Help me tame my out of control bass

Hey all,

Hoping to get some advice on how to tame what appear to be some pretty bad room modes. See my system here:

I’m in a bit of a pickle for a few reasons. First, my NY apartment is on the small side and requires me to set up on the long wall with the listening position against the opposite wall. On top of that I upgraded to my dream speakers, Egglestonworks Kivas. They sound amazing but they’re big and have a lot of low end reach. The combination of these two factors leads to the waterfall you see in my system - a pretty massive bump in low end, particularly at 40-44hz and from 60-70hz.

There’s also a huge bump at 120hz, but I don’t understand how that one is possible. I think that might be a measurement or microphone error - I don’t hear that at all and it doesn’t go away even when I EQ 120hz out completely, but maybe it’s a resonance?

Things I’ve tried so far, each with modest success:
- Plugging the ports gave me about a -5db reduction in the trouble spots (all measurements are with the port blocked)
- I don’t have a ton of placement flexibility but moving them back from their original position gained me about a -3dB reduction in bass
- I added a pair of 5.5” thick GIK bass traps, but they didn’t do much that I’m seeing in the measurements. Maybe a -1-2dB reduction, tops. They honestly helped more with the mids and highs.
- Convolution curve in Roon - this works the best, but doesn’t solve the problem for home theater or vinyl

I’m pretty stumped as to what else I can do. I think that the amount of bass traps needed to fix this is more than my marriage can withstand. I’m considering the PSI AVAA active bass traps, but only if I can do a home trial of them first to see if they’ll actually help - I worry this 8-10dB bump I’m seeing will be too much for even a pair of those. I could get a DIRAC processor from miniDSP and that would at least then work for all digital sources. Vinyl is mostly not a problem since this is so low and most of my vinyl is rock and jazz.

Any other ideas? Rolling tubes that have less bass? Are there any less expensive EQs with digital in and out that I could use as an alternative to the DIRAC for home theater only?

Showing 13 responses by hudsonhawk

@oldhvymec ha, don’t worry the mic is at my head position. You’ve definitely got me thinking though of some creative ways to absorb the boundary issues on the left side where the windows are. On the right speaker because it’s an open room there’s no boundary issues there. 
It is a calibrated mic (miniDSP uMik-1).

I just don’t have any other explanation for that spike at 120hz, which is present even when I EQ 120hz to zero. I’m at a complete loss what that could be.
@djones51 the mic was in the listening position. Given the untreated ceiling and windows on the left it’s safe to assume everything you’re seeing is the room. I can take a measurement directly in front of the speakers tonight or tomorrow, when I’ve done that it’s significantly flatter.
Definitely aware of the back wall reinforcement, however the room isn’t big enough to allow moving the couch forward more than a few inches. I’m also aware that probably limits how much improvement I can realistically make here.

Don’t get me wrong, I’m worried about the suck outs as well - it’s funny, I generated a tone at 55hz after noticing that cavernous drop on the graph and confirmed it’s completely missing in the listening position, and reappears as soon as you move around the room. Room modes are funny things.

That said the humps are the more glaring problem since they have such long decay time they end up sounding super muddy and boomy.
Try miking your speakers like 1' away and see if your 120 Hz bump is still there. If so, it may be a microphone artifact
@erik_squires Yep, still there even mic’d directly in front of the speaker. So to oldhvymec‘s point it could be a crossover issue or a mic artefact like you said. Unlike the other ringing in the waterfall I’m not hearing it, so I’m inclined to think it’s a mic artefact. Would love to do the same with bass traps but I think I’m already pushing my wife’s tolerance for panels.

@oldhvymec to your point, pulling them out does reduce the bass suck, but makes the peaks greater and makes the midrange less flat. Here’s an SPL graph of them pulled out (red) vs their current position closer to the wall (orange):

I have 10 GIK panels in the room right now, in retrospect the mistake I made was getting too many 2” panels and not doing enough bass traps or ceiling panels. They’re crazy expensive but one of the things that appeals to me about the PSI AVAA is that they’re easily moved and don’t require a ton of work to install. 

