VINDICATION! Subwoofer Leading Edge Transients and John Hunter of REL’s YouTube video on setting up a REL “Six-Pack”

musicfirst1

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I just watched a recent video by John Hunter, Head Shaman at Rel Acoustics.

In it he basically says that in order to achieve proper subwoofer integration with one’s main speakers, they must be more or less IN LINE WITH THE MAINS!! The discussion starts at 1:30 in the video.

Furthermore, he says a difference in subwoofer positioning of as little as + 1 mm (~1/32 of an inch) with respect to one’s mains is sonically relevant to leading edge bass articulation!

I’ve been saying this for YEARS!!!

Of course subwoofer corner loading, swarms etc. can provide more bass, but IM0 it CANNOT approach state of the art bass reproduction.

I feel this is true regardless of the quality of the setup. I heard a setup with Wilson Chronosonics XVX and a pair of Wilson Subsonics behind them, (crossed over below 30Hz BTW) and the leading edge bass transients were severely compromised.
Upon disconnecting the subs, bass articulation returned in spades. I much preferred the Chronosonics in this setup without the subs.

“There are a million incorrect ways to setup subs and only one right one”

Kerry
 
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x1992

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I am not trying to argue with the overall aim, but I know this approach would not work for me. I used to own RELs and there was no way to time or phase align by moving the subs either in practical terms or in in terms of maintaining an even frequency response with respect to room modes. My JL pair are setup asymmetrically in order to get an even frequency response. The continuously variable phase is set to the crossover point in the frequency domain for respective right and left channels. That seems basically what he is doing, but I do it from a listening position mic, turning knobs. To get time aligned I would have to to delay the main speakers, probably in the digital domain. The sub circuitry is surely slower than the main's amplifier. Glad you have had success. It is not very easy.
 

Robh3606

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+/- 1mm to integrate subs with mains?? As in you can obviously hear it?? I am not buying that. I can understand them being in approximately the same plane. That's how all my subs are placed in systems but not +/- 1 mm. Your wavelength @ 80hz is 14 ft and at 40Hz 28 ft and 30 hz 37 ft,
If you think you can hear a 1mm offset @ these frequencies your dreaming.

Rob :)
 

MTB Vince

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Quick question. Are the onboard crossovers and EQ signal prossessing in all modern REL models typically used in stacked 6-pack installations completely analog in nature? Because otherwise the signal processing performed in DSP along with the necessary ADC and DAC circuitry adds several milliseconds of latency. And that latency completely pricks the balloon of adjacent baffles offering perfect time alignment.

Another observation is that there is no way I want a huge reflective and diffraction causing surface right next to my conventional direct radiating speaker design. Unless you are running highly directional horn loudspeakers, the negative impact on soundstage and imaging would outweigh any theoretical benefit of wavelength alignment at & below 80Hz.
 
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x1992

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I have to correct myself. REL reports only a 4ms circuit delay (nonDSP). JL, I have read, nominally is 12ms with their DSP. My room would still have the same time vs frequency problem, though.
 

musicfirst1

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+/- 1mm to integrate subs with mains?? As in you can obviously hear it?? I am not buying that. I can understand them being in approximately the same plane. That's how all my subs are placed in systems but not +/- 1 mm. Your wavelength @ 80hz is 14 ft and at 40Hz 28 ft and 30 hz 37 ft,
If you think you can hear a 1mm offset @ these frequencies your dreaming.

Rob :)

+/- 1mm to integrate subs with mains?? As in you can obviously hear it?? I am not buying that. I can understand them being in approximately the same plane. That's how all my subs are placed in systems but not +/- 1 mm. Your wavelength @ 80hz is 14 ft and at 40Hz 28 ft and 30 hz 37 ft,
If you think you can hear a 1mm offset @ these frequencies your dreaming.

Rob :)
Well, maybe not 1/32, but in my system, with the subs time aligned with the main speakers hearing the attack of a kick, bass or kettle drum with the subs moved an inch or two is EASY to hear. I think your argument about wavelength vs frequency is a gross oversimplification of what is essentially a timing issue. We're talking about complex waveforms here, not test tones. FWIW I Have no doubt a pure 30+ Hz test tone would sound viirtially identical with the sub located within a foot or two.

And BTW, I'm not asking you to "buy it" I'm asking you to try it.
 
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Robh3606

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Well, maybe not 1/32, but in my system, with the subs time aligned with the main speakers hearing the attack of a kick, bass or kettle drum with the subs moved an inch or two is EASY to hear. I think your argument about wavelength vs frequency is a gross oversimplification of what is essentially a timing issue. We're talking about complex waveforms here, not test tones.

And BTW, I'm not asking you to "buy it" I'm asking you to try it.

