2 Subs - Dual Mono or Stereo - "Kb ka dB"

Bass&Trouble · 3rd June 2006, 18:35

Quote:

Originally Posted by low_bass_makker

"If we add a similar driver like for eg If there is one 12 inch sub and we add another same drive with same amplification the sound would get double."

The above statment is 100% wrong it was said that there will be 6db increase if the sub are fully in phase. and approx 3db if they are little out of sync.

Now in a mono setup the sub will perfectly in phase but in a stereo setup they will be swinging acording to the track in which there might be some phase change. So in a stereo setup the sound will be less and in a mono it will be more becasue both the subs will be playing.....................

One more thing For example if in a track the whole music is in on right channel and the vocals are on the left channel. So the amount of bass would be less than in a stereo setup be cause only 'ek Baara Inchi' will be playing not 'Do Baara Inchi.'

LBM maharaj, aapke charan kahan hai?

You are saying that if you add another identical sub with same input power and if the subs are in phase then they will be (upto) 6 dB louder. And then you say the statement is 100% wrong. What do you want to happen? The spl should go down by 6 dB?? Increase in 3 dB is the acoustic equivalent of power doubling. Double the power and double the piston area causes +6 dB. Fir bhi dil maange more?

If someone records music by panning 'whole music on right side and vocals on the left channel', there is something seriously wrong with the engineer. That's freak music. Not some good old fashioned regular music that me and Gunbir are accustomed to listening to.

low_bass_makker · 3rd June 2006, 18:56

My bad man My bad , any way mere charan mere neche hai......................

Bass&Trouble · 3rd June 2006, 19:03

Quote:

Originally Posted by low_bass_makker

My bad man My bad , any way mere charan mere neche hai......................

Ok, charan neeche hain to mahurat dekh rahe ho kya? Jaldi se joote pehen lo beta, school ka time ho gaya hai.

low_bass_makker · 3rd June 2006, 19:07

Sir what timing ??????????????

Autophile · 3rd June 2006, 19:25

Guys I see there is a big fuss on stereo vs mono subs.

Before getting into the details of explaination I would suggest, don't mix car audio and 5.1 home audio.

In 5.1 home audio the bass is mastered and recorded mono as seperate channel which is the .1 and a lot of home theatre subs has one input by the name of LFE (Low frequency effects) rather than L+R, in some one of them is indicated as LFE. The Decoders and Recievers and Car Audio DVD players has one output for sub.

Ideally in home cinema all you need is one sub, you will need to add more only in the case you crave for more SPL.

You will rarely come across any audiophiles with high end stereo setup using subwoofers in house.

Now come to car audio. Ideally there should be full range representaion of music in the front stage. But thats not possible because of the limitation of installing big drivers in the front. So you have to use the subwoofers in the back of the car (the only place to accomodate them). Which gives rise to problems like delay in bass, disintegrated sound, phase errors etc. Which can be taken care of by electronics to some extent.

Stereo bass vs mono bass in the car :

Lot of bassheads will never accept the stereo bass in their cars because their main objective in the whole sound reproduction is the bass quantity which will always be more in the case of mono.

In-between two subwoofers playing stereo and mono, mono will be louder as the signal is summed, amplified and the two subwoofers are powered by identical signal, they are perfectly in phase in their entire bandwidth of bass reproduction.

Stereo bass in car is only possible if the HU is really giving out stereo signal in sub out, in most cases it is the summed L+R output available in parallel for convenience to use 2ch / 4ch amps. In this case the subs will play mono, does not matter how do you wire them. You can check this by hooking the subwoofers in stereo and see if balance works on them or not.

If not the debate of stereo vs mono bass in the car audio ends in this case.

Ideally one should have stereo bass in the car (only SQ users) it complements the front stage and imaging very well. Lot of users has single subwoofers running mono and the box is ideally in one corner. Now listen to the familiar track with good musical bass sitting in the driver seat and then in the passenger seat the bass will not sound the same there will definitely be a difference, even if you call it as omnidirectional, difficult to localise. But it will not sound right.

If you have stereo subwoofers this will not happen. It will be the same.

The reason why it happens in mono bass is that the frontstage is stereo and bass is mono so it cannot complement the L & R midbass/midrange at the same time. So there can be peaks in bass which are not required so you end up tuning them with eq.

