To sub or not to sub. That is the question.

[rollo]

There still is much talk about the need to reproduce the lowest frequncies in our systems. IMO the info say below 40Hz is key to the absolute sound. Either a real full range speaker [20-20,000Hz ] or a pair of  subs is absolutely necessary. Whats your take on this?

rollo   

[Bigfish8]

Rollo:

Based on everything I have read most audiophiles would agree that is would be preferable to be able to reproduce the lowest bass notes.  However, it seems most do not add a subwoofer due to issues with intergration and timing.  If that isn't enough room treatment issues become more critical.  I know the thought of it would scare the heck out of me because I am still trying to tame the SP Tech Timepieces.

JRebman will be able to tell us about his first hand experiences as he will soon be setting up the ACI Sapphires with a couple of subs.   

Ken

[Carlman]

I agree... Getting the lowest octave is important but using subs is not usually an easy task.
I've found if you're using speakers with a 4th order crossover, blending a sub is easier than say a 2nd order... If you can use 2 subs instead of 1, you'll get better bass and the visceral impact will 'feel' right.  Your body 'hears' with its skin also... So, if low bass vibrations are coming from a different place than most of the sound, I notice it...

If you have 4th order xovers, can use a crossover and 2 subs, and lots of patience, you have a chance of getting seamless bass with a sub+monitor system.  You should also know how to measure your room for subs.  Oh, and of course, use bass traps correctly...

Have I been beaten by subs... why yes!   Have I seen them implemented correctly? Yes!  I haven't had subs for 2-channel but would consider them again when I get the new room setup... for HT and 2-ch... we'll see how it goes.  Seems like the subs need to cost a LOT to get the right size and amount of bass.

-C

[LKdog]

I have monitors which go well below 40hz  in room.
I have dual subs, though, and would not live without them.
They are all from the same company (ACI) which may be an advantage.
Honestly, has never been a real struggle to set up and these are my second sets of ACI subs.

I do use bass trapping.

[jrebman]

Ken,

I'm getting a second sub?  Wow, how nice of you .  No, actually, I only got the one sub for now, but I'll just have to see what happens down the road.

So, my question is, do our systems need to play those lower notes just to add some fullness to the sound, or do we need them to punch us in the chest?

For me, I think it is the former.  Yes, I like those big speakers that really pack a wallop at 20 Hz or so, but to do that really right requires a lot -- a lot of speaker, a lot of amplifier, and a lot of money -- if it is to be musical at the same time, which I think is the key.

I was quite pleased with the bottom end of the Sapphires when I sat down and listened, and as I turned to one of the folks in the room to ask which one of the ACI subs was playing, they said none were playing.  This guy turned out to be double ugly and I thought he was just pulling my leg, so at the next break I asked Mike which sub he was using, and he said the same thing, then turned the sub on so I could hear the difference.  What I heard was just a nice filling in of the bottom end -- no booming, in perfect integration with the monitors, and while pleasant, and great for a lot of situations, was not absolutely necessary for full listening pleasure -- mine, that is.  I bought the sub anyway because I did like what it added, and my experiences with subs to date hasn't been terribly positive (not horrible, just took away more than it added.)

I also live in a townhouse and have neighbors on either side, and if turning off the sub at night allows me to still listen to a very decent portion of the specturm without it, so much the better.  And if I can turn up something with Edgar Maier playing his double bass and can't tell the sub is on, better yet.

So, who knows, until I hear things here and have everything broken, and dialed-in, I won't be able to say for sure how much an additional sub would add, and if it would be worth the extra $900 or so.

And for my single driver/SET gear in the basement, I know I'm going to be getting one of Ed Schilling's Cubes to fill in that part of the spectrum that the SD speakers I can afford, just can't do justice to.

So bottom line, I like it full, rich, and musical, but I don't need to hear the canons on the 1812 overture push me back into my chair or hit me like a concussion grenade.

-- Jim

[richidoo]

Wavelengths longer than the room dimensions are not directional. So the room size should be considered when choosing stereo or single subs. Of course, the wavelengths above the room dimensions will be heard in stereo so it may be worth having the 2 subs anyway.

The most important aspect of bass clarity, precision, whatever you want to call it. At low frequency, it is easy for the ear to hear phase problems as muffled or fuzzy. Add in room reflections which distort phase, and a second sub and its reflections and you better know what you're doing or you will have the infamous one note bass. haha  Most subs have 2 position phase switch only, which may help compared to none, and is adequate for HT where explosions are really the only low freq info so phase accuracy is not as important. But with music, phase accuracy is necessary to be able to hear texture and tone accurately in bass instruments. So infinitely adjustable phase is critical for playing music in a high end system.

The ACI sub at RMAF was infinite 0-360 adjustment. At the demo, Bryan said it wasn't perfectly fine tuned to the room, but I second Jim's take on the quality sound and good integration of the sub. I was listening to.. what else, string quartet  , and the sub filled in the cello very subtly and naturally. I was more than content listening without it though.

