Bass not satisfying - debug-help needed

How big is your room?
How big is the opening, and to what size area does the opening go?
What do you listen to?
How did you decide where to place the subs?
What's the crossover frequency between sub and main speakers?

In general: If you want room pressurization, you're absolutely right
that an opening into another area adds that area to the size of your
listening room.

Could you show a graph of the subs and mains running together? One of the most critical aspects of getting satisfying bass is achieving a good blending between the subs and the mains. If the area around 80 hz turns out weak due to phase issues, you can lose the critical mid-bass slam factor. Without that, will be less than satisfying.

The nearly square room is also a problem and this is compounded by the fact that the length ang width dimensions are almost exactly 2x the ceiling height.

How's the bass in other locations besides on the sofa? Being up against the wall is typically not a good spot.

You have a nice house curve, everything seems to be good. Maybe you just need more spl's in the lower frequencies, meaning when the volume is higher you might be loosing your house curve because the subs aren't keeping up below 40hz.

I'm not familiar with your subs, so I could be wrong. How close to reference do you have your system and how hot (if any) do you run your subs?

I'll be interested to see what you find when you test them at those higher spl's.

When you say you are missing something in the lower freq., I bet it's more 20-40hz and not down in the teens.

When you say a sub can't do 15hz without sacrificing the higher frequencies I disagree. I think that's what's so great about the Submersive because in my opinion it does just that. It is the most musical sub I've ever heard but it plunges well below 20hz as well.

BTW, full disclosure - I own dual Submersives and am a fanboy.

Cool, I'm curious how those subs will hold up down low so I'll stay tuned.

I would think that if the room were the culprit then you would see a null in the frequency response and that's not the case.

When you get time you should post pics of your room, I'm curious what your screen looks like. I'm jealous of those with AT screens, I wish I had one.

I do believe your room is a real factor here.

I notice that before eq, the response looks quite boomy with a sharp rolloff from the low 30's on down. It has to take a lot of eq for you to get it flat including what amounts to a good deal of boost below tuning to get a flat response to 20hz. Boosting below tuning is usually not a great idea and excessive eq in general sometimes seems to result in a loss of dynamics. I believe you may have the wrong subs for your particular room. I'm thinking that a couple of good sealed subs with a natural second order anechoic rolloff would work well in there.

From what I have researched here on AVS I think many would disagree with you on this point. Especially when it comes to sealed applications. I don't know of many commercially available subs that come close to 15Hz with any type of authority.


I agree with Mojo.


I'm not a Submersive fan per se, but I hear nothing but good things about them. I am however, a fan of the LMS 5400 Ultras DIY route. There are many many users on this forum with a few (or more than a few) Ultras that claim it to be the end all be all sub. Some of which have upgraded from some other serious setups (Epik Conquests, etc...).

Full disclosure - I DO NOT own the LMS Ultra (yet) but am a total fanboy.


I personally think having a sub to handle only the <30hz would be a bit on the extreme side. The only thing I can think of that you would be able to fully maximize the potential of your product would be a rotary sub. Something like the TRW-15. On the other hand, if you were to implement a few of the Ultra's they could handle the extreme lows and upper mid bass without trouble (in a sealed application of course).

If you are wanting to throw money at the situation, seriously consider the Ultra. Hell, you've been around here longer than I, so I'm sure you've seen Notnyt's, Edogg's or Lukeamdnam's systems. I believe Notnyt specifically can comment on how the LMS blend with his JBL's.

Check out one of Luke's sick video's of his setup in action... He, along with the others have nothing missing in the LFE department.

Sometimes with eq, large degrees of cutting the frequencies in several areas of the response can adversely affect the bass "energy" in the room even if it winds up giving you a smooth frequency response in your listening spot. Perhaps you might benefit from heavy bass traps in the room to help acoustically improve the response prior to eq.

How much boost are you running on your sub EQ? Where are you boosting/cutting? What do your mains look like full range without a sub? -3db?

Your full range graph has too big a scale try a scale with a span of 60db on the y-axis and remove all smoothing...... Its possible something might be easier to see if you do this....

As others have stated no real glaring probs but the room issues.

If you dont use audyssey how to you set phase and/or align delay?

Looking at the before EQ graph you posted above and the spec sheet of the similar production subwoofer tell much of the tale. The tuning appears to be in the upper 20s or near 30Hz. You can push below this with EQ, but output will compress quickly as port airflow and driver excursion go non-linear. As you describe, I would expect these to be quite capable of giving a very full kick in your room, but the expectations were just never set to plumb the depths.

Youve got some serious suckouts at 39 and 50 which I would think are room/placement related. Room treatments might help.

For a serious system like yours i would think if going ported, no higher than 20hz tuning..... Your leaving a lot on the bass table with 25-30hz tuning for HT IMO. Most commercial sub's -3db
points are at least an octave lower in room......

You should demo some subs that can get 16hz at high levels. It's an experience you don't want to miss before any purchase that are over a grand. Your sub are very capable for music but for movies, the f3 are too high.

If the BSS London Soundweb is a manual PEQ, it will not provide anything close to the correction granularity that your Onkyo PR-SC5508's Audyssey MultEQ XT32 can give you. I would disable the Soundweb EQ and run through your receiver's Audyssey setup routine. Once that finishes, go into the receiver's audio setup menu and ensure that the speaker sizes are set to "small", crossovers are at 80 Hz, Audyssey Dynamic EQ & Dynamic Volume are "Off", and bump up the gain on the sub channel several dB.

Listen & take some new measurements after you're done with the Audyssey setup. The frequency response should be much improved. If there are any remaining issues you could then do a little fine-tuning with the Soundweb.

Running the Audyssey setup does make some "uninspired" changes to the audio configuration settings. I suspect that folks who run Audyssey and don't like the results are unhappy because they don't go back and make the post-Audyssey changes that I suggested. If you don't like the post-Audyssey results, it's easy enough to turn Audyssey off. The smoothed measurements you posted look great. Smoothed measurements don't give you an accurate picture of the benefits Audyssey is providing however, especially in the higher frequencies.

One other note about Audyssey. The standard Audyssey setting rolls off the high frequencies which is something that doesn't appeal to me. My Denon 5308 has an "Audyssey Flat" mode that eliminates that rolloff. I assume that your Onkyo has a similar Audyssey mode, although it may have a different name.

You complained about your system's sound quality with Audyssey off. Why not try my suggestions, including the post-Audyssey setup changes, before writing them off?

I went from Audyssey Pro back to Pioneer & MCACC due to flat and sterile SQ.