[chosenhandle]

I recently purchased a pair of Force subs for my 2 channel set-up. I did some research here to determine the best way to integrate them into my system. Unfortunately, in each case found, the pre-amp included bass mgt or a sub-out port. I do not have either, and am splitting my output at the pre-amp out and sending one set of IC's to the power amp and one set to the Subwoofers. As such, both are receiving full range.

My speakers are Green Mountain Audio Continuims and very effectively go down to 42hz and use first order crossovers (6db per octave). I understand that the room has a major determination on where the roll-off point should be, but lets just say that it is 42. I am a bit confused as to how to set the crossover points on each of the two crossovers (on each sub) to get a 6db increase starting at 42.

Secondly, I sort of assumed that the way to use the SPL meter with this set-up would be to go to 60hz and get a baseline reading at 70db then go to 20 and starting heading north. Theoretically I should see no rise or fall at 42...in short the sub should roll off as the mains take over. Am I thinking about this correctly? I have the excel program ready and need a little advice on how to attack this integration.

The subs are placed directly inside each of the main speakers, slightly in front of them. I can't think of a reason why I would have to play with the phase in either sub. However, I have no experience and may be totally wrong in my thought process.

Obviously, the room will throw a monkey wrench in the works, but I have to get a better handle on integrating these subs.

I appreciate any input. I really like the subs and look forward to a long relationship with ACI and hanging out here and learning a thing or two.

Paul

[griller]

Paul, I'll take a shot at some of this. Since purchasing my Force XL last Spring I've learned a lot about making a sub play music. I think the main thing I've learned is that it is pretty quick and easy to make it sound good, and pretty time consuming to make it sound PERFECT.  IMHO well worth the time. Once you get there it is very rewarding. All the controls have an effect although it might be very subtle. Like the phase, the manual tells you to adjust it using the SPL meter to get the loudest output around the transition. In your case, that's going to be mid 30ss to mid 55s. Personally, I'd probably start with both crossovers on the sub around 40. I would treat them as one crossover at least for now. Take your measuerments and move the crossover up or down depending on if you have a bump or a hole in the response. One thing I learned was to set it up by the measurements and then listen for a week. This helped me match what I heard to what I measured. Make small adjustments once you have it close. Another tip is that when it is right, you'll hardly know when you turn the subs on. At your low crossover frequency there will be many recordings where  you probably won't know whether the subs are on or not. So be sure to use recordings that really have low frequency content. Have fun with it, I did. Now I'm waiting on a friend to get his Titan so I can help him out 

[griller]

I forgot, I don't think your scenario is unusual, I think it is one of the first setups in the manual. I believe Mike told me this was the most common two-channel setup of all.

[Mike Dzurko]

Paul:

You've gotten some very good advice here from a fellow who's really done it the right way. It looks like your assumptions are correct. Just follow the steps and take your time. Ultimately it is about listening. You will most certainly hear it start to lock in as you get closer and closer to having it really dialed in. Stop back here often, we all learn from the journey!

[chosenhandle]

Well, I had 5 days to play with the subs. Using my handy SPL meter, I charted the test CD and was able to get the frequency response flat +/-3db except as described below.

I moved and tested the subs all over the place. They ended up in the front behind and to the side of the main speakers. The first crossover is set at about 37ish and the second is all the way off. Couple things are curious about the results:

-the best bass response was returned when I put one sub at almost zero phase adjustment and the other almost all the way up (180?). That seems strange to me, yet doing this caused the highest output when testing subs only as well as smoothing out the overall response chart. I assume "it is what it is" and leave it alone, but it puzzles me...mainly cause I am kinda dumb about these things.

-I have a 8db suckout at 35 and 70. It existed before the subs were integrated and adding the subs seemed to "smooth out" (definitely isolated the drop to only 35hz/75hz). I assume that both drops are room created. I use bass traps in the corners as well as some panels on the walls (GIK acoustics). Any ideas there are welcome.

All in all, it was a great experience. As mentioned in the previous post, I really can't tell when the subs are working, but I am definitely hearing a fuller soundstage and more "body" to the music. My "bat-ear" son really liked the results. One of his test CD's was the Nine Inch Nails new record...so don't anyone think that I wasn't using "bass-rich" material.

Thanks again for all of your help. I look forward to learning more and sharing what I stumble upon.

Paul

[Mike Dzurko]

Well, I had 5 days to play with the subs. Using my handy SPL meter, I charted the test CD and was able to get the frequency response flat +/-3db except as described below.

I moved and tested the subs all over the place. They ended up in the front behind and to the side of the main speakers. The first crossover is set at about 37ish and the second is all the way off. Couple things are curious about the results:

-the best bass response was returned when I put one sub at almost zero phase adjustment and the other almost all the way up (180?). That seems strange to me, yet doing this caused the highest output when testing subs only as well as smoothing out the overall response chart. I assume "it is what it is" and leave it alone, but it puzzles me...mainly cause I am kinda dumb about these things.

-I have a 8db suckout at 35 and 70. It existed before the subs were integrated and adding the subs seemed to "smooth out" (definitely isolated the drop to only 35hz/75hz). I assume that both drops are room created. I use bass traps in the corners as well as some panels on the walls (GIK acoustics). Any ideas there are welcome.

All in all, it was a great experience. As mentioned in the previous post, I really can't tell when the subs are working, but I am definitely hearing a fuller soundstage and more "body" to the music. My "bat-ear" son really liked the results. One of his test CD's was the Nine Inch Nails new record...so don't anyone think that I wasn't using "bass-rich" material.

Thanks again for all of your help. I look forward to learning more and sharing what I stumble upon.

Paul

Paul:

You're doing it exactly the way it should be done. Doing your homework, and taking the time to do it right. Your excellent results are the result of putting in the effort. There are many who would really love what great sub(s) do for musical listening pleasure . . . . you're showing them the way 

[bpape]

Yup.  When they're right, they should be basically invisible.

If you give me the dimensions of the room, the location of the speakers, subs and seating, I'll try to take a shot at how best to help with the null at 35 and 70.

If you're sitting in the exact middle of the room width wise, try shifting you and the speakers about 4-6" off to one side and try it again.  Just a hunch on my part.

Bryan