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Primare Knob

How to handle multi Subwoofer setup

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Hi,

 

I have just started setting up my HT room and using 2 subwoofer for the first time.

 

What is the best way when using 2 subwoofers when you only have one LFE output on the AVR/PrePro?

At the moment I am using an Y splitter on the LFE output feeding into both subwoofers.

 

What is the best (starting) position?

At the moment I have placed them behind the Front speakers with a 1 : 1.3 ratio from the back : side wall.

 

What is the best approach for system integration.

Is there a different approach between 2 and multi channel integration?

At the moment I have "integrated" the subwoofers by ear into a 2 channel setup first, using level, phase and a 40Hz crossover setting on the subwoofers themselve. My front speakers are using 10" active drivers up to 350Hz and go down to 29Hz -3dB. After my first satisfying tweaks I adjusted the LFE level in the PrePro  to match 75dB using a -40dBFS test signal from disc. I do use the option to send LFE signals to both front speakers and LFE channel since the subwoofer cut off frequency is set to 40Hz to integrate with the (2 channel) front speakers.

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Wow, those front speakers are subwoofers themselves, so you pretty much have 4 subs. Normally I would place your subs 1/4 in from the side walls along the front wall. But because your speakers are extra subs I would try placing your front speakers exactly  1/4 in from the side walls and place your subs to the rear of the room exactly 1/4 from the side walls as well. This would eliminate most of the room modes. Then it is a matter of getting your distances sorted. In addition I would run your fronts at full range "send lfe to fronts as well" and set your lfe crossover to 80hz to intergrate with your centre and surround speakers. It is worth a bit of experimenting but you will need measuring equipment to get the best out of it.

Edited by brabs

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I agree in that I'd change to 80Hz for your cross-over to better account for your smaller speakers.

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I can set the crossover individual per speaker. Which would mean the front speakers will carry the LFE channel from 80Hz to 40Hz.

 

It also wouldn't be hard to turn the switch back and forth between 40Hz and 80Hz for music vs movie, since it has a locked position for these settings.

 

Putting the 2 subs in the back corners of the room is going to be hard since I have an entry door in one of these corners.

 

 

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6 minutes ago, Primare Knob said:

 

Putting the 2 subs in the back corners of the room is going to be hard since I have an entry door in one of these corners.

 

 

Could you place them 1/4 in from the corners?

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1/4 from the side wall, possibly. 1/4 from the back wall not so much, more like 1/6 of the length of the room.

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Once your distance is dialled in, you should find no boominess with a flatter frequency response. But the best part will be everyone will get a similar response at there seat

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Moderator

personally i would suggest theres a few things here.

 

this is my approach

 

I would dial in subs to perfection with mains for 2ch prowess music etc and to end up with a really good response back at main listening position. (numerous tools available for this. I am using one built in my sub :) and essentially the main and sub work as one large speaker :)

 

for AV and ht and multichannel duties I would utilise a processor that can handle multi sub. note this will also take in your main-sub combo as large speakers. 

 

I would not use Y cables as this doesnt take in anything with regards what specific subs needs re level, phase, delays etc that each may specifically need. as a note though with subs placed in close proximity to mains little to nothing likely needed with regards delays or phase.

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6 minutes ago, :) al said:

personally i would suggest theres a few things here.

 

this is my approach

 

I would dial in subs to perfection with mains for 2ch prowess music etc and to end up with a really good response back at main listening position. (numerous tools available for this. I am using one built in my sub :) and essentially the main and sub work as one large speaker :)

 

for AV and ht and multichannel duties I would utilise a processor that can handle multi sub. note this will also take in your main-sub combo as large speakers. 

 

I would not use Y cables as this doesnt take in anything with regards what specific subs needs re level, phase, delays etc that each may specifically need. as a note though with subs placed in close proximity to mains little to nothing likely needed with regards delays or phase.

I can dial in the subs with software using Paradigm PDK software.

If I place the subs symmetrical with equal distance to main listen position, than I should be able to run a single delay for both units right?

 

The main speakers have a forward firing driver while the sub has a downward firing driver with 2 side way passive radiators. By ear a phase of 45 degree on the subs seems to give a better result at the moment. That is by ear though.

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45 minutes ago, Primare Knob said:

I can dial in the subs with software using Paradigm PDK software.

If I place the subs symmetrical with equal distance to main listen position, than I should be able to run a single delay for both units right?

 

The main speakers have a forward firing driver while the sub has a downward firing driver with 2 side way passive radiators. By ear a phase of 45 degree on the subs seems to give a better result at the moment. That is by ear though.

through Y cable though ? as you mention in the opening post ? which I dont like the sounds of at all ! 

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What are the disavantages of using a y cable? Does it produce a weaker signal?

Edited by brabs

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1 hour ago, brabs said:

What are the disavantages of using a y cable? Does it produce a weaker signal?

we are dealing with low line level signal and would be loath to passively split. also from aspect as well you end up treating sub as one. when they are not :) 

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56 minutes ago, Satanica said:

I have a similar setup to yours.

