That was so stupid of me! The poster was Matt, not Joe. Too much Vicodin!
Someone will always fail at any suggestion.
Structural excitement should always be small, otherwise all bets are off.
Yea, I don't see this as likely. Could happen I suppose, but it would be rare.
Hi MATT!
My money is on this:
I setup my LFs in the steady state. In that case phase doesn't really have any meaning, since it is tied to the frequency response via being minimum phase. Hence, get the amplitude right and the phase will be right. A phase delay of 90 degrees at 50 Hz is about 1 ms. we can't resolve that kind of phase at those frequencies.
My money is on this:
I setup my LFs in the steady state. In that case phase doesn't really have any meaning, since it is tied to the frequency response via being minimum phase. Hence, get the amplitude right and the phase will be right. A phase delay of 90 degrees at 50 Hz is about 1 ms. we can't resolve that kind of phase at those frequencies.
Alright Alright, I guess that makes perfect sense and I should just leave those poor guys alone who use frequency optimization to get the subs aligned.
Oh and yes, my name IS Matt. I can't be that upset, for some reason half of the federal employees I consult for call me Mike. My name isn't Mike, nobody ever introduced me as Mike, the only thing that name has in common is the number of letters and first letter, yet it persists. My middle name is Joe I guess, we can go with that if you like!
As for your agreement that people just don't want to believe, I've seen some really strong evidence of that bias too. I saw someone who took ONE measurement at ONE location after connecting four subs and doing a little bit of optimization. There was a raised area in the response. Not even a rough or peaky response, just that instead of being flat, it had a very broad bump around 80hz. They showed that as proof the method didn't work. I took one look and thought, that looks like a really easy bump to eq out (and in fact, some adjustments of the phase and volume might have helped, who knows, it was very low Q). To me it provided direct evidence of just how well it worked. My guess is if they bothered to take 4 or 5 more measurements at other locations, they would see just how much smoother the bass is at other frequencies.
As for your agreement that people just don't want to believe, I've seen some really strong evidence of that bias too. I saw someone who took ONE measurement at ONE location after connecting four subs and doing a little bit of optimization. There was a raised area in the response. Not even a rough or peaky response, just that instead of being flat, it had a very broad bump around 80hz. They showed that as proof the method didn't work. I took one look and thought, that looks like a really easy bump to eq out (and in fact, some adjustments of the phase and volume might have helped, who knows, it was very low Q). To me it provided direct evidence of just how well it worked. My guess is if they bothered to take 4 or 5 more measurements at other locations, they would see just how much smoother the bass is at other frequencies.
Hello Mr. Geddes,
can be multisub application used for the control room (studio usage)?
Are QDR diffusers allowed (placed on the rear wall for "dead end - live end" type of control room) in multisub situation or is better to avoid them? I have in mind a diffuser which operates between 185 Hz. – 3,450 Hz.
PS: Really interesting discussion here and thanks for all your effors with multisub science. I really appreciate it!
Old thread but a good one for sure. I'm not Dr. Geddes, but I'll give my position: LEDE shouldn't be a problem with multisub, different bandwidths for the most part. In a dedicated studio space, multiple infinite baffle (in-wall/venting to another space) sub locations seems like a really solid way to go about it. A bunch of scattered push-pull manifolds around the room will distribute the bass quite well. The more locations, the less EQ required.
I'm going to be doing 3 dual-12" manifolds along one wall of my room, unfortunately that's the only space available due to my basement layout, or I'd put a couple in-ceiling, and a couple per-wall at varying heights.
Greetings,
thank you for your reply. I really apprecite it. So it´s woth a try...
Anyway is Mr. Geddes still around? GedLee official website says he´s retired.
Feel free and keep me in loop with your own multisub project. Thanks in advance
He's been retired for some years but still participates. Certainly multisub is the best solution for real-world spaces IMO, I've tried a few different configurations over the years and my rig is generally appreciated by listeners for the bass and sense of spaciousness, which is highly correlated to good bass. Frequency extremes tend to help each other, there's an old rule of thumb that if your highs are rolled off your lows should be too, and vice versa, if you're going to have high top-end bandwidth/power response, you need a good sub(s) to balance it.
