A thread was started in the Talk forum about The Phantom Menace and dts, and (among other things), the infamous 'Sony sub' was brought up. Along with other comments, it was stated that this little sub produced 20hz at 90db which is impossible. No bashing involved... it's impossible. Period.
I made some comments about it in the thread, and made it abundanty clear that I was not 'bashing' the sub or anyone else's equipment, however pointing out it's limitations, which apparently some people didn't like.
So, is there any way we can intelligently discuss equipment without name-calling or so-called bashing of others gear? I would really like to hear from other forum members about their sub(s) and what they consider as 'loud enough' or even low enough, for that matter.

well, personally, I have a Velodyne CT-80. I'd like to have a bigger/deeper/louder sub, but in an apartment, that would almost certainly spell eviction.

As far as the little sony sub hitting 20Hz at 90 dB, I'd like to see hard data that says this. While I'm not going to say it doesn't happen, I'd be very surprised if it does.

The relative SPL of your bass must increase as the frequency decreases because the human ear just can't hear lower frequencies if the volume isn't loud enough. The caveat is this though, for the most part(99% of the time)music and movie sound effects do not go below 30Hz. Maybe if you are listening to a pipe organ fugue you will hit below 30Hz.

So what is the need to have a sub that will produce a flat response at 20Hz with a rolloff at 15Hz at a volume that is comfortable and blends in with the rest of your speakers without over powering them and cracking the plaster on your walls? Absolutely none.

Also to realisticly produce lower frequencies at a reasonable volume your sub must move a ton of air. Keep in mind that each octave you move down, your sub must move 4x more air to reproduce the sound wave, so to think that a 10" sub in a small enclosure is going to produce 20Hz at a volume that you will be able to hear is ridiculous, it just wont happen.

When you are looking at buying a sub use some common sense, listen to what the salesman has to say but at the end of the day a small sub is just not going to produce a low frequency response that you can hear. Frequency determines wavelength and at 20Hz the wavelength is 56 feet! Sitting on your couch you may hear some of that bass being produced, but that wave is developing in your neighbors house across the street.

So yes DVD_O_RAMA, you are absolutely correct in saying that a 10" sub just isn't going to produce 20Hz at 90db...it is impossible, no argument. At best that little Sony sub acurately produces bass in the 40Hz-45Hz range on the low end.


For me when I was looking at a sub I had a problem because the time I spend listening to music is equal to the time I spend watching movies. Most subs that are made for HT are just not good for music. I needed a sub that was very musical and at the same time was able to reproduce movie sound effects, effectivly.

I swear I tried so many different subs I became numb to bass. After all was said and done I chose the ACI Titan. The Titan is a very good sub that is extremely musical and at the same time fits perfectly into a HT.

The ACI Titan is a 12" woofer in a 5100 cubic inch enclosure. I tested it out of the box(I have a friend with test equipment) by running some test tones, and at 90db I was able to get down to around 30Hz and still was able to hear it. After I added some outboard bass management gear and EQs I am able to produce around 26Hz that is loud enough to blend in nicely with the rest of my speakers.

A lot of sub amplifiers will produce the higher octave if it can't produce the frequency that is sent to it. I used this trick in the recording studio all the time but just opposite. I would use a sub-harmonic signal processor on the low end to give it more punch. So someone will say that they ran a 20Hz test tone to their sub and it was able to reproduce it very well at a good volume. That is only because the amp is producing the frequency at the next octave higher and because it's an octave of the orginal frequency it is percieved as the 20Hz signal. A real sub amp(high quality) will only produce the frequencies it is fed.

I found your post to be most enjoyable, full of useful knowledge and discussed intelligently, (which is what I was hoping for in this thread- thank you) however, I must disagree with your percentages about low frequency bass in movie soundtracks.
99% do not go below 30hz? Huh? What have you been listening to? (j/k)
I can name a ton of movies that go well below 30hz, with many easily hitting 25hz on a regular basis. Sure, anything below 20hz is a pipe dream to most HT'ers, as most systems simply cannot reproduce those frequencies, but the simple fact is there are soundtracks that utilize these low frequencies as a major part of the film (most notably The Haunting dts and the Phantom Menace DD-EX LD) Hearing them on a capable, calibrated system at reference levels is an amazing sonic experience.

