Finally Set Up...A Subwoofer Calibrating Experience

[the hand of boredom]

Hello Everybody.

Times are now quite joyous here. Several weeks ago we finished the entertainment area in the basement. All the equipment was moved from the upstairs living area (and acoustical nightmare: bare walls with wood-laminate flooring).

Our basement area for the system is 17.5 x 14.5 x 8 ft. There is a bar at the front right corner of the room which extends the dimensions by 4 ft of that side wall. There also an open walkway which extends to the stairs and main floor, so our listening space cannot be enclosed. Acoustical furnishings include, well padded carpeting, a small sofa 3.5 ft from the back wall, and acoustic ceiling panels. The speaker drivers are 3 ft from the back wall and 6.5 feet from eachother, and 13 ft from the listening sofa. We have two Servo 15s stacked in the front left corner, their drivers alligned with the mains' drivers.

I tell ya, trying to do this sub thing is a pain in the gooner! I think before I had both the crossover and level way to high. At moderate levels, the bass was powerful and deep and there was a slight but satisfying rumble that could be felt on some notes. But the minute we got to comfortably loud, the bass became overwhelming and the panels, the plaques on the walls, and every 2by4 that held this place up would rattle irritatingly. This is the way people want to hear it now when they come over. But it just doesn't sound right.

After tweaking the speaker placement and all the sub calibrations (by ear, no money for the fancy gadgets). I think I got it right. I now have the crossover set around 65 Hz, the level on the subs at exactly 50% gain, and the level on the X30 at about 30% gain. I can attest to the difference in imaging that a properly set up sub-bass system can add to the mix. There is suddenly better imaging, clarity, and presence about the music (and videos). The deep bass is almost visible or palpable, and there is much less audible room vibration during louder playback, but that little thud you can feel is there. I await the arrival of the SPL meter and test disc to see how my ear calibration measure up to the special devices.

I'm curious to know from my fellow sonic-holics what your bass experiences are like. Where are your subs? How are you coping with your room difficulties? How do you like your buh-buh-bass? Are you the conservative that likes it accurate or the level-cranking liberal that wants to feel the rumble of every note? When did you know you 'got it right'? For those who have calibrated with an SPL reader, how did your calibrations by ear compare with the device?

THOB

BTW, Matrix Revolutions? Yeah, good bass.

[kexodusc]

Great thread.
Personally, I like an exaggerated bass for HT, but a tight and accurate bass for music. It's a bit tough to find a good blend rather quickly.
I use to have my crossover set at about 65 Hz or so, but recently I used the cut-off frequency built in to my receiver (90Hz) and set my Studio's to "small". This has really helped me get a better blend with my main speakers in most ranges. The only downside to this is that my old receiver's cut-off is fixed at 90 Hz....once in a while the sub gives itself away. I'll gladly accept this rare and small annoyance for the improvement I got. Not sure exactly at what frequency bass signals become non-directional, but I suspect around 80-85 Hz. When I finally get my new receiver with better bass management I suspect this will be taken care of.
I always thought the "small" speaker settings were for those little cube HTIB speakers, but boy was I wrong. Not only is the bass more accurate now, but the mid and high frequencies seem to be handled better by my speakers now that low bass isn't a concern for them. My Studio 40's are about 3 feet from the back wall, and 2 feet from the sides, toed-in with some curtains and small shelves to act as acoustic treatment. The sub is about a foot away from my front left speaker in between it and the TV, and a foot out from the wall.

As for SPL calibration...I fool around with my speaker level setting every week...I can usually be off by anywhere between +7 and +3 dB's. I cannot do what an SPL meter does by myself, even though I swear they sound right to me. After I calibrate it with the SPL, adding 3 dB's sounds a bit louder. A system won't sound bad, but it does sound better when it's calibrated with an SPL meter. Personally, I think SPL meter's are the best $40-$50 dollar investment you can make in your system...just think, everytime you bump a speaker, move it an inch or two, rearrange furniture, etc, it's there for you. Helps allow for some really cool side by side amp or speaker comparisons too by ensuring the volume is pretty much standard between the models your comparing. Takes some of the bias out.
You can usually get one cheap on ebay.

