I have 4xInfinity Primus P363 floor standing speakers, each of which has dual 6.5" subs. I also have a separate 10" sub, not sure what model it is, but it's a pretty low end powered unit, think it might be a Klipsch. Is there really any benefit to having a discreet sub when I effectively have 8x6.5" subs?

Your speakers have 6.5" woofers, not subwoofers.
Speakers are rated to 38hz.
Any reasonable sub will be rated to 30hz
A good sub should get down to 20hz


Music can have outputs below 30hz and movies can have outputs down to and sometimes below 20hz, so yes a sub is needed if you want to hear (and feel) everything

For music you dont have to but you do lack a lot down below.
For movies/surround yes you do.
My main speakers have 4 7inch woofers each with a -3dB at 27Hz and for music i do some with and some without subs but for movies i dont even consider going without my subs.


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Which music goes below 30? Music with deepest bass would go down to between 30hz-40hz at most, and generally speaking with majority of music, the deep bass would stay in the 40hz-100hz range. And secondly how do you know the person even hears that kind of music?

A discrete sub to reproduce the LFE channel in multichannel movies is warranted, with music it's your choice. One advantage using a sub with music to do the low end is the speaker has to work with the mid and highs and can make the mid and highs sound a little cleaner.

Lowest note on the largest church organs is 16Hz. Certain electronic music/dubstep artists (e.g. submotion orchestra, knife party, etc, google to find more), and some hip-hop tracks have basslines that extend below 30Hz.

Many orchestral movie soundtracks have added LFE that extends below 20Hz, e.g. The Pirates of the Caribbean theme from the first movie. Even some of John Williams stuff for Indiana Jones and the like from the 80s gets down to 20-30Hz.

But its important to remember that for music its usually better with no sub than a bad sub. (Or a badly integrated sub)


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That's not the norm with music, as in with the majority of music that's not the case. and i'm not talking of movie soundtracks only 2 channel music. and you just assume the person you are making the recommendation to hears that kind of music? The lowest bass note i've heard in my music collection was down to 33hz.

And that would be 5hz below what the OP speakers are capable of - I think the case is closed

Until we hear what kind of use or type of music its a bit difficult to say, but with a nice sub crossover would probably be at about 80hz with those speakers, so would help out over a large bass range. Does he need it, we dont know.


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The percussion sections of large orchestras can have a lot of content below 30Hz, that's 2 channel. If you listen to a quality recording of the 1812 Overture played with real cannons its digs below 20Hz, no way are you playing it faithfully without subs. I made no assumptions about the OPs music taste, I was merely giving complete information. You say its a minority of music that goes that low but by omitting that minority information you are assuming the OP doesn't listen to those genres of music.

Even with music I highly prefer my subs. Every time I turn them off to see if I could do without them I realize how much they add even though I run them very rolled off.

For music or for movies?

I agree with you 100% for music, at least in theory. I listen primarily to jazz, and jazz bass typically only goes down to 40hz, maybe dipping into the 30's. I tried running my mains without a sub for about a year. The mains have 2 6.5" woofers in a very heavy cabinet and measure pretty flat to down to 40hz and only slightly rolled off at 30hz, but I still found benefit when I added the sub back in.

Lots of music has content lower than 30 hz. Maybe your thinking of just an acoustic bass that the lowest open e note is around 30 hz but theres electronic music to consider. One of my favorite demo songs has a 10hz hit at the beginning of the song and lots of fun lower end. There is plenty of EDM and rap also with 20hz stuff.

All that said Im a firm believer you should always use a subwoofer for multi or stereo listening. I don't know of a professional mixing studio in the world that doesnt use a subwoofer in their mixing rooms.

It's mostly movies/TV, so the general consensus seems to be yes a sub is worth it.

This is AVS Forum. The answer is obviously a resounding YES!

what i see too often in these open ended but sincere and naive (?) inquiries

an obvious (?) lack of knowing what is going on in the room . . .

Got REW?

and as explained above by @Alan P ,
who's "prompted" me admirably for getting it right , TY

that's 40 ft^3 of needed sub . . .

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Is A Sub Really Needed?

Yes.

Are those 4 floor standing speakers placed where you get best soundstage & imaging or did you place them at the locations that provide best bass reproduction in your room?

The advantage with subs is that you can filter the low frequencies to them and located them for best bass reproduction. This frees you up to place the speakers where ever they give best soundstage & imaging, without worrying about compromising bass reproduction. Can't do that with your floorstanders (unless you're handy with a saw).

i have the primus 363's also
when i hooked up the sub12hg, there was a HUGE difference


yes a sub should be used, at least imho

Yes. A 6.5 is a midbass, not a sub as has been pointed out. The midranges in my surrounds are 8"units (they have a 15 for midbass).


