Topic: using two subwoofers

[-sniper-]

my AV/R has only one sub-out. is it possible for me to use two subwoofers for my system with this limitation at hand? i'm thinking of using a splitter but i'm wary of two things:

first, the sound quality
second, if my receiver can handle two subs at the same time

i'd appreciate your comments.

thanks so much! 

[blued888]

Are the two subs identical? It would be pretty hard to calibrate things if they are not the same model.

The receiver will definitely be able to handle having two subwoofers. Splitting the sub-out only splits the signal. The signal will be sent to 2 subwoofers instead of just 1. You shouldn't have any issue about the receiver "handling" the subwoofers at the same time because the subwoofers are self-powered (they have their own amplifier).

[-sniper-]

thanks.

the two subs are not identical. that's another issue i was wary of. i just forget to state it. thanks for reminding me. 

[blued888]

You can try it out just to see how you like the sound. The splitter is probably just P30 to P50. Thing is, if you end up liking the dual sub setup, you might end up selling the smaller sub and getting one identical to the superior one.

[-sniper-]

Thing is, if you end up liking the dual sub setup, you might end up selling the smaller sub and getting one identical to the superior one.

yun lang.   

but the dual sub set-up will just be a temporary thing (i hope)...the second sub is really intended for my separate audio set-up. nagkataon lang unang dumating ung sub-woofer.  i'm still hunting for an amp.

[streetsmart]

1. Use a splitter.

2. Locate the amps at the same distance from the listening position.

3. Set the level of each sub separately to the same SPL reading, by plugging each one individually and running the test tones of the AVR while taking readings with an SPL meter, and then manipulating the volume level at the rear of each sub.

4. Set the level of the 2 subs when they are connected, using the test tones of the AVR and manipulating the level control at the AVR, so that the SPL reading is the same as the other speakers.

This should be the most basic. At least, you get the same volume from each and the sound arrives to your ears at the same time cuz the subs are equidistant from the listening position.

If your AVR has a room correction feature, run the room correction after steps 1 to 3, and after connecting the 2 subs to the AVR.

[-sniper-]

thank you sir streetsmart. 

[blued888]

Any update on what happened to your little dual subwoofer experiment?

[accastil]

if your subwoofer has a loop output, u dont need a Y-splitter. if there is none, i would rather make use of speaker level connection than a Y-splitter(most subwoofers has provision for this type of integration)

[-sniper-]

Any update on what happened to your little dual subwoofer experiment?

none yet sir. sa saturday ko pa kukunin ung sub. 

[markcrenz]

if your subwoofer has a loop output, u dont need a Y-splitter. if there is none, i would rather make use of speaker level connection than a Y-splitter(most subwoofers has provision for this type of integration)

there might not be enough lfe content at the speaker output for the sub to reproduce. it would be better to use an rca splitter at the receiver's sub output to feed two subs. but since ts stated that the subs are not identical, it would be more effective to use just the more powerful one, placed in the optimum room location. using two subs may introduce boosts at certain frequencies and cancellation at other frequencies, creating peaks and dips in the subwoofer frequency response. para kang nag-set ng equalizer na naka-W ang arrangement.

[-sniper-]

no significant developments to post as of now. haven't had the time to fully test the second sub.

i have not yet tested the two subs individually using the same sound stream. i think this is the best way to compare the two. just played a scene in "pearl harbor" once but both subs were on. i used a splitter, by the way.

the dual sub set-up is just temporary (again, i hope  ). i just want to find out which one i would use for movies, and which one for audio.

i have some initial impressions on my little experiment though. i don't seem to have noticed or "felt" any difference. maybe because i have not cranked up the volume? i conducted the test a bit late in the evening, didn't want to bother my neighbor.  or maybe i just missed out on something...

from the looks of it, the weekend is the only time i have to fully test both subs...

[markcrenz]

i just want to find out which one i would use for movies, and which one for audio.

AFAIK subs for music should have fast and accurate response (an advantage of most sealed subs over ported ones). For movies naman it has to go really deep as some movies have lots of subsonic content.

Got this list of movies good for testing your sub capability. Be cautious though, i once blew up a sub in a small vented box tuned at 35hz.  Made a new one tuned at 25hz.

