That's a bit of a difference. Which program did you use to sim your design again? Some of them over-estimate the vent length required for a particular Fb. Note that the effective length will also be affected by nearby panels or walls too.
For my next build, I'll definitely use birch. This box took nearly a full sheet of 3/4" MDF. I'm actually surprised I got the whole box out of 1 sheet and had very little scrap left over, so aside from the other aspects of MDF, it's just stinkin' HEAVY!
I was able to EQ it mostly flat (+/- 2dB from 23Hz to xo) at 1m, but I'm thinking my next step is to treat the room a bit. Glen Fricker made a nice video about some DIY bass traps. I might have to run off to the Home Desperate store and rig me up some of those if I want to tune it much further.
Yeah, it is a bit of a difference. I used WinISD for my modeling, but I now understand folding a port affects the tuning a bit too even though I've calculated the volumetric space and taken that into my length considerations.
I was able to EQ it mostly flat (+/- 2dB from 23Hz to xo) at 1m, but I'm thinking my next step is to treat the room a bit. Glen Fricker made a nice video about some DIY bass traps. I might have to run off to the Home Desperate store and rig me up some of those if I want to tune it much further.
Yeah, it is a bit of a difference. I used WinISD for my modeling, but I now understand folding a port affects the tuning a bit too even though I've calculated the volumetric space and taken that into my length considerations.
I've been poking around on the youtubes and it seems a handful of second hand towels does a dang good job of sound absorption too (at least in the higher registers). A few of those and a couple bass traps might settle my room down quite nicely. I might have to visit my local thrift store this weekend.
You're welcome! The main thing in comparison with my belowed 18" is significantly lower sensitivity.
Your driver must have huge displacement (and coupled distortion) in a pursuit for 30 Hz with such low Sd.
For example, something like 18LW1400 or 18TBX100 would have 4 to 8 times more output at a given power with the same port tuning.
If we doesn't try to squeeze out all juices in pursuit of 30 Hz then 18" with 40 Hz tuning could provide additional 2-4 times.
In case of 15"-18" drivers i would prefer sealed box for minimizing delay and avoiding crumpled phase.
For powering could be used any IRS2092 based ebay/aliexpress amps.
I've calculate and display it in BassBox, not WinISD.
Method are well known - use REW with any calibrated mic and then use results for pre-correction of audio in Foobar with MathAudio Room EQ plugin.
Oh yeah. The Dayton 10HF has really low sensitivity, but pretty high xmax, which is ok for my application in my computer room as space is at a premium. I actually considered running a sealed 15 or 18 with eq instead, but the 10HF was cheaper, provided more of a challenge and learning opportunity as I'm still a speaker building n00b, and matched an amp I had laying around already. If I were doing a PA, or permanent install setup where space wasn't as much of an issue, it would be 15's and 18's all day long.
Your dog will notice the change right away.
Perhaps you should search for reliable information of absorption. Unlike a lot of acoustics, absorption estimation and geometry is fairly straightforward. (My favourite is Tectum substituted for drywall. Many many virtues.)
The best initial course of action is to keep your mic stationary where your head would be when listening, and try REW sweeps for a dozen locations for the sub. Good chance you will find a location that tempers the booming frequencies and boosts the weak frequencies.
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As it's easier to move a mike than a sub, he could put the subwoofer at the listening position and move the mic around and do measurements to find the best location. Then, just swap the subwoofer and the mike 🙂.
Umm, never occurred to me that you could put your listening chair on the ceiling, in a closet, etc. or wherever your mic says is best pickup location.
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It could be on the porcelain throne in the next room over too. Just don't want to overlook any possibilities.
BTW, if you read over my suggestion, you'd see you just made an idiot of yourself trying to be funny. In no way does my suggestion involve changing the listening position.
Have a read - New Sub – Reciprocity Test | LippAudio
Let's keep this, at least, vaguely on topic please. A little humor was added and enjoyed by some. No need to wee in anyone's cheerios if it wasn't your cup of tea.
The listener's chair, at ear height, is the point of reference (although, of course, another location or two can be tested too). That is why you want to put the mic right there and leave it there.
Then, you move the sub around. Even moving just a foot can have substantial differences in the freq response measured at the chair. I speak from experience.
It is of no importance what a mic could pick up in different locations around the room, on the wall, near the ceiling, two feet above the listener's head, or wherever. Each location will be drastically different.
If you move the mic around, you get different pickup patterns based on the room and the speakers and their complex interaction. So you leave the mic in the reference location. That's how science works.
Even if there are shortcomings to this method, at least you are working from a stable and repeatable benchmark setup. You can build your understanding from that point.
It is surprising how you can hit a synergetic compromise location by testing the sub in new locations.
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According to the reciprocity principle, you can swap the position of the mike and the subwoofer - the "effect" of the room on its response will remain the same. As it is a LOT easier to move a mike than a heavy subwoofer, it will be easier to find the best location for the subwoofer by locating the subwoofer at the listening position (including height, which might require putting it on a table to get it high enough) and measuring the response at different locations in the room with the mike. You can even use REW's RTA and pink noise from its generator and just move the mic around the room until the RTA shows the smoothest response. Then, just put the subwoofer where you measured that response. Just be prepared for some interesting locations to be found for the subwoofer. Last time I did this, the room in question was a recording engineer's room, and the mic showed that the best location for the subwoofer was about half-way up one of the side walls.... 🙂
... and even when the Steele method is complete and the sub is hanging on the wall or ceiling or where the sofa used to be or in the middle of the carpet, you still have no idea what so ever what the freq response at the listener's seat will be like.
I leave it to readers to picture in their mind which approach makes sense in their living room.
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I leave it to readers to picture in their mind which approach makes sense in their living room.
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The approach I suggested is also recommended by Genelec. I suspect that they know what they're talking about 😉.
Multichannel Audio | Genelec.com
Look under "Where is the best place to position the subwoofer in a room?"
I've heard what Brian suggests a number of times, but, how can it be so? Moving the sub is going to change the reflections and the points at which the nulls and peaks are distributed around the room
Yup. And the same thing would happen if you move the listening position 🙂.
The reciprocity principle basically states that you can swap the listening position and the sub in the room and the effect of the room on the response will be the same.
A google search on "acoustics reciprocity principle" should bring up a ton of links on the subject.
TLDR. But, punch doesn't come from the subwoofer. It comes from the mid/high cabinets. I know from experience that it's very tempting to set the sub gain much too high, which results in "flabby" bass and lack of punch. Use an SPL meter or something to set the gains properly.
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