A decent sub, or better still subs, will allow you to get the LF out of your mains, freeing them from the distortion that the 6.5's will need to give the modest bass you're getting. This will reduce distortion up into the midrange and allow cleaner dynamics and potentially higher SPL; the latter is not always needed, but it's better to be able to turn it down, than not be able to turn it up on occasion because bzzzzzzt!

Sub drivers are typically larger and have greater Vd (swept displacement; think bore x stroke) which is required as you move lower in frequency. For example, if a given driver needs to move 1mm to give X dB at 80Hz, it will need to move 4mm to give X dB at 40Hz, and 16mm at 20Hz etc. The further any driver moves from rest, the higher it's distortion will be, so it's best to have as many large drivers as possible, moving as little as possible for best sound.

For Music:

Based on the measurements in the link below the P363's are quite flat down to 80Hz or so. This is a good response for integrating with a subwoofer(s). The 12dB roll off of the high pass filter in most AVR's would work quite well as it would be supplemented by the natural roll off of the speaker.

See third chart down - https://www.audioholics.com/tower-sp...3-measurements

Evidently most of the posters above don't consider piano music to be music. That's certainly OK, to each his own. The lowest key on most grand pianos is 27.5Hz.

When a key is struck on a piano it creates an impulse that energizes the entire bridge, which in turn affects the other stings, even with the dampers not raised, the soundboard and the whole frame of the piano. This is part of what makes a piano a piano and makes the sound of one piano different from another. It's easy to feel this effect. On a good sized grand piano put your finger (clean) on the lowest string. Strike a key about an octave above the lowest key. You will feel the lowest string vibrate.

A flat speaker response down to at least 27.5 Hz is good for piano music although further down would be better. Without this extended low frequency response a recording of a piano can sound good, and the lower frequencies might not be missed, but the full effect is absent. Look again at the chart in the link above. There is a triangle of sound missing from, for example, at 27.5Hz from 70dB to 90dB SPL, over to about 80Hz at 90dB SPL, and then back to 27.5Hz at 70dB SPL, if that makes sense. Well integrated subs could fill this triangle as could truly full-range speakers.

For Movies:

Clearly the P363's need sub support for movies based on their response. What if the P363 was flat to 20Hz with little distortion and adequate amplifier channels were available, what then?

In a multichannel home theater setup, for at least Denon/Marantz and likely most (all?) brands when a subwoofer isn't present, the level of the L and R speakers is reduced by 12dB on the digital side. This added digital space is to allow bass from other channels that are set to small to be mixed with the L and R speakers without exceeding 0dBFS, that is, without creating digital overs. This digital signal is then converted to analog. The 12dB is recovered in the analog volume control. Somehow it seems this process would have a negative effect on the S/N ratio plus it isn't clear how happy the volume control is in having to provide positive gain. The datasheet doesn't provide guidance. Is it audible? Who knows?

Quote:

Is A Sub Really Needed?

Humans "need"... air to breath, food to eat, water to drink, clothes to wear and shelter from the elements. The human species "needs" to procreate for the species to survive. Any other use of the term "need" as it relates to humans must be qualified by a want or desire. If I "want" to drive 200 mph, I "need" a Tesla Roadster. If I "want" to fly at the speed of sound, I "need" a Gulfstream X-54. If I "want" to B.A.S.E jump off One World Trade Center, I "need" a Ram Air Parachute.

No human "needs" a subwoofer, so the answer to the question: Is a sub really needed?" is No. But that's not really the correct question to ask. The correct question for the OP to ask would have been: "If I "want" to reproduce X frequency at Y SPL, can I do that with my speakers, or do I "need" a subwoofer. THAT is a question we can answer for him... once we know the values of X and Y.

Here is a chart to get help the OP get started answering the question of the lowest frequency he wishes to reproduce:


Interesting to note, (PI), is that an extended, 108 key piano can have a lowest key of 16 Hz.

Craig

As I was reading through this thread I was wondering if anyone would put up that chart. If they didn't I was going to. One picture answers the whole topic.

The chart is not exactly correct either, especially on the high end.

https://www.cco.caltech.edu/~boyk/spectra/spectra.htm

Use a sub or don't use a sub. Only you can determine if it's needed.
Try one in your home. Just be sure to verify that the vendor has an acceptable return policy (be aware of restocking fees).