The tough thing about renting is not wanting to overinvest in a solution for your current place, in fact our lease is up in a few months and we’re currently considering moving. I’m tempted to just to get a better room for my stereo, where I won’t need to have the LP be against a wall...

Great suggestions all, thanks for the thoughts.
@tomeh45 there’s no manual for the Kivas, but I did talk to Jim at Egglestonworks and he not only had some tips for me, he was kind enough to cut some port plugs for me for the slot loaded bass port. For the transmission line ports, they’re pretty heavily diffused internally so they aren’t super loud, but just to reduce interactions further I have the GIK bass traps hung behind them so they are absorbing anything from them.

Audio2design pretty much nailed the layout, but here’s the floorplan in case you’re curious about the exact dimensions. Ceilings are 8 foot:
@oldhvymec You know it’s funny, I didn’t think I had a problem with mids until I moved them into the current position (the orange line) and you can see that those deep troughs in the MB region improved significantly and it was like lifting a veil.

Agreed on curtains, the other problem with that room is that it’s asymmetrical so you have the windows on the left and then an open kitchen on the right. Maybe I need to get out of this nightmare room and move...
@jimofmaine it never occurred to me until I started getting into measurement and understanding room modes that a reason to get subs is to have more flexibility in placement of where the bass is being generated.

@millercarbon she absolutely had her priorities straight and there was no way I would have ever convinced her to swap places. Sadly she passed away recently but she lived a long life and enjoyed my hobby a lot as it gave her lots of lap time, although like many from her generation she preferred digital to analog (because I never had to get up to change the record).
@audio2design you’re 100% correct. The right speaker doesn’t have a boundary wall next to it, there’s a counter and a kitchen and a hallway going to our office / entryway.

Incredibly impressive deduction.
I didn’t say bass traps don’t work, my two bass traps are 5” thick. I didn’t see much measurable difference but i suspect I would need several more of them to get there, which as I said I don’t think the missus would allow.
@speakermaster Great question and a detail I forgot to mention is that i did decouple the speakers by adding Isoacoustics Gaia feet to the speakers. It didn’t make as big of a difference for the bass as I was hoping (although in retrospect I wish I’d measured before and after, I didn’t yet have the measurement mic) but it did improve the imaging significantly.
The odd thing is that 120hz didn’t seem to be there when there’s no signal. This weekend I’ll do some more measuring, there’s been a lot of good hypotheses about what it could be. I’ll run a test tone at 60hz to see if it’s a harmonic, more mic’ing of the room with no signal playing to see if it’s environmental, and with different sources to make sure it’s not an artefact being produced by my DAC or integrated amp.

@rego placement is the correct way to solve this, unfortunately the speakers are quite large and the room allows limited movement of the listening position or the speakers themselves.

Good news is I got in touch with PSI and am in the process of arranging for an in-home trial of the AVAA C20, which could be a good, if expensive, solution to my troubles.

I’m also planning on a few other measurement trials this weekend with different placement of my bass traps, this thread’s given me a ton of ideas thank you all for your thoughtful responses.
So an update here: nearfield measurement shows the speakers, unsurprisingly, have an almost flat response.

And massive kudos to those who said the 120hz spike was a harmonic - you win a prize for that one. When generating a 60hz tone, the spike at 120hz is visible on the analyzer. Very interesting!

For now, I’ve been able to do a little EQ’ing to address the problem, at least with music played from my music server. Interestingly I didn’t really like the results when using a convolution curve in Roon - it reduced the bass way too much - and I ended up just using Roon’s parametric EQ, using the room’s graph for reference.

Longer term, I’m arranging a demo of the PSI AVAA C20, and waiting to see what happens with our lease before deciding between that and more bass traps.