In need of a little acoustical advice. Room layout included. - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 34 Old 01-24-07, 04:00 PM
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Re: In need of a little acoustical advice. Room layout included.

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My bookshelf speakers are setup as LARGE as well as my rear bipoles (which seems a bit strange as they have small 5" drivers), .
I think that might be your problem...
I tried setting my bookshelf speakers and side dipoles to LARGE at one time and found that the bass was almost non existant, particularly the mid to lower bass..
I finished up setting them all to SMALL, with a crossover to the sub at 90Hz..
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post #12 of 34 Old 01-24-07, 04:32 PM
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Re: In need of a little acoustical advice. Room layout included.

When you say it doens't have that punch you expected, can you elaborate on what you mean by that?

- Jack
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post #13 of 34 Old 01-24-07, 05:00 PM
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Re: In need of a little acoustical advice. Room layout included.

George,

When you set your speakers to large, the processing in your receiver sends the full audio signal to your speakers (everything from 0 Hz to 20 kHz). This may be why your sub is not "rocking" your room. If you set your speakers to small, then the bass management function of your receiver will send all audio signals above the "cutoff level" to your speakers and all audio signals below the cutoff to your sub. Depending on your receiver, you either get to select the cutoff level, or some receivers have only one set cutoff at 80 Hz. Set all your speakers to "small" and if you get the choice of setting a cutoff, set it to 80 or 90 Hz. Then buy a RadioShack or similiar SPL meter. Use the SPL meter (located at ear height at the main listening position) to match the levels of all your speakers. Then use it to set the level of the sub. I personally recommend setting the sub level so the sub test tone reads about 3-5 decibels louder on the SPL meter than the comparison test tone (usually the left front speaker). This is done to compensate for the fact that low frequency sounds just "sound quieter" than high frequency sounds. After you get that done, if it still doesn't sound right, then send us a diagram of how you have all your components connected and try taking some room measurements with REW.

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post #14 of 34 Old 01-24-07, 09:11 PM
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Re: In need of a little acoustical advice. Room layout included.

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BoomieMCT wrote: View Post
Have you tried setting them as SMALL? Set as they are, your reciever might be trying to send low frequency information to the bookshelves that it should be sending to the sub.

Also, basement rooms (like mine too) are notorious for having nasty axial modes. Treatments will go a long way there.
Yes, this is my fear. I was confused as what to do about the LARGE/SMALL setting as I was getting different advice from manufacturers. Athena said that the bookshelf speakers should be run as large as they are capable... so they say. 6" drivers did make me wonder. And the auto EQ on the Harmon set them as large as well. BUT it didn't make any sense to me for the speakers to be set that way.

My next step is going to be locating a SPL meter from Radio Shack aka "The Source". I went to one store today to buy it, but the guys at this particular one near me, hadn't the foggiest what I was talking about. Anyhow, there is one downtown where I have actually seen them on display, and will attempt to go there tomorrow and start the tests. I will go this route and then perhaps on to some treatments if need be.
post #15 of 34 Old 01-24-07, 09:14 PM
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Re: In need of a little acoustical advice. Room layout included.

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Prof. wrote: View Post
I think that might be your problem...
I tried setting my bookshelf speakers and side dipoles to LARGE at one time and found that the bass was almost non existant, particularly the mid to lower bass..
I finished up setting them all to SMALL, with a crossover to the sub at 90Hz..
That is what I am finding for sure. I am going to do the setup setting them all to small and then do the EQ manually with an SPL meter.
post #16 of 34 Old 01-24-07, 09:21 PM
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Re: In need of a little acoustical advice. Room layout included.

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basementjack wrote: View Post
When you say it doens't have that punch you expected, can you elaborate on what you mean by that?
Hi, I would describe punch as thuds in movies/music that you can feel in your chest. My best analogy I can think of off the top of my head is I felt it in the movie theater while watching Resident Evil 2, when the "Nemesis" character is walking toward the police station. It was a resounding thud with each step. But upon watching it at home with my setup, I found the bass in this one spot that I remembered severely lacking. Almost non existent. I kept waiting for that "punch" but it did not come.

I hope that helps explain a bit better what I mean.
post #17 of 34 Old 01-24-07, 09:29 PM
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Re: In need of a little acoustical advice. Room layout included.

