# Dual sub woofer question?? Please help



## alexa7x23 (Feb 21, 2012)

Okay let's keep this simple..I have two subs(def tech super cube 2000s) at two different positions of my home theater, one at front wall and one at rear wall..okay my problem is both of these subs don't have phase controls..so I set the front sub at 75db with the back sub off..then I do the opposite with the back sub..my question is once I check the db reading again with my SPL meter with both my subs "ON" it reads 63db..does this mean there out of phase..and if they are, is there such things as external phase controls for subs??


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## dduval (Feb 26, 2012)

Yes, I would say there is a phase issue. Google MiniDsp, for a little over $100.00 you can set the phase for each sub as well as eq, time decay, etc. You have to buy plugins and you program it with a laptop or pc. It's a handy little gadget and give you plenty of user control options...FYI


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## alexa7x23 (Feb 21, 2012)

Yah my only problem is I already bought two dsp1124..haha..not sure what to do now..


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## dduval (Feb 26, 2012)

Hmmm, if the dsp1124 does not do phase (which I don't think it does), I would sell them and get the minidsp.
I think you may be happier with it vs the dsp1124. Just my 2 cents, but I'm sure you could sell the dsp1124's pretty quickly if that's the route you want to go...hope it works out!


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## alexa7x23 (Feb 21, 2012)

Thankx much!!! I think I will..just which one would u recommend for a 2 subwoofer setup...and another question sorry..how many plugins can u have per miniDSP??


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## dduval (Feb 26, 2012)

I have 2 subs as well and I plan on getting the 2x4 mini revB and the 4 way advance plugin. FYI
Oh, and you can have unlimited plugins as far as I know...


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## alexa7x23 (Feb 21, 2012)

Thankx you've been plenty help..looked like I'm going to be returning my dsp1124 for one of those..haha


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## alexa7x23 (Feb 21, 2012)

looks like the place where i bought the processors from dont have refunds on live audio gear.. so im planning to upgrade my reciever soon... you wouldnt happen to know of any that are 7.2 channels that have individual controls for each subwoofer channel would you?? so i can eliminate this dang phase issue of mine...haha???????

thankx
Alex


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## dduval (Feb 26, 2012)

If you plan on upgrading your avr, then I would go with Onkyo or Denon that has audyssey Multi XT32. XT32 can eq 2 subs but it will not correct phase issues.

The other solution would be to find a used Velodyne SMS-1, should be able to pick one up for around $300.00

Google it. It will solve all of your problems. I used to have one, before I got XT32, and it's a really nice pc of equipment and should serve you well. Not only does it have phase adjustment, it will eq your subs as well. However, you cannot adjust phase on "each" sub, only phase adjustment as a pair combined. In addition, try moving your sub(s) around your room to correct phase issues as well.

Also, a new avr with XT32 will run you some serious dollars, I recently seen a refurbished Onkyo NR3008 (what I have) for $1499.00 @ accessories4less.com. They go up in price from there.

Bang for the buck and ease of use, probably the SMS-1


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## tesseract (Aug 9, 2010)

Check this out. Trinnov processor alone is around $13,000!

http://www.accessories4less.com/mak...urround-Receiver-w/Dolby-TrueHD-DTS-HD/1.html
_
"The Optimizer can raise or lower the sonic location of even a single speaker. With Trinnov and Newcastle you can put the loudspeakers where they fit, use the Optimizer to overcome the shortcomings of speaker placement, speaker response and room interaction and still achieve virtually perfect imaging. An interesting byproduct of Trinnov's accurate 3-dimensional measurements are its ability to auto-correct and auto-assign both speaker phasing and channel assignment.
With Trinnov and Newcastle, even speakers connected out-of-phase and to the wrong channel will be properly recognized, corrected and assigned."_


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## bambino (Feb 21, 2010)

Is it possible to move both subs to the same side of the room?


