Subwoofer / SPL Meter Question

[Olivertmc]

Hi all:

Currently, I use the S&V audio tune-up dvd and Radio Shack analog spl meter to calibrate my equipment. I recently purchased a new subwoofer (SVS PB10) and noticed that the "correct" level for my subwoofer (+3db over the rest of the speakers) results in extremely low output from the sub. My question is, am I doing something wrong? I understand that the sub should not take center stage for music, but the present level seems a bit too low for bass-heavy movies. Any guidance will be appreciated. Thanks.


- Olivertmc

[Pat D]

Hi all:

Currently, I use the S&V audio tune-up dvd and Radio Shack analog spl meter to calibrate my equipment. I recently purchased a new subwoofer (SVS PB10) and noticed that the "correct" level for my subwoofer (+3db over the rest of the speakers) results in extremely low output from the sub. My question is, am I doing something wrong? I understand that the sub should not take center stage for music, but the present level seems a bit too low for bass-heavy movies. Any guidance will be appreciated. Thanks.


- Olivertmc
Setting up a subwoofer and calibrating it with an SPL meter should, if done well, improve the evenness of the bass response. Maybe you are used to a bass hump which is no longer there.

There is nothing to prevent you from turning up the subwoofer level some more until it sounds right. This may also require a bit of adjustment to the crossover. Also, you may find the preferred level for the subwoofer is different for movies and music.

[Sir Terrence the Terrible]

Hi all:

Currently, I use the S&V audio tune-up dvd and Radio Shack analog spl meter to calibrate my equipment. I recently purchased a new subwoofer (SVS PB10) and noticed that the "correct" level for my subwoofer (+3db over the rest of the speakers) results in extremely low output from the sub. My question is, am I doing something wrong? I understand that the sub should not take center stage for music, but the present level seems a bit too low for bass-heavy movies. Any guidance will be appreciated. Thanks.


- Olivertmc

You are probably balancing your mains to a subwoofer in room mode. Every room has modes and nodes. Nodes(cancallations) are usually not as offending as modes(peaks). My suggestion would be to purchase a disk with sinewaves under 80hz. Use this disc and your SPL meter to measure the bass response. Go out and purchase a Behinger feedback distroyer(they can be had for as little as $99), This piece of equipment is a must have for any subwoofer owner, as it has the capacity to correct up to 10 room modes(plenty for most rooms). The difference between before BFD and after can be a night and day improvement(or any degree in between)

I knew my subs were capable of very prodigious bass output, but after installing the BFD, removing a couple of light weight modes, I found my subs has some VERY healthy output at 18hz.

[Woochifer]

As others have said, you probably have a room induced peak at a specific frequency that is driving the SPL reading higher than it should be. With my system, I had three huge room induced peaks that needed correction (one of which was +12 db). In that kind of situation, if you set the bass to the desired overall level, then you'll get these huge boomy peaks popping up at various moments. If you set the level so that the boomy peaks aren't quite as jarring, then it makes the rest of your bass sound weak.

Terrence mentioned using a parametric EQ to reduce these peaks. I use one as well and it makes a huge improvement to the bass because it allows you to set the subwoofer to the correct level with a more even overall sound that doesn't have you jumping for the volume control whenever the music or movies hit certain notes that just boom out at you.

You should also try repositioning the sub. The corner placement gives you the most bass reinforcement, but it also can create the most uneven sounding bass. A good trick to position the sub is to place the sub where you sit, feed a test tone through it, and go around the room (listen low to the ground, crawl if you have to). The location where the bass seems fullest and most even sounding is the likely best location for the sub.

[Olivertmc]

Thanks for all of the advice. Woochifer, unfortunately due to room aesthetics (and the sheer size of the SVS) there is really only one place in the room to put the sub, which happens to be a corner. However, you and Sir Terrence have piqued my interest with respect to using a parametric eq. I took a look at it on the partsexpress website and it seems rather complicated. The applications listed in the product literature include use on a studio soundboard to reduce feedback (or "destroy it"). How does a parametric eq work? Where does it go in terms of the audio chain (I assume between the receiver and sub)? I'm pretty clueless when it comes to the use of such a device. Thanks again for all the help.