Test tones??? Your right it is a timing issue. Let's do a simple math problem. The wave length of 80Hz is 14 ft. So I think we can all agree that one complete phase cycle 360 degrees is 14 ft. That said how much distance is covered in 1 degree?? Well 14 ft. is 4267 mm so 1 degree of phase is 4267/360 which is 12mm about a half inch difference in position. Your +/- 1 mm is less than one tenth a degree in phase difference.

Looking at speed of sound 2 inches is .15msec delay.

It this case phase is essentially both distance and time. So even moving 2" would get you about 4 degrees of phase change assuming you are moving subs directly towards or away from the listener so this is worst possible case.

Now looking at speaker placement we are all listening to our rooms. At the wavelengths over a subwoofers bandwidth changes in room placement 1-2 inches is not going to have any significant effect. The wavelengths are so long that there is no significant change to the room modes excited by small placement changes.

We are not talking about fullrange speaker placement where inches do matter.

I am also using 80Hz for these numbers so any sub crossed lower would have even lower numbers for phase differences.

No thanks on the try I am happy where my subs are.

Call me skeptical.

Rob :)
 
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stehno

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Test tones??? Your right it is a timing issue. Let's do a simple math problem. The wave length of 80Hz is 14 ft. So I think we can all agree that one complete phase cycle 360 degrees is 14 ft. That said how much distance is covered in 1 degree?? Well 14 ft. is 4267 mm so 1 degree of phase is 4267/360 which is 12mm about a half inch difference in position. Your +/- 1 mm is less than one tenth a degree in phase difference.

Looking at time the period for 80 Hz is 12.5 msec divided by 360 is 3.47 -5 msec per degree.

It this case phase is essentially both distance and time. So even moving 2" would get you about 4 degrees of phase change assuming you are moving subs directly towards or away from the listener so this is worst possible case. Delay change is 4x 3.47 -5 so well under 1 tenth of a msec.

Now looking at speaker placement we are all listening to our rooms. At the wavelengths over a subwoofers bandwidth changes in room placement 1-2 inches is not going to have any significant effect. The wavelengths are so long that there is no significant change to the room modes excited by small placement changes.

We are not talking about fullrange speaker placement where inches do matter.

I am also using 80Hz for these numbers so any sub crossed lower would have even lower numbers for phase differences.

No thanks on the try I am happy where my subs are.

Call me skeptical.

Rob :)
Oh, but it's true. Whether it's a speaker or subwoofer placement, IMO, there is the ballpark, outfield, infield, and pitcher's mound. And the closer I get to dead-center pitcher's mound for the optimal placement, the more bass that was once inaudible now becomes audible and that bass which is audible also becomes significantly more well-defined / musical as does the overall presentation. And the next day I may move the speaker/sub ever so slightly in a given direction and it could sound better still (or worse). So yes, ultimately milimeters count. This is old news but seemingly not many take this to heart.
 

Robh3606

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Oh, but it's true. Whether it's a speaker or subwoofer placement, IMO, there is the ballpark, outfield, infield, and pitcher's mound. And the closer I get to dead-center pitcher's mound for the optimal placement, the more bass that was once inaudible now becomes audible and that bass which is audible also becomes significantly more well-defined / musical as does the overall presentation. And the next day I may move the speaker/sub ever so slightly in a given direction and it could sound better still (or worse). So yes, ultimately milimeters count. This is old news but seemingly not many take this to heart.
Hello stehno

On a roll totally screwed up the delay changed to speed of sound which is correct. My point is single degree phase changes and less that 1 msec delay changes are simply not going to be audible. Especially at frequencies where the room completely dominates what we hear. Just look at the BL curve for audibility of group delay

Rob :)
 

Lagonda

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Well, maybe not 1/32, but in my system, with the subs time aligned with the main speakers hearing the attack of a kick, bass or kettle drum with the subs moved an inch or two is EASY to hear. I think your argument about wavelength vs frequency is a gross oversimplification of what is essentially a timing issue. We're talking about complex waveforms here, not test tones. FWIW I Have no doubt a pure 30+ Hz test tone would sound viirtially identical with the sub located within a foot or two.

And BTW, I'm not asking you to "buy it" I'm asking you to try it.
I thought you gave up on having stacks of REL right next to your omnis for reasons of reflections. I find this "setup video" to be more of a advertising for REL stacks than good setup practice, REL is hampered by inadequate crossover adjustability, no Q setting, limited phase settings, they are hard to integrate to some speaker types. Standing next to the subs and setting level, crossover and phase ( by placement only), is a poor substitute for doing it from your listening position. :rolleyes:
 

musicfirst1

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I love all the theorists out there who 'prove' it can't be true but have never actually tried it before saying its inaudible. The proof is in the pudding.
 
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Lagonda

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I love all the theorists out there who 'prove' it can't be true but have never actually tried it before saying its inaudible. The proof is in the pudding.
Are you back to using a full REL stack right next to your Bayz omnies, after having gotten these instructions ? You said elsewhere that you had gone down to one subwoofer per side, because of unwanted reflections. Or are you still stirring your pudding ! ;)
 

Al M.

