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Stereo Sub Vs Dual Mono


Aug 3, 2018
Sorry to be thick, does that mean they are DIY?
Yes, it is 5 loudspeakers (10 channels) in 5 closed volumes DIY box for differents uses. If we define the speakers as A,B,C,D and E from left to right, C is used as center mid/tweeter and B and D as center bass for multichannel. We are planning future uses such as stereo dipole with B and D, or other forms of transaural with all A,B,C, D and E.
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Major Contributor
Sep 8, 2021
Ok,I think I found the most crazy easy song for testing,whoever cares to analyze the spectrum will see crazy stuff.

And no,it's not classical,I know some of you don't like it,so easy stuff,just Bowie's Moonage Daydream.

Igor Kirkwood

Active Member
Forum Donor
Jan 28, 2020
Thank you Sokel for your example of David Bowie's wonderful recording Moonage Daydream.
If we instantly switch the setting of this piece of David Bowie to 4 MONO SUBS or 2 x 2 STEREO SUBS, the difference is not obvious, especially since the 4 subs are cut in linear phase FIR with a slope of 80 dB per octave, so the settings of the subs hardly influence the sounds located above 75 Hz.
We had to with the forumer SB10, and this in order not to be mistaken listening to these 2 settings in blind test A Vs B.
Here is the illustration of this instantaneous blind test technique with the box of Pos (French computer scientist creator of the Rephase software); it was Jean-Luc Ohl who installed this box in the QSC processor which simultaneously controls the choices of the SUBS, the filtering and the equalizations.
Position A corresponds to the 4 SUBS MONO setting.
Position B corresponds to the 2 x 2 SUBS STEREO setting (see photos and screenshots).

For the David Bowie Moonage Daydream The position of the SUBS in 2 x 2 STEREO SUBS gives a more precise bass. The 3D effect of the sound image is slightly improved; and this despite the poorer response curve of the 2 x 2 SUBS STEREO position (note 8.4/10 then the response curve in MONO 4 SUBS obtains 8,9/10 ). Indeed one goal of this setting was not to have the most linear curve, but the one that gave low-pitched sounds in phase opposition, as Griesinger advised.

4 SUBS MONO settings


2 x 2 SUBS STEREO settings

155b B 2 x 2 SUBS STEREO.PNG
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Senior Member
Apr 21, 2019
Some additional perspectives from others that might be interesting to consider:

Fundamentals of hearing 2004
“Various people have reported, sometimes anecdotally, that above 40Hz (and below 90Hz), although one can not localize a sound source, differences in interaural phase can create a sensation of space.. his suggests that for accurate perception of space, 2 or 3 subwoofers may be necessary. This also, as in many other places in audio, creates a situation where what one might consider the “optimum” solution (maximum bass flatness) does not in fact convey the perceptual optimum.”

Soundfields vs human hearing 2012
“Specifically, although one can not LOCALIZE signals below about 90 Hz, one can detect spatial effects from interaural phase differences down to about 40Hz. The AT&T Labs “Perceptual Soundfield Reconstruction” Demo, no longer available, contained a very nice example of these effects, and how they can change “boomy bass” in the 2-radiator case into “bass spread about a room” in the 5-channel case.”

@Thomas Lund
“From 50 Hz to 700 Hz, however, fast-firing synapses in the brainstem are responsible for localisation, employed in a phase-locking structure to determine interaural time difference (ITD). Humans can localise at even lower frequencies, but we will come back to that in a specific ultra low frequency blog.
The ability to position sound sources with precision spherically is a key benefit of immersive systems. Another is the possibility to influence the sense of space in human listeners. For the latter, the lowest two octaves of the ITD range (i.e. 50-200 Hz) play an essential role; but may be compromised in multiple ways”

“With both stereo and immersive, for your room and system to be able to reliably convey the envelopment latent in the content, perceived-direct sound should dominate in the 50 to 700 Hz range – where audible patterns characteristic of the recording space may have been picked up. If they have, you can be sure that the recording engineer has gone to great lengths in doing so. Fig 2 is a recording setup in Olavshallen in Trondheim, Norway, and shows a main mic array with sufficient distance between capsules to capture LF differences and moving patterns – two of the most precious qualities of a hall to preserve….Fig 3 shows the GRADE graphs from section 4.3 of the report, and reveals a monitor to the left which is able to convey envelopment latent in the content; and one to the right that is less able to do so. If listening to the latter, you are unable to judge recorded space precisely. Such ability may also be sacrificed when relying on bass management with only one subwoofer to reproduce all LF sound, rather than multiple channels and acoustic in-room summation. If possible with delicate content, don’t use a higher bass management cross-over frequency than necessary, and preferably below 60 Hz.”

“It's not primarily about localization, more about reproducing the swirling LF patterns a fine concert hall generates when music is being played. With acoustical summation in a reproduction room, there is a chance of hearing them, while electrical summation surely kills such joy. Also, we actually localize all the way down to a static pressure change (DC). It's indoor conditions messing up our senses”

“To faithfully reproduce great acoustic recordings, a flattish frequency response of perceived-direct sound is just one of the goals. More importantly, to me, the monitoring room and sound system need to convey moving patterns of sound latent in the recording, especially between 40 and 200 Hz. This is where to hear the soul of a concert hall or church, in case it has been recorded.
Collapsing discrete channels to a single sub channel should therefore be a last resort, e.g. if the reproduction room/placement is difficult and/or to accommodate multiple listeners.
Taking advantage of discrete channel reproduction at low frequency has even spread outside acoustic recordings. Top pop/rock productions now also make use of such perceptual excitement, which will remain a secret to “collapsers”

Jon AA

Senior Member
Forum Donor
Feb 5, 2020
Seattle Area
No, Denon doesn't offer stereo subs, altho your model can separately set level/delay for two subs. I can't think of any avr that offers that, altho I wonder if some of the top end processors might these days.
As andyc56 mentions later, Denon/Marantz do offer stereo (even Surround with four) subs on their newer mid+ level AVR/Processors. One used to need a Trinnov or Storm, etc, to get this level of Bass Management, but D&M have made it available to the masses.

Something that cannot be left out of this discussion now that it's a reality is Dirac ART. For any capable processor, it will allow stereo (or surround) bass without the downside of having room modes screw up the response of a single sub. The sub nearest the speaker can be made the primary support speaker, while allowing the other subs in the room to contribute at a reduced level only what they need to contribute in order to "smooth out" the response of the main channel. This should preserve all the spatial effects of stereo bass, without any of the (that I can think of) downsides. I don't see why one wouldn't make stereo (or surround) bass their default when setting it up.
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