I don't know how loud it can go, but it seems that ADAU1701 equalization can iron the response down to 10Hz:
I was using single precision ParamEQ block which apparently was producing some noise at low end so I had to go for double precision PEQ, which in turn seems to be limited to three peaking filters (in ADAU1701). Happy with result so far, I wonder if lower Fs driver would bring any benefits here.
I was using single precision ParamEQ block which apparently was producing some noise at low end so I had to go for double precision PEQ, which in turn seems to be limited to three peaking filters (in ADAU1701). Happy with result so far, I wonder if lower Fs driver would bring any benefits here.
There is definitely a problem with this woofer, it simply loses it at very low octaves. To eliminate possible rattle in the box and amp distortion, it’s connected now to 350watts amp and power supply capable of driving down to 2 ohm (TPA3225 in PBTL mode), playing outside the box. Membrane moves freely when pushed by hand, not touching anything while moving.
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Does it have a vented pole piece that is being obstructed while sitting on the floor?
Try driving it with a constant 20 Hz sine signal and slowly turn it up to see at what level bad noises become audible.
Try driving it with a constant 20 Hz sine signal and slowly turn it up to see at what level bad noises become audible.
To me it just sounds like pole vent noise during the high excursions. If this is your driver, it looks like it does have a vented pole piece:
https://mm.jbl.com/car-subwoofers/CS1214_.html
But maybe you have found the limits of what it is happy to do...
https://mm.jbl.com/car-subwoofers/CS1214_.html
But maybe you have found the limits of what it is happy to do...
It seems it does, I will doublecheck the next time I open it. The thing is, it rattles in the box too, that's why I opened it in the first place. It happens around 25-30Hz.
Anyway, I will try another driver when they get them back on stock. In the meantime, did some more optimization in the DSP:
I am thinking going for this driver: https://www.scan-speak.dk/product/30w-4558t00/
I saw it's being used in similarly sized box by Troels. Fs of 17Hz should get me where I want to be 🙂
I saw it's being used in similarly sized box by Troels. Fs of 17Hz should get me where I want to be 🙂
I am a having another weird issue. If I maintain mostly flat FR in the region 20-100Hz, lows around 100Hz sound noticeably worse than on KEF Reference - very unpleasant resonance like experience. If I imitate KEF's response in this region, lows sound much better overall. KEF is yellow, my sub is green. Not sure is this is my room's response or something else.
I am puzzled now: if I can hear this peak resonance around 100Hz, why is this not reflected in the measurement? To eliminate this audible peak, I need to leave this "valley" untreated by peaking filter, pretty much the same as KEF does...
I am puzzled now: if I can hear this peak resonance around 100Hz, why is this not reflected in the measurement? To eliminate this audible peak, I need to leave this "valley" untreated by peaking filter, pretty much the same as KEF does...
If that response graph was taken with the mic close to the sub, .but on your listening position you get the peak ...is a room mode. You need to change your sub position.
But ideally you need to put the mic at the listening position exactly. That way you will see what your ears ..hear
And you can eq better that way, but the best thing you can do is to treat your room with bass traps.
An acoustically treated room is much much easier to eq or almost no eq at all.
But ideally you need to put the mic at the listening position exactly. That way you will see what your ears ..hear
And you can eq better that way, but the best thing you can do is to treat your room with bass traps.
An acoustically treated room is much much easier to eq or almost no eq at all.
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The mic was very close to my head, almost at listening position.
Anyway, I replaced the sub with ScanSpeak, and getting the same oscillation around 25-30Hz, flapping like sound. I have no idea now what this could be... I will be returning ScanSpeak as it makes no difference at all in the same position...
Anyway, I replaced the sub with ScanSpeak, and getting the same oscillation around 25-30Hz, flapping like sound. I have no idea now what this could be... I will be returning ScanSpeak as it makes no difference at all in the same position...
I am not sure how distortion sounds in such a low region, but just in case I replaced the 90W PS with 350W one and the amp with my TPA3225 based in PBTL mode capable of 600W into 2ohm load. I placed everything outside so that I can see a clipping led and eliminate amp/PS rattle. Clipping LED does not light up when this happens. Vibration definitely comes from the box itself.
I did plug a few tiny holes, left the stronger amp and PS outside the box, and all this together does seem to have made a positive impact overall.
The intro of Sting's Shape Of My Heart from "FIP Session Live In Paris At The Pantheon" seems to work better now. This song that is recorded live seems so have unlimited low end rarely present in others. I still have to leave valley around 120Hz untreated to have similar in-room response to KEF, otherwise it's unlistenable.
I did plug a few tiny holes, left the stronger amp and PS outside the box, and all this together does seem to have made a positive impact overall.
The intro of Sting's Shape Of My Heart from "FIP Session Live In Paris At The Pantheon" seems to work better now. This song that is recorded live seems so have unlimited low end rarely present in others. I still have to leave valley around 120Hz untreated to have similar in-room response to KEF, otherwise it's unlistenable.
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Distortion = harmonic distortion = unwanted higher frequency sound created with the fundamental/ lowest frequency
2nd order harmonic distortion is an octave higher than the tone, and this is common. With inexpensive subwoofers I have, but no longer use, the harmonic distortion they made would become dominant just a little below 30hz.
If this is what is happening, you can easily test it. Using a tone generator, play a tone starting at ~40hz. And then step down 1hz at a time. I suspect somewhere around 30hz or slightly below you will hear the tone jump up an octave. And it will stop being a clear fundamental tone. Once this harmonic develops, it may continue if you increase the frequency above the point where it started.
The possible causes that come to mind include the driver itself, air leak around the driver from not being sealed to the cabinet, a hole in the cabinet, the cabinet resonating, a port resonance (If the sub is ported), or something in your room being excited by the low frequency.