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I thought you gave up on having stacks of REL right next to your omnis for reasons of reflections. I find this "setup video" to be more of a advertising for REL stacks than good setup practice, REL is hampered by inadequate crossover adjustability, no Q setting, limited phase settings, they are hard to integrate to some speaker types. Standing next to the subs and setting level, crossover and phase ( by placement only), is a poor substitute for doing it from your listening position. :rolleyes:

Limited phase settings are a problem. A friend advised me to buy JL Audio subs instead, and I am glad I did. To be able to finely adjust phase turned out be crucial to even out my bass and for bass articulation.
 

Robh3606

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I love all the theorists out there who 'prove' it can't be true but have never actually tried it before saying its inaudible. The proof is in the pudding.
I only going on my own experience placing subs and in my rooms and a couple of inches doesn't matter. The only time I have had it happen where it did matter was because the crossover was set too high and the slopes not steep enough and you could hear the subs location. Maybe you have a unique set of circumstances with setup and position?? That's why I said call me skeptical.

The proof may be in the pudding but you can't change the speed of sound or the primary room modes. You can't change the BL curve. They are what they are and you have to work with what you have.

Hey if you are happy great!

Rob :)
 

x1992

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Anyone can and should do better than basic corner loading.The swarm system is a very accessible means to flatten the frequency response throughout the room, creating a pleasant even power distribution. I agree that it is not the ultimate. If one is able to achieve a flat response with their main speakers, time aligning subs while still avoiding low bass problems seems fantastic. I however struggle with the idea of being able to solve timing and frequency issues simultaneously just by subwoofer placement.
 

musicfirst1

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Are you back to using a full REL stack right next to your Bayz omnies, after having gotten these instructions ? You said elsewhere that you had gone down to one subwoofer per side, because of unwanted reflections. Or are you still stirring your pudding ! ;)
No, I'm still using just two Rels, but the timing/phase issue is still relevant, at least in my pudding.
 
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Lagonda

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No, I'm still using just two Rels, but the timing/phase issue is still relevant, at least in my pudding.
With no continuous phase adjustment you are locked in placement wise.
 

musicfirst1

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I have no experience with subs that offer infinitely adjustable phase, so maybe I'm doing manually (with only the 0/180 phase switch available to me) what could be achieved with 'out of plane' placement and incremental/infinite phase adjustment, but I have never heard a system with subwoofers behind the speakers that sounds correct to me.
 
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Al M.

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I have no experience with subs that offer infinitely adjustable phase, so maybe I'm doing manually (with only the 0/180 phase switch available to me) what could be achieved with 'out of plane' placement and incremental/infinite phase adjustment, but I have never heard a system with subwoofers behind the speakers that sounds correct to me.

Even with subs in line with the main speakers there is no correct time alignment. JL Audio says that their sub driver mechanism introduces a time delay because of the heavy magnets, and I assume that the drive mechanism of REL subs is rather similar (as most modern subs rely on lots of power to move their heavy machinery and stiff driver membranes). Without JL Audio CR-1 crossover (which I don't use) you would have to move the subs 10 feet in front of the main speakers to get time alignment, which is obviously not practically doable (IIRC the time delay is 9 milliseconds).

Now I have a setup with subs next to (actually a few inches in front of) the main speakers as well. But even when I had the sub drivers 5 feet behind the main speaker drivers, there were no obvious issues with coherent bass tone and rhythm & timing. It is just that before, with the greater distance of the sub drivers to the ear, the bass tone was slightly more diffuse and less articulate.

I guess that distance just doesn't matter that much for bass timing because, as others have said, the wavelengths are that long.
 
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musicfirst1

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Even with subs in line with the main speakers there is no correct time alignment. JL Audio says that their sub driver mechanism introduces a time delay because of the heavy magnets, and I assume that the drive mechanism of REL subs is rather similar (as most modern subs rely on lots of power to move their heavy machinery and stiff driver membranes). Without JL Audio CR-1 crossover (which I don't use) you would have to move the subs 10 feet in front of the main speakers to get time alignment, which is obviously not practically doable (IIRC the time delay is 9 milliseconds).

Now I have a setup with subs next to (actually a few inches in front of) the main speakers as well. But even when I had the sub drivers 5 feet behind the main speaker drivers, there were no obvious issues with coherent bass tone and rhythm & timing. It is just that before, with the greater distance of the sub drivers to the ear, the bass tone was slightly more diffuse and less articulate.

I guess that distance just doesn't matter that much for bass timing because, as others have said, the wavelengths are that long.
Loss of articulation is exactly what I hear. Try Hotel California live or the interplay between Joe Morello and Gene Wright on Take Five and it's easy to hear on a reasonably resolving system.
 

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