In my last post I detailed the construction of super heavy duty wooden speaker stands. The question that nagged me after spending so much time for design and construction? Would they perform differently then my $15 cinder block stands?
In short, NO they don’t.
So why build them? They have many non-acoustic and aesthetic advantages. I was happy to see they perform as well as very heavy, ugly, difficult to move, and unstable cinder blocks. Nice work me!
At the top of this post are the charts. You may notice they look extremely similar. They are. Bottom line is the speakers direct sound hasn’t changed.
Fascinating details to follow!
This is a spectral decay graph. The y axis is loudness in dB. The x axis is frequency starting at 20Hz. The j axis is bold as love. Each line is a 3ms slice of time with a 50ms window. (I’m still not sure exactly what “window” means here.) So the top red lines are the first (direct) sounds arriving at the test mic.
But what does it mean?
For these tests I used Room EQ Wizard. It’s a useful and free program for testing room acoustics. If you use it be a sport and donate. Room EQ Wizard has definitely saved me $50 which I am giving back to them.
In the tests Room EQ Wizard AKA REW plays sweep tones through my speakers. Sweeps tones are sine waves that “sweep” up higher and higher in frequency. They start as a rumble and then move to a dolphin opera singer. While this is going on a measurement mic is capturing what my speakers are actually producing.
Sweep tones are actual data. Data that is cold and hard like that ex-president we had. The way the speakers reproduce the data is more human and organic like the new president we thought we were getting.
I’ll attempt to explain.
From Wikipedia: In dry air at 20 °C (68 °F), the speed of sound is 343 meters per second (1,125 ft/s). That was helpful? Or just remember sound travels about 1ft every millisecond (1/1000th of a second). If your speakers are 6ft from your listening position or measurement mic it will take the sound 6ms to travel from speaker to mic/ear. After that the sound passes the ear/mic, hits things in the room, and bounces back to the mic. So I’m actually only interest in the first few lines in these graphs.
You can see the speakers are sort of linear (producing different frequencies at nearly the same amplitude) for a while. Then the reflected sound of the room starts coming back and non-hilarity-linuarity ensues. That is, room modes appear and the lower lines (slices) get real wiggly.
If you are interested in my fascinating test methods read on.
I set up a test mic, an omni (Behringer ECM8000 Mic) near my listening position. This is about 6ft from the speaker. Then I ran sweep tones from 10hz to 300hz. This is where troubles will occur with room modes and where I suspect the differences in stands could show up.
I took 8 measurements from the cinder block and 8 from the new wood stands. What you see is an average and good practice.
The only variable was the speaker stand. I took great care to place the speakers in the same position for each measurement. The easiest way imo to do this is by placing a mic stand up against the speaker and taking measurements with a ruler.
Here I have a mic stand in parallel with the face of my speaker, level with it, and the end terminating with the speaker edge. Now swap out the stand keeping the speaker in nearly the same position. Do it!
I hope you haven’t soiled yourself reading this exciting post.