Subwoofer: room 16 x 18.5....


would a small 8" sub be enough low end for this room? This is for music only applications...thanks...
phasecorrect
I don't think so. An 8" driver can't do clean bass and your room isn't that small. Consider a 12" sub from any of numerous companies that make good subs. If space is a concern, the SVS SB12-Plus is quite good. And has built in 2-channel bass management and some analog PEQ. I use it in my office system.
I don't believe a 8" would work either.

For music, look for either a sealed or passive radiator design. The Velodyne SPL series and higher end Polk subs are great for music.
Bob,
How has the SVS SB12-Plus been working for you? Do you think it compares well with some of the 10" subs in the $2000. range? (e.g. JL Audio f:110, REL, etc.)
While floor area is important, the height of ceiling also plays a part. Room size in ft3.
Go to the HSU Research site and look at there room size chart.
That'll give you some idea of sub to room relations.
In any event, 8" is too small a sub, except possibly at low levels?
Bcollins, I'm quite pleased with the SB12-Plus. It replaced an 8" M&K K-9 sub so the difference was pretty drastic with bass heavy material. Build quality is better than I expected. I like that it supports both balanced and unbalanced connections and has a switchable active high-pass (2nd order) filter on the outputs. I'm using unbalanced currently, but I'll switch to balanced when my active monitors arrive. I've not bothered to do any room measurements yet so I can't comment on the PEQ.

My general take on subs based on my experience is that placement and level matching is the key to a good setup. I also strongly believe in high passing the main speakers. So any sub that plays loudly enough for your needs with low distortion should be fine. It doesn't matter who makes it. Fortunately, there are plenty of excellent subwoofer measurements available on the net so choosing a good sub can be done.
Measurements of subs, while a good thing doesn't cut it in a real room.
Google:: 'room mode calculator' and look for nodes /peaks and resonant frequencies below 300hz. they're the worst.
Also, Find the Harman White paper on subs. The bottom line recommendation is that 2 is MUCH better than 1.
In MY opinion, for a budget of over some amount, for me, about 1500$ or 1600$, it is actually better to have 2 subs in an asymetrical setup to reduce room nodes, both plus and minus. A pair of 800$ HSU research VTF3's would almost certainly be a match for ANY equivalent value of another single sub.
In my case, with a completely wacko, room of no less than 8 sides and an off-center vault ceiling, I make do with a lesser single unit. I'm not a crawl-around-the-room with an SPL meter playing test tones kind of guy, but I can detect no boom or suckout....except in my den where there seems to be a midbass peak which exagerates bass drum. I guess my den my be acting as a helmholtz resonator.

Seriously, check out my Google recommendtaions and have a fun read....shouldn't take more than an hour git-2-go.
Measurements of subs, while a good thing doesn't cut it in a real room.

The point I was trying to make is that since we hear the room below 300Hz or so you can use subwoofer measurements to find the best value. Spending more money on a sub with measurements comparable to a less expensive one has zero advantage. Now, if the more expensive sub provides some form of PEQ system (like the Velodyne DD subs) to help manage room modes, then that's another story.
Just looked up PEQ. The recommendation to put the sub where you sit than eq away will have you end up with a single spot...where you placed the sub, as the 'premium' seat.
If you go to the trouble...and man, what a hassle, of putting the sub in 3 or 4 spots, running the eq routine, recording the results THAN entering an average value at each frequency, you may get somewhere. But, overall, you've still got the same room you started with.
My suggestion was to take your budget....and I'll admit it has to be above a minimal value, and divide it between 2 lesser subs. In this way you can minimize room interactions.
The Harman White paper is clear on this point.
Also, for Pete's Sake! the Velodyne is 5000$ (gasp!) For that kind of loot you could get 3 or 4 top-line HSU's and associated cabling. HSU recommends a near-field sub.. maybe just behind your sofa or as an end table. The other pair could be located in other more discrete locations in the room.
I would maintain that a pair of good subs totaling 1/3 the Velodynes cost could easily equal the performance and output of the 'Dyne and have less complexity and therefore less to go wrong.

I think you misunderstood my measurements of subs line.
Measurements of subs, like frequency response and max spl are near-meaningless.
Measuring for location is more advantageous, but still a hassle. Room boundry situations make such measurements in the hands of most of us, me included, kind of dicey.

