The subwoofer is a Boss American 12" Driver powered by a THX 110 watt Marantz mono amplifier.

Does anyone think leaving my old subwoofer on will help any? Will my old sub most likely interfere with the new one? I have a THX-12SUB by Crystal Audio that will be arriving in a few days or so and I would like to leave my old sub running if at all practical.

My speakers are set to large except for the center channel. My crossover is set to 50hz. I did the auto setup using my digital SPL meter. This gives me the equalization settings. I then went back and manually calibrated the speaker volume levels, (75db,Sub at 77db) and fine tuned the bass peak level setting (anywhere from -22 to -19 sounds best to me) to the room. The other channels are run bi-wire by the same mono amps with the receiver but left and right surrounds are powered by a Denon THX Ultra 2 channel amplifier. I like the way 50hz feels going from left to right in the room and the speakers handle it fine and can go as low as 40hz so I think this is ok. If anyone would tell me this is wrong, and people have, please clarify why. I understand that setting them to small sends more bass to the sub, is recommended for my room size, and is supposed to improve things. To me setting them to small seems to make things worse and I am not sure why. When I change the crossover to 80hz I still have problems having to do with the front of the room when they are set to small. I have two bass traps in the rear of the room, tile ceiling, and plenty of carpet. There is no padding under the outdoor carpet.

To give you an idea of what good my old center channel sub does I did some test.

I did the WOTW test also in this forum area

http://www.avsforum.com/avs-vb/show...14&page=1&pp=30


70db @ LP (8 ft)
Timestamp 15:52 in DTS
the room is 1820 cuft not counting the stage/platforms (2 doors not sealed,one is a solid door)
master volume set -11 (calibrated the sub to 77 or 2db hot)

With other speakers on

97db @ LP

I did another test with Lord of the Rings - Fellowship of the Ring

This is the scene where a wraith jumps his horse chasing the hobbits to the fairy.
66db @ LP
Timestamp 56:19 in DTS
master volume set at 0 (calibrated the sub to 77 or 2db hot)

With other speakers on

106db @ LP

This is where the new sub will go.


http://home.mchsi.com/~author29/P1010100_copy.jpg

http://home.mchsi.com/~author29/P1010099_copy.jpg

I would run all speakers small with the crossover set to 50 or 60hz, depending what your receiver has. The Crystal Audio sub-12 is bound to have more output than the old Boss sub so you'll be robbing the LFE channel of any center channel bass if you run it large. Long term I would buy another of the Crystal Audio subs and place them together at the front of the room.

I would run all speakers small with the crossover set to 50 or 60hz, depending what your receiver has. The Crystal Audio sub-12 is bound to have more output than the old Boss sub so you'll be robbing the LFE channel of any center channel bass if you run it large. Long term I would buy another of the Crystal Audio subs and place them together at the front of the room.

So the new sub will likely fix problems I have setting it to small currently. Thats good news. Thank you.

The area in the photo with the hookups I prewired is a low traffic area which I thought made since. Even 3 would fit there nicely I think.

My plan is to get another some day. Adding the two subs to the front would mean running a 100' cable then split that at the front in the ceiling, dropping that to the walls on eather side of my left and right speakers and possibly needing to punch a few holes in my front wall to string it through. I would also need to run a long extension cables for power and feed those out the walls as well. If they were placed together they could fit ok at the front right wall on the floor. There is an ac outlet there but I would still need to run another cable in the ceiling and punch a hole in the wall, install a faceplat and add a Y split connection.

It would be alot more simple to put them at the rear platform by the equipment closet that is being built soon. I could add new faceplates to the equipment closet (sides) and hide the cables better. They could fit together or the sides whichever. They would not be on the floor however. I'm also assuming the subs reflect some light and depending how much, I would never put them at the front.

Is there some good way to describe what I should be looking for as far as the combing issue would go with the way I would currently be adding a sub? What would be a good scene in a movie to test etc? Is there a free program that does not require a internet (for some reason or phone jack doesnt work in there) connection that I should test with instead of listening by ear?

12.3 Why use a subwoofer? Will it help? One or two?
One reason to get a subwoofer is to add bass to a feeble system.
A second reason is to move the lowest frequencies to a separate
driver, and thereby reduce a particular kind of distortion
caused by the nonlinear mixing of different sounds, called
"intermodulation distortion". A third is to increase the power
handling ability of the system and the overall reliability. All
are valid reasons, but it isn't so simple.

To improve the sound of a good speaker system, a subwoofer must
"integrate smoothly" into the system, extending the bass without
causing peaks or dips. Many subwoofers have a crossover that
goes between your amp and your main speaker which sends the lows
to the subwoofer and sends the higher frequency signals to the
main speakers. This may damage the perfect sound of a good
system, it may sound similar, or it may sound better.

Most good small speaker systems have a bass peak at resonance,
which attempts to compensate for the absence of lower bass.
Like it or not, this is the only way to make a small system
sound realistic. If the small system is done well, the
improvement you will get from a subwoofer will be small, but
still real and, to many, significant.

Correctly done, a good subwoofer will enhance the sound of a
good small-box system. Done wrong or haphazardly, anything is
possible. Even a fine large speaker system might benefit from
careful addition of a subwoofer. However, the better the
original system, the more likely it will be that a modest
subwoofer will do more harm than good.

Low frequencies travel less directionally than high frequencies,
so many people say that only one subwoofer is required for good
sound. This is true to some extent, but not completely true.

There are a few reasons for getting two subwoofers. Some feel
that you need two subwoofers to accurately reproduce the stereo
image, no matter how little low-frequency stereo information
there is. Others feel that two subwoofers are much easier to
set up in a room, less likely to excite standing waves in the
room, and give smoother sound.

A third reason is that two subwoofers can produce twice the
sound of one. Finally, even though subwoofers produce very low
frequency sound and very low frequency sound is non-directional,
subwoofers also have output at 100 Hz, and sound at 100 Hz is
directional, so two subwoofers will give a slightly better
stereo image than one. Assuming, of course, that the two are
separated by at least two feet.

Finally, even though original source signals rarely contain any
music with stereo components below 50Hz, there may be some noise
component with low-frequency out-of-phase noise. This unusual
noise might add a sense of space to a recording if it is
reproduced by a system in which the woofers are very far apart.

It is still true that a single good subwoofer, correctly added
to a system will help the sound but two will probably help more.

Be sure my subs are in phase. Good reminder.

I also read the subwoofer setup guide on Audioholics website. That proved to be very helpful. There was illustrations of the various dips and peeks in multiple setup configurations. That gives me a visual aid in what I should be listening for. Although I feel like I'm getting a one week college degree, I think I know whats going on now. The auto-setup with my mic might actually be a great resource here as well.

http://www.audioholics.com/tweaks/get-good-bass/subwoofer-placement-the-place-for-bass-part-1/subwoofer-placement-the-place-for-bass-part-1-page-2

I ended up with a thread about getting a subwoofer, a thread about using it, a thread about how it did, and a thread about my theater. It has been difficult to keep track of all those sorry. LOL The auto-setup calibrated the subs fine.

I ended up replacing the driver in the center channel. The current plan is to get two more of the speakers on the left in this photo.

http://home.mchsi.com/~author29/P1010178.JPG

I'm having the pioneer sub returned for $ or exchange. My amp is to powerful for it and it makes the LFE more quiet. :(