This is the reason why the subwoofers are not used in the stereo setups in home audio. The integration between the speakers and subwoofer in home audio is very difficult. I have tried a lot of times from budget components to ultra high end, bottom line is it just does not work.

On the other hand we can achieve that in car audio by using electronics for adjusting delay, crossover, level, eq in each driver (talking about active system). Even in passive system you can take care of delay, phase and eq to a certain extent but not as extensive as active system.

In a well recorded music with real instruments Left and Right channel will never have same amount of bass energy because of the placement of instruments and microphones on the stage. So the left and right subwoofers will never have the same output. If you sum the signal then the output will be same, hence more but at the cost of loosing detail and seperation.

We are not talking about infrasonic frequencies (<20Hz) where the detail and seperation does not matter we are talking about music reproduction in the band of 20Hz - 80/100Hz which one can hear and distinguish very well and it does matter. Try using 20Hz subsonic filter on the sub it will sound different with the filter on and off. The difference is noticable because you can hear the effect of filter at 20Hz

Today companies are spending money in R&D of high frequency drivers capable of reproducing frequencies above 20Khz. Even there are dedicated super tweeters which are used to reproduce HF from 10-15Khz to 54Khz. Now if we go theoretically humans cannot listen above 20Khz but brain does recognises frequencies above that, one might not notice but it definitely adds to listening pleasure. If our listening band width is 20-20Khz why the hell do we need expensive supertweeters, preamps / amps with frequency response of 5Hz - 100Khz.

Stereo was a big improvement over mono and even today the most advanced 5.1 system cannot touch the stereo setup in music reproduction. And the reproduction of full spectrum in stereo does matter.

I am running 2 X IDQ 12 in stereo on bridged McIntosh MCC404M amplifier. The HU is Mcintosh MX5000 with 4 preouts which goes to MCC404M powering the speakers and the pre-out from this goes to sub amp. The sublevel is controlled by remote bass knob. The integration, timing, kick of bass in front stage, both left and right channel is immaculate which is hard to achieve in case of mono unless you keep the LPF below 50Hz. In which case you have the speakers struggling to play down to 50Hz.

Idea of going stereo is definitely better over mono in case you listen to music with real instruments and want serious SQ system. On top of it if you have the HU which permits sub out in stereo.

kb100 · 3rd June 2006, 20:22

Quote:

Originally Posted by Autophile

Idea of going stereo is definitely better over mono in case you listen to music with real instruments and want serious SQ system. On top of it if you have the HU which permits sub out in stereo.

GURU JB.... AAAPKE Charan kahan hai!!

So Stereo it is!!.

one question.. the HU in consideration is P80RS... So do we run this regular mode??.. or network mode??.(active) to achieve the above... The sub out in stereo that is..

Sam Kapasi · 3rd June 2006, 20:27

Which brings me to the main question:

Does the pioneer P80 have a stereo subwoofer out or a summed mono out?
I've no idea, does anyone else?

kb100 · 3rd June 2006, 20:36

Well.. it allows you to go three way active... Hi-mid-low.. so I guess you get stereo in Active mode..

Wonder if the same is possible while you are in pasive ... Left-right-Sub mode

SOMEBODY CORRECT ME!!... lol

Sam Kapasi · 3rd June 2006, 20:39

It could be 3 way active and YET be summing the Sub out, like a lot of pro active crossovers do.

Sam Kapasi · 3rd June 2006, 20:54

I've had a lot of experience with Live and studio - one thing I can safely tell you: Most sub frequencies are recorded dead centre in a stereo recording.

Even if multiple microphoning is used on a drum kit (quite common), the kick drum is generally panned dead centre.
That said, it is possible to redirect electronic and programmed/synthesised bass towards any direction on the mixing desk and it will happen with electronic music (sometimes well done on purpose, some times badly miked)
I had suggested a dual mono setup to kb100 to avoid phase cancellation if any. Also because it still seems to me that if we're trying our damndest to de-localise sub bass and mount two large drivers next to each other, then to ensure that they run 2 different sounds, seems (to me) wrong.
I agree with JB on one point, you cannot compare this to a home theatre setup, as the channels are 5.1 or 7.1 with a singular, mono sub channel.

