HOW TO SET UP A SUB (dbs hrz dial)

[misterdoggy]

Ok the system is nearing perfection.

The question is when setting up levels, calibration where do we put the volume knob at on the Sub.

You can set the decibels output with a dpl meter but where do you start from. You don't want to end up "boomy" but different sources, and different recordings provide varied information.

The Sub is supposed to be subtle. They say if you can hear it, then theres too much volume.

How can one setting on the volume of a ASW825 for example be good for all the different signals. I have a dpl meter.

[RobP]

Do you have a subwoofer level control on your pre-amp as well?

[RebelMan]

doggy, First ensure that the rest of your speakers have already been calibrated. Adjust the processor's master volume control to the 75db reference point; use only one of the pre-calibrated speakers when doing this. This should be metered from your listening position.

Then a good place to start is with the subwoofer volume control set half-way. While playing a low level test tone, set the db offset (initially should be zero) on your processor for the subwoofer channel to the proper SPL's, (in this case 75db). If the offset range is not sufficient to compensate for the changes necessary, adjust the subwoofer volume control (plus or minus) one third from the midpoint and recalibrate.

[misterdoggy]

Thats what I've done and yes the levels so far have been set in the Processor to 75db.

The new Lexicon which is coming can set levels for each mode/and or source.

But how do you know if you got it right ?

[RebelMan]

It really depends on how you are managing bass, what the crossover frequencies are set to for each channel and the LFE signals that are played back (which is controlled by the mixing engineer). The more bass you redirect to the sub the more evident it will become. However, multiple subs can smooth out the low frequencies and minimize localization. It won't be obvious until the "information" is directed to the sub which again is dictated by the above. In music it can be even more subtle.

[dyazdani]

But how do you know if you got it right ?

"Right" is a subjective term, just ask the high school students around here on how to set their car subs up

I follow the already mentioned practices about calibrating to a 75db level.

One thing is that I believe the RS SPL meter response is off at low freq (you can find curves on the 'net). I think I calibrate my sub to 71-72dB and the speakers to 75dB.

[Karma]

HI doggy,
Considering that I am surrounded by science all day, every day, my method is not very scientific and considerably out of line with what has been mentioned. I find that instruments and calibration material are nearly useless for critical subwoofer calibration. I use the good old way...my ears.

Here's what I do: find a recording that has a prominent bass guitar or viol line and concentrate on it. Listen to the scale runs as the notes go up and down in frequency. If the sub is out of integration, some notes will seem out of place either loud or soft. Usually these occur around the crossover frequency. Room effects are an issue but this method cancels them out because you will hear tand correct the total bass response of the speakers and the room. This is good.

Use the out of place notes as your adjustment landmarks and even them out using the level and crossover adjustments. This works best if the target crossover frequncy is between 30 to 60 or so HZ. 40 to 50Hz is really best which fits my situation. With a little practice, it becomes easy. Our ears are remarkable instruments if we just give them a chance to show their stuff.

You noted an important fact. Different recordings and even different cuts on the same album can have different bass levels. There are two ways of dealing with this. Accept the bass as recorded or adjust the bass level for each case which can drive a person nuts. I use the latter method if I can. I have found that the sub level is a very critical adjustment and minor changes can make a big difference both good and bad. This is the best reason to have a remote control for the subs volume.

I feel so strongly about this that I am adding a remote volume control to my sub channels. I have found a kit, microcontroller controlled, that should get the job done. When it's fininshed and if it works as well as I hope, I will write a report for the forum. Right now it's just a bag of parts but it's not a difficult project if one has just a little electronics background.

Sparky

[misterdoggy]

Sparky,

Separate remote control for a difficult to gauge speaker might find yourself working all the time.

I've actually got it set to below 40hz as the technical dept at b&w said that the 802D's don't handle the 20-32hz area. Its really just the booms and bangs which makes the job even harder.

Dayzdani,

You said there were graphs that showed the miscalculation the spl meters make on sub readouts. Can you recommend one ? I am curious, because my spl meter goes 10dbs up and down when measuring the Sub. I almost have to do it by ear.

