Stereo Vs Mono Sub setup

[Kermit]

I just want to generate some discussion and feedback on stereo/mono sub setup.

 

Understand that in most cases, people use only one sub (mono). But most HU has 2 channel sub-out, i.e. L/R.

 

Has anyone tried stereo connection to two subs running both L/R channels?

 

Why do we want to do that? What are the benefits? What do we lose if we just combine the L/R signals into mono?

[User12343]

sub bass is non-directional, and there are no discernable differences between the left sub bass and right sub bass, esp if they are coming from the boot. one can do a time-domain analysis of ultralow frequencies and most of the time sub bass is monophonic in nature, ie, whatever appears in the left channel is found in the right channel.

 

the only thing though, it is able to play twice as loud as a mono sub.

Edited October 18, 2006 by User12343

[Kermit]

I kinda catch what you're saying. This is what I understand it to be also.

 

However, what I fail to reconcile is that "Why the hell do they give you L/R Sub output?" Might as well just give one mono output all the time? Or to cater to people who play dual-sub, give 2 x mono output lah...

 

I suspect maybe got difference to the SQ...dunnoe leh...

[Ractis]

Maybe some people cross higher, in such cases the harmonics from the sub could still be directional. Also, another thing is perhaps the tactile aspect. In a car, it is easy to tell where the vibration is coming from. So maybe having a sub for both left and right sides can give a more accurate tactile reproduction

 

But I think it is the norm for recording engineers to mix sub frequencies as mono (not sure, maybe about 50hz and below)

[Kermit]

Good thinking.

 

Those you mentioned could be some effects stereo subs can give you. But I thought we always want to "bring the bass/sub to the front" such that we can't tell it's coming from the back? Haiz, still confused...

[Slonez]

I see you're stressed out like me

[Sarong1]

Let me explain and answer this.

 

Mono signal from HU contains no time/phase differentiation vis-a-vis stereo signal(L/R ch). That means, a mono signal fed into a subwoofer does not produce the desired time correction of subranges that is coherent with your front stage. However, stereo sub signal provides time correction on both left and right independently. This means that left channel subranges information from source thru the subwoofer, will arrive at the listener at a different time from that of the right channel, again, dependent on your time correction settings.

 

Lets take a sound track that contains two big drums in a hall, placed in the left and right (all else being equal), both striked together. A mono sub signal will reach the listener at the same time, regardless of whether the left or right drum is hit.

 

As oppose to mono, stereo signal allows time correction to be done on the subranges for both left and right. Thus, theoretically, stereo sub signal provides more imaging than that of mono. i.e. it enhances the left and right drum imaging.

 

Therefore, for SQ folks, to obtain the correct front staging and imaging, and is coherent with the subranges (where the sub is placed in the boot), stereo sub signal is recommended.

 

Whereas, for SPL, where subranges should be felt completely in a car acoustic (or fill up the whole car, such that the rear passengers can experience the subranges), mono signal is recommended.

 

Confused?

[Kermit]

Yes! This may well be it...If I understand what you're saying correctly, without individual channels output to be fed into the sub (single or otherwise), we'll have time correction problems when the bloody instrument that is producing the subrange is placed anywhere but centre of the stage.

 

No wonder...NB my HU gives me only mono sub out and I find it so difficult to achieve nice imaging for big big instruments!!!! "Chase the Goat" in "Swaying Grass"!....

[Wankie]

[Ractis]

I'm using the p80rs, it has stereo out for the sub signal, but there is an option to make it mono. In my case I should think time and phase correction are applied only after summing the stereo to mono, therefore I should still be able to adjust delays, phase, attentuation etc individually for each channel even though they have the same signal

 

Not sure about kermit's case. If you only have a mono rca out then obviously there is no further tweaking possible?

[Kermit]

Ya lah ya lah...must you rub it in????

 

nottie boy....

[Sarong1]

Not the first time you know Ractis.

[Sarong1]

I know P80RS has both options.You will need to try it out in both stereo and mono to feel the diff, provided the current setting is an accurate depiction of the intended information.

 

In Kermit's case, I have always pondered why his HU has not sub TA, only phasing was available. After knowing that his HU has only a sub mono out, everything else falls in place as what is discussed.

[Kermit]

My sub phasing power one leh...got -135, -90, -45, 0, 45, 90, 135, 180....so many settings one leh...nobody has one ok....

 

I hope this will make me feel better...

[Sarong1]

Hmm...quite right...I think the term "tranny" best suit your current setup now...because you have the best of both worlds..

[Coolbreeze90]

Having gone through 4 months of ICE, i realised that every single component in the setup is a study on its own and for subs, it is also a mystery... Well at least or me....

 

Having gone through tonight's meet up session, i understood much more than before at the same time, also much more cunfuse than before...

 

Having read sarong's explanation, it makes sense but is there another reason behind this choice of mono and stereo?? Anyone else care to explain???

 

For newbs who happen to read this post, just a warning before you get into ICE, it is extremely poisonous... I have been poisioned badly....