What is the need? Well, if you are like me and desire reference levels out of your home theater system, a capable sub(s) with flat response is absolutely necessary. I don't know about 'over powering' the rest of the speakers, as that's what calibration is for.

Yes you are right about soundtracks going below 30Hz. I guess what I should have said is that over a course of a single movie's soundtrack the average frequency isn't below 30Hz except for your big thunderous sound effects,etc... in the movie. Also that the soundtracks with the low frequency sub workouts are usually(but not always), limited to action type movies which, in my collection of aroud 200 DVDs, is about 1/3 of them. The rest are dialogue/music soundtrack driven.

In a movie with really just a music soundtrack, and this includes both an orchestral or rock/pop/etc...soundtrack, I doubt the frequencies go below 35Hz to 40Hz on the low end as it is just music.

Also I totaly understand the need for a good flat frequency response down to as low as you can get but the problem is the ratio of SPL compared achieving low frequencies is tough to achieve in the average HT.

What I mean is that in most cases people don't have a dedicated HT with sound proofing and well balanced EQ compared to room acoustics so you have the inherent problem of having to really turn things up to get that good, clean bottom end and it gets to be an assult on your ears and makes it hard to enjoy the movie. Haven't you ever been to the theaters where it was just too loud?..I know I have.

So you have these guys going out and buying a 1000watt subwoofer to put in their 15' x 15' livingrooms when there is no way they are going to get those clean, low frequencies and be able to sit in the same room with it, it's just too loud and doesn't blend in with the other speakers. Plus it is boomy as hell because of the room acoustics. you wouldn't believe some of the crappy set-ups I have heard because people think loud bass is good bass.

Also another thing to consider is that once you get down to around 25Hz you are really feeling the bass more than you are hearing it. Of course that is relative to each persons hearing but on average once you get down to that frequency range the human ear really can't discearn tonal quality.

I have been able to achieve a good flat frequency response down to around 26Hz-30Hz at a "normal" listening volume but that is with external bass management and EQ gear.

Again though I definitely see your points and they are completely valid, I guess my point is the average person that is into HT isn't really too concerned about what frequency their sub can drive and at what level. That is why I made the comment of not really needing a sub that can qualitatively produce those low frequencies. Most just want it to go boom and shake their windows when something blows up.

The consumer definitely needs to educate theselves before going out and spending money on speakers, especially on a sub because a salesman will tell you anything. Of course many people base their decisions on how a sub sounds in a store showroom, that is a big no no. You should only buy speakers and subs from a store if you can bring them back because they are going to sound very different when you get it home.

I do agree though, there is nothing better than a finely tuned HT especially when listening to a great music soundtrack or just music.

BTW, I read through that other post and jeez that guy was nuts what a flame war...absolutely no meaningful information to be found in that thread.

Ahhh yes....sub talk. I just got in my new subs 2 days ago and finally got them calibrated. I did a whole lot of research into these before I bought them. I eventually purchased two SVS subwoofers with a 700w amp. I do agree you need a large sub to produce anything in the low 20Hz range due to air displacement. I got 20-39CS models from www.svsubwoofers.com . Now let me tell you these are wonderful subs but they are anything but small. Their footprint each is only 18" but they rise 39". The bass is wonderful and clean and I love them but they are like ballistic missile launchers in the corner of the room. Quite a statement to people who understand home theater and especially to those who don't. They keep wondering why I have two water heaters in plain view in our room.

As far as bass in the low 20Hz range, it is becoming more common. There are even movies out there going to the high teens in bass frequency for very brief moments. My subs go down to 20Hz +/-3. I decided I wanted these because of the prevelance of more and more soundtracks and movies with this low bass. Sound mixers now want you not only to hear the bass but REALLY also feel it. You really begin to "feel" bass in the low low ranges. It adds quite an effect.

It is more important now adays to look at the bass frequencies you sub can handle simply because of the lower and lower bass in movies. In my opinion something that goes down to 20-25Hz should be sufficent for a home theater but also look at the dB's it is capable of with good clean bass and not just distorted "boomy" bass.

