# Gotta Lotta stuff, how to use it all? Let's see!



## SkiBum (Feb 16, 2011)

Hello all, I am in the process of incorporating several different pieces of equipment. Here is what I have:

Main AVR
Denon 4311

EQing station:
DCX2496
SMS-1

Subs:
Two RE XXX18's sealed on LG14k in stereo under the L/R speakers
Two JBL 4648A's on EPX4000 (currently only have one hooked up until I can get the second dropped off to my house, could take a few weeks, up to a month) in between the L/R speakers and the RE's.

My objective is to incorporate the two subs by using the RE's for the 5-40hz material by putting a 4th order lowpass at 40hz and letting them run wide open below that, and using the 4648A's from 40hz (2nd order HPF combined with its natural rolloff at that tuning freq for a 4th order HP basically) up to 120hz where they will cross to my mains. all the subs will be run via the DCX for filtering purposes, but connecting the devices properly is where I am atm. Since I have xt32 on the denon, I believe I have some connection issues to iron out before I move on, being able to eq two different subs causes a kink. the RE's are stereo off the amp, but just being run with a mono signal TO the amp (still need two cords from the DCX, one for each channel). The 4648A's will be input 2 on the DCX and will have a single cable running from the DCX to the epx4000 run in parallel bridged mode. Here are the options ive considered, tell me which you think is most appropriate:

1) run the RE's from one sub out to the DCX and the 4648A's from the other sub out. next step would be to set the delays of the two seperate sub systems. With them set this way I would assume xt32 would set it's own delays for each system properly since each 'type" of sub is on a different channel. SO in this case: eq the subs before audyssey, get severel filters in there to acheive flat response and run HP and LP filters etc, then let xt32 set the delays of each system (or is this bad since the RE's are the furthest apart and therefore the most different distance-wise from the MLP which is off center by a few feet?)

2)same as above, but dont set the XO points, just eq both systems full range (well up to 120hz), then audyssey (still both seperately eq'd with xt32 and full range), then go back to DCX and set xo's and tweak response around the XO point of 40hz. This may be the way to do it IF xt32 sees one sub's response drop off at 40hz and the other's pick up same spot and tries to do some crazy eqing below that point to compensate, even though i wouldnt WANT that sub to be doing anything down there. Im pretty sure that with the XO filters set in place, that audyssey sees the rolloff as "on-purpose" and doesnt eq if the rolloff is steep enough. 

3) make it so the LEFT XXX and left 4648a is off one sub out from the 4311 and the right two are from the other, obviously have to do the 4648's in stereo mode from the epx at this point, but no big deal there. I would then set the left two subs delay and xo points and all from the DCX before anything else and then do the same for the right 4648 and XXX18. Doing it this way would make audyssey "see" the left pair of subs as ONE sub, and the right pair as the other. This IMO might be a better way to set the OVERALL delay of the system since I could do the initial delay settings between the two different types of subs using the DCX, then audyssey could adjust the OVERALL delay of the combo for the left AND right systems. Have I lost anyone yet?

With all that said, I dont know if the third option is even that critical, since the furthest sub (left xxx) is only about a 3 foot difference from the closest sub (would be the right 4648, but until the second 4648a arrives, the right XXX is actually the closest) 

I dont think ive left anything out, and my initial plan was option 1 until i got to thinking about whether audyssey wouldnt like seeing one sub system sloping off at 40hz, and the other picking up there and going to the top of the range, where that immediately made me think it would do things I didnt want it to do.

Consider the top options and please weigh in!! 

Thanks


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## phreak (Aug 16, 2010)

My thought would be to do connections as per (1). Measure with REW. Run Audyssey. Measure with REW. This will give a clearer picture of how your subs interact with each other and the room. Now you can determine if there is an ideal crossover location, or of there should be some overlap between the 2 types of sub. Turn Audy off, set crossovers, measure with REW. Re-run Audyssey, measure with REW. Now you have a clearer picture of what you need to do for EQ. 
Incidentally, that is a whole lot of sub. What is your room size?


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## SkiBum (Feb 16, 2011)

The most overlap I would be ok with would be to cross the XXX's at 50hz and keep the 4648's at 40. The main reason I want to cross at 40hz is that is the port tune for the 4648's is 40hz and that is also where the XXX18's get very inefficient from there up. Those things are bass pumps, and do AWESOME down low, they just suck a whole lot of amp power up top due to their high moving mass. the impedance curve of the XXX's basically show that crossing them between 30-50hz would be perfect to get all I can out of them down low and let the pair of 4648a's just kill the midbass from there on up.


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## SkiBum (Feb 16, 2011)

phreak said:


> My thought would be to do connections as per (1). Measure with REW. Run Audyssey. Measure with REW. This will give a clearer picture of how your subs interact with each other and the room. Now you can determine if there is an ideal crossover location, or of there should be some overlap between the 2 types of sub. Turn Audy off, set crossovers, measure with REW. Re-run Audyssey, measure with REW. Now you have a clearer picture of what you need to do for EQ.
> Incidentally, that is a whole lot of sub. What is your room size?


room is 11( screenwall)x29 with a 7.5' acoustic tile ceiling. small corridor to an exterior door in the rear about 5x15 and a staircase to the main floor, so not HUGE, but certainly not that small. Ive considered for a while sealing off the hall to the exterior door, it wouldntbe that hard really, but kinda hard to weight the benefits when you really cant test it until its done


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