Sub position in room

[jsteinhauer]

After a long, long time of ignoring this, I did a so-called phase test of my sub today, and found a deep trough in the 50Hz area. 30, 40 and 80 are fine, and 60 and 70 are a tad low. Adjusting the phase on the sub did nothing. Do you think this is something that changing the location of the sub will will help?

[Big Daddy]

Originally Posted by jsteinhauer

After a long, long time of ignoring this, I did a so-called phase test of my sub today, and found a deep trough in the 50Hz area. 30, 40 and 80 are fine, and 60 and 70 are a tad low. Adjusting the phase on the sub did nothing. Do you think this is something that changing the location of the sub will will help?

Welcome to the wonderful world of Standing Waves.

The answer to your question is YES. By moving the subwoofer around, you may be able to improve the results. At best, you will be able to get better bass for one seating position. The phase has nothing to do with it.

You should read A Guide to Subwoofers and A Guide to Subwoofers (Part II): Standing Waves & Room Modes.

In the first link, scroll down about half a page. You will find simple guidelines on subwoofer positioning, crossover setting, phase setting, etc. The second link is far more detailed. It requires a lot of patience to read. However, I will promise you that if you spend the time and effort to read it carefully, it will help you understand how subwoofers function.

A simple, but painful (you have to move the sub around and crawl on the floor) way to position your sub is the Subwoofer Crawl technique. In the middle of the second link, there is an explanation and a link to a video by Axiom Audio.

An easier and more expensive way to solve the problem is to purchase a second subwoofer. With two subwoofers, you can get much smoother bass across the room for all positions.

[jsteinhauer]

Thank you. I've considered the dual sub option, but I only have one sub output from my AVR. It's always been a curiosity to me why my AVR autocalibrates the sub about 15-20dB to hot. I now realize that this is probably the issue. I'll have to get a longer connecter.

[Big Daddy]

Originally Posted by jsteinhauer

Thank you. I've considered the dual sub option, but I only have one sub output from my AVR. It's always been a curiosity to me why my AVR autocalibrates the sub about 15-20dB to hot. I now realize that this is probably the issue. I'll have to get a longer connecter.

The majority of people have one sub output on their receivers. You simply have to use a Y RCA adapter (one male, two female). You can buy it at Radio Shack or any electronic store, including car audio dealers/installers.

[LeoneFan]

Originally Posted by Big Daddy

The majority of people have one sub output on their receivers. You simply have to use a Y RCA adapter (one male, two female). You can buy it at Radio Shack or any electronic store, including car audio dealers/installers.

If your receiver has one mono sub output but the subwoofer has stereo line level inputs can you split the receiver output with a Y RCA cable and connect it to the stereo sub inputs?

[JJ]

Originally Posted by LeoneFan

If your receiver has one mono sub output but the subwoofer has stereo line level inputs can you split the receiver output with a Y RCA cable and connect it to the stereo sub inputs?

That too.

[Driver_King]

When I move practically everything in my room to prepare for my screen I'm going to make (probably next year), I'm going to need to move both of my subs out of corner placement which makes me nervous. I don't know where I'd put them. To make things worse, they are two totally different designs, colors, shapes, sizes, layout, ect!

[Big Daddy]

Originally Posted by LeoneFan

If your receiver has one mono sub output but the subwoofer has stereo line level inputs can you split the receiver output with a Y RCA cable and connect it to the stereo sub inputs?

If you use a single cable from your receiver's sub out and then at the subwoofer end, use a y dapter (1 female, 2 male) and insert the adapter into the stereo input of your subwoofer, you will gain 3db or more without any additional power.

[Big Daddy]

Originally Posted by Driver_King

When I move practically everything in my room to prepare for my screen I'm going to make (probably next year), I'm going to need to move both of my subs out of corner placement which makes me nervous. I don't know where I'd put them. To make things worse, they are two totally different designs, colors, shapes, sizes, layout, ect!

Try putting one in the high pressure zone where all room modes are energized and put the other one in a low pressure zone. You have to experiment. Make sure you hire a chiropractor.

[Driver_King]

I read your article completely about that so I know, thanks. That's a lot of moving I'm going to need to do.

[jsteinhauer]

I've moved this sub around to every possible position, and I cant get it to flatten out, so I've decided to order a second sub. It will be here in a couple of weeks. I would like to know, however, is how flat of response can you expect to achieve with one sub and with two subs in a generally rectangular room that is about three times as long as it is wide? With the one sub, I could not across the range of 30-80Hz get anything less than a 15dB difference between the top and the bottom. This is definitely enough to be noticeable, and the only options were to bump up the sub level (which was really annoying) or leave it at an appropriate average, which made the mid-bass very insipid.

[Big Daddy]

Originally Posted by jsteinhauer

I've moved this sub around to every possible position, and I cant get it to flatten out, so I've decided to order a second sub. It will be here in a couple of weeks. I would like to know, however, is how flat of response can you expect to achieve with one sub and with two subs in a generally rectangular room that is about three times as long as it is wide? With the one sub, I could not across the range of 30-80Hz get anything less than a 15dB difference between the top and the bottom. This is definitely enough to be noticeable, and the only options were to bump up the sub level (which was really annoying) or leave it at an appropriate average, which made the mid-bass very insipid.

With two subs, you can get more even bass across the room for every location. However, if you want to carry it to the extreme, you need an equalizer. A perfectly flat frequency for your subwoofers may be scientifically correct, but I am not sure it will give you more satisfying results.

[jsteinhauer]

Originally Posted by Big Daddy

With two subs, you can get more even bass across the room for every location. However, if you want to carry it to the extreme, you need an equalizer. A perfectly flat frequency for your subwoofers may be scientifically correct, but I am not sure it will give you more satisfying results.

I know I won't achieve a completely flat response, but I am unsure of what my expectations should be. Is a 15dB hole in the midbass within reason? Maybe I am expecting too much. I think I could live with 5dB, but 15 is very noticeable, and if I move the sub to a position where I get the midbass up to match the fronts, I lose either the high or low end. For a long time, I could not understand why the autocalibrate feature on my AVR would always set the sub level 10-20dB higher than the other speakers. It does a pretty good job with the fronts and surrounds, and need only adjust them a little using the SPL meter. I bet, now, that the AVR is trying to level match the midbass from the sub with the fronts, which is why it sets the overall sub level way too high. Irrespective, adding a second sub is more likely to provide pleasing results in more seating positions in the room.

[Big Daddy]

Originally Posted by jsteinhauer

I know I won't achieve a completely flat response, but I am unsure of what my expectations should be. Is a 15dB hole in the midbass within reason? Maybe I am expecting too much. I think I could live with 5dB, but 15 is very noticeable, and if I move the sub to a position where I get the midbass up to match the fronts, I lose either the high or low end. For a long time, I could not understand why the autocalibrate feature on my AVR would always set the sub level 10-20dB higher than the other speakers. It does a pretty good job with the fronts and surrounds, and need only adjust them a little using the SPL meter. I bet, now, that the AVR is trying to level match the midbass from the sub with the fronts, which is why it sets the overall sub level way too high. Irrespective, adding a second sub is more likely to provide pleasing results in more seating positions in the room.

15db hole is a bit too much. I have two subs in my room and I get much better results. Recently, I built a third subwoofer and the results improved more. I may add a fourth one. According to some research, 4 subwoofers will give you the best results.