    * "Das Boot" Arguably one of the best war pictures of all time with bass dipping under 20 Hz. Very loud, very intense.
         1. "Depth charges", Scene 21 (59:30)
         2. "Storm surfing", Scene 25 (1:15:15)
         3. "Hitting bottom", Scene 17 (53:15, Side "B")

    * "The Day After Tomorrow" More end of days theme, that'll have you signing the Kyoto Accords as a private citizen.  Flash frozen movie that was better than expected.
         1. "Freezing", Scene 12 (0:40:20)*
         2. "Tidal wave", Scene 14 (0:49:05)*
         3. "Tanker on the boulevard", Scene 16 (01:02:55)*

    * "Dawn of the Dead"  Remake of the original zombie cult-classic.  Some bass good enough to wake the dead, of course.
         1. "Opening flame sequence", Scene 1 (0:00:40)*
         2. "Explosion", Scene 18 (01:35:50)*
         3. "Another explosion", Scene 19 (01:42:01)*

    * "Fahrenheit 9-11" Politically incorrect, and unabashedly biased documentary about the "war on terrorism".  Surprising bass passages.
         1. "Fireworks", Scene 1 (0:00:30)*
         2. "Credits", Scene 4 (0:13:46)*
         3. "Bombing begins", Scene 16 (01:09:30)*

    * "Fight Club" Dark, brutal, shocking. And that's just the bass. Strong below 10Hz. Take your gloves off.  Wimpy subs don't even try this.
         1. "THX Intro" *
         2. "Mid-air collision" Chapter 8 (0:21:39)*
         3. "Ass-whippin" Chapter 9 (0:21:59)
         4. "Calling Marla" Chapter 10 (0:27:29)*
         5. "Fridge explosion" Chapter 10 (0:27:35)*
         6. "Car wreck" Chapter 27 (1:40:28)*
         7. "My eyes are open" Chapter 35 (2:13:00)
         8. "Final explosions" Chapter 36 (2:15:31)*

    * "Finding Nemo" The usual stunning Disney animation, with a nice story for the entire family.  If you are playing at theater levels, get ready for some SERIOUS bass.
         1. "Darla taps the tank", Scene 25 (1:18:14)*

    * "Godzilla" That's right, the big lizard flick does more than just tear up NYC, it brings you some very good deep bass.  Even the menu for this one is something of a bass reference!
         1. Menu, building crumbling*
         2. "Godzilla enters harbor" Chapter 8 (0:25:23)*
         3. "Godzilla emerges from subway" Chapter 15 (1:20:30)*

     * "Independence Day" Dark comedy thriller with the feel-good ending, and most importantly, strong bass below 20Hz.:
         1. "Intro spaceship flyover" Scene 1 (0:2:12)
         2. "Time's Up" Scene 24 (0:51:55)
         3. "Got Airbags?" Scene 31 (1:05:15)

    * "The Iron Giant" Great family animation with SERIOUS bass, including very strong peaks below 25 Hz. Jump to:
         1. "The Giant Sits Down" Scene 8 (0:20:01)
         2. "Robot Landing" (Train Impact) Scene 10 (25:41)
         3. "Green Boom" Scene 27 (1:11:40)

    * "Mask of Zorro" The last of the opening music is decaying in mid chart. The the opening logo then turns to fire...and a great 25hz signal as the fire burns:
         1. Opening Logo Scene 1 (0:0:50)
         2. "Explosion" Scene 27 (2:04:53

    * "Toy Story 2" A modern animation classic, and one of the few sequels ever to rival the original movie. More deep bass than we've seen in a while. Serious stuff well below 20Hz!   "Monsters Inc." also has a "trailer" prior to Toy Story's start, don't miss it!:
         1. "Door knock"  (Monsters Inc. trailer)*
         2. "Dog growling"  (Monsters Inc. trailer)*
         3. Opening logo Chap. 1 (0:00:55)*
         4. "Aliens explode" Chap. 2 (0:02:30)*
         5. "Game over" Chap. 2 (0:04:21)*

    * "The Phantom Menace" Lesser subs don't even try to reproduce most of the bass in this movie.  Some highlights:
         1. "THX Intro" *
         2. "Ambush" Chapter 3 (0:05:12)*
         3. "Pod race tunnel exit" Chapter 20 (1:01:40)*

[-sniper-]

thanks sir mark. i have 5 out of the 10 in the list.

since you've mentioned it, what's the difference between a sealed and a ported sub? 