I think sat/sub is appropriate in smaller rooms for the flexibility in tuning the system to the room. Room treatment is necessary to make phase adjustment worthwhile though. Any improvement in clarity from phase adjustments will go out the window with bass reflections muddying things up.

If the room is big enough, then having in-phase, quasi point source (in same cabinet) bass is unbeatable, IMO. Stereo bass is easy to hear/feel and the sense of space provided when bass sound moves around the recorded hall or across the pan field can be highly enjoyable. Playing a good performance and good recording of 1812 or organ or even dance music can be a tear jerker.

I think that in our evolution our brains never heard low freq sound, except in thunder and animal hoofs, earthquakes, trees falling, forest fires, all pretty exciting or threatening things. I believe that low freq sounds instinctively cause a big adrenaline spike when we hear them. That's why, IMO, low frequency sounds are such a big draw - Harleys, Airshows, Rock concerts, Action movies, and of course, the ubiquitous jet truck.  Hahaha   


In the old days the church was the only artificial low freq experience you could have. It was so much fun, people would come to church just to get it - well maybe saving their soul had something to do too, but I would have gone at least for the low pipes.

Good topic rollo!! You are an excellent discussion facilitator!
Rich

[wet weasel]

I bought a sub. Haven't hooked it up yet. I like pipe organ music.
I do have the Active Bass Module from a famous motorcycle co. That is hooked up. The helmet keeps me from always saying - HAH?! whenever somebody's lips start moving.
cheers ww

[_Scotty_]

richidoo said,

If the room is big enough, then having in-phase, quasi point source (in same cabinet) bass is unbeatable, IMO.

I have to agree with richidoo, I replaced DIY sat/sub system with a full range system about 3.5years ago and there is no going back. In addition to the positive qualities richidoo mentioned I now have a top to bottom focus of energy at the listening position that greatly improves the realism of everything the system reproduces. I think the coherent wave launch is what has made this such a large improvement over my previous system. Real life does not have frequency and phase discontinuities
fracturing the the wavefront that reaches our ears. The system sounds like a single full range loudspeaker with no crossovers.
  In response to rollo's question, I can enjoy speakers that have about eight inches of cone area covering the bass and reaching 32Hz in smaller rooms but they don't have realistic dynamic scaling or image size. In my experience it takes a lot of cone area devoted to frequencies below 150Hz to realistically reproduce the lower midrange and bass regions of musical instruments. The size of an instrument doesn't shrink when it plays softly. My current speakers have two 12in. woofers,two 6.5in. midranges  and a 7in. planer tweeter. This seems to be about the right ratio of cone area to frequency range to create accurate image scaling. Having enough cone area also provides for accurate dynamic scaling proportional to the size of the instrument being played. I think having the ability to reach 20Hz
or lower with LOW distortion is very important to having realistic music reproduction. 
Scotty

[bpape]

IMO it can be done either way - if done properly and with a sub that's fast enough.  The big advantages of a sat sub are:

- Small monitors just disappear into the room.  It's not that large speakers can't do this but rarely will you get them to do it AND be in the best place for bottom end smoothness/tightness.

- Re above: Subs placed separately allow for bass response to be tailored specifically to the situation without regard for imaging.  With a sub like the ACI, you have 2 2nd order 12db/octave xovers which can be set separately.  This allows you to 'cheat' and get a pseudo EQ effect to blend to the room.  An infinite phase adjustment is also mandatory and included.

- The driver/cabinet of the sub can be optimized to operate ONLY in the bass whereas in most full range systems, the drivers are also expected to do up to several hundred Hz.   Without this additional task, drivers and box alignments can be much more optimal.

- Without the last octave or 1.5 octaves in the mains, you can reduce cavity and cabinet resonance colorations in the other drivers.

- Sub drivers outside the main cabinet allows for narrower front baffles or more freedom in baffle size re the drivers and xover.  Don't even get me started on those silly side firing woofers that are a room integration nightmare.

Having sub(s) is a LOT more work to get right but can be well worth the effort. 

Bryan

[_Scotty_]

I think the biggest problem I have heard in the bass region is distortion. A large number of subs offered for sale have no THD spec correlated to peak output at the subs lowest usable frequency. As an example a good sub should be flat to 20Hz and be capable of at least 105dB at this frequency with less than 3% THD.
Without these interrelated pieces of information you don't know what you are purchasing. It is easy to make a box and stuff it with a driver and call it a sub-woofer. Home theater has created a demand for boom boxes
with built in humps in their response curve before they are even placed in a room. A properly designed sub-woofer should be invisible in operation. You shouldn't know there is one in the room until the the music's spectrum requires its contribution. With the preponderance of boom boxes out there a list of mfgs that give specs including THD at peak output at the lowest usable frequency would be very helpful.
Scotty

[bpape]

Do you expect the same from your main speakers? (105db at < 3% distortion)  That's a lofty goal.  Having no subs and expecting the same thing from a full-range speaker really doesn't happen often until you get WELL up into 5 digits plus (sometimes 6 digits) in price.