- Olivertmc

[Woochifer]

Thanks for all of the advice. Woochifer, unfortunately due to room aesthetics (and the sheer size of the SVS) there is really only one place in the room to put the sub, which happens to be a corner. However, you and Sir Terrence have piqued my interest with respect to using a parametric eq. I took a look at it on the partsexpress website and it seems rather complicated. The applications listed in the product literature include use on a studio soundboard to reduce feedback (or "destroy it"). How does a parametric eq work? Where does it go in terms of the audio chain (I assume between the receiver and sub)? I'm pretty clueless when it comes to the use of such a device. Thanks again for all the help.

- Olivertmc

The corner placement will unfortunately give you the most unpredictable room effects, and the highest potential for boominess. Since you're stuck with that placement, I think the first thing you should do is get a SPL meter and measure the in-room response of your sub using test tones (can download them, buy a test CD, or use the tone generators included with some receivers). If you see a bunch of peaks and dips in the frequency response, the bass will likely sound boomy and poorly integrated with the rest of your system. Using a parametric EQ, you have an inexpensive tool that can correct this problem very effectively.

The Behringer Feedback Destroyer is complicated because it was not originally designed for home use as a subwoofer equalizer. (Behringer makes other equalizers that are easier to use and more intuitive, but they also cost over $300) The instructions are more suited to its primary use as a concert sound processor. The parametric EQ functions are a side benefit, and the whole reason that the BFD has gained so much popularity as a subwoofer EQ is its dirt cheap price (currently selling for $100, but a new model is due out soon that will cost $200).

The BFD plugs in between the receiver's subwoofer output and the subwoofer input channel.

Sonny Parker's BFD setup website is where you should go for more info on the BFD. It has easy to understand setup instructions and a lot of very handy downloads like a spreadsheet with the correction values for the Radio Shack SPL meter, and test tones. Behringer's specs and instructions are not aimed at home users, so you should go to that site first.

http://www.snapbug.ws/bfd.htm

[Pat D]

Thanks for all of the advice. Woochifer, unfortunately due to room aesthetics (and the sheer size of the SVS) there is really only one place in the room to put the sub, which happens to be a corner. However, you and Sir Terrence have piqued my interest with respect to using a parametric eq. I took a look at it on the partsexpress website and it seems rather complicated. The applications listed in the product literature include use on a studio soundboard to reduce feedback (or "destroy it"). How does a parametric eq work? Where does it go in terms of the audio chain (I assume between the receiver and sub)? I'm pretty clueless when it comes to the use of such a device. Thanks again for all the help.

- Olivertmc
In most rectangular rooms, corner placement is best, providing the smoothest response, the deepest response, and potentially the loudest response (which means you can lower the subwoofer's gain). Some years ago, Tom Nousaine publised some measurements of the response of a subwoofer in various rooms and in most, a corner was best. This presupposes a steep crossover at 80 hz or below so that you won't hear midrange material coming from the subwoofer. As well, the corner should be at least 6 feet from a doorway, window, or other large opening, if possible.

[Olivertmc]

The corner placement will unfortunately give you the most unpredictable room effects, and the highest potential for boominess. Since you're stuck with that placement, I think the first thing you should do is get a SPL meter and measure the in-room response of your sub using test tones (can download them, buy a test CD, or use the tone generators included with some receivers). If you see a bunch of peaks and dips in the frequency response, the bass will likely sound boomy and poorly integrated with the rest of your system. Using a parametric EQ, you have an inexpensive tool that can correct this problem very effectively.

The Behringer Feedback Destroyer is complicated because it was not originally designed for home use as a subwoofer equalizer. (Behringer makes other equalizers that are easier to use and more intuitive, but they also cost over $300) The instructions are more suited to its primary use as a concert sound processor. The parametric EQ functions are a side benefit, and the whole reason that the BFD has gained so much popularity as a subwoofer EQ is its dirt cheap price (currently selling for $100, but a new model is due out soon that will cost $200).

The BFD plugs in between the receiver's subwoofer output and the subwoofer input channel.

