Hey guys 'n gals,

Got a client I did a modest theatre for a few years back:

Denon AVR5800
Denon DVD
Tannoy Dual Concentric Towers (LR) and DC center (Think they were called System 8)
Tannoy 10" sub.

Went back recently to add an RTI control system, and the client's son complained because his friends theatre has gobs more low-bass than this system. I had to agree... however the problem is not the sub, its the room.

I've tried:

a) moving the sub to other possible locations
b) adding a second sub (Velodyne DLS4000R)
c) pretending that there isn't a problem.

None of the above is solving the problem. Obviously, due to a wicked standing wave issue, there is very little sensation of low-bass in the key listening area. Around the sides of the room, there is ample (too much) bass.

The room is a smallish room (approx 16x13 or so), and it is oddly shaped.

I'd like to find a good solution because this client just did his upstairs system with us as well, and I'd like to help improve things (client didn't notice the problem until he saw/heard our attempts to fix it, which was started with his son's comments.)

One suggestion we have offered is to add two butt-kickers to the seating. The only other solution I can think of is to add a wack of acoustic treatment.... but I'm not fluent enough in this area to guarantee a fix.

Any suggestions?

Hey,
Have you tried adding another sub?
If you added another Tannoy 10" and put them at opposite sides of room, this might help to even out the bass. My system had a similar problem, with the impression that one listening area had too much bass, and the opposite side not enough. I daisy chained another sub off the first one, and now I only have to run each sub at half volume and there is more then enough bass (and heaps more if ever needed).
I think a lot of installers use this method, and it is seen as a good way to get even bass across a whole room. I have even heard of some installers using 4 subs in larger setups.
Goodluck

I don't even remember where I found it, but Once I ran into a rather lenghthy PDF about Multiple subs written by

Todd Welti
Research Acoustician
Harman International Industries, Inc.

It was pretty good, relatively easy to comprehend... I'd post a link, but I don't know where I found it.

shoot me a message and I can e-mail it to you.

PS it's about 800 Kb.

Do most of you guys use more then one sub in installations?

Brent is referring to the infamous Harman white paper where they discuss sub locations...

As for multiple subs, YES!! as often as possible.

In your application, a single 10" sub of European pedigree will NEVER fill a room of that size with prodigious amounts of throbbing bass to satisfy some young dude with a bangin' car audio fixation and a thick steel plate in his head.

You need CONE AREA, and POW-WER... and you don't have either.

That Tannoy is probably a very good performer with 2 channel, but they really don't have a ground pounder for movie soundtracks.

Your problem can also be helped considerably by placing some premade or homemade bass traps in the corners of the room to absorb some of the energy of your nasty room modes before they can get back out into the listening area and cancel the subwoofer's output.

Is this a living space type media room theater?? or a dedicated themed out theater?? or something in between??

In my travels, I have discovcered a very simple way to get superior bass:
- thousands of dollars in room modeling, measurements, and room treatments
- multiple cabinets loaded with big drivers that have big motors and big power handling
- big rack mounted amps to drive the snot out of those big subs
- a multi-band parametric EQ which will be calibrated with a room averaged, multiple mic 1/24th octave RTA

If some, or many, of these options are out of the picture, consider adding a Butt Kicker... a little rumble goes a LONG way....

Ok,
Ideas for subs? Brands etc?
Will a sub with a bigger cone, rule it out for music playback, or is it just as good?
(have heard larger cone + more bass, but slower response from cone limits usefulness with music? Could have heard wrong....)
Whats best for movies?
Music?
A good compromise for both?
(and getting back to point of thread, think multiply subs seem to be the way to go)

Agreed. 10" are not going to get you much power in a large room.

Mulitple subs. Sure try puttin ghtem at opposite sides of the room and reversing the phase on one. (Had that work real well in one install.)

Buttkickers and Clarks can really save teh day with messed up room boundriesd plus they give the client that kicking fell without the loud volumes.

Did you try moving the listening position out of the room modes?. Adding subwoofers will help making the bass response more even around the room but if your listening position is in null you wont solve the problem. Also using equalization will help, but moving the listening position is the key to success.

Mr. Druid, I have a suggestion: temporarily place the sub at the main seating position, on the chair or sofa, and on a small table if it helps, and then crawl around the room, especially anywhere that might be a good location for the sub.

Play a movie or music that has relatively constant low-frequency signal to reduce the time this takes. You may or may not find a place near a wall, maybe or maybe not in a corner, but wherever the bass sounds strong is a good sub location.

Now, place the sub in this (or these) location(s) and see if the bass is stronger than before. Experimentation is still needed, but this method can save you quite a bit of time. It's faster to crawl than it is to keep relocating the sub. Good luck!

Try the Cerwin-Vega L-36 Earthquake. You might have to look to find a pair, but there's nothing that will thump better.

A Bass is a type of stringed instrument. Low End is what subs output.

Does the bass behave differently in different surround modes? I know the older Denons as well as a few other brands do not put sub signals out on the LFE output or when you are in certain sound modes. They have changed this on newer models. Even if I use a sub, if I have speakers that have good bass response I set them up as large, it definately gives you a fuller sound. When working for a previous employer we used to build theaters with a separate sub for every channel plus the LFE, one job had 4 side speakers, 2 rears and LCR for a total of 9 subs plus 2 LFE subs.. all on ADA amps.

Most receivers will send no signal to the subwoofer when you set all speakers to large. When speakers are set to large, program material with a .1 or LFE channel will only send signal to the LFE output, if you have one.

My favorite subs for our mid-fi systems are non ported. The best one I've heard to date is the M&K V-76. I hope M&K get back on their feet soon.

One little trick we use is very technical and requires gobbs of instruction: stick a rolled up sock in the rear port (s). I've found more subs lie about their frequency roll off and cause crappy boomy bass because of the reverberative port airflow. Closing the port stiffens the cone so you can increase the power level without bottoming out the driver. Even cheaper subs will give you better thump instead of boom. It seems to be easier to detect dead spots in the room as well.

my .02.

If your client is sitting in a 'null' a million jigawatt sub isn't going to fix it. And, as for a 10" sucking, the Definitive Technology Supercube I rocks. I would suggest running a second sub to help tame the room modes/nulls. You might be able to fix some of the problem with the phase dial.

Do you have all the speakers set to small? Sub turned on in the setup menu? Cross over maxed out on the sub itself. Set the reciever to 80hz if the mains will ahndle that. (Let the receiver do the crossovering sp?)

I'd get a really long cable and move the sub all over the room INCLUDING points in the middle of the room. Then report back to us.

Regardless what subs you add or change follow Ernie's advice. The problem with low base is probably more to do with the seating being in a null point. Ernie's method is a simple method to determine the best seating position without doing the math (design) or buying software tools.

Cheers