Should I add another sub?

this is my sub starke sound sw-12 measurement, its placed in front right near 1/4 pt from right wall. can anyone tellls me if the output is dropping too early around 80hz? if will adding another 10" sub to fill in the 80~150hz range works? the reason im asking is because i have a consistent dip at the 90~100hz region as shown (as for surr and atmos speakers) and I suspect the sub isn’t providing the necessary output in that region or its just a room mode that I can’t solve? Thanks everyone for your help.

sub response:

LCR+sub response:

Two subs will help even the response, but using the same sub will help. Just plan the location well or use the miniDSP / REW app to help.

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Looking at the freq response. There are two things you MUST do to get dramatic improvements to your overall listening experience:

Go dual subwoofer, Period. No other way out
You are losing SPL as early as 74Hz. The critical range for that mid-bass kick is from 70Hz - 100Hz. You are missing tons of SPL. To reclaim those “missing” SPL, pls get another subwoofer, preferably the same make, model and driver size. If you can’t go for the same 12" enclosure, then go for at least 10" of the same make and model. Place the 2nd subwoofer diagonally across the room (preferred) but if you can’t due to space constrains, put it at the same 1/4 pt from the left wall, making flushed with the LCR.

You have a room mode issue
Either move your speakers or your main listening position (MLP). The constant dip from 80hz onwards is showing up for the entire speaker arrays and not just the subwoofer which points to room mode. No amount of EQ will fix that. Use the Harmon Room mode calculator (see my post: Getting Good Bass for your Home Theater Setup - #6 by desray) to determine where to shift your MLP. Bottom line is NOT to place your listening position at the null location. It will improve your listening experience drastically and even fix your subwoofer and speaker freq response as well. Guess what, this ,method if used correctly, you don’t even need to spend a single cent, except for the 2nd subwoofer that I firmly believe is a necessity for you.

Hope it helps…

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Great help! I’m afraid I can’t move my LP coz I’m in a small bedroom and sitting directly in front of the wall mounted TV. So guess I have To get the 2nd sub but will be limited to small form factor sub like the KEF HTB2 if placing in diagonal opp position, but can go same 12” sub in front left 1/4 pt.

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+1 with desray’s inputs.

Need some clarifications on your FRs. Also, for members to help u better, can u advise:

  1. for the 2nd photo (group of FRs), for LCR, are the FRs representing sub+speakers or just speakers only? Is Room EQ on/ off on those 3 FRs?

  2. post a layout/ sketch of your room and indicate where are the speakers and your MLP? Measurements of your room’s width and length is appreciated.

  3. A photo of how your LCR is placed in front will greatly help.

If the answer to (1) is that the FRs are “only speakers” and not “speakers+sub”, then looks like u have a wide band deep suck out for your 3 most impt speakers. This is impt bass range for mid bass and its tactile, and needs to be addressed.

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Hi, looks to me it may be a bass management crossover or phase /distance issue?

One easy way to check is to measure sub alone then either one of LCR alone, then measure the Sub + L etc etc.

Plot them together and you can see if there is a good sub across the bass management crossover. A good sum will be higher than either sub alone or mains alone in the crossover region.

Reason I ask, because the sub alone response looks good, no dip. After cutting the 65hz peak, the response is actually quite uniform with natural room gain in the lower end.

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@GundamUnicorn, since bro Gavin brought this up, can you share what is the x-over of your LCR given by Audyssey? Audyssey has the tendency to provide speakers near to the wall/corner at 40Hz. That’s too low. If you didn’t do anything to the x-over, then you should consider increasing the x-over between 60Hz and 100Hz. 80Hz will be a good starting point. Afterwhich, re-do your REW measurement.

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I’m using the A1 Evo audyssey optimizer and had raised this issue in the avs thread but the author points out that is more of a setup or room mode issue. My LR are small satellite KEF 3005 series center speakers that have a roll off 120hz but my sub output roll off 80hz so my thought is I need another sub to fill in this gap.

The xo are inline with speakers natural capabilities so it seems the sub is not able keep up

The FRs are LCR+sub, to show the broad dip. Room is 3.42x2.67m. Center speaker “stand” is temporary lol as I’m figuring out the ideal height and tilt angle.


Thx for the pics!