I vote you go for a MiniDSP 2X4 HD and REW.

I not so long ago integrated my two subwoofers using a MiniDSP 2X4 HD and DEQX, see here: https://www.stereo.net.au/forums/topic/127660-subwoofer-placement-integration/?tab=comments#comment-1894021

You are still using the AD DA function of the unit right? It's not going to work if I try to output LFE via USB to the HD and 7 channels audio via HDMI to the PrePro since we are talking about 2 separate audio devices. It would have been nice when the nanoAVR HDA could strip the LFE channel and output it on any sellectable analog output.

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52 minutes ago, :) al said:

we are dealing with low line level signal and would be loath to passively split. also from aspect as well you end up treating sub as one. when they are not :) 

The lfe is a mono Channel, so my understanding is as long as they are equidistant from the listener the should be treated as one

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41 minutes ago, Primare Knob said:

You are still using the AD DA function of the unit right? It's not going to work if I try to output LFE via USB to the HD and 7 channels audio via HDMI to the PrePro since we are talking about 2 separate audio devices. It would have been nice when the nanoAVR HDA could strip the LFE channel and output it on any sellectable analog output.

Yes I'm using the AD to DA function. Would it not work for you if you mixed LFE into the left and right channels?

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33 minutes ago, brabs said:

The lfe is a mono Channel, so my understanding is as long as they are equidistant from the listener the should be treated as one

Yeah however just because equidistant doesn't mean they are interaction or in response exactly the same in a room.

 

ive seen subs placed mirror image in a room one responds quite different to other as one next to structural external wall. Other next to an internal wall.

 

youll find most av processors with quite sophisticated dual sub systems to measure and eq to calibrate and setup for integration :)

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47 minutes ago, :) al said:

Yeah however just because equidistant doesn't mean they are interaction or in response exactly the same in a room.

 

ive seen subs placed mirror image in a room one responds quite different to other as one next to structural external wall. Other next to an internal wall.

 

youll find most av processors with quite sophisticated dual sub systems to measure and eq to calibrate and setup for integration :)

Are you saying they should calibrate them individually first?

personally I think the summed response should be calibrated. I say this because room modes will behave differently with 2 subs playing the same signal together.

for instance I use no eq with my 2 subs and get a reasonably flat response, if I turn one sub off, the response has no resemblance.

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8 minutes ago, brabs said:

Are you saying they should calibrate them individually first?

personally I think the summed response should be calibrated. I say this because room modes will behave differently with 2 subs playing the same signal together.

for instance I use no eq with my 2 subs and get a reasonably flat response, if I turn one sub off, the response has no resemblance.

You'll find dual sub systems that  will ping and measure separately and then will eq together.

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5 minutes ago, :) al said:

You'll find dual sub systems that  will ping and measure separately and then will eq together.

Gotcha 👍

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1 hour ago, Satanica said:

Yes I'm using the AD to DA function. Would it not work for you if you mixed LFE into the left and right channels?

What would be the end result? Can be done at the PC source or done in the PrePro

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9 minutes ago, Primare Knob said:

What would be the end result? Can be done at the PC source or done in the PrePro

So your PrePro has a left and right output right?

And if so this left and right output (with LFE included) could be fed into a MiniDSP HD.

The MiniDSP can be configured to mono output (X2) the summed left and right input with a low pass filter with EQ and with time alignment included.

Edited by Satanica

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6 hours ago, :) al said:

personally i would suggest theres a few things here.

 

this is my approach

 

I would dial in subs to perfection with mains for 2ch prowess music etc and to end up with a really good response back at main listening position. (numerous tools available for this. I am using one built in my sub :) and essentially the main and sub work as one large speaker :)

 

for AV and ht and multichannel duties I would utilise a processor that can handle multi sub. note this will also take in your main-sub combo as large speakers. 

 

I would not use Y cables as this doesnt take in anything with regards what specific subs needs re level, phase, delays etc that each may specifically need. as a note though with subs placed in close proximity to mains little to nothing likely needed with regards delays or phase.

 

4 hours ago, Satanica said:

I have a similar setup to yours.

I vote you go for a MiniDSP 2X4 HD and REW.

I not so long ago integrated my two subwoofers using a MiniDSP 2X4 HD and DEQX, see here: https://www.stereo.net.au/forums/topic/127660-subwoofer-placement-integration/?tab=comments#comment-1894021

What would the suggestion be for subwoofer placement? Technicly my front speakers go down to 29Hz -3dB

Both in the front of the room.

Both in the front corners of the room

One in the front one in the back

Both in the back of the room

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15 minutes ago, Satanica said:

So your PrePro has a left and right output right?

And if so this left and right output (with LFE included) could be fed into a MiniDSP HD.

The MiniDSP can be configured to mono output (X2) the summed left and right input with a low pass filter with EQ and with time alignment included.

Can't it do the same with a single channel? Or will this not work with integrating the low end of the front speakers. I would like to bypass any AD for non LFE/Low end frequency.

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