[dyazdani]

You said there were graphs that showed the miscalculation the spl meters make on sub readouts. Can you recommend one ? I am curious, because my spl meter goes 10dbs up and down when measuring the Sub. I almost have to do it by ear.

Yes, let me see if I can find one and I'll post the link. It's not for all SPL meters though, it is model specific. The one I'm talking about is for the Rat Shack version.

Mine also swings on the sub, probably 4dB though - I can usually get it to settle down. You could also use the "slow" response if your meter allows.

[dyazdani]

I found this information from a lab test a guy did to calibrate the meter.

10Hz +20.5
12.5Hz +16.5
16Hz +11.5
20Hz +7.5
25Hz +5
31.5Hz +3
40Hz +2.5
50Hz +1.5
63Hz +1.5
80Hz +1.5
100Hz +2

125Hz +0.5
160Hz -0.5
200Hz -0.5
250Hz +0.5
315Hz -0.5
400Hz 0
500Hz -0.5
630Hz 0
800Hz 0
1KHz 0

1.25Khz 0
1.6KHz -0.5
2Khz -1.5
2.5Khz -1.5
3.15Khz -1.5
4KHz -2
5KHz -2
6.3KHz -2
8KHz -2
10Khz -1

12.5KHz +0.5
16KHz 0
20KHz +1

Also, try doing a google search on "radio shack sound level meter calibration" or something similar.

[Karma]

HI doggy,

Sparky,

Separate remote control for a difficult to gauge speaker might find yourself working all the time.

I've actually got it set to below 40hz as the technical dept at b&w said that the 802D's don't handle the 20-32hz area. Its really just the booms and bangs which makes the job even harder.

Dayzdani,

You said there were graphs that showed the miscalculation the spl meters make on sub readouts. Can you recommend one ? I am curious, because my spl meter goes 10dbs up and down when measuring the Sub. I almost have to do it by ear.

I guess it depends on what you call work. Adjusting the subwoofer levels for a custom fit as necessary is only work if you have to get out of your seat and go across the room to do it. Having a remote for the subwoofer takes the work out of it. If I had to get up every time (as I do now) I simply won't do it.

As far as actually making the adjustment to attain the proper bass balance is concerned, it takes a bit of practice. You will be an expert in short order. BTW, I'm only talking about music, not movies. For movies I use Denon's calibration facility and I don't make bass adjustments often. I find movies far less critical than music.

Your lack of interest puzzles me. This is not the type of thing to be dismissed as stereo lunacy. You have gone out and spent a huge amount of money on your system. Now you imply you don't want to go to a little bit of trouble to learn how to really optimize your bass levels to gain a much more enjoyable experience. Or, maybe you don't believe my claims. Well, do the experimentation and see for yourself. I'll be interested in your findings.

Trust your ears!!!! They must be good or you would not be here. You are acting as though the bass adjustment is beyond your abilities to judge right from wrong. I don't buy it, not for one minute.

Sparky

[dyazdani]

The remote volue control is a neat idea. I've used a helper in the past to adjust the sub volume itself. It's a little easier IMO than using the pre/pro and going from music to test tone back to music again.

[misterdoggy]

Well Guys another beast has arrived. I've got the Lexicon MC12BV5 up and running. The setup has 2 Mic's that come in a James bond looking case that I am to understand are very expensive and delciate and sensitive.

You separate the 2 mics at head height in the sitting postion at nearly both ends of the main couch. The you run calibration and distances.

The huffs Phzzzzzzzzz then Meows YiiiiiiiiiiiOuuuuuuu on each and every speaker including the Sub. Then its set. I've got a feeling this is a lot more accurate and involved than the RatShack dpl I'm using for $39. I'll go with this.

Wow what a sound. The spearation in the front left and right is really noticeable much more clarity and separation than the Halo C1.

Ease of setup was nothing to it. And it has a Proprietary Digital Sound called 5.1 L7 which they claim is better than DD or DTs. Sounds pretty good but I have to listen to it. Star Wars was pretty impressive. I will create a thread when I have more to say.

So hopefully Sub problem resolved. All you have to do is spend a fortune on a processor that calibrates for you.