[blued888]

thanks sir mark. i have 5 out of the 10 in the list.

since you've mentioned it, what's the difference between a sealed and a ported sub? 

Sealed enclosures have tighter bass and tend to be smaller than ported subs.

[threadlock]

thanks.

the two subs are not identical. that's another issue i was wary of. i just forget to state it. thanks for reminding me. 

This would be very difficult to setup because two non-identical subs will give different frequency response. The lower extension also of the better sub might be masked by the lesser sub. But you can try it, you might get good results. 

AFAIK subs for music should have fast and accurate response (an advantage of most sealed subs over ported ones). For movies naman it has to go really deep as some movies have lots of subsonic content.

This depends on the design of the box and the sub driver used. There are some box design like LLT which can act like a sealed sub at 30Hz and above but can go very deep up to subsonic frequencies. Look at SVS PB-13 Ultra, it's ported yet many owners are saying it's fast, accurate and musical.

Got this list of movies good for testing your sub capability. Be cautious though, i once blew up a sub in a small vented box tuned at 35hz.  Made a new one tuned at 25hz.

Ported box can easily be blown because of over-excursion below the tuning frequency, this is part of the behavior of a ported box. This can be prevented by using a highpass filter or lowering down the volume during intense deep bass scenes.

Sealed enclosures have tighter bass and tend to be smaller than ported subs.

Some reasons for this is that ported subs has a very steep roll-off and a very high THD levels below the tuning frequency and a very high group delay at tuning frequency. At exactly the tuning frequency, the port takes over driver in reproducing the bass and it's not quite good to hear. But ported subs can also be tuned lower so that it will act like sealed sub for music use-- LLT design.
LLT Link: http://www.hometheatershack.com/forums/diy-subwoofers-sealed-ported/1820-llt-explained.html

[-sniper-]

This would be very difficult to setup because two non-identical subs will give different frequency response. The lower extension also of the better sub might be masked by the lesser sub. But you can try it, you might get good results. 

i agree.

anyway, is it a good move to auto calibrate the two subs one after the other? i mean --- auto calibrate the system with one sub connected. then remove that sub's connection and auto calibrate again connecting the other sub. then re-connect the first sub.

[streetsmart]

i agree.

anyway, is it a good move to auto calibrate the two subs one after the other? i mean --- auto calibrate the system with one sub connected. then remove that sub's connection and auto calibrate again connecting the other sub. then re-connect the first sub.

What's your AVR?

[-sniper-]

What's your AVR?

pioneer, sir. (vsx-516)

[streetsmart]

pioneer, sir. (vsx-516)

Ah .. if you had a Denon or Onkyo, I would be more familiar with the room correction technology (Audyssey). D ako familiar sa Pioneer.

In any case, the principle is that you set the levels of each sub separately so that they are equal (using volume at back of sub, SPL meter and test tones) but the audio calibration is done with both subs connected at the same time.

[blued888]

pioneer, sir. (vsx-516)

Does this Pioneer model have MCACC?

Ah .. if you had a Denon or Onkyo, I would be more familiar with the room correction technology (Audyssey). D ako familiar sa Pioneer.

In any case, the principle is that you set the levels of each sub separately so that they are equal (using volume at back of sub, SPL meter and test tones) but the audio calibration is done with both subs connected at the same time.

How would audio calibration be done with both subwoofers connected at the same time? Won't the output of one, affect the reading of the other?

[iceman90a]

since they are not the same models / type, i would place them in different parts of the room,

1. set up first sub in relation to HT speakers, til you get ïdeal"sound
2. with 1st sub working, set up the 2nd sub in other location (should be same phase as the other sub) and work on different parameters (1st sub could be going really low - while 2nd sub is for slam)

[-sniper-]

Does this Pioneer model have MCACC?

yes, sir. it has MCACC

[streetsmart]

How would audio calibration be done with both subwoofers connected at the same time? Won't the output of one, affect the reading of the other?

Remember that the OP said he will use an auto-calibration procedure. If that's the case, it will be some form of auto-equalization. In this case, you must have both subs connected at the same time.

