Subwoofer calibration: Why you need an SPL meter

[craigsub]

Guys - It's time to discuss setting up a subwoofer. This whole concept of "I opened up the subwoofer, put it in the corner, ran Audyssey and then fired up ___________ (insert movie here)" is not the proper way to set up a subwoofer.

There is a terrific set up guide as written by Bossobass several years ago, and it still works today.

The setup guide is available here as a PDF file.

Let's start with this basic concept: Audyssey, Audyssey bass EQ, SVS bass EQ, Antimode 8033, Yamaha YPAO, Behringer's various EQ boxes ... ALL are great for fine tuning a subwoofer.

They are NOT, however, capable of defeating the laws of physics, nor should they be the first thing one uses when setting up a system !!!

When purchasing a new subwoofer, the first week, in the minimum, should be spent manually tuning the subwoofer into your system and room.

Take the time to get something like the Radio Shack meter and do a full manual calibration on your system.

Make sure the subwoofer levels match up against the levels of your other speakers.

If you are having a hard time getting good sound and performance from your subwoofer, in your system, then take the time to get it right through placement.

One tried and true method for finding the best place for your subwoofers is the subwoofer crawl method: place the subwoofer at your listening position, run the bass tone from your receiver or a test tone source, and crawl around (usually the perimeter) of the room until you hear the BEST bass.

EDIT: Here is a basic video which demonstrates the subwoofer crawl (compliments of our friends at Axiom Audio). A google search for "subwoofer crawl" might yield more results.

Consider this an open thread - and post your ideas for the best ways to get GOOD bass BEFORE applying a bass EQ device.

[D.T.MIKE]

You mean your not supposed to turn the gain knob to 12 or "halfpower" :biglaugh: since thats were your last sub was?

[Zing]

Make sure the subwoofer levels match up against the levels of your other speakers.

In calibrating with the RS meter, I have found that if I match the sub level to the speakers, the sub's output is simply way too loud. This Compensation chart may be beneficial in that regard:

Radio Shack Compensation Chart - When looking at the values at any given frequency, add the adjustment below to get a fairly accurate reading:

At 10Hz add 20dBs to the meter's readings and at ...

12Hz add 16.5dB
16Hz add 11.5dB
20Hz add 7.5dB
25Hz add 5dB
31.5Hz add 3dB
40Hz add 2.5dB
50Hz add 1.5dB
63Hz add 1.5dB
80Hz add 1.5dB
100Hz add 2dB
125Hz add .5dB

[myc52002]

I have always considered my self quite adept at setting up speaker systems and reasonably well educated about room acoustic effects on sub set ups, albeit not an expert. With that said, in a sentence, Craig couldn't be more accurate in his statements.

I also was a little underwhelmed at first but felt it was my room setup and not the sub. Once I was able to "see" the room through use of equipment like the RS meter and REW it was VERY clear it was the room. So after a lot of experimenting with positioning, polarity and phase adjustments, I found I was not as educated as I thought I was when I started. I would agree it does need some break in time as well but should easily be fine within a week.

As I mentioned in my thread there is nothing more important than going through the manual set up process of positioning. You have to have some method of "seeing" the room IMO. At best by ear you might get lucky and be close to a good location and the more difficult the room the less likely that will be the case.

Case in point, I helped my brother set up his sub last night with REW and found that by moving his sub just 2 feet in one direction and adjusting the phase setting to 180 it virtually completely eliminated a huge null between 50-75Hz. That alone addressed his biggest issue with his sub, no "hit you in the chest" kind of power. He had GREAT low end extension from 35hz to below 20hz but seemed lacking "power". It was missing the articulation (seemed sloppy even though it had a strong low end). Then tweaking with the electronic side of things can be done if you prefer but you can really get a very good setup just by positioning, proper polarity and phase settings. I think it most cases that alone would be very satisfactory for most people. In his case it was and he has zero electronic capabilities for adjusting the sub other than the standard adjustments you normally get.

I do not think there is a need to be any better than +/-3db on measurements simply because you can't really hear much difference better than that. I would even suggest slightly worse than that can still yield very good results if things are fairly well balanced across the bass spectrum.

