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Stacking subwoofer - what's the benefit? (e.g. Rel Stack)

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#1
My local audio shop heavily promote this Rel stack hype recently. I kinda understand that multiple sub placement + DSP can help with room mode.

But this kind of configuration - Stacking 3+ subwoofers and using high level input (so, no DSP?) and putting them back behind each main speakers running full-range.

Is there any actual benefits? Anyone experienced/auditioned or saw the different in measurement?

EDIT: Example of stacking subwoofer below
 
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Tks

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#2
I don't even understand the logic tbh. I thought one center sub would be enough for all (or perhaps 2 per stereo channel I suppose?)

Three though? Meh, I just don't get it, even as someone with very little knowledge about speakers.
 

CDMC

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#4
It greatly assists in transferring money from you wallet to theirs. Everyone knows six is better than two.

Seriously though, if you want to setup your subs for the best sound quality, you must high pass your mains to reduce their distortion in the bass (even large floor standing speakers) and minimize phase issues. REL continues to push their same BS of using only high level inputs to match the amp sound while ignoring phase and distortion issues.


https://rel.net/reference-line-arrays/
 
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Thomas_A

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#5
What is meant by stacking? Is it just another word for multiple subs?
 

pozz

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#6
There are known benefits in live reinforcement given that you can steer coverage using delays and EQ. Separately, in-room, you can control modal issues by raising a sub above the ground.

But these companies offer just SPL and looks, frankly. You couldn't set a stack of subs next to your mains and expect all the bass issues to fix themselves.
 

Kvalsvoll

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#7
As already pointed out by several others - DSP and proper calibration is the first thing to fix, if the main speakers run full-range and there is no eq on the bass-system, this is not possible to set up properly and no "stacking" will fix that.

I have measured this, and also listened to the test set-up, configured to equal frequency response, and on-the-fly switching between one unit height and full floor-to-ceiling coverage.

At very low frequencies, there may be a small difference. Higher up into the mid and upper bass range, the size of the radiator becomes large compared to wavelength, and this affects in-room frequency response and intensity and particle velocity.

There is a 10dB difference in velocity in the vertical direction, in the midbass range. Just like the theory predicts.

But keep in mind I start here with a unit that has a vertical radiator size of 1100mm height (already half-way from floor-to-ceiling), and the "stacked" system covers twice this height, so full ceiling-to-floor.

The blue and green lines are pv in vertical direction with one unit in height (1100mm), the red is with 2x units covering floor-to-ceiling:

4x 2x 1x V110 v h.png
 

Chrispy

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#9
Stacking could address different room modes....plus the benefits of subs placed within a quarter wavelength of each other....

But why even bother with Rel in the first place? (aside from the goofy connection practice....)
 

ernestcarl

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#10
I can understand wanting to try elevating one or more subs in a multi-sub configuration, but stacking one on top of the other (in a home residence) does not make sense to me.

 
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#11
Yup, stacking helps with directivity, but having no crossover and delay etc management is just wrong. On the video, there's a pair of Magico speakers, so price for a few Rels is not relevant.
 
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#12
This has been done before by Ken kreisal who originated from the excellent MK sub brand before the more sophisticated dsp systems arrived it works.
 

win

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#13
Seriously though, if you want to setup your subs for the best sound quality, you must high pass your mains to reduce their distortion in the bass (even large floor standing speakers) and minimize phase issues.
I would disagree with this. The primary benefit of having multiple subwoofers is that you have multiple bass driver locations. Why eliminate the benefit of your mains as yet another bass driver location? Technically I still high pass my mains, but more in an attempt to give them a predictable crossover slope for integration reasons. Also, phase 'issues' with bass can actually help with peaks and nulls in your overall system frequency response.

Back to the OP: the concept of high level inputs is probably fine if you don't feel like using dsp, I guess, but it's far from optimal. I would rather have access to dsp, have subwoofers that cost 1/3 the price, and use rca inputs if I actually cared about how the system sounded.

side note: am I the only one who can't stand the tacky branding all over REL subs?
 

Chrispy

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#14
This has been done before by Ken kreisal who originated from the excellent MK sub brand before the more sophisticated dsp systems arrived it works.
You mean stacks to take advantage of different room modes?
 
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#15
My local audio shop heavily promote this Rel stack hype recently. I kinda understand that multiple sub placement + DSP can help with room mode.

But this kind of configuration - Stacking 3+ subwoofers and using high level input (so, no DSP?) and putting them back behind each main speakers running full-range.

Is there any actual benefits? Anyone experienced/auditioned or saw the different in measurement?

EDIT: Example of stacking subwoofer below
Your local audio shop wants money and will recommend whatever most satisfies that need. Multiple subs can help if they are distributed around the room so as to spread room modes into an overall smoother response. Search on Earl Geddes and multiple subs.
http://www.gedlee.com/Papers/multiple subs.pdf
 

raistlin65

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#16
Could it be because REL subs are wimpy? So instead of saying, "I'm sorry we don't make a subwoofer to compete with the SPL with that model Rythmik," they decided to make stacking subs the new audiophile cool trend. lol
 
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