Basic subwoofer question

MickyP

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Apols for low tech question but could someone explain in layman's terms why adding a subwoofer enhances the bass and doesn't just add more or deeper bass to the bloated bass your speakers are already outputting? Or maybe outputting. I mean, the woofers are still putting out the same amount of oomph, are they not, with or without a sub?

Thank you!
 

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It’s all down to how you set up the sub …needs careful gain adjustment and a cutoff frequency to integrate with your main speakers. Access to REW and a measuring mic are essential imho.
 

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Apols for low tech question but could someone explain in layman's terms why adding a subwoofer enhances the bass and doesn't just add more or deeper bass to the bloated bass your speakers are already outputting? Or maybe outputting. I mean, the woofers are still putting out the same amount of oomph, are they not, with or without a sub?

Thank you!
If your main speakers have ‘bloated bass’ then it probably isn’t a good idea to add a sub. I think it is a good idea to treat the bass with bass traps before adding subs. Even small subs go down to about 30hz - I have tiny REL Tzeros and they have some output that low. Unless you have large floor standing speakers driven by a powerful amp, they are unlikely to go as low, be as dynamic and resolving as even a quite small sub. When I recently added pairs of subs to a couple of my systems the sonic improvement wasn’t just in the bass, they improve the midrange and imaging as well.
 

MickyP

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Thanks both, but what I'm struggling with is the existing woofers, surely, put out the same as they did with or without a sub, so whatever the sub adds will be compounded to the overall bass output. Or does the crossover adjustment wind in the woofers, or deploy some other witchcraft?
 

rdale

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Thanks both, but what I'm struggling with is the existing woofers, surely, put out the same as they did with or without a sub, so whatever the sub adds will be compounded to the overall bass output. Or does the crossover adjustment wind in the woofers, or deploy some other witchcraft?
My Klipsch stand mounters drop off quite sharply at about 40hz, and so I’ve set the REL T5x crossover so that it comes in below that. There is often a big suck out below 100hz caused by the floor intereracting with the bass of stand mounts, and having a couple of subs can help even that out if you set the crossover to partly overlap with the mains.
 

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Can you describe how your speakers sound, I wouldn’t describe your speakers as having bloated bass if that’s what you think??.
 

Lawrence001

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Apols for low tech question but could someone explain in layman's terms why adding a subwoofer enhances the bass and doesn't just add more or deeper bass to the bloated bass your speakers are already outputting? Or maybe outputting. I mean, the woofers are still putting out the same amount of oomph, are they not, with or without a sub?

Thank you!
Some subs have a speaker level in/out that takes the amplifier output, drive the sub from it and send out a signal without the bass, effectively an active high pass crossover. That will solve the bloat, as would DSP/active crossover at the amp stage.
 

MickyP

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Can you describe how your speakers sound, I wouldn’t describe your speakers as having bloated bass if that’s what you think??.
Hi
I was asking how subs interact with woofers not for a view on my main room speakers, but thanks anyway!

So... some have a high pass filter. I get that (thanks Lawrence), but what if they don't? Is it just a case of producing more articulate lower frequency info at lower volumes, so main woofers are called into play less?
 

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Find a manual for a REL Studio or Stentor online and the blurb includes how to connect (high and low) and the whys and wherefores (and pitfalls) of integrating a sub into your system. I don’t think any of us here will explain it better.
I’m sure measurement makes it easier but it’s perfectly possible to integrate effectively using your ears and a bit of patience.
 
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Pedro2

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Hi
I was asking how subs interact with woofers not for a view on my main room speakers, but thanks anyway!

So... some have a high pass filter. I get that (thanks Lawrence), but what if they don't? Is it just a case of producing more articulate lower frequency info at lower volumes, so main woofers are called into play less?
Your second paragraph (nearly) hits the nail on the head in that the aim of a sub is to produce articulate bass below that produced by your main speakers’ woofers. However, it should be at all volumes, rather than just at low settings.

The problem with integration is that where overlap occurs, this can accentuate certain frequencies and produce a ‘bloated’ bass sound that makes overall sound quality worse rather than better. If your system has no way of high passing your main speakers, you are reliant on only using low pass (on the sub itself) and setting it at or around where your main speakers tail off. Depending on your speakers, this can range from 50-60 hz for small standmounts down to 30 hz for others.

If you are able to high pass, you can make a sub work up to 80hz or above - modern subs can achieve this easily, and your main speakers can then concentrate on producing mid/upper bass. Most, but not all subs are active, so they have their own dedicated amp to do one job only.

It’s worth hearing a well integrated system with low and high pass filters driving one or two subs as well as the mains. I would not want to part with my sub which works really well with small active stand mounts. The retailer that supplied my sub actually uses subs across a wide range of systems, including large ATC floor standers - he is convinced that when done properly, they improve overall sound quality. I have no reason to believe he’s not right.
 

