Pls help integrating mains and sub

[strange_brew]

I need help figuring out how to best integrate my mains. Here is what I have so far:

Sub is an SVS PB12-Plus/2 with ports set at 20Hz
I also have a house curve set:
20Hz +5.0
80Hz 0.0

This is what it looked like before I started (sub only):


Here is the first crack with the BFD filters (obviously a big null around 105Hz):


Then I turned on the mains - I played around with the phase and this is about as good as it gets:


So then I decided to use the notch filter on my pre (B&K Ref50) to kill the hump at 80Hz, tweaked the BFD a bit more and ended up with this:


I have 3 questions:

1. I am using the Sub calibration signal to integrate my mains. Past 80Hz am I trying to hit the 75db line, or should it be dropping like the Sub target line? In other words, if you look at the hump around 94Hz, is it a hump relative to 75db or relative to the sub target line?

2. As its currently setup, as shown in the last graph, it looks reasonably good to me (haven't had time to listen to it yet). But when I go back and check my speaker levels, my Sub is about 10-11 db "hot" relative to the other speakers. If I knock down the gain on the sub, won't I kill this curve (lower frequencies will go down relative to higher frequencies in the mains). How do I get the speaker levels right?

3. Should I be worried about the big dips past 100Hz (or again, are they really dips)?

Thanks!

[brucek]

If possible can you repost the graphs using log scale. Sound is usually never graphed in linear scale as you've done. Press the Freq Axis button icon on the top right hand corner of REW. Makes a huge difference and a lot easier to evaluate..

Just go into edit in your post and edit out the attachments and repost the log graphs........ sorry, I know it's a hassle.

brucek

[strange_brew]

No hassle - I completely forgot about the log scale. It should be fixed now.

[brucek]

Great, thanks.

OK, excellent job on the sub equalization - couldn't ask for much better.

When you added the mains it created a peak around 80 - 90Hz which is fairly common. This is corrected by changing the phase control on the sub. If you're lucky enough to have a variable control you should be able to get it quite flat. If you've only got a 0-180 switch, then choose the best position and try the subs speaker distance control on your receiver and see if you can get rid of it. If not, try moving the sub somewhat in relation to the mains to get the best transition at that crossover area. You can also eq it a bit and see if that works.... actually the simple notch filter worked pretty good.

As far as the hot sub signal at the receiver is concerned. You should get the level of the sub from the receiver set to satisfy the correct input level of the BFD and then never touch that again. After that, all level adjustments of the sub should be with the sub amplifiers gain control. (are you familiar with setting up the BFD input level? If not read the section in http://www.hometheatershack.com/forums/the BFD Guide on that subject).

The dips past 100Hz aren't equalizable. You can treat the room or live with it. Peaks and dips in the mains are not as noticeable as those room mode peaks and dips in the sub..

Overall though, your response is very good now. I prefer the sub a bit hotter, but that's simple preference.

brucek

[strange_brew]

brucek wrote:

When you added the mains it created a peak around 80 - 90Hz which is fairly common. This is corrected by changing the phase control on the sub. If you're lucky enough to have a variable control you should be able to get it quite flat.

I do have a variable control, so I'll mess around with it some more. I tried it at 1/4, 1/2, 3/4 and full phase shift and didn't get better than what I showed. I'll play around some more with smaller shifts and see if it helps.

actually the simple notch filter worked pretty good.

yeah, that surprised me too - the good 'ol B&K still has some tricks up its sleeve

As far as the hot sub signal at the receiver is concerned. You should get the level of the sub from the receiver set to satisfy the correct input level of the BFD and then never touch that again. After that, all level adjustments of the sub should be with the sub amplifiers gain control. (are you familiar with setting up the BFD input level? If not read the section in the BFD Guide on that subject).

I am familiar with that and did set the inputs correctly. I was referring to the gain on the sub amp. I'm not going to touch anything "pre-BFD" (if that makes sense). After demo'ing some material I ended up dropping the sub amp to about 3db hot relative to the mains. What I still don't understand is if that is hot relative to the house curve, or whether it is simply part of it?

The dips past 100Hz aren't equalizable. You can treat the room or live with it. Peaks and dips in the mains are not as noticeable as those room mode peaks and dips in the sub.

I have treated the room pretty significantly already with good help (Bryan Pape) so I don't think I'm going to do much better.

Overall though, your response is very good now. I prefer the sub a bit hotter, but that's simple preference.

That's good to know. As I said, I'll play around with it a bit and see if I can get it any better. But I'm guessing I'm at the point where the differences are not going to be significantly audible?

Just out of curiousity, should that I be aiming to hit the 75dB line, or should the mains fall down the line with the subs? I was wondering if its a function of the type of signal for the sub that is output and whether it has any relevance beyond a certain point...

Craig.

[brucek]

should that I be aiming to hit the 75dB line, or should the mains fall down the line with the subs?

The target for the mains is the same as it is for the sub - 75dB (as shown in first pic below). And you've accomplished that. You're only a few dB either side of the target, so any more adjustment wouldn't reveal anything too much better to your ears. The only minor, minor thing that might be considered weak in the diagram below is the area from 45 Hz to 80 Hz. This area has a lot of information in it, and would give a bit more punch if a bit higher. It certainly isn't a room mode lowering that, as evidenced by the picture at the bottom below (yellow trace). Actually a simple wholesale level change with the sub amp gain control would fill that area in (but may make the 15Hz to 45Hz too hot for you....

At this point though, your ears are the best tool for telling you if you like the sound. If you feel the sub is a bit hot or cool, you only need to adjust the level on the sub amp a bit......







brucek

[strange_brew]

That makes sense. I played around with the BFD a bit more in the 45 - 80 range and ended up with the response below. I haven't played with the phase yet to try and fix the dip at 70Hz, but that will be my next step. I did get a chace to demo some materials and we watched a movie last night. It sounded much fuller and deeper. I may turn up the gain 1-2 db as you suggested, but otherwise its very, very good.

[mojomike]

Why not use the sub's crossover control to lower it's output in the 80-100hz range. That should help to bring down that hump.

[Wayne A. Pflughaupt]

mojomike wrote:

Why not use the sub's crossover control to lower it's output in the 80-100hz range. That should help to bring down that hump.

Judging from his graphs in the first post (specifically the yellow vs. magenta plots), it looks like the 80 Hz problem is appearing when the mains are added. If so, making adjustments to the sub will probably have little (if any) effect.

Regards,
Wayne

[Blaser]

Yeah...If the receiver has an eq at that frequency for the mains, it may solve this issue better. But this bump could be masked as well by raising a bit the subwoofer level as per Sir Brucek advise!