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Discussion Starter · #1 ·
This is the graph I get, using SB Audigy and RS SPL meter with RS calibration file.


something is not right. I can see the meter moves up and down during the sweeps, but it's not registered in the program.


Only using lineout to receiver and line in to the SPL meter.

In the mixer I have to select "what U hear" instead of "line in" in order for the program to pick up in the UV meter.

I think I am using the wrong input.. I could select line-in but it won't pick up anything for some reason, unless I also enable the line in in the playback, but then I get feedbacks.
 

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Discussion Starter · #2 ·
I got it to work (recording setting has to be "record without monitoring")

then it let me enable the mixer playback without the karaoke effect.


Here is my question is a 12 db dip at 70 hz the end of the world?
 

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Are you using "Measure" to run sweeps? Change the graph limits to 15-200Hz, top and bottom to 115dB and 45dB, and run a 15-200Hz sweep.


If you click "Graph" at the top, you can export the current view as a jpg, so you don't have to do "PrintScreen"



What kind of sub do you have? Is the graph sub only, or sub and mains? It would be more telling if you did it to 200Hz. From the graph, it looks like you have a sub that has weak low end, with a 70Hz dip. OR, you're getting a lot of room gain at 55Hz and 75Hz+.
 

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Discussion Starter · #4 ·
It is with the mains, and receiver cross over at 80hz.

ED A3-300 sub, bed room size but with desks, chairs and 5.1 setup etc.


Thanks for the tips. What do you think of this 200hz sweep?

I am thinking of getting a EQ but want to run this first so I know what to expect.
 

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Discussion Starter · #5 ·
here is one all the way to 1000, speakers and subs are level matched with SPL. I guess the room gain is mostly 50-100hz.
 

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Try moving your speakers a few inches here and there (either in the receiver set up or physically) as well as the sub. That might help that cancellation you're getting in the upper 60's. Where is the mic/spl? Where is the sub in the room?
 

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Looks to me like that 70Hz dip is in between 2 peaks... could be a phase issue... try inverting the phase on the sub.
 

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Discussion Starter · #9 ·
I changed the phase to 180, (knob could go anywhere between 0-180) how does it look now?


also should the meter be set slow or fast?
 

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Slow
 

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Discussion Starter · #11 ·
it seems like I moved the large dip from 67 hz to 87 hz by flipping the phase,

although the over all graph looks better.


What do you think?
 

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The bigger concern is extremely low response below 45Hz. For movies it is going to sound very weak with very little room pressurization.


Sorry, what subs do you have again? If they should be giving you more volume down low, then the 45Hz+ range could be high because of room gain. WIth an eq you could bring down the higher range so it's more in line with the sub-45Hz range.


If you look at my graphs in my signature, you can see I had 2 big peaks due to room gain, which I brought down. I also had a section from about 100-130Hz that was really high, but I was able to bring this down by experimenting with sub distance settings (I have that graph in my gallery, in signature).
 

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Discussion Starter · #13 ·
it's a single elemental designs A3-300 (12" 300W) located next to the center stand, below the TV off to the side, I have not much flexibility to the placement. The performance should be decent, but it is front firing and huge and not easy to move around (about 100 lbs). I have it on a 5" riser becaue it was too close to the floor I feel, but I have not tried to remove the riser and see.


I also set my volume of the sub looking at the bounce of the SPL meter on test tones, a guess at best.. I think it is possible I have room gain in the peak area, and if I have a EQ I would lower it down. The sub should have a bit of headroom as I currently don't strain it out at all.
 

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Quote:
Originally Posted by PoorSignal /forum/post/18191814


it seems like I moved the large dip from 67 hz to 87 hz by flipping the phase,

although the over all graph looks better.


What do you think?

Doesn't look all that different to me except you moved the dijp. that indicates it is indeed a phase issue. If it's continuously variable, that's good. Use the control to the best of it's ability and find just the right setting for it. This might be easiest if you emit pink noise and "listen" with REWs RTA function, so you can see changes in real time, and turn the control slowly.


When that dip is fixed, you'll probably see the peaks on either side of it diminish as well, which will make the sub 45Hbz region look not as bad.


Room gain, once it takes effect, should not diminish much as you go lower in frequency until you hit the lower limit of your sub. In fact, it can increase.
 

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Discussion Starter · #15 ·
Can you explain how to use "RTA"? I do not know what that means.

Do you recommend playing pink noise at the dip freq? In that case if I move the phase knob wouldn't it shift the dip over and it would get louder, then I find the new dip again?
 

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Go over to REW's "waterfall" tab, generate one then post it. That will help us make distinctions between what is phase related and what is room related.


Frank
 

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Discussion Starter · #17 ·
water fall of the phase 180 setting



I am trying to move the phase towards 0 slowly, all that happens is move towards 60hz and the dip gets bigger
 

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Discussion Starter · #18 ·
I tried all possible increments of 0-180 phase, seems the 180 phase is best for me, otherwise there is a big dip. I'd rather have a small dip above 80hz.

I also found the door to the front of the room opened the response is smoother. Here is the graph and I think when I get a EQ it should be able to tone down the peak. Maybe try a house curve also.

 

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On those waterfalls, rescale the y-axis to 45-105dB.

The dooropen plot looks like the dip and peaks around it are flatter. This would indicate either a modal problem or the door just happens to be a refection point causing a cancellatoin... that last one is very highly unlikely for a number of reasons...

But... If yo uclick the spectrum tab in REW, you can switch it to RTA mode... this effectively gives you a FR reading in real time... you play pink noise... by definition, pink noise isn't at a single frequency, it's full spectrum...
 

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The graph looks pretty nice! If you could bring down that pyramid-shaped rise around 45-80Hz, it would be very very flat! If that graph is with the mains running, experiment with the sub distance setting in the receiver to see if you can bring down the bump at 100-160Hz. a graph[/URL] showing differences in frequency response with only changing the sub distance setting in the receiver (range was 3'3" to about 8 feet).


There's no dip at 80Hz, you just have room gain on either side of it.


Your waterfall looks strange, btw. It should look more like . Play around with the settings to try and get something that looks more like mine. The point is to see how quickly the sound goes away at certain frequencies, versus how long it echoes and booms in your room. You can check hometheatershack or the REW manual/help doc for help and/or settings for how to make the graph look right.
 
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