Adjusting Subwoofer volume [Archive] - Audio & Video Forums


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Ace H
01-21-2008, 03:44 PM
Using the A/V Receiver's test tones ONLY what is the best way to adjust the volume of the subwoofer?

I have a Yamaha A/V Receiver with the crossover set at 80, the sub (JBL SUB 12) is turned to the highest crossover setting. All speakers (5.1 setup) are set to small. Sub's volume is set at the next mark past the half way mark. I have the A/V Receiver's sub output volume set at +2. When I run the test tones, the sub's volume is much lower than the other speakers yet when listening to a source the sub's volume seems ok. I don't understand why the sub's volume is low during the test tones. What am I missing here?

01-21-2008, 10:41 PM
Sounds like you've set it up right. You're probably just experiencing the fact that low frequency noise doesn't sound as loud when at the same setting as midrange noise. Your ears are not a good tool for this; only a sound pressure level meter will give you an accurate reading. The cheap but useful Radio Shack meter will tell you if it's putting out acceptable sound levels and help you adjust the output accurately.

01-21-2008, 10:44 PM
You should have your sub connected to the JBL Sub12 using the line level input marked "LFE" which is either the left or right input only, with one single cable from the receiver's sub output. Set the sub toggle switch on the JBL Sub12 to "LFE" not normal. Now the crossover and volume contols on the JBL should be bypassed (if the volume level knob is still active then set it at the half mark). The crossover and volume for the sub are set using the receiver's sub controls. Using the receiver test tones and your ear, or better yet, a Radio Shack sound level meter, about $40 (the analog one is superior to the digital one for this test) set all of your 5 speaker levels to the same exact sound output from your main listening position, try 70, 75 or 80db's (although 80 is quite loud for this test)(use "C" weighting, "slow" response settings). Hold the meter away from your body, at ear level and at a 45 degree or so above horrizontal. Your ears are OK but not nearly as accurate as the sound level meter. Buy one when you can, it really makes a noticable improvement in a smooth precise surround level. Try to get all speakers within 1/2 db of each other. Now set a matching sub sound level using the sub volume control on the receiver and the receiver's test tones. Many times depending on the receiver you have to turn the level up even as high as +10 to match the sound level output of the other 5 speakers. Later you can tweak the sub level slightly up or down depending on your taste and whether listening to music or movies.

You don't mention your main speakers. The 80hz crossover setting on the receiver is good if your 5 speakers are medium or large and have at least a -3db frequency response lower falloff at 70Hz-80hz or lower. If you have smaller speakers with a - 3db low response of higher than 80hz then set the receiver crossover at the same or 10db higher as the -3db frequency. If your receiver has an individual crossover setting for each of the 5 speakers all the better. Setting all speakers to small is correct. Tweak these settings as you like.