[Stephan Mire]

I know folks tend to use subwoofers for movies and/or 50/50 split but what I would like to know from the experts is if there are any solid arguments for using subwoofers strictly for 2 channel.

I don't believe there is much subsonic content for music so bass extension isn't really much of an advantage in my mind, so then what is the point of using subwoofers in a stereo only system? Let's assume you have full range mains.

Any advantage/disadvantage to using subwoofers for music?

 

[Adamg (Ret-Navy)]

I know folks tend to use subwoofers for movies and/or 50/50 split but what I would like to know from the experts is if there are any solid arguments for using subwoofers strictly for 2 channel.

I don't believe there is much subsonic content for music so bass extension isn't really much of an advantage in my mind, so then what is the point of using subwoofers in a stereo only system? Let's assume you have full range mains.

Any advantage/disadvantage to using subwoofers for music?

Hi Stephan,

Great questions. The first and sometimes forgotten element about adding powered subs is how using the AVR crossover settings can redirect a large chunk of power offloaded from the AVR to Powered Subs amp. This results in more amp power available for the Main Speakers. Added head room and reduced distortion. In effect the low end of the FR requires the most power. So it’s like adding pre-amps to your system. Powered Subs will outperform Fullrange speaker in all cases, unless the Fullrange speakers have a power cord and a onboard amp to drive the woofers.

Powered Subs have very powerful amps just to drive that one driver. They make a huge difference. Biggest single improvement I ever experienced.

 

[DonH50]

Up to you to define "much subsonic" and it depends how low, and how well, your "full-range" main speakers go.

Organ music, symphonic music, drums, piano hammer strikes, plucked strings, etc. all have content well into the subwoofer region. Most speakers distort significantly when presented with large bass signals anywhere near their -3 dB point.

I first added a DIY servo sub to my system around 1979. I had Magnepan MG-I's that spec'd 50 Hz LF corner. I found the sound and measured performance was much improved with a sub, and was still much better when I upgraded to MG-IIIa's, with a 35 Hz corner, about a decade later. More/better bass and the upper frequencies were better because it wasn't handling the deep bass. My impression did not change as I rotated through some full-range Infinity and KEF speakers during that time frame, plus a number of other speakers (B&W 800-series etc.) that were in my system for brief trials. This was all well before HT was a thing. My listening tastes were primarily classical and jazz with a fair amount of rock (mainly progressive rock like Pink Floyd and Yes) and country mixed in.

I have had sub(s) in my system most of the time since then, and the few times I have not for whatever reason, I have always been much happier when they were added again. Even with music that extra lower octave or three seems to help support the rest of the music.

Remember subs also allow the in-room response to be flatter/better; the best place for the subs and deep bass is rarely the best place for stereo imaging IME.

The biggest counter argument I have read is the limited amount of LF energy on some recordings. Maybe I just tend to get better recordings as I have not noticed a lack of sub-50 Hz bass. Note the low E on a guitar is around 40 Hz, the lowest string on a standard piano is around 27 Hz, and percussive from drums and such reach into single-digit territory, so there is stuff there to be recorded.

IME/IMO - Don

 

[HarleyRider]

I have tried to go the "purist" route and use only my towers for 2-channel music, but I always felt like I was missing something. No mater how low they were rated to go they were no substitution for my good old 15" servo controlled sub. It can be a lot of work and a lot of trial and error to get the sub(s) seamlessly integrated (at least it was for me), but the payoff is worth it.

 

[Stephan Mire]

Up to you to define "much subsonic" and it depends how low, and how well, your "full-range" main speakers go.

Organ music, symphonic music, drums, piano hammer strikes, plucked strings, etc. all have content well into the subwoofer region. Most speakers distort significantly when presented with large bass signals anywhere near their -3 dB point.