But let me tell you this - look at the indications

Sound recording all over the world for movie, indicate a mono sub channel. Real life situations would demand bass from all directions, however since the chanel is sub-bass, hence de-localized, a mono channel is provided for maximum output, minimum fuss and no phase cancelling.

Most cars use a single sub, often set at lower freqs than home audio subs, again to prevent the pinpointing of the source.
As gunbir said, a lot of new HU's with a dedicated sub out, offer a summed mono bass out.

These indications show that I'm not alone in thinking the way I do.

However sound is like that. Like my mom's daal. Your mom could cook till the cows came home and roses fell out of the sky, I'd still like my mom's daal.
Everyone's perception of "good" sound is relative. To what they like listening to and what they believe in. So KB, since Gunbir's the man who represents the subs you're installing, I'd take his advice quite easily, I am 100% sure they both(him and JB) know exactly what they are talking about.

Just my 50 cent.

Autophile · 3rd June 2006, 20:59

KB 100 i would suggest go passive front stage with your amplifier. Don't think further on going 3-way active.

Correcting myself:

As far as the question of sub out is concerned in Normal/Network Mode. The summed mono output might change to independent L-R subwoofer channels in NW mode i will still check and get back to you.

The point which leads to above thought is that in case of Time Alignment in P80RS, you can only give delay for single (mono) subwoofer in standard mode which changes to independent delay to Left and Right subs in Network Mode. Now the question is whether the signal is pure stereo or its just an option for independent delay for each output. That I will test and get back.

Sam Kapasi · 3rd June 2006, 21:03

Quote:

Originally Posted by Autophile

As far as the question of sub out is concerned in Normal/Network Mode it will be summed in both cases the as the summing is done from L+R channels. I don't think the summed mono output will change to independent L-R subwoofer channels in NW mode.

.

Lo karlo baat. So after this whole shebang, we find out that he has a dual mono HU.

KB100, you made me write the longest post i have all week for nothing

Autophile · 3rd June 2006, 21:09

If the bass has certain notes which are out of phase, they will be out of phase in the midbass/midrange also. Hence there will be cancellation in midbass/midrange area it can happen in tweeters also. Since in most cars the midbasses are facing each other the cancellation will be more apparent.

gunbir · 3rd June 2006, 21:09

Quote:

Originally Posted by Sam Kapasi

Lo karlo baat. So after this whole shebang, we find out that he has a dual mono HU.

KB100, you made me write the longest post i have all week for nothing

Hehehe... Well it was entirely KB100's call. He wanted to have 'a discussion'.

Autophile · 3rd June 2006, 21:25

Correcting my previous post, got confused

Here is the clarification guys.

Pioneer P80RS has stereo sub outputs in both Standard and Network mode.

Though I would still like to test the outputs for genuine L-R signal.

3rd June 2006, 18:56	#32
low_bass_makker Senior - BHPian Join Date: Mar 2006 Location: Faridabad Posts: 6,813 Thanked: 306 Times View My Garage	My bad man My bad , any way mere charan mere neche hai...................... Last edited by low_bass_makker : 3rd June 2006 at 19:02.
	() Thanks

