that I've found can be summarized as:

 

1. significantly increased perception of bass (so much so that I had to re-demaster my stereo recordings).

2. overall apparent depth and seamless soundstage improvements, and an indescribable naturalness of sound that's easy hear with live acoustic instrumentation recordings

3. elimination of harshness, particularly of acoustic instrumentation like acoustic guitars, violins/violas/cellos/double basses, and wind instruments (brass & woodwinds).

 

Chris

[Schu]

19 hours ago, Dave A said:

at what point in time, distance wise, can human senses even perceive the time arrival difference from various drivers? Does .187 milliseconds even matter?

purposely mis-align/delay (digitally) the signal and see if you can actually discern the difference or if it's actually audible enough for you to care...

[Edgar]

36 minutes ago, Chris A said:

Those listening effects of time-aligning that I've found can be summarized as:

 

Chris, I don't often get to the Dallas area, but someday I hope to have the opportunity to listen to your system. Not my intent to invite myself, but you've certainly done a lot of the things that I've thought about over the years, but didn't have the time, resources, or room to try.

[Chris A]

Anyone wanting to hear the difference due to time alignment has to first get them time-aligned and then listen to them--in order to hear the differences that you describe.  [I believe that is what I referred to in post #6, above.] If you don't know if they're time aligned, you can almost bet that they're not--unless they are MEHs or perhaps higher priced studio monitors (which have the issue of nearfield reflections due to their lack of full-range directivity, as I also stated above). 

 

To my knowledge, I know of no stock Klipsch loudspeakers other than dialed-in cinema (professional) loudspeakers like Jubilees or MCMs--all the others use passive crossovers and are not designed to have time-aligned drivers using those passives, and all others beside the Jubilees and MCMs have direct radiating woofers.  It takes the combination of full-range directivity and time alignment with suitable room treatments to suppress in-room early reflections to maximize the audibility of time alignment.  Khorns, Belles, and La Scalas all have significant time misalignments as sold by Klipsch, i.e., you'd have to tri-amp them and dial them in using a DSP crossover to hear the difference. 

 

Chris

[Chris A]

1 minute ago, Edgar said:

Chris, I don't often get to the Dallas area, but someday I hope to have the opportunity to listen to your system.

The offer is open, but presently subject to the recent constraint of pandemic quarantine.  The offer will again be open to all that wish to hear what I've described. 

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To others reading this that are not often through the D/FW area--note that there are a few other Jubilee owners spread out geographically in the US and internationally that I've also helped to dial-in their setups using REW and DSP crossovers, too.  I'll let those people self-identify.  Those individuals here wanting to hear the difference won't be disappointed in what they experience.

 

If you alternatively get a chance to hear Synergy™ MEHs, these loudspeakers are also inherently time-aligned and have full-range directivity.  The only variable left in those cases is room geometry/placement and acoustic treatments to suppress early reflections (within 3-4 feet of room boundaries, acoustically reflective furniture, or electronics equipment), but also retaining  boundary gain (1/4 space or 1/8th space) for low bass distortion.

 

Chris