Finally Set Up...A Subwoofer Calibrating Experience

[Woochifer]

In that size a room, you're likely to have a room-induced problem somewhere in the low frequencies. If you're using two Servo-15s (that's about $3,000 worth of subwoofer right there), you absolutely should make the extra investment of $170 in a SPL meter, test disc, and Behringer Feedback Destroyer (or other parametric EQ). I would even present the argument that you're much better off with ONE properly tuned Servo-15 than with two untuned Servo-15s.

Because of how differently we perceive low frequencies, I would say that it's impossible to properly match the levels between the mains and subwoofer just by ear. Believe me, when you do a frequency chart with a SPL meter and test tones, you'll probably be shocked at how inaccurate your bass actually is. These inaccuracies in the lows are predominantly influenced by room acoustics, and in a small room, the longer wave lengths of low frequencies inevitably interact with one another and create huge peaks and nulls in different spots within the room.

When I got my subwoofer, it was a boomy ungainly beast out of the box. Even with a SPL meter to match the subwoofer level with the mains, it still sounded horrible. After measuring the frequency response, I spotted three huge peaks. These frequency peaks dominated what I heard from the subwoofer, and it alternately sounded boomy at times, and thin and weak at other times. The reason is because those peaks drove both what I heard and what I measured. Overall, the bass was actually too low, but to go any higher would make the bass sound even boomier because of those peaks. An example is with an acoustic bass where everything sounds fine until it hits just the right note that hits you hard and leaves your head ringing.

When I ordered my sub, I knew that my room would present a problem, so I bought the parametric EQ and test disc at the same time I got the subwoofer. Believe me, the EQ made an absolutely critical difference. By allowing me to set the frequency center point and the bandwidth for the equalization, the parametric EQ honed in on the exact problem spots that I had noted. With additional testing and fine tuning, I was able to get my subwoofer pretty much flat all the way down to 25 Hz, with serviceable bass all the way down to 20 Hz. By eliminating the peaking, I was able to raise the overall bass levels without inducing any boominess, which allows for a full and balanced sounding bass that integrates very well with the mains. Without the EQ and all that measuring and adjusting, I probably would not have kept the subwoofer.

Right now, I have a pretty good system going. Terrence and others have recommended that you set the subwoofer about 4 db higher than the mains because our ears are less sensitive in the lower frequencies. I agree with that, and that's my default position for music. With movies, I typically bump it up by another 2 to 4 db, depending on the soundtrack.

The chart below shows my sub's before and after measurements using the parametric EQ.

[omikey]

Whooch - as you know I'm in the process of setting up my new system. In a couple of weeks I anticipate that I'll be ready to begin tuning it.

How long did it take you to go through the process of tuning the sub ?

[Woochifer]

Whooch - as you know I'm in the process of setting up my new system. In a couple of weeks I anticipate that I'll be ready to begin tuning it.

How long did it take you to go through the process of tuning the sub ?

I spent about 1 1/2 hours doing the initial subwoofer calibration. When I installed an audio rack in the corner, I did some remeasuring and tweaking, which took about half that time.

[the hand of boredom]

Woochie,

Being a site addict has greatly improved your post quality.

Thanks for the link. The list of downloadable sines is clutch and I will make use of them as soon as I get back to the house tonight.

The two 15s might be a bit excessive and it's true that two poorly tuned Servos will not sound as good as one properly tuned Servo, but did you ever think about two properly tuned Servos, young mang? You did not...muwahahahahahha!!!!!

THOB

[Woochifer]

Woochie,

Being a site addict has greatly improved your post quality.

Thanks for the link. The list of downloadable sines is clutch and I will make use of them as soon as I get back to the house tonight.

The two 15s might be a bit excessive and it's true that two poorly tuned Servos will not sound as good as one properly tuned Servo, but did you ever think about two properly tuned Servos, young mang? You did not...muwahahahahahha!!!!!

THOB

Gee, I don't know whether to thank you or punch you! I didn't think that there was anything to improve upon with my posts as a "Senior Member" or "Site Newbie", but glad to hear that they've gotten better anyway!

Anyway, I was just posting a suggestion that if you're short on cash, you could always unload one of those Servo-15s to buy yourself some EQ and measuring tools. And if you are indeed selling and need a buyer, you'll let us all know, right?

[the hand of boredom]

Gee, I don't know whether to thank you or punch you! I didn't think that there was anything to improve upon with my posts as a "Senior Member" or "Site Newbie", but glad to hear that they've gotten better anyway!

Anyway, I was just posting a suggestion that if you're short on cash, you could always unload one of those Servo-15s to buy yourself some EQ and measuring tools. And if you are indeed selling and need a buyer, you'll let us all know, right?

If I am made an offer for a sub that I can't refuse, the easy decision can be made. However, I know that one day I will have a system of my very own in a large listening area, and for sure will have dedicated HT and 2-channel rooms. Two subs in one room or two subs in two rooms, it's the worst of two evils at this point, my man. At the moment, there are things more important than a gadget that measures the levels of various sounds frequencies. There are credit cards and utilities to pay and a couple hungry stomachs to fill. I know it won't be long before I can get the necessary goods. It will make calibration all the more enjoyable knowing how long I've had to wait and how much I've had to sacrifice in order to make the gain.

THOB