3rd June 2006, 19:07	#34
low_bass_makker Senior - BHPian Join Date: Mar 2006 Location: Faridabad Posts: 6,813 Thanked: 306 Times View My Garage	Sir what timing ??????????????
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3rd June 2006, 19:25	#35
Autophile BHPian Join Date: Sep 2005 Location: New Delhi Posts: 931 Thanked: 4 Times	Guys I see there is a big fuss on stereo vs mono subs. Before getting into the details of explaination I would suggest, don't mix car audio and 5.1 home audio. In 5.1 home audio the bass is mastered and recorded mono as seperate channel which is the .1 and a lot of home theatre subs has one input by the name of LFE (Low frequency effects) rather than L+R, in some one of them is indicated as LFE. The Decoders and Recievers and Car Audio DVD players has one output for sub. Ideally in home cinema all you need is one sub, you will need to add more only in the case you crave for more SPL. You will rarely come across any audiophiles with high end stereo setup using subwoofers in house. Now come to car audio. Ideally there should be full range representaion of music in the front stage. But thats not possible because of the limitation of installing big drivers in the front. So you have to use the subwoofers in the back of the car (the only place to accomodate them). Which gives rise to problems like delay in bass, disintegrated sound, phase errors etc. Which can be taken care of by electronics to some extent. Stereo bass vs mono bass in the car : Lot of bassheads will never accept the stereo bass in their cars because their main objective in the whole sound reproduction is the bass quantity which will always be more in the case of mono. In-between two subwoofers playing stereo and mono, mono will be louder as the signal is summed, amplified and the two subwoofers are powered by identical signal, they are perfectly in phase in their entire bandwidth of bass reproduction. Stereo bass in car is only possible if the HU is really giving out stereo signal in sub out, in most cases it is the summed L+R output available in parallel for convenience to use 2ch / 4ch amps. In this case the subs will play mono, does not matter how do you wire them. You can check this by hooking the subwoofers in stereo and see if balance works on them or not. If not the debate of stereo vs mono bass in the car audio ends in this case. Ideally one should have stereo bass in the car (only SQ users) it complements the front stage and imaging very well. Lot of users has single subwoofers running mono and the box is ideally in one corner. Now listen to the familiar track with good musical bass sitting in the driver seat and then in the passenger seat the bass will not sound the same there will definitely be a difference, even if you call it as omnidirectional, difficult to localise. But it will not sound right. If you have stereo subwoofers this will not happen. It will be the same. The reason why it happens in mono bass is that the frontstage is stereo and bass is mono so it cannot complement the L & R midbass/midrange at the same time. So there can be peaks in bass which are not required so you end up tuning them with eq. This is the reason why the subwoofers are not used in the stereo setups in home audio. The integration between the speakers and subwoofer in home audio is very difficult. I have tried a lot of times from budget components to ultra high end, bottom line is it just does not work. On the other hand we can achieve that in car audio by using electronics for adjusting delay, crossover, level, eq in each driver (talking about active system). Even in passive system you can take care of delay, phase and eq to a certain extent but not as extensive as active system. In a well recorded music with real instruments Left and Right channel will never have same amount of bass energy because of the placement of instruments and microphones on the stage. So the left and right subwoofers will never have the same output. If you sum the signal then the output will be same, hence more but at the cost of loosing detail and seperation. We are not talking about infrasonic frequencies (<20Hz) where the detail and seperation does not matter we are talking about music reproduction in the band of 20Hz - 80/100Hz which one can hear and distinguish very well and it does matter. Try using 20Hz subsonic filter on the sub it will sound different with the filter on and off. The difference is noticable because you can hear the effect of filter at 20Hz Today companies are spending money in R&D of high frequency drivers capable of reproducing frequencies above 20Khz. Even there are dedicated super tweeters which are used to reproduce HF from 10-15Khz to 54Khz. Now if we go theoretically humans cannot listen above 20Khz but brain does recognises frequencies above that, one might not notice but it definitely adds to listening pleasure. If our listening band width is 20-20Khz why the hell do we need expensive supertweeters, preamps / amps with frequency response of 5Hz - 100Khz. Stereo was a big improvement over mono and even today the most advanced 5.1 system cannot touch the stereo setup in music reproduction. And the reproduction of full spectrum in stereo does matter. I am running 2 X IDQ 12 in stereo on bridged McIntosh MCC404M amplifier. The HU is Mcintosh MX5000 with 4 preouts which goes to MCC404M powering the speakers and the pre-out from this goes to sub amp. The sublevel is controlled by remote bass knob. The integration, timing, kick of bass in front stage, both left and right channel is immaculate which is hard to achieve in case of mono unless you keep the LPF below 50Hz. In which case you have the speakers struggling to play down to 50Hz. Idea of going stereo is definitely better over mono in case you listen to music with real instruments and want serious SQ system. On top of it if you have the HU which permits sub out in stereo.
	() Thanks

3rd June 2006, 20:27	#37
Sam Kapasi Distinguished - BHPian Join Date: Jul 2005 Location: Mumbai (but wat Posts: 6,935 Thanked: 2,480 Times View My Garage	Which brings me to the main question: Does the pioneer P80 have a stereo subwoofer out or a summed mono out? I've no idea, does anyone else?
	() Thanks