I would agree that 'Spending more money on a sub with measurements comparable to a less expensive one has zero advantage' So, for the person who is going to spend/budget say.....1500$ for a good sub, what would be wrong with a pair of lesser units for the same money?
Link to article:
http://www.harman.com/wp/pdf/multsubs.pdf
Bob, Thank you for your comments. How would you rate the quality of the built in high pass filter? Do you think it would be transparent in a high resolution system?
Magfan,

How would you connect two subs into a system when there's only one sub out connection on a receiver? I am looking into this two-sub solution for an HT setup in a room that will be 16 (W) x 23.3 (L) x 10 (H). Do you just use one of those two female RCA to one male RCA connectors and connect to the sub output?

FrankC
one of those 1 into 2 splitters would appear to be the way to go. ONLY proviso would be if the impedance drops too low. This would only happen if both subs are fairly low to begin with.

If subs are located near the amp, you could also go with speaker level. Are speakers full range? Speaker level input on a sub is very hi impedance so it won't load down amp.

I've seen some plate amps w/both low level inputs and outputs.
Speakers go to 55hz...should I hi-pass? If so..what is the best route to go?
Bcollins, It's just a guess, but likely that the high pass filter in the SVS SB12-Plus is the same quality as that in the SVS PB13-Ultra. They are both 2nd order active filters. Based on the Larry Greenhill PB13-Ultra review in Stereophile, I'd say yes it's definitely transparent enough for a high resolution system. Larry compared a single PB13-Ultra to a pair of Fathom f113 plus a Bryston 10B SUB crossover. The Bryston crossover alone is $1000 more than the SVS sub. Larry high passes his Quads and he did favor the substantially more expensive JLAudio + Bryston system.

In my office I sit at arms length from a pair of M&K nearfield monitors and I haven't noticed anything missing. But, I'll readily admit to not being the most critical listener -- it's too much work. :-)
Magfan, I agree with you about using multiple "lesser" subs. That was my point about using measurements. You can look at FR and distortion graphs and pick a less expensive sub (or subs) and save a ton of money. And, of course, you can use a Velodyne SMS-1 ($600) to PEQ those two subs.

Measurements of subs, like frequency response and max spl are near-meaningless.

Subwoofer measurements are especially beneficial, because whether it's a $500 Hsu or a $3K Velodyne they both will generate the same room modes placed at the same locations in the same room. So buy the one that plays loudest cleanly for the least amount of money.

If the intended use is music, then you can relax the criteria for max SPL and the lowest octave and stress group delay more. If you're mating the sub with small stand mount speakers, then the upper frequency response of the sub had better meet up with the lower response of the main speakers. Some subs (like REL) aren't designed to be crossed over very high so using them with small speakers will create a hole in the FR. Without outdoor measurements you're just buying blind.

Then after you have picked a sub that best meets your needs, you can worry about placing it in your room by doing room measurements. And you can EQ it as well.
How would you connect two subs into a system when there's only one sub out connection on a receiver?

Several subs have LFE in and out jacks so that multiple subs can be dasiy-chained together. In that case there is no need for splitters.
Phasecorrect, I assume the specs for your speakers say the low end is 55Hz. They likely do not say how much distortion is generated at some SPL level at some distance at 55Hz. Go to the B&W site and take a look at the specs for any of the 800 series speakers. You'll get an idea how much distortion even very expensive speakers produce.

I would have no hesitation high passing your main speakers at 80Hz. Your choices are to use a sub with bass management built in or use a separate bass management controller.

Whether you high pass the main speakers or not you'll need an analog SPL meter and a set of test tones to match the levels between the sub and the main speakers.
the Human Ear is fairly insensitive to Bass Distortion. Several % should be doable, if not more. I know there is research, but I'm scared to look it up. That same amount of distorion at 5 or 6khz would drive bats from the room.

EQ'ing a room may make a certain seating position a sweet spot, but Will Not effect room modes. They are a function of the geometry of the room and sub placement. Multiple subs will excite the room and produce, best case, complimentary peaks / nulls which will give reasonably flat response over a larger area. Also, I suspect slightly lower distortion at higher levels.

