First attempt with REW, how am I doing?

**Darren** · **06-15-06, 07:06 PM**

Ok, I got my RS analog meter hooked up and went through all the calibration. I then took this measurement from the listening position:

I then set up 8 filters and they look like this (I also added a new house curve for this):

Then I cleared the filters in REW and put them into my BFD and took the following measurements:

I'm concerned about the dip at 18Hz and the subsequent peaks and dips at 36Hz and 48Hz.. I can correct the two latter ones but I already have 8 filters. The 18Hz issue is a tough one, I could apply a wide filter but it really messes > 20Hz up... I want good response below 20hz for this IB. I also need to bring the peak down above 80Hz to at least 100Hz I suppose. That's a lot of filters. Any suggestions on how to bring the number of filters down? I've just begun to experiment.

Here is another attempt with fewer filters, better? What about below 20hz, do you think this will sound boomy?

Here is the real life measurement with the filters applied:

**Darren** · **06-15-06, 08:08 PM**

I've been listening to bass heavy music and I seem to have a problem. It sound great in the corners of the room but terrible in my listening position near the back middle of the room. My IB is at the front centered in the ceiling between the speakers. The house curve I showed above is what I used. The bass sounds thin, hollow in the listening position. Is there a way to correct for this?

**brucek** · **06-15-06, 08:47 PM**

Well, the bass will be louder in the corners.

For your listening position you'll need to add a house curve to the standard target you're using.

A simple one if you're using 80hz as a crossover would be:

30 5.0
80 0.0

Save it in notepad under housecurve.txt and load it into REW.

Also change your graph axis to match the same as we all use here. It's easier to analyze that way.

See this link in the beginning part about axis limits..

http://www.hometheatershack.com/foru...ng-graphs.html

brucek

**Darren** · **06-15-06, 09:25 PM**

I have been trying a few things but short of drastically increasing the output between 40 and 70Hz nothing works. Even when I do that it isn't really good tight bass and everywhere else it is terribly bloated. Correctly calibrated it is almost non existent bass in the listening position.

**brucek** · **06-15-06, 09:59 PM**

Have you done a full sweep including the mains to see how they integrate at the crossover and also the overall level compared to to the sub? The response of the sub looks quite good.

brucek

**Darren** · **06-15-06, 10:09 PM**

I haven't done a full sweep yet with the mains, would I just be measuring the sub response during this sweep?

The response does look great, I agree... maybe my expectations for the old school rap bass are out of reason? It sounds great in the corners and just under the sub (ceiling IB). Some music like The Eagles DVD sounds great. I was using the rap and a Bass Mechanik CD to get a feel for the bass.

I can do a full sweep in the morning and post the results.

**brucek** · **06-16-06, 06:22 AM**

Quote:

I haven't done a full sweep yet with the mains, would I just be measuring the sub response during this sweep?

No, I mean a sweep with both the sub and mains playing from 20Hz to 10Khz...

brucek

**Darren** · **06-16-06, 09:36 AM**

Quote:

brucek wrote:

No, I mean a sweep with both the sub and mains playing from 20Hz to 10Khz...

brucek

Thanks for the clarification...I'll get to that as soon as I can today.

I did some experiments this morning though for more info:

1. Checked and the two sub drivers are in phase with each other, they are also in phase with the mains.

2. Measured the response in the corners where the bass sounds really good and reproduced that curve for the listening position (40-80Hz was up about 10db in the corners) and it moderately improved the sound in the listening position but dramatically reduced the quality of the bass everywhere else in the room, almost slappy, terribly bloated.

3. I'll be trying the full sweep soon.

I'm beginning to wonder if the test bass I'm using is just not good quality. I'm using old rap and a Bass Mechanik CD.

**brucek** · **06-16-06, 09:53 AM**

Quote:

1. Checked and the two sub drivers are in phase with each other, they are also in phase with the mains.

Yeah, means very little until you do that sub + mains sweep we talked about above. Then you can adjust the phase to reduce any unwanted reinforcement of the signal level around the crossover frequency. This can cause quite a hump that doesn't sound good.....

Quote:

but dramatically reduced the quality of the bass everywhere else in the room

This is something that can be a big problem for those that have rooms with lots of seating and you want everyone to enjoy the same sound. Sometimes you either have to be selfish or compromise the sound so everyone gets kinda OK sound...

Quote:

I'm using old rap

rap and hip-hop usually have artificially enhanced bass. Try some different music.

brucek

**Darren** · **06-16-06, 09:58 AM**

Quote:

Then you can adjust the phase to reduce any unwanted reinforcement of the signal level around the crossover frequency

I don't believe I have an option for "adjusting" phase other than 180. I'm new to this EQ and tuning stuff

I'm setting up for the sweep now.

Here is a full sweep with no filters, not sure how to get the whole chart to show yet though...:

Here is a full sweep with the filters I came up with that conform to my house curve:

**brucek** · **06-16-06, 11:24 AM**

And so how does the last graph sound at the listening position?