I said it before and I will say it again, if someone finds they are not satisfied with these units, I suggest the issue is with the setup and not the sub. They are more than capable of delivering the goods. It is imperative one takes the time and effort to do so if you want to get the best out of any sub. Of course this is all IMHO!

[Mike_TX]

Guys - It's time to discuss setting up a subwoofer. This whole concept of "I opened up the subwoofer, put it in the corner, ran Audyssey and then fired up ___________ (insert movie here)" is not the proper way to set up a subwoofer.

There is a terrific set up guide as written by Bossobass several years ago, and it still works today.

It's available here as a PDF file.

Let's start with this basic concept: Audyssey, Audyssey bass EQ, SVS bass EQ, Antimode 8033, Yamaha YPAO, Behringer's various EQ boxes ... ALL are great for fine tuning a subwoofer.

They are NOT, however, capable of defeating the laws of physics, nor should they be the first thing one uses when setting up a system !!!

When purchasing a new subwoofer, the first week, in the minimum, should be spent manually tuning the subwoofer into your system and room.

Take the time to get something like the Radio Shack meter and do a full manual calibration on your system.

Make sure the subwoofer levels match up against the levels of your other speakers.

If you are having a hard time getting good sound and performance from your subwoofer, in your system, then take the time to get it right through placement.

One tried and true method for finding the best place for your subwoofers is the subwoofer crawl method: place the subwoofer at your listening position, run the bass tone from your receiver or a test tone source, and crawl around (usually the perimeter) of the room until you hear the BEST bass.

Consider this an open thread - and post your ideas for the best ways to get GOOD bass BEFORE applying a bass EQ device.

Craig -
Your "here" link is missing the PDF link.

Mike

Here is an older thread with some links...

"Room / Speaker Analysis and Calibration / Correction"

[sbisheff]

I have the Bossobass setup guide as a PDF. If anyone wants it just PM me your email addy and I'll shoot it over.

[Mike_TX]

Subwoofer Setup Guide by Bossobass(PDF)

I have the Bossobass setup guide as a PDF. If anyone wants it just PM me your email addy and I'll shoot it over.

PDF enclosed...


Mike

[sbisheff]

PDF enclosed...


Mike

Sure ... I guess that's an easier way to do it ;) LOL!

[fitzwaddle]

I have an SPL meter. Its says 105. Am I done?

[graydodge14]

Dont know if anyone will take me up on this, but id like to know about how to properly do all this. The 18.2 is my first sub purchase EVER so i have no idea about REW or SPL meters or how to do any of that.

If someone wants to pm me and explain what i need and how to do all these calibrations i would greatly appreciate it, i love the hobby already and love my 18.2 but i basically set it in my corner and ran audyysey and let it play, so i would definately like to get better performance out of it.

[Mike_TX]

Dont know if anyone will take me up on this, but id like to know about how to properly do all this. The 18.2 is my first sub purchase EVER so i have no idea about REW or SPL meters or how to do any of that.

If someone wants to pm me and explain what i need and how to do all these calibrations i would greatly appreciate it, i love the hobby already and love my 18.2 but i basically set it in my corner and ran audyysey and let it play, so i would definately like to get better performance out of it.

You should read Craig's post and the Bossobass PDF (possibly more than once), try it, and then you'll have more experience to help in answering questions and interpreting answers.

Mike

[graydodge14]

Alright i will definately do that, im slowly trying to learn it just all seems a little overwhelming at first.

[craigsub]

Hey guys - This is an important note regarding something which has happened a few times now. This is in regards to the setting for the parametric EQ on the Dayton Amp.

Please make sure the Parametric EQ level control is set to "0" when calibrating and CS-18 series subwoofer.

"0" is not "all the way to the left" as most volume knobs would be. It's actually at appx. "2 o'clock".

If your level knob is turned all the way to the left, it is attenuating your subwoofer by 14.5 dB centered at whatever frequency is showing on the "FREQ" knob.

At the risk of sounding like a wise guy, -14.5 dB is bad. :huge:

[dguarnaccia]

haha, I did that initially and was totally perplexed why I wasn't getting any midbass slam...I zeroed it out and ka-boom...magic!

[engtaz]

Craig,
A better way is to show all the knob settings for each of the amps so everyone has a recomended starting point.

Just a idea.