Dual Subwoofer placement and Isolation or not

Snappy

New Member
Apr 17, 2025
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King County, WA
With a center channel stand coming, I need to decide on one of two possible locations for the sub I have been using as a center channel stand. I will likely just move it over to the right between the center channel and the front right main. The other option is to place it next to the couch. The other subwoofer will stay in the corner next to the couch in any scenario. The subs do work nicely as an end table and I wouldn't mind lifting them up a little. Currently I use 4 ea. Herbie's Fat Dots under each sub.

My questions are;

I am strongly inclined to keep the sub in the front, but curious on others thoughts on if the sub would balance better with the one in the corner by the couch with the other sub on the front right wall or at the opposite end of the couch, one sub on each end? I know I should just test them but access through the crawl space is a pain.

Would something like the Iso Accoustics Aperta Sub XL offer any benefit other than me wanting the subs to be taller for end table use? Since I am not using the spikes and floor pucks that came with my Diablo Stands I could use those if I can find the right insert to install on the bottom of my subs. They are about 70 pounds each, DIY ScanSpeak Revelator 32W 4878T's in 1.5 cubic foot sealed enclosures'. There is plenty of material to install the spike screw inserts.



I am making some changes to my Family Room and considering these options for subwoofer placement. 2-channel is my priority and I've been using a subwoofer as a center channel stand and it has been fine. I've just replaced 3 ea. Dynaudio Contour 20's with 3 ea. Focal Diablo Utopia Colour EVO's. The FL/FR Diablo's used as mains are on Diablo Stands. I've just ordered a Focal Viva Utopia stand I plan on modifying to use as a center channel stand for the 3rd Diablo I use as a Center Channel. It is the perfect height with similar if not identical cosmetics. Focal mentions I may have to drill new holes since the Viva and Diablo stand mount screw holes are slightly different.

I use StackAudio Auva 70 feet on all three stands. Not so much to change the sound or performance of the diablos but because I move them out into the room for critical listening for small groups and up against the wall to get them out of the way when hosting a larger group. The felt on the bottom of the feet make moving them easy, adds width and stability, and put the FL/FR tweeters at the right height. I don't have the Viva stand yet but hope I can adjust the Auva 70 feet to tilt the CC up just a bit.

This is a multi-purpose room my wife takes pride in managing the decor in. It is every bit as much her hobby as audio is mine. Room treatment is not an option. I need to rely on Anthem Room Correction via my STR preamp and Audyssey when using Home Theater Bypass and the Denon AVR. The room has 10 foot ceilings, lots of windows but with heavy wood slated shades, open to an eating nook and kitchen and via hallways and a door size opening, the rest of the house.

Thank you

Family Room – 2.2 system: Anthem STR Preamp, Bryston 6BSST, 2 ea. Focal Diablo Utopia Colour EVO, 2 ea. Scan-Speak 32W/4878T Revelator 13" Subwoofer’s, QSC PLD4.2, VPI Prime Signature 21 turntable, Ortofon MC Cadenza Bronze Cartridge, Cambridge CXC CD Transport, network and an Apple Camera Connecter, connected via the USB input, to play ALAC files using the STR DAC.

5.2 system-STR HT Bypass: Denon AVR-X6500H, LG 77 CX, 3rd Focal Diablo Utopia Colour EVO for CC, 2 ea. Infinity Cascade Model Nine surrounds, Apple 4K TV, Panasonic DP-UB820, XG1v4.

Family_Room_SUB_Options_1000p.jpg
 
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These were the STR Anthem Room Correction results with the Contour 20"s and the sub locations shown in above pictures. Of course the CC is not active when using the Anthem STR.

ARC_FL_FR_Results.JPGARC_Sub1_Sub2_Results.JPG
 
I have a negative opinion of arc processing so take my suggestions with that in mind.

I’m a proponent of first step subwoofer crawl room positioning and Velodyne DD Plus idiot proof Auto EQ followed by some minor manual parameter custom preset adjustments.
Your subwoofers waveforms appear alarmingly spiky and rolled off. Possibly may very well be your rooms bass sucking null locations.
Are those DIY cabinets and drivers? Did you use the QSC PLD 4.2 user adjustable preset adjustments and monitor those graphs via the USB?
I enjoy various preset +dB’s after mid 30Hz in my room.

Your wife has assembled a beautiful room. I’m almost certain optimal sub positioning would be frowned upon. Optimal room positioning requires far less gain and the degradation from most any type of processing.

I gave up on spikes decades ago. My subwoofers reside on soft casterd dollies with closed cell boogie board and heavy latex foam. An almost twelve inch increase in hight. The combination required a change in the subs parameters resulting in increased low frequency definition and a stunning reduction in low frequency born travel throughout the structure of our dwelling.
 
I installed StackAudio Auva 70's on the subwoofers and speakers. They make it easy to move the speakers for cleaning or pushing closer to the wall when a large group is over.

They are DIY subwoofers; 32cm Scan Speak 32W 4878T00 in 1.5 cubic foot sealed enclosures. I replaced the QSC PLD 4.2 with a SpeakerPower SP2-1400-HT.

I finally ran ARC Genesis on the STR and an Anthem AVM 90 for when the STR is in Home Theater Bypass mode. I have pushed the limits of placement options since decor is my wife's passionate hobby. With our challenging space the systems still sound amazing. Thanks.

Focal_Diablo_Auva_70_Collage_1200p.jpgAnthem_STR_FL_FR_Sub1_Sub2_ARC_08302025_Rev_Screenshot_1600p.jpgAnthem_AVM_90_ARC_08302025_Rev_Screenshot_1600p.jpg
 

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