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adogand6kids wrote: View Post
George,

When you set your speakers to large, the processing in your receiver sends the full audio signal to your speakers (everything from 0 Hz to 20 kHz). This may be why your sub is not "rocking" your room. If you set your speakers to small, then the bass management function of your receiver will send all audio signals above the "cutoff level" to your speakers and all audio signals below the cutoff to your sub. Depending on your receiver, you either get to select the cutoff level, or some receivers have only one set cutoff at 80 Hz. Set all your speakers to "small" and if you get the choice of setting a cutoff, set it to 80 or 90 Hz. Then buy a RadioShack or similiar SPL meter. Use the SPL meter (located at ear height at the main listening position) to match the levels of all your speakers. Then use it to set the level of the sub. I personally recommend setting the sub level so the sub test tone reads about 3-5 decibels louder on the SPL meter than the comparison test tone (usually the left front speaker). This is done to compensate for the fact that low frequency sounds just "sound quieter" than high frequency sounds. After you get that done, if it still doesn't sound right, then send us a diagram of how you have all your components connected and try taking some room measurements with REW.
I will check out my manual again for these settings, thank you for the much appreciated step by step approach to doing this. It can be a bit overwhelming, so much to check. I hope no one will mind some inevitable questions once I start using the REW software. I am quite looking forward to using it though.
post #18 of 34 Old 01-24-07, 09:46 PM
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Re: In need of a little acoustical advice. Room layout included.

Ok George, I have some advice for you...

Ok first up, the large small thing...

I did extensive testing with my reciever to figure out what was going on, yours might be different, but these are things to look for...

Large/small is misleading.
It should be labled:
Do not use crossover/Use Crossover.
In Large, not only is the full 20-20 signal going to the speaker, but none of it is getting routed to the woofer - This became apparent to me when I'd play content and my woofer didn't turn on.
It was even more confusing, becuase the .1 track in a 5.1 movie Does turn the woofer on.

(BTW, my reciever has a MAX mode, where the sub is always given the lower 100hz, even if the fronts are set to LARGE check to see if yours does too...)

ther other option is Small, but as I said, it should be labeled "use crossover" You might have huge speakers that go down to 35 hz, but you'd still want to cross them over and let the sub take over at some point.

There is a common belief that asking a driver to do 20-80 AND 80-xx is just asking too much of a driver, and that if you can route 20-80 to your sub, the 80-xx will improve as a result..

ok now on to the bass suggestion...
The phase of your subs must be in alignment with the phase of your front drivers...
if the phase is 180 degrees off, then the sub will cancel the fronts.
if the phase is 90 degrees off, then the output will be at 50% of max
if the phase is in alignment, then the output will be max


you tune the bass by putting on something that has some bass output that covers the crossover region - this could be a tone, but music with LF content works also...
with this playing, adjust the variable phase on your subwoofer until the bass is the loudest.
If you dont have a variable phase on your sub, you can achieve the same thing by adjusting the distance of your sub in the speaker setup of your receiver- distance is used by the reciever to set delay time, and delaying the signal is the same as adjusting the phase. the distance you end up with may be way off from reality (Ie it might show 27 feet when the sub is only 10 feet away) - this is ok. What is important is that you are aligning the signal so that the resulting pressure wave from all your front drivers is in sync.

- Jack
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post #19 of 34 Old 01-25-07, 05:21 PM
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Re: In need of a little acoustical advice. Room layout included.

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distance is used by the reciever to set delay time, and delaying the signal is the same as adjusting the phase. the distance you end up with may be way off from reality (Ie it might show 27 feet when the sub is only 10 feet away) - this is ok. What is important is that you are aligning the signal so that the resulting pressure wave from all your front drivers is in sync.
I concur...This was one area that I had problems with...The Receiver was setting distances different than the measured distance to the speakers, and it wasn't until I discovered that it's also taking into account time delay, that I ever got it to sound right..

I would also advise you to go into all your manual settings after the receiver has set them automatically, just to make sure everything is set right..

Another area to check is your spatial settings ie delays for fronts, relative to distance from the front wall, and delays for surround speakers..
With these set right, it can make a huge difference to the projected sound..

Good luck with it all...
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post #20 of 34 Old 01-26-07, 10:54 AM
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Re: In need of a little acoustical advice. Room layout included.

I would change all your speaker settings to small. Next try sliding that sub about 6 ft towards the couch. Get it out of the corner.
What are the output settings on the reciever and sub? Are they both turned down low? Is one low and the other maxed out?

I'd also get some absorbtion at the first reflection points. Your main speakers are against the walls which will reflect and cause a blurred image. Rigid fiberglass or GIK panels will help this immensely.
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