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## alexa7x23 (Feb 21, 2012)

Yes..but what I've head you getter better cinematic effect having one on the front wall and one on the rear wall..not really sure thgh ..haha


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## bambino (Feb 21, 2010)

alexa7x23 said:


> Yes..but what I've head you getter better cinematic effect having one on the front wall and one on the rear wall..not really sure thgh ..haha


I wouldn't worry about the cinematic effect so much as to what you think sounds best.:T I personally would move the subs around to different locations of the room to find out where the "sweet spot" is for both subs,. The more subs the better in my book but just may take some work to get it right.


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## The_Beerswine (Apr 23, 2012)

I'm just gonna throw my 2 cents in here when running multi subs there's a lot of pro's and con's.
The chances are why there was a drop in spl when there was 2 subs in the room was because of cancelation due to Phase inversion . The wave length of a bass tone can extend far beyond 30' , that’s why the bass sounds deeper outside of the room in most cases.
So you can imagine the bass notes coming from 2 different sources adjacent from each other depending on the freq will have some spots where it’s reinforced and nulls in other areas.
Thats why they say to run a single sub when it comes to those low freqs so they don’t infringe each other or at least group em together.
If it’s the LFE yer lookin for you could try generating lets say a 25hz tone and move them around the room or change the phasing until the optimal effect is reached in the listening zone, at least that will give you the punch...If you can get it to work.
In the past I used to just put them behind the couch and filter around 40-60hz to keep the boom to a minimum. 
Now with all these tactile transducers coming out on the market I have a set of them in the couch and dialled back the subs a bit, since most of the so called subs under a $1000 don’t do much work below 15hz anyways because of porting ect....
Guarantee you gonna have some fun tryin to make it work...


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## robbo266317 (Sep 22, 2008)

The_Beerswine said:


> I'm just gonna throw my 2 cents in here when running multi subs there's a lot of pro's and con's.
> The chances are why there was a drop in spl when there was 2 subs in the room was because of cancelation due to Phase inversion . The wave length of a bass tone can extend far beyond 30' , that’s why the bass sounds deeper outside of the room in most cases.
> So you can imagine the bass notes coming from 2 different sources adjacent from each other depending on the freq will have some spots where it’s reinforced and nulls in other areas.
> Thats why they say to run a single sub when it comes to those low freqs so they don’t infringe each other or at least group em together.
> ...


This is why most subs have phase controls which can be adjusted to get them in sync using sound analysis software, eg REW. lddude:


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## The_Beerswine (Apr 23, 2012)

Ya I know but the phasing will only ocurr in a select group of frequency's, that's why I picked 25hz.
After you climb up an octave or 2 it becomes irrelevant or not so noticeable.
25hz is a nice deep feeling bass without the boom, much like a 40-60hz bass which is EZ to reproduce.
I have some 15" Velodines in each corner and if I change one of them over 45 degrees i get an awesome low effect that starts to rattle the windows in this old house with little input but the 40-60hz bass drops off a bit. If I leave them both at 0 deg. there's more of a 40hz boost which isn't bad but I like it deeper and more vibrant. But I found that 2 of those Tactile Transducers with a 3.5lb slug in each really puts it to ya all the way below 10hz, now that's subsonic that you can FEEL....


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## Timoteo (Jan 7, 2012)

My Yamaha RX-A2000 has individual phase settings for each of the dual sub outs. Also includes individual parametric EQ adjustments for each sub AND each speaker. Unbelievable flexability!! Now I don't need an external DSP. I have been able to get my system very flat with placement, sub settings & the RX-A2000. In my eyes the Aventage line of AVRs is arguably the best line of receivers IMO. I have listened to my speakers with both the Audyssey XT32 & with YPAO, both sounded great but YPAO had more user control.


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## bambino (Feb 21, 2010)

Not to sound arrogant i would try my idea and play with the controls on the amp. you never know what you come up with till you try.:T Also all of the above posters have great answers too.


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## zheka (Jun 11, 2010)

i'd also try changing distance settings for the subs in AVR while measuring SPL/frequency response. normally this technique is used for correcting frequency response at the crossover point but I suspect it may affect how the subs interact with each other too.

do you use REW at all? I find that using RTA feature in REW is much better than pure SPL measurements for the sub crawl task.


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