I first added a DIY servo sub to my system around 1979. I had Magnepan MG-I's that spec'd 50 Hz LF corner. I found the sound and measured performance was much improved with a sub, and was still much better when I upgraded to MG-IIIa's, with a 35 Hz corner, about a decade later. More/better bass and the upper frequencies were better because it wasn't handling the deep bass. My impression did not change as I rotated through some full-range Infinity and KEF speakers during that time frame, plus a number of other speakers (B&W 800-series etc.) that were in my system for brief trials. This was all well before HT was a thing. My listening tastes were primarily classical and jazz with a fair amount of rock (mainly progressive rock like Pink Floyd and Yes) and country mixed in.

I have had sub(s) in my system most of the time since then, and the few times I have not for whatever reason, I have always been much happier when they were added again. Even with music that extra lower octave or three seems to help support the rest of the music.

Remember subs also allow the in-room response to be flatter/better; the best place for the subs and deep bass is rarely the best place for stereo imaging IME.

The biggest counter argument I have read is the limited amount of LF energy on some recordings. Maybe I just tend to get better recordings as I have not noticed a lack of sub-50 Hz bass. Note the low E on a guitar is around 40 Hz, the lowest string on a standard piano is around 27 Hz, and percussive from drums and such reach into single-digit territory, so there is stuff there to be recorded.

IME/IMO - Don

Hi Don, thanks for your post! Some people I have discussed the matter with seem to think that subwoofers are designed almost exclusively for movies. How many times have you heard someone say "subwoofers are designed for home cinema". I've heard it a lot!

I don't know where this perception came from.

A friend of mine tells me that careful placement of his speakers in his room can reduce the effect of standing waves.

 

[m. zillch]

I know folks tend to use subwoofers for movies and/or 50/50 split but what I would like to know from the experts is if there are any solid arguments for using subwoofers strictly for 2 channel.

Subwoofers generally cover frequencies below 80Hz or so, and are beneficial to the reproduction of sound, including all genres of music, but they aren't as necessary if one uses large, floor standing towers as they are for smaller speakers because big towers already can go well below 80Hz (although only a handful go flat all the way down to 20Hz and below like many subs can).

Erase from your mind it has anything to do with "video". That's marketing BS.

Another common ploy they use is to pooh-pooh subs because they generally make more money selling a consumer two large towers than they do a sub and two bookshelf speakers. Also having a consumer aware of the concept of "bass management" sudden kills their profits in general. If a consumer no longer feels a need to buy speakers that go much lower than 60/80Hz, or so, then the dealer ends up selling markedly less expensive speakers to them.

You need subs for jazz, rock, and classical 2ch music unless you have gigantic towers.

 

[emcdade]

Subwoofers make big BOOM for Transformer movie. Subwoofer is good.

 

[Ratman]

Back in the old days, before AVR's and "home cinema"... there were subwoofers for stereo audio.

 

[DonH50]

Hi Don, thanks for your post! Some people I have discussed the matter with seem to think that subwoofers are designed almost exclusively for movies. How many times have you heard someone say "subwoofers are designed for home cinema". I've heard it a lot!

I don't know where this perception came from.

A friend of mine tells me that careful placement of his speakers in his room can reduce the effect of standing waves.

Thank you and you are very welcome!

I don't either. Subs have been around (and their benefits known) for a long, long time (decades). I first heard them with ESLs and the HQD system, even before small'ish bookshelf speakers became the rage. Nor do I understand why room correction improves the sound so much for movies but is somehow detrimental to music. My room greatly benefits from treatment and room correction SW and neither it nor my ears care if it is a movie or music playing.

Moving a speaker can reduce the effect of reflections (SBIR) and room modes (true modes occur in the bass region and are related to room dimensions). The problem is that it is a rare room that speakers placed for best imaging and soundfield is also the best place to counter room modes even if the main speakers reach deep enough. I have owned planar dynamic speakers (Magnepans) most of my listening life and placement and toe-in was critical but not for room modes; more for comb-filter effects from the back wave when I couldn't (or didn't) damp it.

