Room Correction DSP or Physical

Hi All

I am in the search for new speakers but hitting issues with bass nodes in my near cubic room. (3.6x4.3m).

Quick question, is the DSP in Roon (with correct measurements etc) going to be all I need to sort which ever speaker I choose ? Or will I have to use physical room correction products to get great results ?

Or do I have to settle for smaller speakers that don’t extended as low ?


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As far as I have read the preferable route is room correction first then DSP.
You might want to say which speakers you are experiencing the problems with so other users can give you some feedback.


Thanks for the input.

I dont know which speakers yet, i am auditioning various options.


You might find help even so. There’s a lot of “tried that” experience here that could help. You might want to think about saying what your source/amp chain is and ideas as to speakers and placement or enhancements.
Or just ideas for bass traps or DSP tweaks.

Good Call

Current System is Roon>AlloDigiOne>Vitus RI-100 with integrated DAC. I am moving over from a Naim system, so running SBL;s at the moment.

Looking at most options in the 7-12K GBP new range. Tried some Kudos 606, S20A and Avalon Ideas so far. Going to try some standmount options, shahinian Obs and anything else that’s local until i find the right answer. Hard to dealer Demo many speakers with the Vitus due to limited stockists.

The Ideas and 606 where both very good but due to having more bass extension than the SBL;s cause some issues at the bottom end.

Yes you may well be overspeakering that size room. I can see how SBLs would be a good match. What’s the problem withe SBLs? Perception of light bass?
Obelisks would probably be a bit boomy too. They aren’t the most controlled kit. (I have Compasses and Super Elfs and Naim kit)

Not really on the bass side. More on the realism, openness, detail, sound stage etc side of things.

I was wondering if some Standmount options may be a better fit. Not something i have looked into much

Wow that is some amplifier. I hear good things about Harbeth for the characteristics you are describing or Living Voice.

In that price range consider Kii Threes. They will go 95% of the way of dealing with room issues. They are active though.

You can DSP away the booming bass, but you cannot (and should not) try to flatten the sharp dips in the frequency response that you will have in an untreated room. You need physical room treatment to handle those.

But once you have treated your room enough to get rid of the sharp dips in the lower frequency, you can handle the rest with DSP. Be warned though, in some rooms that can be a lot of room treatment (in my 3.5x4 meter room I have over 2 cubic meter or stone wool). But my walls, floors and ceiling is concrete.

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Thanks for the suggestion


When you say the sharp dips in Freq response are you talking about say above 100Hz or across the entire freq. range. I did some measurements with a calibrated Mic and i think the issues are just around 40hz, but i need to spend a lot more time on the measurement in REW.

I dont want to treat any higher freq with DSP, can do that with correct room treatment at reflection points etc. The problem is getting enough mass into the room to treat bass boom below 100Hz is not compatible with a shared listening room :wink:


See picture below, with DSP you can fix the top at 45Hz and 60Hz, which is probably producing very bad boomy bass. But you cannot solve the dips at 49 Hz since boosting this would only result in a lot of distortion (its a so called null node). The same with the dips at 80, 110 and 210 Hz.

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Compare the previous picture (my room with no treatment), to this one after I treated the room:



That’s great to hear as its the boom that i really need to control, as i have a similar spike at about 40Hz

May i ask who’s products you used to treat your room and if its was trial and error to get the correct product in place.


I built my own room treatment from cheap industrial things. Closets with isolation inside, and cloth-covered absorbents meant for noisy industrial environment. Very effective, but like 1/5 of the cost for HiFi absorbents.

But even with this in place, I still have a little spike at 43 Hz, but nothing that digital room correction can’t solve.

Bass traps are easy to build. I built the John Risch recipe I got from AudioAsylum, back when all I had for tools was an electric saw. They work great. There are other designs out there, and, if you measure your room’s response, you can build them to suit to a certain extent, but that will require overcoming a learning curve.

You may want look into these speakers from Finland. Looks interesting how they are built in order to minimize room impact.

If you want some physical room treatment, try this carpet


So let’s speak about bass correction.
In more than 90% of the cases there are two problems encountered :

  • room modes, creating peaks and dips at certain frequencies
  • reverberation/decay time : walls/furnitures basically reflect bass waves. This means that the reverberation/decay is usually too high, across the whole bass range (no peaks and dips). The consequence is that bass notes take too much time to vanish and are “sustained” too long, “masking” the whole musical signal.

Room modes can be corrected with DSP or physical bass traps. Bass traps can be either broad band (glass wool, rockwool…) or narrow band (panels, Helmholtz resonators). If you use a broad band bass trap, you will still need EQ as the whole bass range will be lowered, therefore the peak will still be visible.

So room mode cancellation is better achieved with DSP or narrow band basstraps, or a combination of both. The effect is to be seen on the “SPL view” of REW.

Reverberation/decay time over the bass range cannot be reduced via DSP. It requires physical treatment in the form of bass traps. Use the “spectrogram” or “delay” tab in REW, not SPL.

In conclusion: if you have a reverberant room in the bass range like >90% of us, it is always a good idea to start with physical bass traps to reduce the reverberation/decay time to a reasonable level. Room modes can then be easily addressed with DSP/EQ. Only use minimum phase filters here, try to avoid gains lower than -6dB and Q above 10 if possible.

In my setup, I have 3 DIY bass traps: 0,5m3 hemp wool / 48 Hz panel resonator 0,6m2 / 48 Hz Helmoltz resonator 0,6m2. Then EQing everything with REW EQ.

This is SPL before (red) and after (blue) basstraps, before EQ:

Spectrogram before and after basstraps, showing an average 30% reduction in decay time up to 120Hz at least. Doesn’t seem much but very spectacular, no more boomy bass, clearer musical message, less listening fatigue, easier to pump up the volume…

Finally, EQing with REW (left channel shown here)

Shape of EQ filters on top (blue=left, red=right) and final SPL curve including bass trap and EQ at the bottom.

For those who don’t mind French here is a fantastic article on room measurement and correction:
Chapter 1 and Chapter 2.
See also here my panel and Helmholtz calculator (Excel), again in French sorry. Don’t use the calculator for bass resonators, it’s way too imprecise.