What happened to my room acoustics

I measured the spectrogram for my room at my MLP, and the FFT results are as follows:

- There is a roll-off before 20kHz.

- A dip is present around 12kHz.

- There is a noticeable boost between 50Hz and 1.5kHz.

- The bass rolls off around 33Hz at -3dB, consistent with the factory rating.

Comparing these measurements to the Burchardt measurements, there are some differences:

- It doesn’t exhibit a roll-off before 20kHz.

- The dip is around 15kHz.

- The boost between 50Hz and 1.5kHz is not as pronounced as in my room.

I’m curious about what might be happening with my room acoustics. If a fix is possible, what would it entail?

Spectrogram from my zoom


My room / speakers setup


Measurements from Burchardt


Helmholtz resonators are the basis of mechanical acoustics...

As you know i used them in my first room a lot ...

Distribution and location matter ...

Now in my second room with smaller speakers , i designed a new porthole for them using different straws tuned for this goal exactly as when we compute the right size of the neck volume and diameter of the resonator body ...


Then you understand my perspective ...

My goal was first learning acoustics then improve my sound without cost ...

Thanks for the information...

My best to you ...



In the late 70’s Randy Hooker aka RH Labs. Made a subwoofer that was a helmholtz resonator. It was a passive subwoofer down firing into a slot. It was huge in comparison to modern subwoofers, about 3 feet by 2 feet by 2 feet. They made beautiful if somewhat colored bass. Inside the enclosure the driver was housed in a larger compartment which was slot loaded into a smaller compartment. It resonated at 20 Hz forcing the driver to go down low. It was a pleated 12" paper driver, nothing special. There were no subwoofer drivers back then.

the simplest solution is usually the best.

I would pull the speakers forward 1 foot and move closer 3-4 feet.

What are your speaker stands and height? To me the gel seems an ok solution

The stand is 32-inch high, placing the tweeter below ear level, but the 5-degree tilt of the front baffle on the S400 compensates for this gap.


I also have a pair of Buchardt Audio S400 MkIIs, and just a couple of recommendations based on experience.....though I have never measured the room. I am building a new audio room, and have a DSPeaker Anti-Mode to install at that time.

(1) In my experience, 3 feet into the room for the Buchardts is too much, I found the cleanest and most accurate bass at about 20 inches from the front wall; Buchardt recommends closer placement to the front wall.

(2) I'd reach out to Mads Buchardt for his opinion, I have found him (along with Don Sachs and Alvin Chee at Vinshine) to be most generous with his time and help. He  frequently posts and answers questions on the Buchardt Audio Worldwide Owners Group.....or just email them, you will definitely get a response.

Oh, and I agree.....you are sitting about 3 to 4 feet too far away, and are hearing too much room influence. Mike Major at GIK Acoustics also might be of help, mike.m@gikacoustics.com