I recently placed a second sub in my living room. This was for no other reason than I bought two empty Lima enclosures at a very low price and had a pair of jbl gto804 drivers.
The drivers are less efficient than the single 12" 96L unit I was using, so some adjustment to the gain was needed. The headroom is probably less, but the effect of two subs is very good.
The quiet spot at one end of the couch has gone and the low end is now noticeable in that it does not wipe out in certain spots or frequencies. Film effects still go boom! But bass in music doesn't now Then I spotted this thread.........
The drivers are less efficient than the single 12" 96L unit I was using, so some adjustment to the gain was needed. The headroom is probably less, but the effect of two subs is very good.
The quiet spot at one end of the couch has gone and the low end is now noticeable in that it does not wipe out in certain spots or frequencies. Film effects still go boom! But bass in music doesn't now
Then I spotted this thread.........
Hello guys.
As I mentioned above, I´m bulding DIY mixing studio (control room) and would like to use multisub solution to tame room modes.
I have one question. Is possible to close the port of the originally ported subs to achieve faster sub response? I´m planning to buy few Presonus T10 active subs. Could sealing the ports make any damage to the drivers?
Thanks.
As I mentioned above, I´m bulding DIY mixing studio (control room) and would like to use multisub solution to tame room modes.
I have one question. Is possible to close the port of the originally ported subs to achieve faster sub response? I´m planning to buy few Presonus T10 active subs. Could sealing the ports make any damage to the drivers?
Thanks.
You may get a few replies to this! Generally, for the same driver a vented enclosure will be larger than that required for a sealed enclosure. My experience with an 8" driver in a sealed box designed for a 10" resulted in the coil smacking the metalwork. I thought someone had thrown a tennis ball at the car. Nope.
Are the T10s designed to be switchable vented/sealed? If not I would advise against it.
PS there are some really mixed reviews on that sub. Try before buy?
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To me, the enclosure design for a subwoofer is irrelevant. That's because if you are doing multiple subs then you really need to have individual control of each sub. So I would just seal off the port. I've done this dozens of times, to the point that I only build closed box and never even consider the box size. With DSP control none of that tuning stuff matters.
Hi Earl,
Since a low ported enclosure gives the bottom octave almost free, so a 10" sealed could be replaced by 8" ported. Boxes could get smaller especially for rooms that have no modes near the box tuning frequency. So all subs are in phase there and thus share the SPL. If any sub needs flipping the phase (as needed by multi sub procedure ) then that sub can be made sealed by stuffing the port, is my understanding correct? The others can still remain ported and benefit in the lowest octave.
Thanks,
WA
Hello. Thank you for your reply.
Originally Presonus T10 is ported design, it´s not mentioned in the user manual to be switchable vented/sealed. I´m sure Audiokinesis´s systems The Swarm and Debra are switchable, I´ve talked to Mr. Duke and his colleague from Europe.
I´ve read a lot of positive user reviews for those subs considering what they offer in that price range. I´m not sure I there will be any possibility to try before buy (Prices in Slovenia are high and they usually don´t have a stock of multiple pieces, so buying from abroad is my only option), I guess I´ll be forced to sell the if they will not show results I would like to achieve.
Hello Dr. Geddes,
thank you for your response. I´ve wrote you a message on Facebook about a month or two ago but I guess you´re not using it so often anymore.
I´m planning to control the subs with DBX DriveRack 260, allowing me full control over each and every sub/main speakers. Do you find MSO app (made by Andy C) useful for finding the right settings for the DSP?
Thanks a lot!
I also, like Gedlee, never put vents on my dsp-ed subs. The sealed ones have a tighter bass. Ports give this flabby bottom and you cannot dsp it away. Easy to test when closing the port with a plumbing plug ( the type where the hard plastic thread screws into the rubber seal).
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