3rd June 2006, 20:36	#38
kb100 Senior - BHPian Join Date: Feb 2006 Location: Bangy Boy! Posts: 1,556 Thanked: 23 Times	Well.. it allows you to go three way active... Hi-mid-low.. so I guess you get stereo in Active mode.. Wonder if the same is possible while you are in pasive ... Left-right-Sub mode SOMEBODY CORRECT ME!!... lol
	() Thanks

3rd June 2006, 20:39	#39
Sam Kapasi Distinguished - BHPian Join Date: Jul 2005 Location: Mumbai (but wat Posts: 6,935 Thanked: 2,480 Times View My Garage	It could be 3 way active and YET be summing the Sub out, like a lot of pro active crossovers do.
	() Thanks

3rd June 2006, 20:54	#40
Sam Kapasi Distinguished - BHPian Join Date: Jul 2005 Location: Mumbai (but wat Posts: 6,935 Thanked: 2,480 Times View My Garage	I've had a lot of experience with Live and studio - one thing I can safely tell you: Most sub frequencies are recorded dead centre in a stereo recording. Even if multiple microphoning is used on a drum kit (quite common), the kick drum is generally panned dead centre. That said, it is possible to redirect electronic and programmed/synthesised bass towards any direction on the mixing desk and it will happen with electronic music (sometimes well done on purpose, some times badly miked) I had suggested a dual mono setup to kb100 to avoid phase cancellation if any. Also because it still seems to me that if we're trying our damndest to de-localise sub bass and mount two large drivers next to each other, then to ensure that they run 2 different sounds, seems (to me) wrong. I agree with JB on one point, you cannot compare this to a home theatre setup, as the channels are 5.1 or 7.1 with a singular, mono sub channel. But let me tell you this - look at the indications Sound recording all over the world for movie, indicate a mono sub channel. Real life situations would demand bass from all directions, however since the chanel is sub-bass, hence de-localized, a mono channel is provided for maximum output, minimum fuss and no phase cancelling. Most cars use a single sub, often set at lower freqs than home audio subs, again to prevent the pinpointing of the source. As gunbir said, a lot of new HU's with a dedicated sub out, offer a summed mono bass out. These indications show that I'm not alone in thinking the way I do. However sound is like that. Like my mom's daal. Your mom could cook till the cows came home and roses fell out of the sky, I'd still like my mom's daal. Everyone's perception of "good" sound is relative. To what they like listening to and what they believe in. So KB, since Gunbir's the man who represents the subs you're installing, I'd take his advice quite easily, I am 100% sure they both(him and JB) know exactly what they are talking about. Just my 50 cent.
	() Thanks

3rd June 2006, 20:59	#41
Autophile BHPian Join Date: Sep 2005 Location: New Delhi Posts: 931 Thanked: 4 Times	KB 100 i would suggest go passive front stage with your amplifier. Don't think further on going 3-way active. Correcting myself: As far as the question of sub out is concerned in Normal/Network Mode. The summed mono output might change to independent L-R subwoofer channels in NW mode i will still check and get back to you. The point which leads to above thought is that in case of Time Alignment in P80RS, you can only give delay for single (mono) subwoofer in standard mode which changes to independent delay to Left and Right subs in Network Mode. Now the question is whether the signal is pure stereo or its just an option for independent delay for each output. That I will test and get back. Last edited by Autophile : 3rd June 2006 at 21:16.
	() Thanks

3rd June 2006, 21:09	#43
Autophile BHPian Join Date: Sep 2005 Location: New Delhi Posts: 931 Thanked: 4 Times	If the bass has certain notes which are out of phase, they will be out of phase in the midbass/midrange also. Hence there will be cancellation in midbass/midrange area it can happen in tweeters also. Since in most cars the midbasses are facing each other the cancellation will be more apparent.
	() Thanks

3rd June 2006, 21:25	#45
Autophile BHPian Join Date: Sep 2005 Location: New Delhi Posts: 931 Thanked: 4 Times	Correcting my previous post, got confused Here is the clarification guys. Pioneer P80RS has stereo sub outputs in both Standard and Network mode. Though I would still like to test the outputs for genuine L-R signal. Last edited by Autophile : 3rd June 2006 at 21:32.
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