Why not?
But I agree that a helmholtz absorber probaby needs to be very big (~5% of room volume) to have an audible impact.
You can resolve this with a very simple notch filter (band stop) based on opamp gyrator topology, if you like to play with opamps.
I made one for my listening room, where I had a strong resonance at 35Hz that would be difficult to absorb and it was very effective.
On top of that, I have a 31-band EQ for other minor adjusts.
I know a DSP can do all this automatically, but I like to do it myself with analog electronics.
1xTL074 + 1xTL072 (3 opamps per channel)
LTSpice FR
+1 on the notch filter... I struggled getting my Sub to integrate with the system, until I measured the in room response, and found the nasty room peak that was the source of the problems. A similar mono notch filter, in line with the sub, cured it, and made the system sound much more balanced.
Why not try with a quarter-wL closed cylinder/column of air? Maybe just an angled panel attached to the walls of a corner? Or a 1/2-wL open-ended column along the ceiling or floor? Volume of column will affect the level of damping and the Q factor. Helmholtz may have spikes outside desired freq.
http://hyperphysics.phy-astr.gsu.edu/hbase/Waves/opecol.html
https://amcoustics.com/tools/amroc
http://hyperphysics.phy-astr.gsu.edu/hbase/Waves/opecol.html
https://amcoustics.com/tools/amroc
Last edited:
Changing the listening spot is easy and effective solution too. Could be height issue though...
Longest length is 15 ft so
f = 1115 ft/s / (2 * 15 ft) = 37.2 Hz (approximately) for fundamental.
Bass trap 2 of the corners.
Or any standard multiband EQ is what we tuned rooms with.
They are usually wide boost / narrow cut.
So you just pull down the 40 Hz slider till it sounds right.
Pretty typical, rooms vary in size obviously.
But most of them designed with same old generic lengths.
So 40 , 55 , 65 and 75 Hz are pretty typical fundamental nodes.
Your case likely 37 , 74 and 111 Hz
Audiophiles like to huff and puff about EQ
when most of the intention of multiband EQ is cut not boost.
Far as moving speaker, it means rearrange the whole room. ( most dont)
Project towards shortest length or project to longest length.
On longest length projecting towards shortest try middle or offset.
Usually offset and not were you would like them is what works.
f = 1115 ft/s / (2 * 15 ft) = 37.2 Hz (approximately) for fundamental.
Bass trap 2 of the corners.
Or any standard multiband EQ is what we tuned rooms with.
They are usually wide boost / narrow cut.
So you just pull down the 40 Hz slider till it sounds right.
Pretty typical, rooms vary in size obviously.
But most of them designed with same old generic lengths.
So 40 , 55 , 65 and 75 Hz are pretty typical fundamental nodes.
Your case likely 37 , 74 and 111 Hz
Audiophiles like to huff and puff about EQ
when most of the intention of multiband EQ is cut not boost.
Far as moving speaker, it means rearrange the whole room. ( most dont)
Project towards shortest length or project to longest length.
On longest length projecting towards shortest try middle or offset.
Usually offset and not were you would like them is what works.
Last edited:
The same problem (minus the volume) - total vent/cross-cylinder area must be large enough. DSP or active analog notch filter is easier and more effective.
Great bass trap is a soft couch at the end of the longest length
And corner shelfs.
People want expensive magic audio solutions.
For mid and high early reflections= drapes or carpet
Aka what movie theatres used in the old days.
Alll the way down the longest walls. Magic
And corner shelfs.
People want expensive magic audio solutions.
For mid and high early reflections= drapes or carpet
Aka what movie theatres used in the old days.
Alll the way down the longest walls. Magic
I will build book shelfs for pocket books. As I do not want to have books that close to the floor I have space along the floor about 20cm deep 20 cm high and 200 cm long.
If I use this space to reduce the standing wave floor to celing at 72 Hz. So the space is a pressure maxima and velocity minimum.
Membrane, Quarter wave pipe or something else?
If I use this space to reduce the standing wave floor to celing at 72 Hz. So the space is a pressure maxima and velocity minimum.
Membrane, Quarter wave pipe or something else?