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Subwoofer/Speaker Delay.....


SWL

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On 10/11/2017 at 1:52 PM, SWL said:

.....the real upgrade was tweaking the KLF-30 at a 45 degree angle. Sounds so much better this way. The sound is liquid. So much more detail. So much more...everything. Just gotta tilt yer head a little.emoji14.png1724c31f990df4eec255b52e00ef6577.jpg

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decoupling it from the floor would reduce midbass from around 300 down but mostly at around 125 to 250 ime

 

subs + mains are combining for too much 

u could raise the mains off the floor a foot or more (at least the diameter of the woofer) to get a similar effect

u could move them off the back wall further

or flip them over and raise them to just below tweeter ear level to eliminate the floor coupling or

PEQ could reduce the peak and reduce decay time with them on the floor

 

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  • Klipsch Employees
On 10/9/2017 at 2:27 PM, MetropolisLakeOutfitters said:

 

Are we talking about two different things?  If you don't delay the mains to match the sub you can get a big fat null at the crossover point.  I've got a screenshot somewhere showing 0.1 foot increments in the sub distance which slowly turned a chasm of death into a smooth response.  

ok but what is the wavelength of 80 Hz?  the null that you may be getting may have to do with room position of the sub and/or mains, not necessarily bringing the mains and sub into time alignment.

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@Chief bonehead the wavelength of 80 Hz is 4,25m or 13,12ft.  But, please, continue your explanation.  As I am struggling a bit to integrate my subs with my mains.  

If I get your explanation right, you mean that when you get your mains and subs time aligned, that doesn't necessarily mean you get the smoothest response in the crossover region.

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43 minutes ago, joop said:

@Chief bonehead the wavelength of 80 Hz is 4,25m or 13,12ft.  But, please, continue your explanation.  As I am struggling a bit to integrate my subs with my mains.  

If I get your explanation right, you mean that when you get your mains and subs time aligned, that doesn't necessarily mean you get the smoothest response in the crossover region.

 

Crossover frequency, slope and a bit of EQ is what you need to get right, time alignment should be the last thing to worry about if at all.

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On 11/9/2017 at 12:55 PM, Chief bonehead said:

ok but what is the wavelength of 80 Hz?  the null that you may be getting may have to do with room position of the sub and/or mains, not necessarily bringing the mains and sub into time alignment.

 

The calculators say that the wavelength of 80 hz is 14 feet.  That ought to mean that you only need to be 7 feet off to be completely out of phase.  Even being 3.5 feet off is a quarter wavelength and could be significantly detrimental to the output at the crossover frequency.  It is easy to be off by that distance and the results is not out of line with what I was seeing.  

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When we time align subs to mains the crossover is often 80ish and because of this the distance setting repeats every roughly 7 or 8ms.  So lets say swl finds 0ms to sound good.  If we measured the response a similar low end response would occur at say 7ms and 14ms delay.

 

What would change is the integration of the upper low end bass as you go to 7ms and 14ms.  Precisely the range being discussed.

 

Delay is extremely critical and has up to a 15db gain or loss around the crossover but also has huge effects on nulls.

 

Time alignment ime is more important than everything but placement and treatment.

 

 

 

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On 11/10/2017 at 3:23 PM, Wim M said:

@Chief bonehead the wavelength of 80 Hz is 4,25m or 13,12ft.  But, please, continue your explanation.  As I am struggling a bit to integrate my subs with my mains.  

If I get your explanation right, you mean that when you get your mains and subs time aligned, that doesn't necessarily mean you get the smoothest response in the crossover region.

Your output at, above and below the crossover are at their highest.  If youd like to see an example im sure ive got some measurements.  

 

What many people do is this....set your crossover frequency....then reverse rhe polarity of the sub (s).  Change the distance until you haventhe biggest null - suckout or huge dip in response.

 

Once found change the polarity back and you then have optimized the crossover timing.

 

 

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Imo alignment of sources is about distance from sources and at lower frequencies the room is the most important factor...blending multiple subs is entirely room dependent.   so yes outdoors will be different because the low end only has the ground for reenforcement while inside there are the walls and ceiling.  