Sonny Parker's BFD setup website is where you should go for more info on the BFD. It has easy to understand setup instructions and a lot of very handy downloads like a spreadsheet with the correction values for the Radio Shack SPL meter, and test tones. Behringer's specs and instructions are not aimed at home users, so you should go to that site first.

http://www.snapbug.ws/bfd.htm

Woochifer:

I went to the Sonny Parker site - what a great place for information, thanks for the link. As I was going through his detailed instructions, I got to a section regarding numerous measurements on the spl meter. My question is, how do I know when the tone playing is the tone I'm supposed to be measuring? My test tone disc has a sweep, but I don't know what hz are playing at what time. Am I missing something? I'm excited about doing this, but just hoping that the measuring and adjusting isn't beyond me (I fear math/numbers). Thanks.

- Olivertmc

[Tom V.]

Hi Oliver,

Be sure you have all speakers set to small in the speaker setup menu, and check that no "midnight listening mode" dynamic range limiters are engaged on the receiver.

If you are used to setting bass levels by *ear*(which almost always results in the bass being way too loud)...the first time you listen to SPL meter calibrated bass it is very common to feel like the bass is WAY too low. However, if you give it some time...you may begin to appreicate the lower bass levels..:) A good rule of thumb on bass is(in music listening)...when you walk into a room, you don't even want to know a subwoofer is in operation. Only if the subwoofer is turned off(and the bass disappears from the recording)...will you realize it(the subwoofer) was working.

Tom V.
SVS

[Olivertmc]

Hi Oliver,

Be sure you have all speakers set to small in the speaker setup menu, and check that no "midnight listening mode" dynamic range limiters are engaged on the receiver.

If you are used to setting bass levels by *ear*(which almost always results in the bass being way too loud)...the first time you listen to SPL meter calibrated bass it is very common to feel like the bass is WAY too low. However, if you give it some time...you may begin to appreicate the lower bass levels..:) A good rule of thumb on bass is(in music listening)...when you walk into a room, you don't even want to know a subwoofer is in operation. Only if the subwoofer is turned off(and the bass disappears from the recording)...will you realize it(the subwoofer) was working.

Tom V.
SVS

Thanks Tom - I'm going to make some additional adjustments tonight and give myself time to get used to the difference. By the way, the PB10 is an excellent product, I can't believe the difference it has made in my enjoyment of my system. Keep it up!

- Olivertmc

[Woochifer]

Woochifer:

I went to the Sonny Parker site - what a great place for information, thanks for the link. As I was going through his detailed instructions, I got to a section regarding numerous measurements on the spl meter. My question is, how do I know when the tone playing is the tone I'm supposed to be measuring? My test tone disc has a sweep, but I don't know what hz are playing at what time. Am I missing something? I'm excited about doing this, but just hoping that the measuring and adjusting isn't beyond me (I fear math/numbers). Thanks.

- Olivertmc

The sweep is only good for identifying whether or not you got problems and how big those problems are. It won't tell you exactly where the problems occur. For that, you'll need to either download test tones, or buy a test disc from Stryke or Rives Audio. (The Rives disc also includes a set of test tones calibrated to the Radio Shack analog SPL meter)

[Stu-r]

Hi all:

Currently, I use the S&V audio tune-up dvd and Radio Shack analog spl meter to calibrate my equipment. I recently purchased a new subwoofer (SVS PB10) and noticed that the "correct" level for my subwoofer (+3db over the rest of the speakers) results in extremely low output from the sub. My question is, am I doing something wrong? I understand that the sub should not take center stage for music, but the present level seems a bit too low for bass-heavy movies. Any guidance will be appreciated. Thanks.


- Olivertmc

The SVS subwoofer guys have a correction chart on the web for the Radio shack meter, if it wasn't included with the paperwork that came with the speaker. I've found that I have to use an exceptionally high crossover frequency to keep lower frequency interactions between my speakers from drivng me nuts. There's enough delay among them that the bass almost echoes when they all operate simultaneusly at low frequencies. I guess my room is an example of multiple low frequency sources being too much of a good thing. When I use the sub as a sole source of low frequencies, the system sounds superb..