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Discussion Starter #1
So, I have a large null in my theater room. I spent all weekend doing the sub crawl with an SPL meter and got both my sub's in the bester location. What else can I do? I ordered a umik1 and it is on the way. I have no room room treatment as of yet. I will post measurement when it arrives...is there anything I can do in the meantime?
 

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Have you moved the mic front to back or left to right to see if you can determine where the null is coming from?
 

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Discussion Starter #3
The mic has not arrived yet. I have only used an SPL meter.

Do you mean, move the mic around or change its orientation?
 

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Understood. Just walk with the meter front to back and side to side and see where the null changes. Try to keep it at seated head level.
 

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Discussion Starter #5
Ok...i walked the slp meter around the room to diff spots. I am down around 7 to 10 db in about a 6ft oval around the mlp. There are a couple of other spots but nobody sit in them. My room is 23d 15w 8 ft ceiling. Mlp is about 15 ft off the front wall on the long side. I don't know what to do next?
 

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How many subs do you have? I am thinking that if you were to have 2 or 4 subs (whatever you can handle) in the room you could change the null. I have 2 subs (centered on the front wall and rear wall), and have thought about getting 2 more subs to center on the side walls to get more bass to the front row. I know that having multiple subs will even out the bass, just not sure if it will solve your problem. Bryan will know if it is possible or might have another suggestion.
 

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Discussion Starter #7
I have 2 18s...they are in the ft corners. I have moved them to every poss placement option available. They are in the best place for output at the mlp. I plan on getting 2 more in the future. I just wasn't sure if there was anything I needed to do or add to help. I have no room treatment or eq-ing of any kind until my new marantz arrives. I am changing almost my entire system and wanted to "do it right" this time.
 

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I have 2 18s...they are in the ft corners. I have moved them to every poss placement option available. They are in the best place for output at the mlp. I plan on getting 2 more in the future. I just wasn't sure if there was anything I needed to do or add to help. I have no room treatment or eq-ing of any kind until my new marantz arrives. I am changing almost my entire system and wanted to "do it right" this time.
Gotcha. :)
Check out the download graphs here... http://www.harman.com/innovation


Are your subs facing the MLP or aimed toward the center?

You are def on the right track trying to get the sound as good as possible before running Audyssey, as it will have an easier time getting it perfect for you.
 

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I'm gonna read it right now...thanks
Here is the image of the sub placements... I used (a), but I will go to (c) if I get 2 more subs.
 

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Discussion Starter #11
Both of mine are in the front corners. One is angle toward the mlp the other is straight. This is what I found yeilds the best result and gives best imaging with front and rears.

I don't have rew setup yet, but have played with sub distance on my pre/pro. I read that phase can be adjusted that way. Something like 12 ft is 90 degree. Again it all by ear and SPL meter.

The suns sound a lot better now. But I plan on builds some corner trap this weekend. Lowes has some mineral wool insulation I'm going to try. Not sure if I should just order a kit from gik tho. I have read that the custom made corner kit don't do a lot in every room.
 

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Discussion Starter #12
I have to place them I'm the corner until the projector and screen get put in later this year. This will bey first attempt at prof room treatment
 

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If the null is in an area that large then yes, you'll need to play with sub position. Did it change a lot side to side?
 

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Discussion Starter #14
More ft to back...about 3 ft in ft and back of me. I have moved them everywhere along the walls. I can't put them in the middle of the room so I didn't try. I may just have to live with it
 

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It could be a non-modal null off the wall behind you. Thicker treatment in the rear would help if that's the case.
 

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Have you tried turning the all the way around (facing the wall behind them). I have seen this work very good.
 

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Try moving the LP forward. The room length divided by 1/5 is 4.6'. 1/5ths and 1/3rds are a good place to start for avoiding nulls. Assuming I read your post correctly about being 3' off the wall. Are you using the built in test tone to measure?


Sent from my iPhone using Tapatalk
Also, I'm pretty sure move the sub distance in the avr will be a "by guess, by golly", since the lfe test tone will only activate the subs alone, and won't do anything for a null, since it's really just a delay. You could adjust and listen, but REW will definitely show you in living color. It will help with impulse response, and smoothing the crossover region, but you'll need to play a tone at the crossover frequency(i.e.: 80hz). This will activate the subs and the mains at the same time, and at that point you'll look for the most output on the spl meter. YouTube has test tones, or the App Store has some nice tone generators.(android might too).
AƒG - Audio Function Generator PRO by Thomas Gruber
https://appsto.re/us/pgCw1.i
This is the one I use. AirPlay, or mini to rca.
 

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Discussion Starter #19
My decrease in SPL is about 3ft in front and behind my mlp. Each sub is in the front corners.
The left is about 8" off the front wall and maybe 4" off the side. It points almost directly facing the mlp. Maybe 25 degree angle.
The right is about 20" off the front wall and maybe 2" from the side. It faces parallel to the side wall.
This is the best I can get them to sound.

When you say the 1/5th thing. Is that from both ft and side wall? Cause that will be in the middle of the room. Putting the sub in front of the mains.
 
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