Does a sub supplement or replace?

[Dan Twomey]

Basic subwoofer question. Should I tune my subwoofer to supplement the lack of low frequency on my mains
or use a high pass filter on my mains and let the subwoofer produce all low frequencies? What is the 'normal' accepted practice?

Regards,
Dan

 

[Tony V.]

Hello Dan, Normal practice is to let the subwoofer take the lows on its own as its going to to reproduce those frequencies much better than the speakers would in most casses

 

[JStewart]

Using a crossover of typically 60 to 80Hz has the benefit of reducing the demand on the mains amplifier and very likely benefit of reducing distortion at the lowest frequencies the mains can produce.

 

[ddude003]

If this is for a Stereo Music system then I would Crossover the Subwoofer about 10 to 15 Hz above the roll-off point of the Mains... Supplement...

If this is for an AudioVideo system then you might High Pass the Mains and let the Subwoofer do the heavy lifting down low... You may have a way to set your Mains to "Small" in the AV Pre/Pro to accomplish this... Replace...

 

[Dan Twomey]

Here's a basic sweep of my two mains. My goal here is to integrate my sub into a nice music system with a house curve.

 

[ddude003]

Not knowing anything about your system, I would start at 35Hz and move up a few Hz at a time to see how it sounds and blends... You could also use REW to see how it blends too... You will have to adjust volume/gain a bit along the way too... I would stop short of 100Hz as this is were you start to get some localization... This is not about getting a pretty picture... It is about how it sounds to you in your room with your kit... Have fun and listen to some of your favorite music as you do this...

 

[JStewart]

You could also use REW to see how it blends too...

Specifically REW’s Alignment Tool which will allow you to see spl and the effects of phase (delay or distance changes) through the transition range.

 

[Johnnie]

Here's a basic sweep of my two mains. My goal here is to integrate my sub into a nice music system with a house curve.
View attachment 38807
[/QUOTE]
You’ll want to set your graph up first to read your room better.
Select ”All SPL” so you can see all your sweeps together and set your “graph limits”. I usually pick my noise floor, 35 or 40 hz and about 10hz above the highest peak. Also your beginning and end frequency, like 20 to 20000hz
PS; there is an initial shock as to how bad our sound looks on a graph. But that’s what we’re trying to make better.

 

[highstream]

I’ve found that there are two schools of thought about sub crossover points. One says to set the point high, say 80 Hz, and let the sub(s) do its thing. The other says that there’s a reason why one likes their main speakers, so set the crossover point where they start to roll off (Likewise, there are differing views on whether to add an external crossover or to let the main speakers’ low end roll off naturally). I’m inclined to the latter view, but try both and see what you like. In either case, the point, at least in an audio system, is to extend the low end seamlessly, so the sub(s) seem to disappear.

 

[Johnnie]

Actually every system is different but you’re missing the elephant in the room, which is the room itself. The room will dictate where your crossover is best and to make this the best possible scenario is to have two or more subs on opposite sides of the room so when the crossover points reach higher than 80 Hz you still can’t tell where the bass is coming from. And the “only” way you can tell is to measure the different settings using REW.
The rabbit hole is deep

 

[polorolo]

If this is a stereo system don't ruin it by adding a sub at all for music. It seems to have a good bass response as it is. If this is for music leave well alone.

 

[MediumRare]

If this is a stereo system don't ruin it by adding a sub at all for music. It seems to have a good bass response as it is. If this is for music leave well alone.

wow, with all due respect, you are 100% wrong. I rarely say that

@Dan Twomey: Properly adding one (or up to four!) subs to even very good-sounding mains is always a plus because, aside from filling in the frequency response down to 20 Hz and pressuring the room for full bass impact, a sub + mains provides smoother bass response, minimizing room nulls. The other responders to your question are giving good advice.

 

[BenToronto]

Using a sub since 1968, no direction loss on music with XO at least as high as 130, providing slope is sharp and speakers not producing harmonics to tattle. Mixed-bass signal prolly better than stereo signals if using multiple subs.

Any bass you can keep out of the main speakers will be beneficial to their performance.

You can use small sized main speakers and then locate the sub (or better, subs) in best location for acoustics (use REW of course) and decor.

 

[JStewart]

I personally think a sub, if it can be well integrated is the better choice. At the same time I recognize there are instances where others will think mains only sound better. And they may be right due to their preferences or an obstacle to good sub integration.

It’s likely a moot point though since the OP seems to have a sub already. His question was should he use the sub to fill in the missing lows or use use a high pass on the mains (and I assume a low pass on the sub, i.e. a crossover. )

@Dan Twomey , Either can yield good results or not, depending on your limitations. There are additional benefits to the XO approach that have already been mentioned and are perhaps not meaningful to you. So I suggest to pick either one and give it a go. You can always try the other too and then choose what sounds best to you.

 

[Head_Unit]

What is the 'normal' accepted practice?

To argue about it endlessly
What nobody has brought up yet is that it depends on the excursion and tuning of your mains: CRANK THEM ON UP, how do they sound? If fine, highpass crossover-less is OK. If they distort, it would be foolish to not have a highpass because the sub won't help that, maybe just mask the crud.
- Highpass can reduce the thermal load on the amp, BUT not necessarily the clipping, since some more recent investigations have shown that the highpass filtering "slew rate"* can increase the peak voltage which cutting the lows reduces. (*that's NOT the right phrase)
- Your mains go very low, so some might cross over the sub very low and as noted "let the mains do their thing." However you have not mentioned anything about room correction software-is there any in your amp? In the sub?
[seems I'm too new to post a link but search stereophile dot com jl-audio-fathom-f110v2-powered-subwoofer-measurements
shows a contrary case, with JL recommending that if there is no correction on the mains, to run the subwoofers much higher than usual so their correction can help up into the midbass.

 

[JStewart]

To argue about it endlessly

 

[Kal Rubinson]

Hello Dan, Normal practice is to let the subwoofer take the lows on its own as its going to to reproduce those frequencies much better than the speakers would in most casses

Yes. And they do so because they are purpose-built for extended low frequency performance and because they can be placed for optimal low frequency performance. Main speakers are generally (and appropriately) placed to optimize imaging and wide-spectrum balance.

 

[Sonnie]

I typically set my crossover about one octave above their rated low-end response, provided the measured response shows they can produce that crossover frequency adequately. However, I try to keep it at a max of 80Hz so that the bass does not become directional. Currently my mains are rated down to 22Hz (they happen to have two 12" powered woofers), and I use a crossover frequency of 50Hz because their roll-off in the room starts at about 40Hz and I don't want to have to boost any of those lower frequencies. They roll-off considerably because they are pulled out a good distance from the room, as Kal mentioned, for the best imaging, sound stage and depth acuity.

I play a LOT of music that has response down in the teens and 20Hz range, so a subwoofer is very much needed and I suspect my SB16-Ultras are probably about as clean as any speaker when it comes to frequencies below 80Hz.