Why Every Man Needs Two Subs for Stereo

[heliumflight]

H Guys,

Trying to gain some knowledge about Subwoofer from you all. I have Nad Power Amp & Ar2ax speakers. I wanted to know if it is wise move to add a a pair of subs. In two minds, left part of my mind says that having single sub doesn`t make them stereo, stereo is a dedication of 2 separate left and right channels whereas the sub channel is a dedicated sub frequency mono channel. The right side of my mind wonders whether it is stupidity, ignorance or perhaps people who own 2 mono subs do not want to know whether stereo is actually detectable after spending a lot of money on their setup.

Any HFM having similar experiences may please enlighten so that I can take an informed decision.

Read a few articles and came across an interesting read - Stereo Subwoofers
- http://kenrockwell.com/audio/stereo-subwoofers.htm

HiFi: Asus Xonar STX Sound Card > JRiver > Nad 2240PE > AR2ax Speakers

 

[sound_cycle]

Hi,

I am curious.

Sound localization is based on phase and amplitude difference. The method the brain applies is not uniform across frequencies. Above 1600 Hz (IIRC) it is amplitude. Below 800 Hz it is phase.
Below 100 hz the ability of the brain / ear for sound localization becomes very low.
That is higher than the range you might want to use your sub at.
When the directional clues that are important for localization do not apply how do you create the stereo illusion ?


ciao
gr

 

[elangoas]

Am not accomplished with technical terms, so i will put it simply from my experience having used multiple set-ups in the same room..

From 2.0 to 2.1 to 2.2 with & without EQ ( Audyssey XT32), 2.2 is the most satisfying stereo experience in my room so far.. (In the process of getting my speakers positioning right..)

One of the reasons, which i think is due to the flexibility in adjusting the SPL of the bass from dual subwoofer, which can't be achieved with a FS/BS..

 

[Hari Iyer]

If i have to use a single sub then i should be having the flexibility of putting them in between the left and right speakers so that the lows are equally getting distributed on both sides of the room. Also this reduces directional cues (if any) and reduces boom and helps in better center imaging imo.

 

[prem]

If you are using a single sub it normally works best in one of the corners.

 

[Hari Iyer]

How about in a small room like mine? If my room is around 10 feet wide IMO the low freq loss would not be more for a mean distance of 5 feet in-between the two walls. For larger rooms i agree the mid room placement would not work. The only way to find out is check it out.

 

[prem]

Normally Hari, a single sub works in corners. But yes trying it out at various positions is the best way out. IME adjusting the sub crossover and vol level for 2 channel music is not easy. You need to clearly know what to listen for.

 

[elangoas]

If i have to use a single sub then i should be having the flexibility of putting them in between the left and right speakers so that the lows are equally getting distributed on both sides of the room. Also this reduces directional cues (if any) and reduces boom and helps in better center imaging imo.

How about in a small room like mine? If my room is around 10 feet wide IMO the low freq loss would not be more for a mean distance of 5 feet in-between the two walls. For larger rooms i agree the mid room placement would not work. The only way to find out is check it out.

Am saying this from what i have read..Placement of single sub is better, where it is has a smoother/flat response (REW).. So you will need to measure it at multiple locations & then decide on placement based on response..

 

[elangoas]

Normally Hari, a single sub works in corners. But yes trying it out at various positions is the best way out. IME adjusting the sub crossover and vol level for 2 channel music is not easy. You need to clearly know what to listen for.

Quoting this, only as an example and for better understanding..

Ex.. 2.1 set-up with AVR.. Most have auto calibration, which set the 75 dB SPL for the speakers from listening position.. So the sub & speakers are level matched..Assuming one uses 80Hz crossover on AVR, is the user missing anything?

 

[heliumflight]

@Hari Sir. is a TL sub design easily to integrate than traditional bassreflex sub? What are benefits and weaknesses over the latter?

 

[anirudhchandrashekar]

I think I had auditioned a dual sub setup. Felt more gelled-in and dynamic

 

[newlash09]

I've never heard a dual sub setup so far. But again most stereo Amps come with one sub out. And using y splitter to distribute it to 2 subs in not going to help in sound separation, unlike the main speakers which renders a stereo image.

But if we were to use a avr with 2 sub outs, understand that audessey xt32 EQ's both indipendently. But does it also take the sub cross over frequencies from the left and right channels and pass it on to the left and right subs ?

If it does this, then maybe just saying maybe there will be some improvement with imaging and sound stage definition. But I really don't know if this is possible.

But Iam right intrigued by the idea of 2 subs for stereo setup. We all love adding more to our setups don't we

 

[elangoas]

But if we were to use a avr with 2 sub outs, understand that audessey xt32 EQ's both indipendently. But does it also take the sub cross over frequencies from the left and right channels and pass it on to the left and right subs ?

Yes.. It would.. We set the individual crossover for all channels, anything less than that will be directed to sub(s)..

But Iam right intrigued by the idea of 2 subs for stereo setup. We all love adding more to our setups don't we

You already have the AVR with capabilities of handling dual subs.. You should consider one..

 

[Hari Iyer]

@Hari Sir. is a TL sub design easily to integrate than traditional bassreflex sub? What are benefits and weaknesses over the latter?

Bass reflex sub can have a single note bass at the port tuning frequency and hence the sub can boom at that single note as the air velocity and the system output is high at that particular frequency than the entire band from 20Hz to 100Hz


A TL sub even if its mass loaded and has high damping does not have a single note response. Also in a ML TL the enclosure needs to be reasonably stuffed for 70% of the box for minimizing or removing the odd harmonics. Hence the TL sub will have a smooth and punchy bass in its band width.

Integration of the sub to the main speaker and the room has more to do with the phase response. Hence having a continuous variable phase control is much better than having just a 0 Deg and 180 Deg phase switch. Even with the variable phase control you can get phase coherency only for a narrow band of frequency by varying the phase control. For other frequencies the system will still be out of phase for common frequencies and cancel out.

Hence imo putting a subwoofer and expecting it to solve all your low frequency worries is a misnomer. After installing the subwoofer, consider yourself lucky if you can find the sweet spot and got the level, crossover frequency and phase issues sorted out soon. Else you are heading for more nightmare than before to deal with another set of speaker system.

My 2 paise again.

 

[square_wave]

https://www.youtube.com/watch?v=SCWL-zusyqw

Earl Geddes did a phd in this subject.. multiple subs is the way to go.