Not trying to be confrontational - just putting things in perspective.

Bryan

[_Scotty_]

Yes, that is what I expect from from my main system. I can meet my goal as long as my room is not too big.
My current room is about 3500cu.ft.,a 5000cu.ft. room is probably the absolute upper limit where my woofers would run out of linear excursion at 20Hz.
  I agree that this level of performance is seldom achieved most of the time without a hefty price tag. It takes a lot of cone area and a large well designed enclosure which most manufacturers charge a premium for. Adding a pair of good, low distortion subs to large MTM monitors makes a lot of sense if you are trying to kick the performance up another notch.
Scotty

[rollo]

It appears we are in agreement that low bass is required for maximum enjoyment. Now how thats accomplished is another story. Lets hear more.


rollo

[miklorsmith]

As usual, some well-considered thoughts have been proffered.  I think nearly everyone would agree that, in theory, having good response into the 20's is a great idea.  Putting that idea into practice is where it breaks down.

I personally think it was a mistake to go away from tone controls.  Odds of new speakers working perfectly in a new room, even using the best "educated guess", are poor.  The current audiophile strategy as I perceive it is to figure out what speakers seem like they would be best for the room, buy 'em, and hope for the best.  Some folks can audition first but even in a big market only a fraction of what's available can be taken home on demo.

Where are the problems?  Why in the bass of course.  In addition to ceiling/floor bounce that most rooms have, bass acts crazy in closed spaces in many ways.  The deeper it goes, the more extreme solutions have to be to manage it.  Bass trapping 30 hz?  Oy, scary.

The most common way to "get bass" is to buy some big floorstanders, a big-time amp, and let 'em rip.  Even if there are enough placements to allow imaging OR bass optimization, final locations will most likely be a compromise.  The chances that there are no bass issues at all are practically nil and there is no way it will be perfect for stand-up bass and movie special effects. 

The monitor/sub idea is a good one too but to do it right, stereo subs should be used and probably big ones.  That means you probably need space for 4 sizable transducers, plus the rack on the front wall.  If you have a TV too, good luck.  I think the "monitors placed for imaging, subs for bass" is a good idea that likely proves impractical in many rooms.  I totally agree that any self-respecting audiophile sub should have continuous phase adjust.  However, I also think subwoofers should go further in flexibility.

Having used a TacT with basically a monitor/sub setup made me really appreciate crossovers.  With a monitor/sub setup, there is a high-pass XO for the mains and a low-pass XO for the subs.  The monitors probably won't give any control over their XO - it'll be whatever it is in the room, whereever it drops off.  It will have a slope as well as a cutoff, just like any other crossover.  In my opinion, the sub should have not only frequency adjustment, but slope adjustment to blend as well as possible with the mains.  In addition, some are now offering parametric EQ bands to deal with floor/ceiling bounce and other room anomalies.  Bass traps are good, but when we're talking 20 hz extension some EQ is probably equally or even more valuable. 

I honestly think the camp that doesn't worry about sub-bass is practicing damage control of sorts.  I wouldn't (didn't) worry about the deepest bass until I had everything else worked out.  Getting 25 hz at any pressure isn't cheap or easy.  Lots of rooms won't support 25 hz or even higher.  My room is pretty big and a giant bass trap in itself and it only goes to 25 hz.  The subs are jumping out of the frames at 20 hz but I can't hear it and barely can feel it.  It's still cool to "know" it's there though.

[_Scotty_]

In my experience when 25hz to 15hz is reproduced at spls above about 90dB it is like there is an invisible
monster in the room with you. You know he's big and some where in the room with you but you can't see him. I have easily achieved 105db at 20 Hz in the listening room in the townhouse I  had my system in.  Any frequency lower than 20Hz. in an above ground frame structure is going to require a heck of a lot of large drivers and copious amounts of power. A frame house is like a cardboard box to frequencies lower than 20hz. It fact 20 Hz. test tones were almost as loud outdoors next to my listening room as they were inside. I now live on the 12th floor of a purpose built condominium building. I have a concrete floor and ceiling and fiberglass filled walls with at least a 1 ft. airgap between me and my neighbors. So far I have had no complaints but I seldom play bass heavy music at levels above 85dB on a regular basis. Rap music is not on my play list either. One of these days I will have to find a CD containing test tones lower than 20Hz. on it. and see what happens. 
   When I ran a sat/sub system I used the crossover to notch out the worst room mode frequency. I would use the speakers 6dB/oct.roll off that I had setup with a passive network between the preamp and poweramp and the sub crossover to set up a gap between the mains and the sub at the major room mode
frequency. This technique can eliminate the worst frequency problem and passive bass traps can deal with higher frequency modes above the main problem frequency. In order increase your dynamic range and reduce distortion you have to roll off the main speakers and not ask them to reproduce bass frequencies at high spls. This is one way to to have deep bass without quite as many problems as just using the built in crossover in the plate amp in the sub.
Scotty