The kef 3005 system is lovely. I was previously also using 3001C SE as my fronts for a while with kef q200c as centre. They perform amazing for the size and value, and is great for a small room. :slightly_smiling_face:

Your sub roll off at 80hz on your sub FR could be due to room mode issue with respect to sub placement / mlp position. And maybe not be due to the sub’s capability. I expect a 12 inch sub to be stronger at the regions of 70hz-120hz vs the lower bass range.

To determine whether it is room mode and also check for phase/timing issue bet speakers and sub, can u post the following FRs?

(Graph 1) Post FRs overlay of your CENTRE speaker:
(i) running full range (set as BIG), w/ room EQ off ; and
(ii) set as SMALL, w/ room EQ on, avr xover engaged (without sub. Switch off sub when u run rew sweep.)

(Graph 2) Post FRs overlay of SUB only:
(i) running full range, w/ room eq off, avr over disabled; and
(ii) avr xover engaged as per your centre speaker’s, w room eq on.
(iii) avr xover set as 250hz, w room eq on.

(Graph 3) Post FRs overlay of:
(i) CENTRE speaker set as SMALL; w/ room EQ on; avr xover engaged (without sub. Switch off SUB when u run rew sweep)
(ii) SUB only with room eq on and avr xover engaged.
(iii) CENTRE speaker + SUB (room eq on; avr xover engaged)

For all FRs with room eq on, the Dyn Eq and Dyn Vol must be turned off pls. (I assume u are using audyssey)

With this above, we shld be able to see what is the issue.

3.42x2.67m > which is width and and depth of room?


Thx! Wah… 2.6m is the width and 3.4m is depth ah… :sweat_smile: Plus your mlp is at rear wall. Tough to optimise the experience for HT. Cos means your L+R speakers likely can’t acheive the minimum angle recommended by dolby

Thanks for the info omn the x-over for all your speakers. They looked about right for the KEF 3005 speakers. My recommendation remains. get a similar subwoofer to gain more SPL and headroom so that you can enjoy more “feel” at the desired range where it needed the most. Experiment with the placement and find the best “spot” before attempting to re-run Audyssey.

As for the mains, it is clearly not looking good with huge dips at critical freq range. There is nothing much you can do except to change the speaker position or do some acoustic treatment on the sides. Get a rug to fix the first reflection point and thick curtains by the side will do some good as well. More importantly, if you can get a second subwoofer to fill in the “void” (between 70Hz and 110Hz), your system should sound fine as the low freq effect (LFE) will be handled by your subwoofers which takes the “strain” off the back of your KEF speakers.

The most glaring issue here is your MLP. I fully understand the space constrains here. There is no way you can acheive good and balanced sound (with sub + LCR properly integrated) when you are sitting so near to the wall. I guess you are using that big art work to alleviate the reverberation in your room.

Get a second subwoofer is what you “can” do to help improve the listening experience by making the mains to integrate with the subwoofer at the right x-over (i.e. 80hz). In your case, it is doable.

No choice just try to get the best out of the setup. My LR is quite close to isosceles triangle

Yes sourcing for sub, given that I need to fill the 70~150 void, would 8” suffice?
As for the MLP close to the wall, I actually place a 3” absorber on the sofa back right behind my head. Definitely take care of some reflection and bass hum.

Non identical subs will be v hard to integrate. And diff headroom.

Best to get 2x identical subs. U won’t regret it. If your space cannot fit another starke 12", I would sell the starke away. And get 2x identical subs w small form factor.

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I had the Starke, it is a really small sub… you can’t go too small and expect DB unless you pay $$$$
Another of the same will be ok
Will need some elbow grease to make it happen…
Who is selling these subs now anyway?

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Buy two small built subwoofers Velodyne SPL-800 Ultra.
It is big in wattage, small driver but large voice coil.
You won’t regret.

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I know this is not what the sifus’ recommend but my experience with adding a small non-identical sub was very positive. My main sub, a SVS PB12/2, which can do 110db@20Hz is near field at about 0.5m behind me. The system had such roof rattling bass that a neighbor 3 houses down the street complained, but not the mid-bass slam as in many of the test videos that @Ronildoq provided. Adding a SVS 3000 Micro directly in front of the LP, which has two 8" opposing woofers and 2,500W peak power, added that mid-bass slam in spades. Its also only 10kg and easy to move around. I also now turn off the main sub when listening to most music as this little sub is quite fast and musical.

Stereophile review of SBS 3000 Micro