If we are talking about the Sony SAWM40 I though it used a long throw (high Xmax... dunno how "High") 12" driver in a 4th order vented box. With proper placement I could see it hitting 20hz. I've listened to this sub in person and helped a friend set his up in his house. The sub seems very slow to respond... low bass seems boomy and muddled at the same time. Great for those rumble effects of movies... not good for music. Very little detail out of the sub. Lots of SPL and it does move quite a bit of air. I'll have to borrow the sound Docimeter from the test lab again and run it through some sine sweeps one day and compair it to my SVS and DIY subs.

Since I'm no expert (just an enthusiast) I cannot comment on amplifier producing a higher octive and all but...

I built a 3 cubic feet 4th order vented sub tuned to 20hz using a AudioC SV10 driver and I was able to get output at 20hz only 3db down when corner loaded (even though my computer model using WinSpeakerz showed it to only be 2db down at that point). The SV10 does have unusually high Xmax numbers 16mm one way). I can't say if my amps were outputting whatever octive signal or whatever mumbo-jumbo... since I did just what you said and played sine waves through a Cd transport from my test CD's to my subs.

Since I'm a geeky engineer (Mechanical) I'd love to learn more about this phenomenon... how I can spot it... how I could stop it... how I could test for it... etc. Great post BTW!

Oh yeah... you can never go loud enough or low enough! I keep my system properly level matched... but if I want to crank the system up I want it to be able to produce any frequency sound wave I throw at it from 1hz to 30khz up to 120dbl... call me crazy

I use a SVS 25-31cs and a designed my me 2nd order sealed sub using a AudioC LE10 driver (to tighten up that upper sub-bass in the 50-80hz range... the SVS couldn't cut it for music). Love the SVS for those rumbles though!

It is just something amp makers put into their circuits. You can really tell in car audio amplification. For the most part HT sub amps are not going to do that but your lower end gear probably will.

As I said I used this trick in the studio in my musician days. What I did was opposite of what the amp manufacturers do. They do it so that real low frequencies that are out of the amps frequency range can be heard by producing the next octave higher.

What I used to do is when mastering the bass guitar and kick drum tracks I would sometimes throw a sub-harmonic processor in the output stage of the ADAT track to produce a lower sub frequency. This has a really cool effect when it is played through a properly tuned sub-woofer. All of a sudden this low-end bass will just appear out of nowhere and be totally transparent. It really grabs your attention, I know it's a cheap trick(and you would be supprised how many producers use it) but it is very effective because it just livens up the track. The downside however is if it's not on a properly tuned system you just wont hear it, the sub just can't reproduce it. Unfortunately I would say that 90% or more of the systems out there don't have a properly tuned sub.

As far as the Sony SAWM40 we are talking simple physics here. This sub has a 120watt amp in it. There is no way it can physically output clean bass at a reference SPL at 20Hz in a box that size. Sure it's going to rumble with the sound effects but thats all it's going to do. There is no quality to the output, and isn't that what we want to achieve here? Maybe not for most people, I don't know.

For me personally, when I am listening to my copy of "Damn!" by Jimmy Smith and he hits a low B on the Hammond B3 organ and kicks in the Leslie speaker I want to hear that note with all it's swirling, soupy, luscious tone, come through nice and clear. I don't want it to just rumble and shake my windows.

I was checking the calibration on my speakers yesterday (a routine check keeps things sounding right), and I noticed that my cheap little KLH (and my cheap old ears) quit at 35hz. Couldn't hear past that, and the SPL dropped to zero about there. The sub is definitely the weak link in my system. Maybe next year.

O Rama, thanks for starting a no-flame thread!

o' rama,

i don't think i ever accused you of flaming anybody in the aforementioned thread. somebody advised our troll friend that he could get one decent sub for the price of his two sonys, and i simply took exception to that, since i own and am exceedingly pleased with my pair of sony's. i have one tuned for music and dialogue driven movies and another that only gets turned on for action flix. makes for a pretty terrific $300 combo.

anyway, my point in the other thread wasn't to flame anybody. it was simply to ask that we leave this very capable budget sub out of it whilst "spanking the troll"...

hmmmmm....that just sounds dirty.

anyway, here's the original thread (it's actually sort of funny in spots):

http://www.dvdtalk.com/forum/showthr...0&pagenumber=1

and my post, which i assume predicated this thread (note that i address the 20hz/90db claim):

anyway, cool thread...

you guys take it way to serious...... (changed to meet moderators complaint' added smiley', if needed I will remove comment to any it offends. sorry)

I myself love audio and consider myself to be picky at what my ears hear, ..... so what do I own? well since I have no budget (lol, and I mean no money) I bought a jvc out of the box HT.