As for X-over frequency, I cross my Maggie 1.6s at about 40 to 45hz. Lower limit for the Maggies is about 40 or so? Maybe 36, depending on who you read. Anyway, I dial 'em in for a little overlap, so as the maggies drop away, The sub picks it up. I do NOT use test tones / meter since I'm nuts anyway and this would be just like trying to put out a fire with Gasoline. Like, how obsessive can I get?
Besides, there is an art to the science of SPL measurement and you'd probably also need someone to help you take the data. Multiple repeats, a spreadsheet and I've finally flipped. Sheesh, Science ain't easy!
I may be able to wring a little more performance out of my system if I were to hi-pass the Maggies at 60-70hz and the lo-pass the sub at maybe 50-60hz. I will probably NEVER find out, unless a few volunteers show up with a bunch of stuff and some Single Malt!

Also, from our 'for what it's worth' department, Somewhere above 80hz or so, you can begin to localize the sound, so you gotta be careful there, too. With my current setup, I simply can't find my sub.
Magfan says, "Measurements of subs, while a good thing doesn't cut it in a real room."

"Measurements of subs, like frequency response and max spl are near-meaningless."

"Measuring for location is more advantageous, but still a hassle. Room boundry situations make such measurements in the hands of most of us, me included, kind of dicey."

"I do NOT use test tones / meter since I'm nuts anyway and this would be just like trying to put out a fire with Gasoline. Like, how obsessive can I get?
Besides, there is an art to the science of SPL measurement and you'd probably also need someone to help you take the data. Multiple repeats, a spreadsheet and I've finally flipped. Sheesh, Science ain't easy!
I may be able to wring a little more performance out of my system if I were to hi-pass the Maggies at 60-70hz and the lo-pass the sub at maybe 50-60hz. I will probably NEVER find out, unless a few volunteers show up with a bunch of stuff and some Single Malt!"

I say, It is not difficult at all! Measurements do matter! Measurements are the reality! Doing it by a test tone and meter is a waste of time. You need a program designed for this. Fortunatly there is one, and its for FREE. It is the Room EQ Wizard from the Home Theatre Shack. All you need to do is to download the program and an a Radio Shack SPL meter. No more crawling on the ground for Magfan!
The science is easy, the results can be eye opening.
Magfan, try this and post the results here. There are lots of members who will give you plenty of opinions:) If you live anywhere near Connecticut I will bring the Scotch.

Bob
Thanks so much for the kind offer! Even though I am on the 'left' coast, feel free to drop in.
But, I must respectfully differ. One theme running thru many posts is that measurements DoNot matter. The fuse guys and some of the cable guys are good examples. Nobody has demonstrated a way to measure a fuse good/bad. So, too, the cable goes unmeasured except for the measures of resistance and Capacitance we are all familiar with...and yet! there is something more to it.
I can see myself (I know me!) going absolutely nuts with an SPL meter, test tones or even analysis software. Since in my professional life, I am a cleanroom technician for a semiconductor manufacturer, I am Very Familiar with experimental design, and the use of JUMP analysis software.
Nope, I'm going to leave it fun, just listen and treat those known defects of my room. My room, just for laughs, has 8 sides, is very unsymetrical and has an off center 12foot vaulted ceiling.
Now, if I had a certified / calibrated microphone..........
Magfan said, "One theme running thru many posts is that measurements DoNot matter. The fuse guys and some of the cable guys are good examples. Nobody has demonstrated a way to measure a fuse good/bad. So, too, the cable goes unmeasured except for the measures of resistance and Capacitance we are all familiar with...and yet! there is something more to it."

I say, measurements do matter. But thats just me ( well maybe not JUST me ), and yes, measurements do not tell the whole story! But an in room frequency resposne, RT and waterfall plots do say something! If you are a "scientist" it must count for something. This takes about 1 hour of your time if you are good setting up and downloading the program. Try it and see.
Bob
I may do so, in the future. BUT, I know my character and once I start down this path, I'll be nuts until I figure it out.
Yes, there are 2 schools of thought on this 'hobby / avocation'
1. Just listen and enjoy
2. Analyze and measure
I DO have a radioshackup SPL meter in Analogue form AND I sent away for the Rives Audio disc which has test tones calibrated to the RSmeter. The RS meter has known rolloff curve so, the tones are biased.....either that, or they provide a 'if this....add or subtract this much.......table.
I don't know! I never opened the box! I figured, 'There Be Madness'.
the Human Ear is fairly insensitive to Bass Distortion. Several % should be doable, if not more.
Agreed, but we're talking about >10%. For example, http://www.avtalk.co.uk/forum/index.php?t=msg&th=22062&start=0&rid=14&SQ=1178450584

At 95dB and 30Hz ==> 24% distortion.

My point is that with free field measurements one can choose a sub with better characteristics without breaking the bank.