Ah, well, you see this is where I fall down again! I haven't even got a real computer that can run that kind of software.... How do I manage you ask (probably), in this world of technicolor s(t)imulations where minute differences in a curve mean so much. The answer is (in case anyone is interested) I don't, I live in the real world that (inconveniently) is full of pesky variables that I haven't the time (or inclination) to tell the computer about (and it would probably ignore them anyway because whoever designed the software didn't have me in mind). So, I have used my microphone and scope to "measure" the output (it produces a nice curve in real time!) and it's scarily flat down to 20Hz. My experiment with IB is going quite well at the moment, the next thing I'm going to try to do is damped down the vibration in the wall a bit more. Does anyone have any ideas please?
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A chance your vibrations will show up as 2nd or 3rd harmonic distortion. And that will be quite clear on a real-time analysis display (which will show the specific frequencies where mysterious notes are showing up) as well as the familiar harmonic distortion sweeps.
No DIYer in your neighbourhood that can lend a hand?
Damping whether a dishwasher or a speaker cab usually is simple. Essentially takes just (a) stiffening and/or (b) a glue and a gooky/heavy element. Gluing a brick using construction cement might be appropriate to your panel.
Ben
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Mine is flat from 65hz down to 20hz then whatever
Two 15" in a manifold. Processing done using Acer Revo mini itx pc. Running Ubuntu 16.10 with Jack Audio Connection Kit in Low Latency real time and JACK-RACK from Steve Harris plugins and Multi Parametric EQ doing DSP
My kitchen door is mostly open, and I'm not fussed. Hoping to disguise lounge side as a fireplace. In my English semi detached, its a silent chuckle when my neighbor asks why his window shakes!
Mike
Two 15" in a manifold. Processing done using Acer Revo mini itx pc. Running Ubuntu 16.10 with Jack Audio Connection Kit in Low Latency real time and JACK-RACK from Steve Harris plugins and Multi Parametric EQ doing DSP
My kitchen door is mostly open, and I'm not fussed. Hoping to disguise lounge side as a fireplace. In my English semi detached, its a silent chuckle when my neighbor asks why his window shakes!
Mike
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I've found it can be quite interesting what does and doesn't work. I braced the inside of my U frame subs with battens and shelves and that worked very effectively at raising the resonant frequency good and high. I then found at very low frequencies the whole cabinet was "twisting", I tried adding mass top and bottom but it made no difference. I had some old sorthabane shoe insoles and cut them up and placed them underneath, problem solved.
The plasterboard studding wall is between the door frame and a stone wall and is only about 16" wide, so making it solid would be very simple. First off though I'll try damping it with something more pliant, see if that does the trick.
My kitchen door is mostly open, and I'm not fussed. Hoping to disguise lounge side as a fireplace. In my English semi detached, its a silent chuckle when my neighbor asks why his window shakes!
Mike
Ah, thanks Mike, that's encouraging! I figure it has more in common with a large OB than a closed box. I would be happy with that as I find the pressure of a closed box in my smallish room uncomfortable on my ears, if that makes sense.
If you built a box like my newly built one, and use 4 woofers instead of two (I intentionally left room for 2 more to be symmetrically placed on there if I needed more power) , and give them twice the power I'm giving mine, I'm sure all of that surface area will give you whatever you are looking for. My input power is limited by the 35v caps I chose to use. I knew I could have gone with 50v or more, but I didn't. With the ports uncovered, max power only gets around 1/4 - 1/3 of Xmax, cover the ports and it doubles, (just for comparison: put the woofers in free air at the same power level and Xmax will be reached). So, my design could probably maintain high volume at likely even 4hz with the right amplifier. I'm using super cheap $22 MCM Electronics 15" woofers with I think they say a 6mm overhang Xmax, 200Wrms 400W peak, although at very low frequencies it takes a fraction of that power to reach Xmax.
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You post in order to get everybody's advice and then give back nothing in return.
I learn just about nothing from all the construction posts where somebody does this or that and swears their accomplishment is truly amazing.
There's not a soul at DIYaudio who couldn't produce useful before and after comparison measurements for zero dollars.
Ben
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Just be careful when bridging amps. A bridged amp will "see" an 8 ohm load as 4 ohms, 4 ohms as 2 etc. A slightly leaky IB is not that big beal IMO as long as things aren't vibrating. There's no back pressure like in a box.
Hi, it's worked out very well, no vibration now. Do you have IB? The main reason I chose bridged was that I already had a couple of speaker wires embedded in the wall to that corner and wanted to connect the speakers and amps most efficiently. I've wired the speakers in series so the amps are still seeing 8 ohms each driven from the balanced output of an equaliser. It is supplementing the U frames very well for the bottom octave and still without the pressurisation which I personally find uncomfortable
Correct. There are only a few members here who have I.B. subs. I highly recommend the manifold mounting technique (opposed force-cancelling).
Otherwise the wall vibrations are a REAL problem.
Please, if you can, show a sketch of the layout. Your door will probably rattle on some bass notes, depending upon the volume intensity.
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