I dont care for listening to the radio or even cds, I have my loud speakers for that. I bought it for space and DVD's !!!

I will say I'm suprised what the JVC 12 " sub that says pushes 125 watts can produce for sound. cranked it sound great.

Bru,

Please read the following passage from the first post in this thread, and decide whether or not you can abide by it.

Feel free to talk about your own experiences, but leave your value judgements about those of others out of it. At the very least, in this thread.

Thanks.

-stevevt

stevevt : your a moderator ????? hhhmmmmmm.....

well I guess I should have put a smiley face next to that post as thats not at all how i thought i came off, but I have learned over the years on the net there are all kinds and some people take things differently than others.

however I came off to you was not my intention and was in jest and also I myself am insulted that you are comming off the way you are to me so I guess steve it goes both ways!

in the future please do not accuse me of doing something that I did not or as you say 'abide by the rules' as its just as insulting to myself as you took me.

I guess its easy to misunderstand people on both sides, eh steve ?

Thanks for reminding me,

Bru

what is the lowest level the human ear can hear? When I played tones on my sub I couldn't hear anything at 12.5 hz but my spl meter was picking it up.

16 Hz or so. I believe that you are supposed to feel not hear the lowest frequencies.

The smiley face you added to your post made a significant difference in how your post came across to me. Thank you for adding it. Agreed that intent and tone is hard to "hear" in an online format.

Thank you for clearing up your intentions. I apologize if I came off as harsh or insulting.

My intention was to reinforce the idea that I'd like this thread to be a place where people can exchange detailed information on the topic of home theater bass reproduction, and the limits and challenges of subwoofer design and purchase at various budget levels.

Again, thank you for clarifying the tone of your post.

I stated above my initial intention; I apologize if I insulted you.


I'll send you an e-mail to make sure you see this post. I now ask that anyone who has any questions or comments about this post make them to me via e-mail.

-stevevt

np steve , thanks.

I guess sometimes I forget you have to be specific and people cant see your expressions. but as a long time member I assume too and no one posted anything of the sort being bothered by it so I was suprised by your response. as you see the rest of my post was low tone and just figured it spoke for it self.

peace,

bru

One thing to note about the SAWM40, is that the amplifier probably has a boost circuit tuned around 35Hz (which is typical of cheaper sub amps). That'll cheat the FR figures to give extention down to 20Hz at -3dB at low power. Some enthusiastic HTers probably extrapolated that to mean the sub hit 90dB at 20Hz.

But agreed, 90dB at 20Hz outside of near field is one of those "Capin , I cannaw change the laws of physics" issues.

I like my Rava from Adire. I'm pretty happy above 25 Hz at SPL's of 95-100dB. I'm not in a rush to get a bigger sub (i.e. water heater, Dharman) for extention to 20Hz or less at SPL's of 100dB+. That's the diminishing returns point for me.

That pretty much summed it up, and in a very funny way too.

Just to clarify things, the only person who I ever heard mention the Sony putting out 20hz at 90db was the person in the thread chess linked to.
And yes, near-field and anechoic measurements that speaker manufacturers like to list as 'specs' are misleading. My Def Tech BP2002TL's are a prime example; I love the wide soundstage and low frequency response they are capable of, but do I for a second think they can hit the 17hz that Def Tech claims? Not unless I was sitting with my ear against them, perhaps (which is a littler closer then I like my primary listening position to be)

I plan on upgrading again soon, and have had my eye on a pair of SVS CS16-46 subs with a Samson S700 amp, but dammit if SVS didn't up the ante with their CS-Ultra line. Anbody else seen these? In a word...WOW. 90db at 20hz? Yep.

And yes, I take this stuff very seriously