It is also worth remembering that crossovers do not drop to zero on ether side. Given an 80 Hz crossover there can still be significant energy in the mains down to 40 Hz and in the sub to 160 Hz (though subs tend to have sharper HF cutoffs). That is the main reason I always strive for mains that have a -3 dB corner at 40 Hz or below even with an 80 Hz crossover.

 

[m. zillch]

It is also worth remembering that crossovers do not drop to zero on ether side. Given an 80 Hz crossover there can still be significant energy in the mains down to 40 Hz and in the sub to 160 Hz (though subs tend to have sharper HF cutoffs). That is the main reason I always strive for mains that have a -3 dB corner at 40 Hz or below even with an 80 Hz crossover.

I get your point but I think you are being overly precautious. Heck if we had to make it a point to buy mains that go down to 40Hz or below we aren't all that far off from 20Hz so why not go to there and omit subs all together?

 

[DonH50]

I get your point but I think you are being overly precautious. Heck if we had to make it a point to buy mains that go down to 40Hz or below we aren't all that far off from 20Hz so why not go to there and omit subs all together?

Yeah, probably... Practically speaking, I see a fair number of speakers rated to around 40 Hz, but far fewer to 20 Hz. Heck, just a quick check shows Polk T50's at $150 each are rated to 40 Hz at -3 dB (https://www.polkaudio.com/products/t50). I doubt they perform well there (but do not know). It does rule out most small monitors and bookshelf speakers, but I have always preferred larger speakers. That is my preference and no doubt some bias on my part; plenty of folk have smaller speakers, and a number of them extend to 40~50 Hz.

I also left out my usual preference of crossing over one octave but generally no more than 1/2 octave above the -3 dB point. It's a general rule of thumb so there are probably plenty of exceptions. I was weaned on bigger speakers and just never got away from them. The few times I have had smaller mains, like the little Mirage OMD-5's I had for a while, I have not felt the sound was as good as when I had larger mains. The big caveat is that I have rarely had larger bookshelf speakers so don't have a good reference for them. I will say Rogers LS3/5a's were not my cup of tea. Yes, could be my eyes as much as my ears, but with the type of music I like small mains would either distort badly or be crossed high enough that bass was too localized (constraining my sub's location).

And (yes, I know you know this) placement is IMO a good reason to get subs -- it is hard to balance the bass and treble in most rooms if you only have the single pair of speakers. Usually the bass suffers because the stereo image is most important. As an extreme example, I used a pair of subs with my Infinity QRS 2 system (which did reach to about 20 Hz) not because they lacked bass but because the room dimensions and layout put me in a null. I could either get a nice stereo sounds sans bass, or get bass and lousy stereo. A couple of subs nicely filled in the deep bass. And that was back in the 80's.

All of this experience and experimenting was many years before home theater was around.

 

[m. zillch]

Heck, just a quick check shows Polk T50's at $150 each are rated to 40 Hz at -3 dB (https://www.polkaudio.com/products/t50). I doubt they perform well there (but do not know). It does rule out most small monitors and bookshelf speakers,

Every single bookshelf speaker Polk currently makes, in fact.

 

[Worf]

Judging by the cars that roll down the street, music seems to have a lot of low frequency energy...

 

[Stephan Mire]

Steve Guttenburg seems to think subs aren't needed for music :

https://www.cnet.com/news/the-case-against-subwoofers-for-music/

What do you guys think of his argument?

 

[m. zillch]

^I stopped at the first half of this sentence because it shows he's incompetent:

" . . . but music rarely has extremely deep, under-50Hz bass, and most speakers with 5-inch (127mm) or larger woofers can muster 50Hz bass in small or midsize rooms. "

This video may not play here so hit the Youtube Logo in the top center to be taken there:

Not sure if it is true of this Youtube rendition, all I have on me right now is $39 headphones, however this piece has 16 Hz content. [Notice that organ in the vid has pipes several feet wide and the entire instrument is like 3 stories tall.] Many recording engineers attempting to record this piece don't have a proper mic for the infrasonic content or they forget to disengage their low cut filter. One of the best versions of this piece is found on the BAS test disc.