[kingdaddykeith]

I'm curious to know from my fellow sonic-holics what your bass experiences are like. Where are your subs? How are you coping with your room difficulties? How do you like your buh-buh-bass? Are you the conservative that likes it accurate or the level-cranking liberal that wants to feel the rumble of every note? When did you know you 'got it right'? For those who have calibrated with an SPL reader, how did your calibrations by ear compare with the device?

You can never get close by ear, I use a Test Disc that I made myself with sine wave test tones starting at 10Hz to 120Hz at 1 Hz spacing, and a modified RS SPL meter with a pana mic wand (DIY). This will show you where your peaks and dips are, but even then you cant do anything about them if you don’t have a Parametric EQ like the Behringer Feedback Destroyer. Once finished the sound is night and day different, my 2 Maelstrom Subs are flat in room from 15Hz to 80Hz.

[magictooth]

Once finished the sound is night and day different, my 2 Maelstrom Subs are flat in room from 15Hz to 80Hz.

Holy smokes,

2?!

Maelstroms? How big is each unit? Do you have any place to sit?

About the real thread though, go and get a test disc and SPL. It's amazing that you're unwilling to spend a little bit in order to get the best out of both your Servo-15s. That's a large amount of money you've spent on subs.

[bikehikefish]

You can pick up a Rat Shack SPL meter on EBAY for less than 35 bucks. Then get a Stryke Bass Zone CD with all the test tones for about 12 bucks.

Once you graph out your bass, you will WANT to get the Behringer Feedback Destroyer (on EBAY from $50 - $90).

I moved my Paradigm PS-1000 from the corner to between the front speakers and that flattened the curve, but there were still two peaks, one at 40 HZ and one at 55HZ. The BFD got rid of the peaks. After the booms at those two frequencies were eliminated, I had to turn up the volume on the sub to match the fronts. This was a good thing, as the bass is now at an appropriate level from 30 - 80 HZ, instead of the level being dictated by the 40 HZ peak, with the other frequencies being relatively lower.

[the hand of boredom]

Holy smokes,

2?!

Maelstroms? How big is each unit? Do you have any place to sit?

About the real thread though, go and get a test disc and SPL. It's amazing that you're unwilling to spend a little bit in order to get the best out of both your Servo-15s. That's a large amount of money you've spent on subs.

Magic:

To add to my original post, and to reply to yours I know that I don't quite have it perfect, but it is MUCH better now that I am closer to perfection. The money spent on the 15s is well worth it, I enjoy the performance alot.

I really am excited about obtaining an SPL an test disc for a few reasons:

1. to see just how imbalanced the response is
2. to play with more audio toys
3. to see how close (or far) my ear's calibration is to that of the device

However, with the finishing of the basement and all the other economic perks of moving into a new house I don't have enough dolla-bills to drop on a parametric EQ. After getting used to the sound of the system in the basement there doesn't appear to be a noticeable peak, but I know for a fact that there is a null somewhere along the response curve that I can do nothing about at the moment.

When I start working again in a week I'll be able to have some interest in shopping around for an EQ. At that point, the fun can start.

THOB

[the hand of boredom]

You can never get close by ear, I use a Test Disc that I made myself with sine wave test tones starting at 10Hz to 120Hz at 1 Hz spacing, and a modified RS SPL meter with a pana mic wand (DIY). This will show you where your peaks and dips are, but even then you cant do anything about them if you don’t have a Parametric EQ like the Behringer Feedback Destroyer. Once finished the sound is night and day different, my 2 Maelstrom Subs are flat in room from 15Hz to 80Hz.

Waddup Player!

Where did you get those sine waves from? I tried using Kazaa search to no avail!

