Subwoofers in stereo connection

Teo

Well-known member
Nov 13, 2013
75
3
18,545
Hello
I have an active sub added to my bookshelves speakers connected thru the high level output of the amplifier ( aka the speakers output) . Works fine , it changed the sound ,added just a bit of bass where I needed . I cut the frequency at about 75-80 HZ and the Volume at about 35%.

I Want to change and make some upgrades of the system with minimum cost . For the beginning I want to buy another sub ( same brand and type) and use in stereo configuration .I hope it would enhance the stereo imaging and the accuracy of low frequencies .
In the same time , I want to try to connect the subs in a different manner , using the PRE OUT output of my Consonance A100 linear amp ( it desn't have a dedicated subwoofer output).
So , I think I should use two subwoofer dedicated RCA-RCA sub cables , one for the left and other for the right Pre output , ending each at one sub . But at the subwoofer end this cable should be connected only one or to both input RCA ( red and white , using a Y splitter ) ?
 

dkontos

Well-known member
Apr 24, 2021
56
10
545
Hello
I have an active sub added to my bookshelves speakers connected thru the high level output of the amplifier ( aka the speakers output) . Works fine , it changed the sound ,added just a bit of bass where I needed . I cut the frequency at about 75-80 HZ and the Volume at about 35%.

I Want to change and make some upgrades of the system with minimum cost . For the beginning I want to buy another sub ( same brand and type) and use in stereo configuration .I hope it would enhance the stereo imaging and the accuracy of low frequencies .
In the same time , I want to try to connect the subs in a different manner , using the PRE OUT output of my Consonance A100 linear amp ( it desn't have a dedicated subwoofer output).
So , I think I should use two subwoofer dedicated RCA-RCA sub cables , one for the left and other for the right Pre output , ending each at one sub . But at the subwoofer end this cable should be connected only one or to both input RCA ( red and white , using a Y splitter ) ?
Which sub is it ?
 

abacus

Well-known member
Sep 24, 2008
765
451
19,270
Does the sub have a dedicated LFE input or one of the stereo connections marked for LFE, if so use this instead of using a Y connector, if not just connecting to the left channel of the stereo input should be fine, but if you feel happier using a Y connecter do so as you shouldn’t notice any difference. (I am assuming the sub has both high level (Speaker) and low level (RCA) inputs)

Bill
 

Teo

Well-known member
Nov 13, 2013
75
3
18,545
Does the sub have a dedicated LFE input or one of the stereo connections marked for LFE, if so use this instead of using a Y connector, if not just connecting to the left channel of the stereo input should be fine, but if you feel happier using a Y connecter do so as you shouldn’t notice any difference. (I am assuming the sub has both high level (Speaker) and low level (RCA) inputs)

Bill
It has Left/right input low level Line in
 

Teo

Well-known member
Nov 13, 2013
75
3
18,545
Given that bass is largely non-directional, I'm puzzled why you'd choose this as a first solution. I can't see it helping with stereo imagery.
I wanna argue with my wife about WAF theory and practice on my living system !:)
There is a whole debate on the non -directional bass . and because the ''largely'' but not ''absolutely'' , I wana try this .
And my Magic 8 sub is a bit lonely , he's ok with the Eposes , but he'd love one of his own.;)
 

SeattleChris

Active member
Apr 15, 2021
19
8
25
Hi Teo - hopefully the link below works to a prior post of mine on the subject. I did what you are contemplating, left pre-out to left sub and right pre-out to right sub. Split each RCA cable at the subwoofers and use both inputs for a free boost in performance. Dual subs help with bass "peaks & nulls" in your room, and I believe it may even help with the soundstage as well but admit it might be the placebo effect.

 

AJM1981

Well-known member
Mar 26, 2021
337
89
970
Here it depends

If you have speakers that go low, 2 subs are not necessary. Unless you use it for a purpose like stabilizing the output. Because as mentioned before here its output at the lowest frequencies is non directional.

You could in theory have dual subs for stereo when you use satellite speakers that cover mainly the upper mids and treble. Then the sub is playing full range till the lowest midrange frequencies. I never tried a configuration like that, but it can be interesting.
 

SeattleChris

Active member
Apr 15, 2021
19
8
25
While the low sub bass is surely non-directional, when you set the low pass filter at 80Hz (common) that's only where it starts to roll off at a certain dB/octave slope and the sub is still producing sound well above that depending on slope. If I'm actively listening from a center position I believe I can hear if a single sub set at 80Hz is off-center. This is why I feel dual subs improve the soundstage in addition to the "peaks & nulls" correction. I wired mine stereo rather than dual mono just in case that helps any further.
 

AJM1981

Well-known member
Mar 26, 2021
337
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970
While the low sub bass is surely non-directional, when you set the low pass filter at 80Hz (common) that's only where it starts to roll off at a certain dB/octave slope and the sub is still producing sound well above that depending on slope. If I'm actively listening from a center position I believe I can hear if a single sub set at 80Hz is off-center. This is why I feel dual subs improve the soundstage in addition to the "peaks & nulls" correction. I wired mine stereo rather than dual mono just in case that helps any further.
I don't know if that is a good idea. Dual subs are also a thing in marketing to just sell you more subs. Yes, in some cases it might work. But these are usually big exceptions on general conditions.

I have quite large standmounts that go pretty deep and my B&W sub only rarely kicks in. (With a bottom limit of around 23hz depth, playing Max Richters Sleep is like a small audio experience) The speakers themselves offer a great soundstage and the sub is totally not pulling that soundstage away while turned on. I don't think a second B&W sub will do anything to the soundstage, but it will perhaps create a bit more sense of bass.. if my room would be big enough for the effect to make sense.

Also take notice at this practical experiment and notice that expected positive measurements failed and made the writer go back to a single sub configuration.


Maybe a nice experiment when one can borrow a sub. But I would not buy one to discover it doesn't improve anything and having it on sale again 3/4 price.
 
Last edited:

Tinman1952

Well-known member
May 19, 2021
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While the low sub bass is surely non-directional, when you set the low pass filter at 80Hz (common) that's only where it starts to roll off at a certain dB/octave slope and the sub is still producing sound well above that depending on slope. If I'm actively listening from a center position I believe I can hear if a single sub set at 80Hz is off-center. This is why I feel dual subs improve the soundstage in addition to the "peaks & nulls" correction. I wired mine stereo rather than dual mono just in case that helps any further.
Exactly so. Having more than one sub is about correcting for standing modes 'peaks' and cancellations in the room, not stereo imaging or 'more bass'. There is a famous study which found the best solution is to have a sub in each corner! Try getting 'significant other' approval for that! 😁
 
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AJM1981

Well-known member
Mar 26, 2021
337
89
970
Exactly so. Having more than one sub is about correcting for standing modes 'peaks' and cancellations in the room, not stereo imaging or 'more bass'. There is a famous study which found the best solution is to have a sub in each corner! Try getting 'significant other' approval for that! 😁
Indeed

Plus that a room needs to be of cinema-like proportions for subs to really display this correcting effect for the people sitting at different places. Maybe a solution for the happy few or actual cinemas.

Marketing did its work well given average earners mentioning that two subs is best and companies will 'off course' always show a setup with two subs on their product pages. Hifi stores are happy to have customers buying a second one.
 

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