 

[Stephan Mire]

I had an argument with my friend last night about this. He says and I quote "all tower speakers can be equalized, and a few can be equalized in just the bass without affecting midrange and treble. Any tower speaker with a built-in subwoofer that includes a line-level input, or any tower speaker with speaker-cable binding posts that allow the bass section to be separately amplified, can be optimized for smooth bass response in your listening chair even if the speakers are placed for the best midrange/treble performance. All you have to do is connect a low-frequency equalizer such as the Velodyne SMS-1 or the MiniDSP, then dial in the EQ for flat bass response.".

 

[m. zillch]

[Guttenberg:] " . . . but music rarely has extremely deep, under-50Hz bass, and most speakers with . . .

Perhaps he's never heard of the rather exotic instrument rarely seen in most genres of music with a fundamental frequency on its lowest note of 27.5Hz. . . . It's called a "piano".*



*[special varieties even go lower than 27.5Hz, but I was citing a standard 88 key model.]

 

[sk373]

I had an argument with my friend last night about this. He says and I quote "all tower speakers can be equalized, and a few can be equalized in just the bass without affecting midrange and treble. Any tower speaker with a built-in subwoofer that includes a line-level input, or any tower speaker with speaker-cable binding posts that allow the bass section to be separately amplified, can be optimized for smooth bass response in your listening chair even if the speakers are placed for the best midrange/treble performance. All you have to do is connect a low-frequency equalizer such as the Velodyne SMS-1 or the MiniDSP, then dial in the EQ for flat bass response.".

Tell your friend that it’s not that simple, especially if you are sitting in a null. You can easily run out of headroom trying to compensate for nulls with EQ.

 

[DonH50]

I had an argument with my friend last night about this. He says and I quote "all tower speakers can be equalized, and a few can be equalized in just the bass without affecting midrange and treble. Any tower speaker with a built-in subwoofer that includes a line-level input, or any tower speaker with speaker-cable binding posts that allow the bass section to be separately amplified, can be optimized for smooth bass response in your listening chair even if the speakers are placed for the best midrange/treble performance. All you have to do is connect a low-frequency equalizer such as the Velodyne SMS-1 or the MiniDSP, then dial in the EQ for flat bass response.".

Yup, all towers, or any speaker for that matter, can be equalized. But check the frequency response to see how much EQ you need to add to get flat bass response, then look up equal-loudness curves (e.g. https://en.wikipedia.org/wiki/Equal-loudness_contour) to see how much extra power is needed in the low bass region to sound as loud as in the midrange. For a speaker rolling off at 40 Hz you probably need at least 6 dB EQ boost, a four-fold increase in power, at 20 Hz. Now add another 10-20 dB to get that bass to sound good and loud and you need another 10x - 100x, so 40x to 400x net additional power. Finally find the distortion curves for the speaker driven with that much power at 20 Hz (or even 40 Hz). Just because you can do it does not mean you should.

Speakers with built-in subwoofers area special case; yes, you can independently adjust the bass, but that still does not cover the placement issue. It doesn't really matter how much EQ you add if you are sitting in a null. Built-in subs or not.

You are unlikely to change your friend's mind and in the interest of friendship I probably wouldn't try. But decades of experience and measurements disprove his argument in the general case. He may be one of the lucky ones with a combination of built-in subs and speaker placement but the odds are against it.

IME/IMO - Don

 

[m. zillch]

People with the rare speakers with subs built in [I've sold some from Polk, for example] have the advantage that they are exciting the room with two subs, not one, and most importantly from two different locations so the in-room response from seat to seat is more uniform and smoothed out some, compared to using just one sub.

Their disadvantage to owning two subs in the speakers is there is almost no flexibility in placement for optimal results: the location is dictated to the user based on the placement of the of the left and right edges of the sound stage, which itself is (often) dictated by the left and right edges of the chosen TV display screen location.