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Thanks both, but what I'm struggling with is the existing woofers, surely, put out the same as they did with or without a sub, so whatever the sub adds will be compounded to the overall bass output. Or does the crossover adjustment wind in the woofers, or deploy some other witchcraft?
Once I had some small speakers with a slightly raised bass. I made a sub, and serendipitously their relative phase cancelled out to smooth.the transition, resulting in a nice smooth response.
Better subs have phase reverse switch and some even have a variable phase control to help the meeting of the two.
 
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Rayymondo

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If your amp doesn't have bass management - you won't be able to cross the speakers and sub over at a given frequency so in that scenario your main speakers and sub could well be both playing the same notes at a certain frequency. What I do (using the pre outs of an integrated amp) is set the sub to it's lowest setting which in my case is 60Hz (my mains are quoted down to 58 but in reality will be going a bit lower with the ports and boundary walls etc to reinforce.) I then have the gain setting on the sub quite high, about 3/4. This way the sub will kick in where the mains are fading out and you should be able to get a good transition between them and not experience a "hole" in the bass. However, if your main speakers boom at a certain frequency a sub won't solve that problem - unless as mentioned above and by others you have some kind of bass management on your amp (this feature is more common on home cinema type amps)
The above is to the best of my knowledge as I have been on a steep learning curve with subs since Christmas when I purchased one for myself. It did take a lot of faffing about but I think I got it about right in the end - although I still fiddle with it on occasion just to check!)
 

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As mentioned the mains should be high-passed, also ideally a pair of subs and a mic should be used.
 
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Lawrence001

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Once I had some small speakers with a slightly raised bass. I made a sub, and serendipitously their relative phase cancelled out to smooth.the transition, resulting in a nice smooth response.
Better subs have phase reverse switch and some even have a variable phase control to help the meeting of the two.
I can't see how having the sub at opposite phase to the main speakers can sound good. Suppose you did set the volume of the sub so that it just cancelled the "excess bloat" of the main speakers, you would still have an out of phase bass signal below that which would drive me nuts in a very short time!
 

dave

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I can't see how having the sub at opposite phase to the main speakers can sound good. Suppose you did set the volume of the sub so that it just cancelled the "excess bloat" of the main speakers, you would still have an out of phase bass signal below that which would drive me nuts in a very short time!
More subtle than that, and completely accidental, The "sub" was a home made bass guitar amplifier with an 18" fane driver. I had to do opamp low pass filter EQ to get it to go flat up to 100 Hz and then it naturally rolled off, I can only guess the phase difference was about 90o, but was a partial, not total cancelation. At the time, late 90s, I had a BSS Varicurve and microphone, so I could measure ;)

607881ee-5dba-4a72-a0cf-4e471e82a153-1.jpg

https://gearsource.com/product/fcs926-varicurve-equalizer-analyzer-master-bss/
A very nice toy incorporating a 1/3 octave RTA. Microphone at my listening position, flat 20Hz-20kHz (no eq). I have never again achieved that natural un-forced effortless bass, (room 10 x 11 ish feet) but I am working on it.
 

Pedro2

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More subtle than that, and completely accidental, The "sub" was a home made bass guitar amplifier with an 18" fane driver. I had to do opamp low pass filter EQ to get it to go flat up to 100 Hz and then it naturally rolled off, I can only guess the phase difference was about 90o, but was a partial, not total cancelation. At the time, late 90s, I had a BSS Varicurve and microphone, so I could measure ;)

607881ee-5dba-4a72-a0cf-4e471e82a153-1.jpg

https://gearsource.com/product/fcs926-varicurve-equalizer-analyzer-master-bss/
A very nice toy incorporating a 1/3 octave RTA. Microphone at my listening position, flat 20Hz-20kHz (no eq). I have never again achieved that natural un-forced effortless bass, (room 10 x 11 ish feet) but I am working on it.
Interesting. What were your main speakers that the sub was paired with?
 

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Various ways to integrate subs with mains. Using a miniDSP as a crossover and for EQ works well and is useful if you have a sub without continuously variable phase control and built in EQ. Generally speaking, when using a miniDSP, possibly with Dirac, the benefits far outweigh any very slight deterioration in sound quality which adding the to the chain the unit may impart. Using Dirac can make the sound flat and uninvolving but with care in setting it up it isn’t inevitable and it can give excellent results.

Another very effective way, and the one I am using at present, is to run the main speakers full range and use the sub out of phase with speakers at a hump in the frequency response. This can smooth out the frequency response and extend the bass into lower frequencies. This does require a decent subwoofer with continuously variable phase control, probably built in EQ and some experimentation with relative distances of sub and mains to listening position. It might be possible to get a reasonable result by ear, but measuring with REW is all but mandatory for the best results. Whilst an excellent result can be had at the listening position the bass may not be so good at other positions in the room.
 
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