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Discussion Starter #1
Alright all,

Well, I've finally got some measurements completed and thought I'd submit them for your thoughts. Take a gander and let me know what you think please.

The first graph is of the sub only. It's crossed over at 200hz.

The second graph is of the sub and mains crossed over at 80hz.

I think the graphs look pretty decent from a newbie point of view.

The sub is an svs Ultra 12 tuned to 16 hz. I have no BFD and haven't messed with the built in PEQ of the SVS yet.

Let me know your thoughts!

Best wishes,

D
 

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Please post using the standard graph settings of vertical = 45db-105dB and horizontal = 15Hz-200Hz.

Let's see a sub alone, and a sub with mains with the cross left at 80Hz in both cases.

brucek
 

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Discussion Starter #4
Alright Brucek,

Here are the plots you request. The first is the sub only with the crossover activated for 80 hz.

The second plot is the sub and mains together at 80 hz.

Nuance:

The PEQ function allows you to cut one frequency that your having problems with in your room. If your buddy had a 60hz spike in his room, he could use the PEQ to dial it in for that frequency, pick the width of the frequency range (EX. -70HZ), and then adjust the amount of cut you would like in order to tame that peak to better match the rest of your curve. It's kind of like a 1 channel BFD.

Ok, have at it!
 

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You still didn't change your graph settings. In the top right side of REW you will see graph limits, for sub only use vertical = 45db-105dB and horizontal = 15Hz-200Hz and with full range use 15Hz-20,000Hz. Also, after clicking on measure, change start freq to 15 and end to 200 for sub only and 20,000 for full range. Make sure to disconnect mains when doing a sub only. You can also uncheck the mic/meter cal and soundcard cal in the graph. Good luck
 

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Alright Brucek,

Here are the plots you request. The first is the sub only with the crossover activated for 80 hz.

The second plot is the sub and mains together at 80 hz.
Looks like you overlooked 1/2 of brucek's request:

Please post using the standard graph settings of vertical = 45db-105dB and horizontal = 15Hz-200Hz.

Let's see a sub alone, and a sub with mains with the cross left at 80Hz in both cases.

brucek
Regards,
Wayne
 

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1st graph scale is fine. Looks like it is not calibrated right, way high, or the EQ has the low end boosted? Make sure you go through the entire calibration process. 2nd graph need to be same as 1st but up to 20k. look at my post above. You stopped the full range measure at 2,000 instead of 20,000, not a big deal.

When you do the full range, make sure to use 1/3 smoothing.
 

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but up to 20k
Yeah, but that's only if you have a full range mic, which he does not. It shows as a Radio Shack meter, and can only be use to 3KHz.

Anyway, your low end appears to really be exaggerated. Assuming you have everything calibrated, I might try and lower the subs bottom end a bit by perhaps moving it out of a corner (if that's the case).

I would also play with the subs phase control to try and fix the dip at the crossover point (80Hz).

brucek
 

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Discussion Starter #12 (Edited)
Thank you Gentlemen for your replies,

Brucek is correct. It's a radio shack meter, not a full range mic. As far as calibration goes, if I have the calibration file for the radio shack meter loaded, isn't that the extent for calibration of the meter? I could see if I had the calibration between the actual meter reading and the REW value is off, it could result in high db readings (I did match them up though), but wouldn't the plot curve basically still look the same? It would just have lower db values would it not?

Also Al, there is no eq'ing involved at the moment.

I used the recievers YPAO measurement to set the levels of the speakers and sub, and did not boost them. It really doesn't seem like there is an abundance of bass, but I guess measurements can tell the real story.

Thanks fellas. I'll still keep plugging away at this!

D
 

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Discussion Starter #13 (Edited)
Alright guys,
I've been messing around with the sub a bit, but haven't been able to move it due to kind of a tight room. I am looking at moving the sub as a last resort. The sub is currently on the front wall between the center channel and right main speaker. It's not really in a corner, other than the joint between the wall and the floor.

I have a couple questions.

1. Yep, my bottom end does seem a bit exagerated, but I think it is accurate. Assuming that I want to keep this sub location, can I correct the 15hz hump and 40 hz hump with a bfd?

2. This sub (svs pb12 ultra) has a peq. Do you think I should try to use it to cut either of the above frequencies?

3. I don't know why the low end level seems so exaggerated. It was set at that level by the Yamaha recievers YPOA, and is almost at a min. Is YPAO pretty inaccurate for something like this?

4. I've been working on smoothing out the 80 hz dip with the phase control. I'm tried different degrees of adjustment, but can't quite get rid of it completely. Should I be able to get rid of it completely or is it due to my sub location? My room is 13X18X7.7, and I'm using the 13' dimension for my screen with my row of seats about 10' back. Not sure if that helps or not, but thought I'd throw it out there.

Let me know your opinions if you would.

Thanks for reading,

D
 

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Discussion Starter #15
BFD's lowest filter is 20Hz.


No reason why not.


Yes, but we can't tell since you haven't posted a mains only graph.

brucek



Thanks for your reply Brucek,

I will post more of my other charts when I get back home. We are in the middle of a BIG March blizzard.

I wonder if the big peak at 15Hz could also have something to do with me having the svs sub tuned to 16 hz, along with my room. I noticed when Ikka ran his sub tests on the 12 ultra tuned to 16hz that he had a bit of a bump go on at the tuning frequency. I suppose I could try a 20hz tuning and see what would happen.

I will have to play around a bit with the sub a bit more.

Thanks, as always, for your help,

D
 

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Perhaps you should try to just turn down the volume on the subwoofer a bit, and see what effect that has on your graph. Depending on which Yamaha reciever you have it may not be doing a very detailed job on EQing the subwoofer.
 

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Your sub is outta phase with your mains (thus the dip in the 80Hz region). Try setting the distance of your subwoofer 3 feet closer or further and see if it improves. You'll want to turn the sub down a bit while doing this too...once you get the phase aligned, you won't need the volume as loud.

What you really want to do is measure the sub with xover by itself, then measure the mains with xover by themselves, and then measure both together. Put all the plots on the all measured tab. Where the sub only and mains only cross, you want the combine to be +6dB.
 
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