I have asked that question myself over the years,

As a teenager, do I need a subwoofer for the car? Well, considering the limits of 6.5 inch speakers--you bet! Back in the dorm days, the same question of "need" popped up. I had a small pair of bookshelves that I loved the sound quality--it was perfect except for "rock star" (party) mode. Used a pair of 15 inch PA speakers to do high SPL party mode--all good? No, wanted the bass of the PA speakers so--I purchased my first subwoofer. Did the sub crawl to get it in the right spot--shock and awe--it was not in the same location of my bookshelves. However, I finally was able to go down to 30Hz with the bookshelves and the die was cast. Years go by, I purchase a new pair of smalllish speakers with more SPL capability, more efficient and then went with a 25 Hz capable subwoofer. Pondered getting a second one to get better coverage since I was not single anymore so--purchased another sub and it was mo bettah!

My new speakers went down to 35 Hz before rolling off slowly (sealed speakers) but even when listening to music that did not have deep bass, they sounded better with subwoofers and it was obvious when several people were involved. For me, for the music I listen to and the fact that Youtube, TV programs, movies and video games on occasion get pipped through--subs work the best for me. However, I don't listen to bass shy records, only listen to AM radio rock etc. so if you do--the demand for subwoofers will be less. This does not mean you get the befefits of multiple subwoofers or to place the subs in the best location to get the most even bass response. If you live alone, have the chair to listen in a specific location you can go with one sub properly managed or even no sub depending on your room acoustics and use. That question is how important bass response is to you, how much bass and how low it goes in your music and so on. I can't answer for you.

Be aware that the subwoofer was invented in 1968 by Infinity so your question has been asked for over 50 years. The correct answer is "that depends" but you might have noticed that from the unicorn of the late 60's to professional use in theaters in the 70's to car and audiophile use in the 80's then HT in the 1990's--they are not going away. The 2 channel receivers of yore are now a niche' product with the rise and domination of the AVR. When I purchased my first AVR it was to drive a "2.1" system which morphed to a 3.1 system then 3.2 to 5.2 and so on. It has been 30 years plus since I was a kid building ttwo 8" sealed subwoofers to solve my bass problem. The problems and acoustic issuez still exist be in car, boat, PA, HT or simple 2 channel. The first subwoofer system in a house that I was able to touch was a 2.2 system. The guy was in his late 30's and had a taste for classical music so two big M&K subwoofers was his solution (and EQ etc.)

I do find it odd that some people think that 2 channel means only 2 speakers. This would exclude subwoofers, bi/tri-amping and anything over the past 50 years to improve the stereo experience. Pro audio went mutli-channel systems decades ago even if it only "left/righ". Don't be afraid to use subwoofer os active crossovers and mutliple amplifiers if the juice is worth the squeeae. After all, when all the subwoofers and bi/tri/quad active systems started to make a move the record was still the top seller at the local music store , Sears or curcuit city. (remember them?) It is just a silly hobby, nobody "needs" 2 channel anymore than they "need" subs--mono works just fine! If you want better sound quality, more even bass response in your room, have multiple people listening to the music/moves etc. then subwoofers can and will help. I know they did for me--30 years ago by your mileage may vary. If you have friends that own subs, maybe you can pay them kickback money to "borrow" them for a weekend and play around with the things. If that won't happen, you can ask if you can learn and listen to how they system operates. I've taught dozens of people over the years how they work but generally won't let them take them home--I am cruel that way. Most people just ask because it IS an investment so best to play around with a system by a person that knows how to do it properly first.

Another idea is to find an AVS get together--the DIY side tends to do that fairly often. They ALWAYS use subwoofers but also test various speaker designs without subwoofer support as a test. If you could attend one of the DIY get togethers, you might learn more about subs than you ever wanted to know. Be aware that you might then spend a ton of money and take over the living room with subs and large speakers--you have been warned! It is hard to explain it with words, much easier to digest when you get to pay around with a system setup properly by a person that knows what they are doing. Just consider it a field trip but this time you can bring the beer and wings. That is what I would do if it was still a question in my mind.

Just remember, this is supposed to be fun and educational--jump right on in, the water is fine! Good luck.

It's definitely needed if you want to hear full range music. Let alone movies. Piano goes down to about 30Hz. Organ much lower. Bass guitar around 40hz. Not to mention techno/rap/hip hop/dubstep. That being said I'm in an apt now and out of respect for my neighbors am not using my subwoofer. It's still enjoyable to listen with my bookshelf speakers that only go down to around 50hz. It's only when I listen to certain types of music or of course lfe tracks on movies that I'm really missing out.

If you are watching movies I think you'll be pretty surprised if you add a good sub. Your speakers have a -3dB point of 38hz but there's a big difference between that and flat to 20hz!

My 5s and 6s have a low B around 30Hz