Setting Subwoofer Level

N

Nuglets

Full Audioholic
I have calibrated my Denon AVR-1603 reciever to 75 dB from each channel except the subwoofer. If I set the subwoofer to 75 dB it is extremely quiet, I can hardly even tell it is there, so I set the level to my listening preference, a level where the bass seemingly comes from the front speakers but I can at least hear my Paradigm PS-1200. The problem is when I check my settings using my SPL meter the readout I get from the sub channel is about 88 dB. From what I have read, the LFE level for Dolby Digital is supposed to be +10 dB in relation to the rest, but I read that the reciever should compensate for this, and I shouldn't have to set my Sub level to 85 dB? Any advice and/or corrections to my knowledge will be greatly appreciated. Thank you.
 
jeffsg4mac

jeffsg4mac

Republican Poster Boy
There is no easy answer I am afraid. It sounds like maybe you have a null where your test tone is centered around. Try using a wider band of pink noise sent to the sub and maybe you will get a little more accurate level. It is almost impossible to set a subwoofers level correct until you have corrected any peaks in the response.
 
agarwalro

agarwalro

Audioholic Ninja
I think you are confused between setting reference level and calibrating your setup. When you set each channel to play pink noise at 75dB you are level matching your speakers. This is done so that all speakers play equally loud. Once this is done and you use the same volume setting on you receiver while watching movies you know that you are listening at Reference levels. This is only the first step in calibration.

The second step is to take SPL measurements from 15Hz to 20,000Hz at the primary listening position and plot them on a graph. The aim is to get as close to a flat plot (at 75dB SPL) across the frequency range. This will help you identify bumps and dips in your frequency response. I am fairly certain that your low end has some serious dips due to room acoustics. Because of this you have to play the sub extra loud to overcome the room response.

Keep in mind that the Radioshack SPL meter is inaccurate in the low end. A brief guide on how to calibrate and the corrections for the meter can be found on the SVS website here, http://www.svsound.com/questions-faqs.cfm#meter

Hope this helps.
 

Buckle-meister

Audioholic Field Marshall
agarwalro said:
...the Radioshack SPL meter is inaccurate in the low end.
The correction values in Agarwalro's link are to compensate for the c-weighted curve that the SPL meter uses. However, the SPL meter itself is innacurate from around 250Hz up.

Regards
 
Last edited:
N

Nuglets

Full Audioholic
Thank you

Thank you for the replies. I have been thinking about getting the Rives Test CD for some time now but haven't had the chance to order it. I will definately do that, and I will soon be getting an apartment with a room that should be far superior, in terms of sound and acoustics to the one I have my equipment in now. Also some Paradigm 90P's are on their way to their new home(my house), so I will just wait for them before pursuing any type of calibration at the moment. I guess what I was really getting at in my original question is if anyone is familiar with my reciever and what Denon uses as their reference level for surround calibration, but I think I will just go the route with the calibration cd. It sounds more promising, as I get to go through the frequencies, plot the sound, and find out where exactly my problem lies, and hopefully position my speakers more freely than I have the opportunity to do now. Again thank you for the replies, I had a feeling my room was contributing a lot to my somewhat lacking bass. The room is on the 2nd story and the house is not very solid, I can hear more bass downstairs in my kitchen(directly below my room), than I can in my room. Hopefully I get all the small things(or big depending on how you look at it) worked out when I get my new apartment.
 
GlocksRock

GlocksRock

Audioholic Spartan
Buckle-meister said:
However, the SPL meter itself is innacurate from around 250Hz up.Regards
So why do we want to use this if it's innacurate? Is it just so we can have something to make sure that all the speakers are set at the same level, even if the device used to measure that is inaccurate?
 
jeffsg4mac

jeffsg4mac

Republican Poster Boy
GlocksRock said:
So why do we want to use this if it's innacurate? Is it just so we can have something to make sure that all the speakers are set at the same level, even if the device used to measure that is inaccurate?

From Rives "We have found this meter to be very reproducible, but not very accurate. It is also very inexpensive and easy to obtain."

Reproducible is the key word there. Which is why one would want to use the Rives CD and not just any test tones.
 

Buckle-meister

Audioholic Field Marshall
GlocksRock said:
...why do we want to use this if it's innacurate?
For the low frequencies that a sub would reproduce, the meter will give negligible error compared to measuring devices costing far more.

GlocksRock said:
Is it just so we can have something to make sure that all the speakers are set at the same level, even if the device used to measure that is inaccurate?
This is well spotted; :) that to an extent it is irrelevant that the meter isn't 100% accurate given that the error for each speaker would be constant.

Regards
 

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