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Discussion Starter · #1 ·
Hello Everyone,


So I have been reading some old and new threads about getting better bass... mid bass to be exact.


Using this as a reference - http://www.avsforum.com/t/1281387/what-is-mid-bass-range#post_19296365


I have been thinking about DIY solutions for increasing/supplement my mid to upper bass - ideally the 50-250Hz range. See about getting more of that 'punch' everyone talks about.

I am pretty happy with sub 50Hz although I do plan on getting one or two more 18's as I am still not getting a WOW effect on the Irene or HTTYD scenes... (problem for another day)


Background

Got a 9.x setup.

AVR is only powering front L+R

2x external amps powering remaining speakers.

3x Subs - Paradigm Sub15, DIY 230L DO Dayton RSS460-18, DIY DO LMS-R 15 (DIY Clone powered)


Current Xover on AVR

60 for Front and Rear (I have full towers)

80 for the rest


I don't have a lot of space left and would ideally like to locate the units next to the respective front L/R speakers. 17L net should be an easy fit and the Inuke DSP can easily handle the HPF and LPF.

Did some research and thinking and came up with this idea....




The Dayton 10" seems to be the perfect fit but would like some input on weather it will provide a substantial improvement.





My concerns


How directional is the 50-250Hz range as some threads mention locally the units as close at possible to the MLP?


Any other suggestions that I should possibly look at?
 

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As long as you'll have full ability to measure and time align the midbass modules, to both the mains and the subs, this would likely offer significant improvement.


In the meantime, some simple experimentation with your current subs, located up near your mains ... and carefully adjusted and blended with regard to time alignment
 

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Cont.

Would be an interesting experiment.


Also, be mindful bass trapping and overall room decay measurements are a key components to tight, visceral, punchy bass.
 

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my guess is your problem is simply not enough rig for the gig. your mid-bass is a low sensitivity 8" driver running off an avr, so you are probably 20db short of target. an ultimax 10" probably isn't the best choice for a mid-bass unit. a pair of high sensitivity 12's or a 15 or even an 18 would be a much better option, powered with an external amp even better. room modes and decay are something to consider as well. not that the ultimax 10" couldn't do it, just that you'd need more than 1 or 2.
 

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Discussion Starter · #5 ·
My AVR with only two channels actually performs pretty good all things considered. It certainly can provide more power than the front speakers could handle.

I hooked up the front L/R to my Rotel 1575 and up to reference volume I doubt in a double blind I could tell the difference. At 91db they are pretty sensitive.

http://www.audioholics.com/av-receiver-reviews/rx-a3000/rx-a3000-measurements-cont


I actually have some acoustic panels up but have 50 50mm high density sheets in the garage that are waiting to become new panels and corner super chunks.


FOH

- I just don't have the real estate to locate the subs on the front stage any where near the front L/R due to their size.


LTD

- Can you please recommend some high sensitivity 12'' that I should be looking at? I am pretty certain that 15'' will be just too big for my current space.


It is a little busy but here is my room layout. The front right actually has a wall mounted cabinet that run from the floor to about 2m. Need access to it so can't place anything in that corner.


I'm looking at placing two small towers each side of the TV cabinet. They would rest between the front L/R and the cabinet essentially.

 

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there are many that would work. kind of depends on how much power you have, how much money you have, and how much spl you want.


ae speakers td12h would be good. a pair in 2.75 cf tuned to 43hz and powered with 1000 watts would get you about 125 db or so. you won't actually play it that loud, but having that is reserve means the lower spl won't be compressed, clipped, and/or distorted.




with a pair of those or similar per side and properly powered, the considerations that remain would include minimizing the room screwing up the bass from modes and/or reflection, and time alignment with the other gear.
 

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if that is too much money, a pair of eminence defnimax 12ho in 3 c.f. tuned to around 45hz gives quite similar frequency response across your range of interest.
 

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You guys mention time alignment. If i have a 5.2system how do I check/know if it's aligned properly now ? Rew measurements ?
 

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Chal, I would guess they are talking about something like Audyssey. My speakers are physically about 12 feet from my LP. My FrontL speaker is set by Audyssey to about 12, the FrontR to 12.5. The sub is in the corner another 2 ft away, and it is set to 25 feet. I assume that is all about time alignment.


I just realized, if you didn't have an AVR which could control all that, how would you time align your speakers if you just had a pre-amp and separate amplifiers? I'm still living in the 20th century with my thinking about audio.
 

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"You guys mention time alignment. If i have a 5.2system how do I check/know if it's aligned properly now ? Rew measurements ?"


if the subs are located next to the speakers, just flip the polarity on the speaker. adjust the distance setting until the suckout cancellation is maximized. then flip the polarity back. if you are adding a little bit of delay to the mains, you are probably on the right cycle. if you are adding something like 20 feet, then you are probably aligning the waves, but are one full cycle off.
 

