Warpdrv's Dual Opposed 18" LMS's..... "The XLerators" - Page 8

Gentleman,

"Tonight's the night."

-Dexter-

I am looking forward to 4 p.m. today...although I might be def by the time I head home.

At first I thought you were talking about the season premiere of Dexter. I got all excited and hoped I still have it set-up to record on the DVR as I won't be at home tonight.

I hope your not planning on killing people with massive bass

"Curious, any good work I can read on sealed box heating."

we explored it a little bit in this thread:
http://www.avsforum.com/avs-vb/showthread.php?t=1111204

Haha, sorry about that. We don't have to wait much longer, though; the premier is september 26th. I can't wait!

Let's do this!

Here's what we came up with after a good amount of work:



The room provides no room gain down low, at least not below 25Hz, and certainly not enough to boost the ULF's. We ended up with one of the subwoofers behind the TV, and the rest remained where they were. If anyone has any ideas on how to boost between 20-15Hz, we're all ears. I just don't know if it will work in a room this size.

Thanks to Patrick for his hospitality (as always) and to his awesome "sugar mama" for the wonderful dinner.

Try to bring down the >20hz stuff to get that more in line with your target curve. Can't do too much boosting below 20hz with a DCX.

A Marchand Bassis would be great too.

Dumb question, but at 76db, shouldn't those subs still be able to deliver more than that below 20hz? I would have thought that kind of roll-off would have been seen higher than 20hz at that low of a level, even in that size of a room no?

Is it possible to run sweeps at higher and lower levels than 76db to see what happens?

Well geez man, instead of spending all that coin on more subs and amps, put some some cheap drywall!

LOL - hilarious!

By the way, I like the quote in your sig. Dunlavy was a Pioneer IMO.

Bingo. You and I are no dummies, and we realize the room is the Achilles heal, but we have to do what we can. I think we succeeded for sure, especially considering what we're working against (the room).

Warp, the mic2200 might be a nice start if you wanna try boosting the <20hz area. It's a quarter the price of the Bassis but that's a variable L/T too so it should be more expensive. I'm going to get one for myself once I go sealed but I've thought about picking the 2200 up and trying it as well. Maybe you can find out if it works well for that.

Because the MIC2200 does not behave as labeled, I think you'll have the best luck if you set up a calibration loop for REW and then insert the MIC2200.

There are some sweeps in my photobucket
http://s111.photobucket.com/albums/n...e/AVS/MIC2200/

i'm not sure how the dcx treats filters that extend past 20hz. if you want to boost below 20hz, try a "high shelf" filter with a *negative* gain.

example:
frequency: 20hz, slope: 12db/octave, gain: -10db, type: high shelving

this should give a pretty close approximation to an LT given your frequency response.

perhaps something to experiment with.

http://www.avsforum.com/avs-vb/showt...ghlight=bassis

That's my thread on using the Bassis with my LMS and Maelstrom subs. I had a graph like you, and you can see the final product post-Bassis on that thread.

Yeah, saw it in an interview of his (someone linked to it on here). Really resonated. Somewhat humorous when you read so many people stating "who cares about measurements it's about how it sounds".

While I love SQ and understand even a flat measuring speaker may not sound great, as Dunlavy stated quite nicely, "if you think about it" if the speaker doesn't measure well in the first place, well, it can't sound good either.

Also reminds me of all the arguments about D6500 and HD709 specs for video ... if your TV isn't measuring well ....

I suspect you'll be fine when you begin to open 'er up. It's close, but you've got enough HP under the hood to extend down into the single digits.

This MIC2200, I searched that term and get a Behringer mic pre...

The ED eQ2 (2 band parametric) that I have is labeled to eq down to 10hz. ..... $50/channel msrp. The mono Bassis is resonable also, and I'm sure it's got a much more inherently extended response.

George Massenburg Labs (he invented parametric eq) make THE eq for mastering, it's bottom 2 bands dip to 15hz, so there you go. Also, it's on sale for 10% off @ Sweetwater, 10k down to 9k,...


When it's said and done, you'll have IB capabilities...(running for flame suit) just kidding, this project is epic.

"This MIC2200, I searched that term and get a Behringer mic pre..."

yeah, i was desufnuc (<-) too when i first looked at it.

it has two parametric eq's and can high pass 2nd order down to 10hz. i think it can increase home audio to pro audio voltage as well, but i'm not sure about that last one.

for 99 bucks, it has a lot going for it.

Hi Warp,

Sounds like fun at the Warp Drive Warehouse.

Beginning with the basics, a shelf filter will boost as low as the FR of the unit providing the shelf filter. If the unit rolls off at 10Hz, so will the shelf boost.

Reason #1 to use the Bassis; it's flat to 2Hz.

Step 1) Place the subs all equidistant to the LP. Cancellation may result down low if the subs are throwing long waves from different distances to the LP. To check this thought, set the measurement mic at a point that's equidistant from all 3 subs and check that measurement against what you have already done.
Step 2) Get a close mic FR of all 3 subs and average the traces.
Step 3) Get a FR at the LP with no EQ.
Step 4) Adjust phase/distance to get the best FR without EQ.
Step 5) Set the Qs and Fs (F3) from the close mic trace on the Bassis.
Step 6) Set the Boost on the Bassis from the close-mic vs LP traces.
Step 7) Adjust Qb to fine tune the FR at the LP.

A 'modded' Bassis is any Bassis that's set up to your specs vs the stock Bassis. Here's an example of one that has fixed Fs and Qs, 3-position Boost selection, 2-position Qb selection, polarity reverse, 12-position phase adjustment, every 15 degrees, affecting only one of 2 (balanced XLR) outputs to reconcile time between dual sub placements and selectable 'none', 10Hz or 18Hz 2nd order HP filters for vinyl and other scenarios. This is optimal for operating my new Blackbird systems:



I only have the graphic as Phil is working on it now. I'm positive that a stock mono Bassis will easily tame your mammoth system. As I said, it's flat to 2Hz, so whatever boost setting you select will affect FR to 2Hz, and it has infinitely selectable boost to 24dB (256 times!!!). They are stupid accurate and can be used in more ways than the controls suggest.

I'm not a big fan of the idea that sympathetic vibration of a floor sucks out everything below 20Hz. That's just not a likely scenario.

Although you haven't mentioned the specifics of the measurement hardware, I'm certain that you'll have to raise the sweep level to get above the noise floor of the mic/pre/interface to see any reliable data below 20Hz.

I can lend you a Bassis if you think that might be something you'd like to try. I'm sure I have an idle one around here somewhere.

Bosso

Bosso

A mono Bassis is around $400.

Question 3 answers question 2. Just put the Bassis 1st in line. After it's tweaked, apply PEQ. If you're EQ'ing the 3 subs each differently, you'll need to double Y the output of the Bassis, but maybe you could ask Phil to build one with 3 XLR outs.

IMO, it's better to EQ a single signal to the 3 amps vs separate EQ for each sub, which is quite the nightmare in my experience.

Bosso

warp, if you already have a dcx...

did you catch post 230?

a 12db/oct shelf filter is pretty much an LT for all practicle purposes.