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12 hours ago, Chief bonehead said:

Interesting answers. Any more want to chime in?  Let me ask this, does polar pattern matter at 80 hz?

 

Yes

 

 

12 hours ago, Chief bonehead said:

 Is it more or less important in a room than, let's say, outside?

 

More important in a room as it relates to constructive or destructive interference.

 

12 hours ago, Chief bonehead said:

another one.....is the alignment for sources that are displaced front to back or side to side?

 

Hmmm.... Our ear/brain perception or lack of perception is sensitive to amplitude, time and direction of arrivals from sources. The sources can be the actual loudspeakers or their room boundary reflections as perceived at the listener's location. So time alignment and our sensitivity to and how we will perceive it will be affected by the location of the sources relative to the listeners ears.

 

miketn

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I'm certainly not an expert, I'm just trying to learn something.  So this would be my best guess: As a starting point I would use the actual distance listening position - driver.  So when horn loaded speakers are used, the length of the horn path should also be reckoned.  The speaker the furthest away from listening position should be set at 0ms.   From there on I 'd take measurements (using REW and a cal. MIC) of, let's say 20 - 120 Hz sweeps,  then change distance with 1ms, take another measurement and so on...  until you see the smoothest response in the crossover region appear.

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some very good answers and is always a little of both.  xover freq and slope are very important.  the steep slopes mean the interference band is narrow.  outside, as someone mentioned above all you really have to deal with is the speakers in an open space.  so having walls and ceilings creating nulls and peaks is out the window.  and at bass freqs, and since they have very wide polars at 80 hz, in a room, you will have the walls and ceilings produce very large amplitude "reflections". and of course room modes and then if you have one speaker left and one speaker right and then have on sub.....you get the drift.  with all that going on, time delay really falls to the bottom of the priority list.  the best you can since you have all these interactions is do as someone said, dial in the delay until you get max response at crossover at your favorite position.  and this assumes that you do the left speaker first and then try the right which may be different since your left and right may not be sitting on your sub.  and of course, you cant delay the left and right cause then you have just killed any shot at getting any type of imaging.  i guess you can put the sub in the center between the left and right but then some old guy said to put a speaker in the corner because it sounds better.  well for a sub it certainly reinforces the bottom end.  maybe dual subs?  but that assumes a symmetrical room so you have to have a left wall and right wall.......you guys get the point now.  

 

the best answer, as someone partially wrote above is to dial in delay at crossover for maximum output....plus...try to use steep slopes to minimize interference from sub to mains....because the polar response at 80 is quite wide....and you will have other acoustic "sources trying to chime in" namely walls, ceilings and floors.  because afterall, at 80 hz, delay is only part of the solution in a room and not necessarily the top priority.

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here is a set of measurements showing the value of dialing in distance/delay.

 

the 10 measurements have identical everything except they differ by 1ms in subwoofer delay -- 100hz crossover setting.

as you can see frequencies as low as 50 hz are affected by the 100hz crossover as are frequencies up to 150hz.

 

audyysey does not get this right very often

 

placement and room treatment are more important but failing to adjust the delay can result in terrible midbass

and getting it right creates an almost flat graph across all frequencies

 

 

with multiple subs they must first be dialed in together and then delay set as a group

again since audyssey cannot set delay properly (with regards to the sub channels ONLY) I would always recommend someone with multiple subs dial in the subs first manually and then treat as one sub for integration purposes

Measurements showing 100hz crossover with 1ms increment differences in delay 10 shown.jpg

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5 hours ago, RoboKlipsch said:

here is a set of measurements showing the value of dialing in distance/delay.

 

the 10 measurements have identical everything except they differ by 1ms in subwoofer delay -- 100hz crossover setting.

as you can see frequencies as low as 50 hz are affected by the 100hz crossover as are frequencies up to 150hz.

 

Great measurement example RoboKlipsch...!

 

For those not familiar with using and setting time delay as Roy pointed out when he said "your favorite listening position" it's important to understand when you have multiple spaced sources reproducing the same frequencies that by optimizing delay for one listening location can often degrade another listening location if multiple listening positions are being used.  In the case of multiple listening positions all positions need to be evaluated and weighted as to importance and a best overall compromise delay setting chosen.

 

miketn

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