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Quote:
Originally Posted by wvu80  /t/1525685/mid-bass-supplements#post_24567323


I just realized, if you didn't have an AVR which could control all that, how would you time align your speakers if you just had a pre-amp and separate amplifiers? I'm still living in the 20th century with my thinking about audio.
 

You would physically alter the distance between yourself and the speakers such that the waves arrived at the right time. You could theoretically also run some *really* long cables, but given the difference in the speed of light vs the speed of sound, moving the speakers would be way more effective.
 

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Quote:
Originally Posted by LTD02  /t/1525685/mid-bass-supplements#post_24568727


"You guys mention time alignment. If i have a 5.2system how do I check/know if it's aligned properly now ? Rew measurements ?"


if the subs are located next to the speakers, just flip the polarity on the speaker. adjust the distance setting until the suckout cancellation is maximized. then flip the polarity back. if you are adding a little bit of delay to the mains, you are probably on the right cycle. if you are adding something like 20 feet, then you are probably aligning the waves, but are one full cycle off.

ok so minions are my fronts right now on top of the martycubes. So I switch polarity on minions, adjust the distance from its current setting of 11' and go up. To hear this suckout cancellation I play pink noise and measure spl ? . Will sound spl go down as I increase the distance, then bottom out and then rise ? I want to set my mains so there at the bottom of that cycle ?


I read the article but pretty technical for me.


Sorry for off topic a bit of the thread but I am sure a few people are in the dark like me.
 

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11 feet sounds like a lot of delay. I'd start at about 2 feet and increase from there.


yes. run a sweep. increase the distance by a fraction each time. when the sound is perfectly out of phase, it will almost completely cancel out at the crossover frequency. then it will begin to rise again when more distance is added. the target is the worst null, which occurs at 180 degrees out of alignment or perfect "misalignment" if you will. once that is hit, flip the polarity on the mains back to normal, the suckout will completely disappear and the mains/subs will be perfectly aligned.
 

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Chalugadp, time/signal alignment ...


Yeah LTD02 is right, the null method, the article details, etc., good stuff.


Audyssey does this, and Audyssey is fantastic, however it is mistake prone often setting the time alignment (distance settings) somewhat less than ideal.


So, the savvy approach may include some manual setting of distances confirmed via measurements ... to achieve ideal coherent response through the region.


That said, once positive acoustic summation is established, and the above alignment is achieved, one can begin to meddle with settings, away from the theoretical ideal ... for even greater smoothing. One such example, by adjustment of low pass filtering of the subs, the acoustic blend is manipulated and additional smoothing can result.


It's an iterative process, often tedious, over and over, checking the result each time. All aspects are interdependent, so constant re-checking of the response is beneficial.
 

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Quote:
Originally Posted by LTD02  /t/1525685/mid-bass-supplements#post_24568964


11 feet sounds like a lot of delay. I'd start at about 2 feet and increase from there.


yes. run a sweep. increase the distance by a fraction each time. when the sound is perfectly out of phase, it will almost completely cancel out at the crossover frequency. then it will begin to rise again when more distance is added. the target is the worst null, which occurs at 180 degrees out of alignment or perfect "misalignment" if you will. once that is hit, flip the polarity on the mains back to normal, the suckout will completely disappear and the mains/subs will be perfectly aligned.

When I say 11' I am in the speaker distance setting of my umc200 preamp. Is speaker distance and delay the same thing. I always thought you just used a tape measure from the actual speaker to the lp. I will put the mains to 2' speaker distance and go from there.


FOH


you mentioned low pass filtering can improve smoothness of subs. Is that lowering the crossover point or changing the slope ?
 

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I don't like the OP's original idea.


Looking at the measurements at Stereocrock and the description of the construction, the Q900 is a very screwy design. Kal also describes it as a bit lightweight sounding and the measurements seem to back that up.


Here's what I'd do*.

Line out from the L/R to a DSP xover. High side to a power amp to the coax. Use the biwire terminals (finally something useful for them to do) to short out the LF driver.

Low side to a poweramp then to a TD12/15 sealed placed immediately adjacent to the Q900's. Cross at least LR4 and probably somewhere around 2-300Hz. EQ as necessary. Run to 60-80Hz then hand off to the subs. The bass management in the AVR should be sufficient for this.






* That's actually version 2. Version 1 would involve going 3 way active with the KEF coax and a TD15 sealed below it, all in one new cab. Steeply cross between the MF and HF and notch out the resonances in the MF driver and run it as a proper 3 way keeping any LF out of the MF driver, a must with a coax in my experience.
 

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that's awesome alpha niner, i actually wrote something very similar...then deleted it figuring it might not be taken the right way. :)
 

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"Is speaker distance and delay the same thing."


yeah...through the speed of sound.


1ms correlates to roughly 1 foot.


delay can be spec'd in either feet or milliseconds, but its the same thing.
 
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