Placement is another issue. You may locate the subs independently and there are some typical locations such as center front and center back. The problem here is that if the subs are located at different distances from the main listening position, their sound will arrive at different times. Thus, you need to inject a delay into the sub that is nearer. That adds to the complication. The simplest, though perhaps not ideal, is to locate them symmetrically in front.

You can also play around with phase, especially if the subs have variable phase controls. You can adjust each one's phase independently until you get the smoothest frequency response.

The other problem with placement and phase is that if you don't have an RTA, you will be using your ears alone and its quite difficult to use your ears to get the flattest frequency response.

Bottom-line: If you don't have a good auto room correction feature in your AVR, its very difficult to handle 2 subs. If the subs are different, its even harder.

[markcrenz]

thanks sir mark. i have 5 out of the 10 in the list.

since you've mentioned it, what's the difference between a sealed and a ported sub? 

sealed - totally closed ang box, there is no interface between the air in the box and outside. Great low frequency power handling, the best transient responses, and smaller enclosure sizes than most other designs. However, magnet structures will not cool as well as they do in some ported enclosures, and distortion in the upper bass frequencies is more noticeable than ported enclosures, but can usually be compensated for by lowering the crossover frequency.
ported/vented (also called bass reflex) - a box with a port or vent (usually circular or rectangular) which reinforces the sound at a specific (tuned) frequency, hence the greater efficiency at the expense of slightly less accurate bass response. but below the tuned frequency power handling is poor and damage to the woofer is likely to occur if over driven. - thats what happened to mine!

[-sniper-]

The simplest, though perhaps not ideal, is to locate them symmetrically in front.

what i did was to place them both in front, equidistant from the center speaker.

You can also play around with phase, especially if the subs have variable phase controls. You can adjust each one's phase independently until you get the smoothest frequency response.

this is another predicament that i have. the second sub only has a knob for volume. it has no phase and cross-over controls.

anyway, i tried the one-sub-after-the-other auto calibration thing last night. then played the same chapter from the same film thrice -- one for each and one with both subs connected. individually, they seem to have sounded the same.

but i liked the sound when both subs were connected. i don't know if that was for real or if it was just a psychological thing. 

will be doing it again this weekend, at high volume this time.  it's hard to crank up the volume at night, i have to consider my neighbors. 

[markcrenz]

This depends on the design of the box and the sub driver used. There are some box design like LLT which can act like a sealed sub at 30Hz and above but can go very deep up to subsonic frequencies. Look at SVS PB-13 Ultra, it's ported yet many owners are saying it's fast, accurate and musical.
Ported box can easily be blown because of over-excursion below the tuning frequency, this is part of the behavior of a ported box. This can be prevented by using a highpass filter or lowering down the volume during intense deep bass scenes.
Some reasons for this is that ported subs has a very steep roll-off and a very high THD levels below the tuning frequency and a very high group delay at tuning frequency. At exactly the tuning frequency, the port takes over driver in reproducing the bass and it's not quite good to hear. But ported subs can also be tuned lower so that it will act like sealed sub for music use-- LLT design.

yes that's why i tuned my new box at 25 hz, just a bit higher than the sub resonant frequency but way lower than regular musical frequencies of 40 hz & up. so it acts like a sealed box when reproducing a bass guitar or a kick drum, and can also handle lots of sub bass passages for ht.

[-sniper-]

finally tested (and abused) the dual sub set-up. a bit tiring though.

i did three separate auto calibrations -- first, auto calibrated with my old sub connected. second, i repeated the process connecting the second sub and disconnecting the old sub. after the two auto calibrations, i then connected both subs. i did not turn off the power on both subs. was thinking that doing so might delete the auto-calibraton settings. i played several movies using the same track -- one with both subs on, then with new sub at zero volume, then with the same sub disconnected from the avr. i did the same thing with the old sub. (i had to run the same track for five times  )

the third auto calibration was simpler -- i had both subwoofers connected.

the results were the same -- the settings, the boom, the rumbling, the shakes.

bottomline -- i like the dual sub set-up (oh no!  ). the subs were both placed in front.

i was thinking of placing one sub beside the right surround, facing the other surround speaker (and not towards the front). any thoughts on this placement?

[blued888]

Placing the subwoofer nearfield would allow you to feel more of the midbass, hence more chest-thumping feeling.

[jackryan]

why not put those bass shakers or buttkickers too?