Subwoofer Help please

Think of trying to talk to someone while next to a freeway, expecting to get all the detail of their lovely soothing voice, with about 90dB worth of multi-directional Doppler Effect going on in your ear.

The point, more than likely, it's not the sub but a poorly integrated subwoofer who's output is in conflict with the room's acoustics. The net affect of all these sound waves arguing with each other is, smeared sound quality.

My recommendation would be to download, install room measuring software and learn how to read a spectrogram as a spectrogram graphically displays the affects of poorly integrated sound; tight vs sloppy sound quality.

I'm not picking on anybody in this choice of image.



If you'll note, at the 48Hz and 60Hz range you'll see sort of blue flame going towards the top of the spectrogram graph. Not knowing the proper terminology, I'll call it sonic bleeding and this measurement was taken outdoors as opposed like your situation, being taken as a room reading where one has to deal with a boatload of reflected/standing wave sound issues.

The point, until all the sound problems are dealt with, due to a poorly integrated subwoofer sound system, one cannot definitively say that the smeared sound is the fault of the subwoofer.

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Edited by BeeMan458 - 3/5/13 at 1:20pm

Sure, it could be his sub is poorly integrated with his room. But it's most likely that his Klipsch just isn't able to play as loudly as it does without having dramatic distortion.

I don't really think the Dayton 18" HO should be considered "budget". Well, sure it's more budget friendly, but it doesn't mean the sub is cheap or of low quality. There are more expensive 18" drivers to choose from, but those are just more expensive than already awesome drivers. You have to think too that this driver probably costs about the same as a $1500 ID sub's driver, if not more. The price savings in DIY come from your hands, not from cheaper components.(Or at least it should)

I have a single sealed Dayton 18" HO in about the same sized space and it's great. The output is tremendous while maintaining clear and accurate bass.

Anything you would recommend in particular?

I have seen some progams for use on smart phones but I am guessing cellphone mics are not as accurate (since cellphones only need to use a limited hz range).

I have seen people recommend Radio Shack's Digital Sound Level Meter, but I do not think it can connect to a computer to produce a graph like that (maybe it can). Also I heard that the Radio Shack one is mainly for speakers and does not do subs well.

This: http://www.hometheatershack.com/roomeq/

See here for a very easy setup guide: http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/270#post_22823228

And here for discussion on AVS: http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs

And here for discussion at HTS: http://www.hometheatershack.com/forums/rew-forum/#axzz2Kp2eq7U7


SUBWOOFER INTEGRATION RULE #1:
The most aesthetically pleasing subwoofer location will always produce a null at the main listening position

This is kind of tongue-in-cheek, but you get the point. Your proposed sub placement may be just fine - but you'll never know unless you measure.

I agree with BeeMan - try to integrate what you have as best you can before throwing money at it, you just may be surprised what you can accomplish with what you already got!

Have you done the "sub crawl" to find the best location for your sub yet? If not, Google it.

.....^^^.....

What he said.

It's great that you did the sub crawl and found the best spot for your sub, but when moving into the world of multiple subs it gets much, much more complicated.

Getting another sub to "not make the room look off kilter" is the wrong reason to go dual - what you will get from duals is higher output, smoothing of room modes and a more even frequency response across a wider area, but only if set up correctly. The only way to set up multiple subs correctly is with some sort of measuring software, anything else is a guessing game.

Usually, the best placement of dual subs in on opposing walls (i.e. one in the front of the room and one in the back), so a second sub is probably not going to help your "off-kilter-ness" at all. Now, 3 or 4 subs might get you a good response with 2 up front....but that's a whole other can-o-worms.

From what I know about spectographs (which is very little), that one ain't lookin' half bad. You got the FR and waterfall to go along with it?

Hard to tell what's going on with the settings on that graph.

Try resetting the FR graph to:

Top - 105
Left - 15
Bottom - 50
Right - 200

Same for waterfall, but with a time range of 600ms.

BTW, you never mentioned your budget for your new and/or additional sub. What is it?

I've got no experience with the RW-12D nor the Daytons, so I will let others more knowledgeable comment on that comparison.

Looking a bit more closely at your FR graph (I know, I know...you don't wanna talk about it), you look to be pretty flat from 30hz-50hz with a very steep drop off above that. Where is your crossover set and do you have the crossover on the Klipsch disabled?