15 Hz is lethal. Good show. Are the Maelstroms 15 inchers?

THOB

[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.

[Woochifer]

Waddup Player!

Where did you get those sine waves from? I tried using Kazaa search to no avail!

15 Hz is lethal. Good show. Are the Maelstroms 15 inchers?

THOB

I guess all those downloaders on Kazaa aren't audio hobbyists!

Here's a great website that has pointers on how to EQ a subwoofer using a Behringer Feedback Destroyer. It's the site that I mainly used when setting up my subwoofer (there is a learning curve, but the results are worth it). It also has a series of sine wave MP3 files posted, as well as an Excel spreadsheet that you can use to plot your frequency response (it also has the correction values that correspond to the Radio Shack analog SPL meter, which gets progressively less sensitive in the lower frequencies).

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

[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 ?

[magictooth]

2. to play with more audio toys
THOB

That's all the reason I need to justify a new purchase...even if the wife disagrees.

[magictooth]

Waddup Player!

Where did you get those sine waves from? I tried using Kazaa search to no avail!

15 Hz is lethal. Good show. Are the Maelstroms 15 inchers?

THOB

I think that they're 18" drivers. The Tempest is a 15". The Maelstroms apparently have a higher sensitivity so you don't need a more powerful amp to drive them.

[kingdaddykeith]

Waddup Player!

Where did you get those sine waves from? I tried using Kazaa search to no avail!

15 Hz is lethal. Good show. Are the Maelstroms 15 inchers?

THOB

The Maelstroms are 18” drivers made by Adire, I’ve built 2 sonotubes using these and my experience mimics Woochifer’s, they sounded quite bad until I added a BFD and used the software program to plot the room response. Here ars some links to the Tone Generator and Room response program.


Tone Generator (freeware)
http://www.nch.com.au/tonegen/#104

Room response program
http://www.pvconsultants.com/audio/eq/peq.htm

[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]

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.

[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

[the hand of boredom]

The Maelstroms are 18” drivers made by Adire, I’ve built 2 sonotubes using these and my experience mimics Woochifer’s, they sounded quite bad until I added a BFD and used the software program to plot the room response. Here ars some links to the Tone Generator and Room response program.


Tone Generator (freeware)
http://www.nch.com.au/tonegen/#104

Room response program
http://www.pvconsultants.com/audio/eq/peq.htm

'
Sa-WEET Damn!

That thing is a bee-yute! Two 18 inch drivers?! That is quite insane. The sub looks really nice, man. It compliments the the decor of the room from what I can see. I hope they bring you hours of visceral abuse. How many watts running into 'em?

THOB

[kingdaddykeith]

Thanks:

I'm running a Mackie 1400i trrough a Behringer Feedback Destroyer. With the VC paralleled (2 Ohm) thats approx 700W per sub in a 14x14.5 room, more then enough. I actually made them to fit the decor of my main speakers more then the room.

[the hand of boredom]

Thanks:

I'm running a Mackie 1400i trrough a Behringer Feedback Destroyer. With the VC paralleled (2 Ohm) thats approx 700W per sub in a 14x14.5 room, more then enough. I actually made them to fit the decor of my main speakers more then the room.

Visually, quite impressive. You've done some nice work. So let me get this straight. You have a 14 x 14 room with two 18s. You should get some medication for your bassoholism.
That mains look interesting. What can you tell me about those? Are they DIY?

THOB

[kingdaddykeith]

That mains look interesting. What can you tell me about those? Are they DIY?

THOB

Yes there DIY:
The drivers are Scan-Speak 8530-K00 midwoofers with a Vifa XT25 tweeter in a MTM config. The entire system 2 woofers 2 mains, 2 subwoofers and center and surrounds are actually all DIY and all active through Marchand XM9-3kk and XM44-4 electronic crossovers fed by all Sony ES amps and preamp. Right now the tweeters are 1st order electrical at 3k and the mids are 4th order at 2.8K, but I'm still working on that and I'm about to get the Halo C2 and 2 A52 amps soon.