It looks OK, although there's a bit of a dip around 100Hz. Did you reverse your sub phase and try again?

Also note this post with respect to graphs. http://www.hometheatershack.com/foru...s.html#post121

brucek

**Darren** · **06-16-06, 11:49 AM**

I read the post about graphs and set up accordingly...what am I doing wrong?

The second graph in the above post didn't sound right for movies, I have been experimenting all morning and I think I'm making progress...

This one sound great for music, might need some fine tuning... the dip after 100 for example:

And this one sounds perfect for movies, very impressive without bloated bass:

**brucek** · **06-16-06, 11:57 AM**

Quote:

I read the post about graphs and set up accordingly...what am I doing wrong?

Sorry, I didn't mean anything was wrong. I just wondered if you read and applied the post I referenced on pre-impulse settings..........

For sure I have two programs set up in my BFD. I have one for music two channel (PRGM #2) and one for movies 5.1 (PRGM #5)..........

Looks like you've done a great job there..

brucek

**Darren** · **06-16-06, 12:11 PM**

Crud, I set that last night but the setting didn't stay, I thought it would save it. So, I was set at the default for that

What will that affect? Will I have to start all over with my graphs or will it affect how they look. I know I like the sound but I want accurate graphs.

I read the thread but some of that is above my head

**brucek** · **06-16-06, 01:06 PM**

Quote:

I read the thread but some of that is above my head

Yeah, that's heady stuff for sure. Really all you have to know about it is to set it each session you record and the fact that it doesn't save like other things do. Next version is going to have that preset as the default, so you won't have to worry about it.

It only changes somewhat the look of the graph, but certainly not enough to redo them. Leave it be. Live with the sound for a while. Then if someday you want to do some more messing around you can use the new version when it comes out....

brucek

**Darren** · **06-16-06, 01:24 PM**

I'm finding that I might need to mess around a bit still. U-571 depth charge scenes are missing the deep bass that I used to hear. Also Blade chapter 4 footsteps, 4 Pinned, 17 invitation, 20 Door blown down not much there except for the door scene. The Finding Nemo Darla tapping the tank scene is very impressive though. Might be the difference between my PR'd Box sub and the IB though. I'm trying to get that back without bloating other movie scenes.

**brucek** · **06-16-06, 01:48 PM**

Quote:

U-571 depth charge scenes are missing the deep bass that I used to hear

You don't really have much of a differential between your mains and your subs overall level.

Some people like it that way and some don't. It depends on the room and their taste.

If I can give you an example of my system. I have what might be considered a large bass boost.

Here's a graph of my sub and mains for movies: (60Hz crossover used)

brucek

**Darren** · **06-16-06, 01:53 PM**

I see, so did you apply the boost to the sub just by increasing the gain or did you apply wide filters to boost the overall level? I assume increasing the gain or signal to the subwoofer would be the best bet to try this out but it will negatively impact my music. I'll give it a whirl, let me know if I'm off base.

EDIT:

I tried adding a bit of gain to my subwoofer through the receiver and it made bass heavy movies like LOTR Fellowship waaaay too hot. Clipped right away. This might just be an issue because I only have two drivers in my IB with two holes plugged. It is intended for 4 to get the levels I want.

By the way, thanks for being so patient with me as I learn this process. My room may be a contributing factor as well since it is 16' deep by 18' wide. I wonder if two 10" X 4' half round bass traps at the back walls near the corner would help. Wife probably wouldn't go for that but I might be able to pull it off.

**brucek** · **06-16-06, 03:37 PM**

Quote:

so did you apply the boost to the sub just by increasing the gain or did you apply wide filters to boost the overall level?

Just increased the overall wholesale gain of the sub amplifier. Then adjust the filters to match the target after that.

The 60Hz crossover helps me keep that 'too much heavy bass' sound to a minimum. You do have to have fairly capable mains to use a crossover that low though.

Quote:

Clipped right away

Do you mean your sub amplifier clipped?

Quote:

My room may be a contributing factor as well since it is 16' deep by 18' wide.

That is a fair sized room for sure. Traps really aren't that effective way down low unless they're the size of a bus. That doesn't usually get rave reviews from the woman of the world, although I don't know why for the life of me.....

brucek

**Darren** · **06-16-06, 03:55 PM**

Yes, the subwoofer amplifier clipped and the BFD was clipping as well. I had to get it quite hot to get any umph out of the depth charges in the beginning scene of U571... But when I switched to LOTR it was VERY dynamic and way hot. I assume the amp clipped because I'm running it close to it's limits for 8 ohm stereo although I only have it about 2/3rds of the way up. When I get two more drivers I'll be running 4 ohm stereo and will have plenty of headroom and the increased output of double the drivers.

My mains are GR-Research AV2's, they are crossed over at 60Hz as well. They reach 55Hz but that is stretching a little. My crossover point is tight but I did a full sweep at 60Hz and at 80Hz and they seemed to blend better at 60Hz. I'm no pro though so I might be mistaken in my conclusions on that.

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