With that big of a drop off above 50hz, you probably have a big hole in your bass response between 50hz and your crossover point (80hz?). Do you have a measurement of the sub with your mains?

I know you're itching to throw some money at this...but, really dude, you should at least try to get what you got working properly first.

Are you asking if the Dayton 18" HO would sound better than the RW12-D? If so, then yes. I have no experience personally with the Klipsch, but I have no doubt that the Dayton would sound much better.

What your spectrogram tells me, you have a hump and a steep drop off slope. The red is deceiving. It is a color, but not an indicator. See the colors as one might see colors on a topo map. It indicates high, low and differences in color as opposed to graphed.

Your graph image corroborates my above in your below posted graph.



If there's a 10dB increase/decrease in output, there's a "PERCEIVED" doubling/halving of volume. So look at the peak of the graph, and come down 10dB and one is "PERCEIVING" half of what they're perceiving at the peak. The mid-bass slam is in the 40Hz to 100Hz range so looking at the graph, one can see they're losing much of the mid-bass slam and in the lower octave, they're going experience a smearing of the bass.

Spectrograms are terribly revealing about the quality of a room's acoustics.

The rising green area is the ringing, or lack of tight bass; smearing. Based on the graph, the usable bass is from about 23Hz to 62Hz. This is not to say your graph is set in stone and cannot be changed, what the spectrogram tells me is, the owner of this graph not taking full advantage of their subwoofer's capability and there's much room for improvement.. And based on the above graph, you "DEFINITELY" want to get a second RW-12d as my bet, your room is large and is sucking the life out of your mid-bass slam.

Based on the posted room measurements in your OP and your follow up room measurements, you "DEFINITELY" need a second sub. Definitely. Not want.......need.

"You're going need a bigger boat."

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Edited by BeeMan458 - 3/6/13 at 8:35am

Both mains + sub.

I don't mean to sound condescending, but you definitely got something going on with your setup judging by the graphs you've posted - either that, or your measurement techniqe is off. I think the RW-12D isn't nearly as bad as you think. That being said, there are definitely better sounding subs out there for $500 and I don't blame you for "chasing the dragon" of better bass - I've been doing it for 20+ years.

But how much more can you expect to get out of an RW12-D? Realisticly?

It seems that only 60 to 80Hz+ bass is being wasted with his current setup. You can't expect to get much more out of that sub can you? It's digging fairly deep and he's lucky he doesn't have a bigger suckout around 23Hz or so.

Without a doubt, he would have drastically improved performance with a higher quality sub, in the exact same spot his current sub is in.

Agreed, but even the 12D should be strong(er) up to the crossover point - the reason I suspect something amiss in his settings.

You shouldn't have any problem breaking below 20Hz but the measured question will be, what is the box tuned at and how much gain will your room provide? And one will need room measurements to be able to share the epilogue.

Sorry. I was speaking of room analyzing measurements as opposed to the physical measurements of the room. Our room analyzing measurements show that with room gain, the subs go down to very usable 23Hz and then things start to fall off fast,

Hey Shady, glad your still fighting the good fight with that 12D.

I just re-read this whole thread and you never said three important things:

What AVR are you using?
Where are your crossovers set (in the AVR and on the sub itself)?
Are your speakers set to large or small?

This is always a possibility.

If that's the case then you have several choices. Invest in either a DSPeaker, Anti-Mode to bring your mode down further. Invest in a miniDSP that is able to tie directly into REW, do both, spend a fortune on room treatments, build an ideal room, buy a new system, or live with what you have.

I went with Anti-Mode, Audyssey, MultEQ XT, REW and a boatload of effort and still have a >72Hz, 1/4 octave, 12dB dip/null that I'm going have to live with. The good news, in my opinion, although not perfect, the <72 Hz shoulder resides in the +/-3dB ideal and all crossovers are set to 60Hz or less so I doubt the best ears are going notice anything during normal movie viewing although, I'm of the impression that an off board, Emotiva, XPA-5 amplifier would be a nice add for more speaker based headroom.

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Edited by BeeMan458 - 3/8/13 at 5:28pm

Does the 12DF have a phase control? You should try playing with that while taking measurements WITH you FL/R on, especially if you move the sub to the back of the room (usually needs to be at 180 back there).