My diy site
http://www.geocities.com/kingdaddyke...?1078331805978

[the hand of boredom]

Wooch and all,

Hooked up the laptop to the ol' system and ran the low frequency sine waves in WinAmp. Now although I can't give you a graph, I can tell you a few things.

1. There seems to be significant output from 75 to 90 Hz
2. Output immediately above 90 Hz drops off a bit
3. Some of the ceiling panels produce audible vibrations between 80 and 90 Hz and 40 and 45 Hz
4. 31 Hz rattles the insides of the TV like it ain't a joke.
5. 35 Hz rattles some of the ducts
6. the lowest frequency that moved the cones was 15 Hz.

I guess the next step is to do this all over again with the proper tools. I'll keep you all posted on this process.

THOB

[Woochifer]

Wooch and all,

Hooked up the laptop to the ol' system and ran the low frequency sine waves in WinAmp. Now although I can't give you a graph, I can tell you a few things.

1. There seems to be significant output from 75 to 90 Hz
2. Output immediately above 90 Hz drops off a bit
3. Some of the ceiling panels produce audible vibrations between 80 and 90 Hz and 40 and 45 Hz
4. 31 Hz rattles the insides of the TV like it ain't a joke.
5. 35 Hz rattles some of the ducts
6. the lowest frequency that moved the cones was 15 Hz.

I guess the next step is to do this all over again with the proper tools. I'll keep you all posted on this process.

THOB

Definitely repeat the process once you get a SPL meter. If you're getting vibrations from the TV, ceiling panels, and ducts at specific frequencies, you very well might have significant peaking at those frequencies. With that kind of peaking, a parametric EQ would help. I would also add that if you have a ported sub, it probably won't matter at all that the cones still vibrate at 15 Hz. What you actually hear depends on the tuned frequency of the port, and the actual output will decline significantly after that point regardless of what the cones are doing.

[the hand of boredom]

Definitely repeat the process once you get a SPL meter. If you're getting vibrations from the TV, ceiling panels, and ducts at specific frequencies, you very well might have significant peaking at those frequencies. With that kind of peaking, a parametric EQ would help. I would also add that if you have a ported sub, it probably won't matter at all that the cones still vibrate at 15 Hz. What you actually hear depends on the tuned frequency of the port, and the actual output will decline significantly after that point regardless of what the cones are doing.

OK, but what about if the subs are sealed enclosures, as in the Servo 15?

As far as parametric EQs go, I've looked at the Rane products, Symetrix and Behringer. Those seem to be the most popular at a reasonable price.

THOB

[Woochifer]

OK, but what about if the subs are sealed enclosures, as in the Servo 15?

As far as parametric EQs go, I've looked at the Rane products, Symetrix and Behringer. Those seem to be the most popular at a reasonable price.

THOB

With a sealed enclosure, the dropoff will be a lot less steep than with a ported enclosure. The tradeoff is that the dropoff begins sooner, whereas a ported enclosure (if designed right) will have a more even response and higher SPL down to the tuned port frequency, but the dropoff is a lot steeper. Some people have argued that the steep dropoff makes the lows sound less natural, which is why sealed subs are often referred to as "more musical" sounding than ported subs.

The Behringer is the most oft mentioned EQ on this board at least because it's the least expensive ($120 from Musician's Friend). I use it and can tell you that there's a very steep learning curve because it was not designed for home entertainment use. Rather it was designed as a feedback reducer for live concert sound rigs, the parametric EQ is more of a secondary function. The Rane (at least from appearances) is a lot simpler to use because it was designed solely as a parametric equalizer, however because it is an analog model with manual switches, it does cost more. The Behringer is a digital model, and people who've tried the Behringer in the midrange and highs say that it creates audible noise and colors the sound. But, because those shortcomings do not affect the low frequencies, even users who are otherwise analog purists will still recommend the Behringer for subwoofer equalizing.