I am having a problem when I calibrate my subs to match my center and surrond speakers. When I calibrate with AVAI and a sound level meter I can match the level of the subs to the Front speakers. However when i attempt to do the same with the Center and Surronds they are about 8 to 10 DB louder then the Sub level according to my sound level meter. This happens both on analog and digital settings. I adjust the subs using the controls on the subs level and phase. The crossovers on both subs are disabled since the Outlaw ICBM handles all crossovers. Raising or lowering the level controls for the sub on the prepro seem to have no effect on the subs. I have also noticed on the LFE test on AVIA the LFE level seems low.

I should note that when actually listening to music there seems to be more then enough bass.

I am using an Pioneer 811S as a prepro with an Outlaw 755 amp. All bass mangagement takes place through a Outlaw ICBM which is situated between the prepro and the amp. DVD player is a Pioneer Elite 45A which is connected to the prepro by both analog and digital connections. The level controls are set to varible instead of fixed. On the DVD player all speakers are set to 0 except for the sub which is set for highest level (6)

Speakers are:

Front: Mirage OM9's
Center: Mirage OM-C2
Surronds: In Ceiling Speakers not sure of the brand
Subs: Mirage OM200 and SVS 21-39 PC Plus

I have a feeling I am missing something but I can not figure how to correct this problem if it is a problem. I dont see how, but would having two subs cause this problem.

I hope I explained myself clearly. Thanks for any input

Peace, Luvthekeys

P.S. I have also posted this question on the AVS forum.

Matching a sub to the rest of the system can be a real bear! The test tone for the sub is a warble tone, meaning it is not 1 continuous frequency. as a result you'll notice that the needle on your flutters quite a bit while setting the output. try detting your main and surround outputs so that they match each other as closely as possible and then set your sub output around -5db less.

Hope this helps.

------------------
My HT v4.0

Sorry in advance for my flip answer but, when I set the level of my lfm-1 the true limitation is how loud I can set it without rattling things in my house. I had an interesting experience recently. I've been listening to my 5.1 setup for months now. When I went downstairs to listen to my living room stereo it sounded incredibly bass-shy to me. I've gotten used to steak; hamburger doesn't do it for me anymore! LOL!

Jay

I also have an ICBM between processor and power amp. I have gone through quite a few different setup routines to find a balance between loudspeakers and subs.

One of the most frustrating aspects of adjusting the phase and level of a sub are the standing waves that develop in a room. If you are not familiar with this, the effects can be quite amazing. In my setup, if I send a steady tone of somewhere between 30Hz and 70Hz, and slowly move about the room, I can find spots where the level is double the average, and other spots where the level is almost nil. This means that whether I am using the good ol’ RS analog SPL meter, or something akin to TrueRTA with 1/24 octave resolution, I will find differing results depending on where the microphone is placed.

Using low frequency noise as a source is an attempt to avoid the worst of the standing wave issue by generating a myriad of frequencies within the subwoofer’s range simultaneously. Even though standing waves do occur, the idea is that the peak nodes and the null points for many frequencies are mixed throughout the room, and as you move the microphone from one point to the next, you might be moving into a null for one of the frequencies present while at the same time move into the peak of another frequency as well as be at a mixed average level point for yet several additional frequencies.

Compounding the issue, when using the analog meter, are two things: the plus-or-minus 4db swing I observe when using noise as a source, the meter is more sensitive at some frequencies than others.

I’m going to save a lot of words by skipping more description of various techniques I’ve tried and get to my “how to get close in a short time” method. Your adjustments can be refined later, but it’s a way to get up and going in about an hour.

With the LFE connection to the ICBM disconnected, I set the levels of all non-sub speakers per results of analog meter readings at the prime listening position – no one speaker will sound louder than another at the prime listening position.

Because my two subs are close to my front left and right speakers, I set my sub phase in this way: I place my left main speaker so that the woofer directly faces the sub’s driver with about an inch between them. If I had a down-firing sub, I would lay it on its side temporarily. I purposely reverse the leads to that main speaker so that the woofer of the main speaker will be 180° out-of-phase with normal. I send a steady tone to the both the sub and the main speaker at the crossover frequency via the ICBM. I then adjust the phase and level of the sub until I hear virtually no sound at the crossover frequency. This means I have gained two things: the two drivers are moving 180° out-of-phase, they are moving at levels where both are putting the same amount of acoustic energy into the air. I then move the left main speaker to its original location and restore the wiring to normal phase. If I knew that the frequency I used in this test were the exact frequency at the center of the crossover area, I would now know that at the crossover point, both my main and my sub would be contributing equal amounts of energy to the room and that they are doing so in phase.

Repeat this process for the right main speaker and sub.

Spend a few minutes listening to familiar material with this setting. Does the bass seem to be in proper balance with the rest of the sound?

I perform one additional test as a confirmation or as a quick refinement, using frequencies approximately one octave lower and higher than the crossover point. In my case I use 80Hz as a crossover point. First, I know that my RS analog meter is approximately 3 db more sensitive near 160Hz as it is near 40Hz. (+0.5db at 160Hz, -2.5db at 40Hz.) This means that my target meter-reading level for frequencies near 40Hz will be 3 db lower than the level I read near 160Hz. I place the meter’s microphone as close as I can to the woofer of my main speaker without touching the cone when it is vibrating, to minimize room effects from the reading. I then take readings at about 140, 160 and 180 Hz. I then take similar readings of the subwoofer at about 35, 40 and 45 Hz. If the subwoofer readings are not approximately 3db lower than the main speaker, I adjust the sub’s level.

I repeat this test on the other main speaker and sub.

Listen to the same familiar material again. Did this refinement help or hurt?

I now know that, for a given note of an instrument that has fundamental frequencies within my subwoofer’s range and harmonics that are in my main speaker’s range, that the ratio of energy being put into the room by the fundamental and harmonic frequencies mimics the original ratio produced by the instrument. Low-end bass notes should sound neither muddy nor lacking, but be both “tight and full.”

I know that this method does not take into account the effects of room response, which can enhance certain frequencies while suppressing others, but I have found this to be a good method to establish a starting point for further refinement.

If I have established the proper balance of sound between my main speakers and my center/surround speakers, then when I establish a good mains-to-subs ratio, a similar ratio is in effect for center/surrounds-to-subs levels. I have confirmed this by listening to stereo sources in 2-channel stereo mode, DPLII surround mode and 5-stereo mode. In all cases, whether the resulting overall volume level rises or falls when the mode is changed, the amount of bass from the subs remains in correct balance with the speakers that are active in the mode selected.

After I have achieved a good balance in this manner, I go on to re-connect and balance the LFE level with the other bass level in the calibrate position. Then I set the LFE control back to –10db.

If you have only one sub, you may use the level settings on your sub, its amp, or on the ICBM. If you are using two subs, once the level on the first sub is set in conjuction with the ICBM, don't change the output level of the ICBM when adjusting for the second sub, only change the second subs level on the sub or its amp.

I hope you find this helpful.

P.S.: If the driver on your sub is significantly larger than the woofer of your main speakers, then you may have to adjust your sub(s) even lower than 3db down in the 35/40/45Hz to 140/160/180 Hz comparison test. Because this test is easy to do, and easy to reverse, try 1 db at a time up or down. Once I reach an "in the zone" setting, I can really tell a musical instrument that has a good mix of sub and normal range frequencies sounds just as it should.

[This message has been edited by bestbang4thebuck (edited March 16, 2004).]