Starting Over. Sub EQ, Speaker EQ, room treatment

**rolyasm** · **04-15-09, 01:37 PM**

Hello all. It is so sad. About 2.5 years ago I hooked up my subs, EQ'd them with BFD, then have mostly sat on them until now. Here was the project:
http://www.hometheatershack.com/foru...new-forum.html

Have had odds n' ends speakers and such, but nothing permanent. My full system is ready to go. Here was my tortuous REW path last time:
http://www.hometheatershack.com/foru...st-graphs.html
for those of you who want a good laugh/cry.

Anyway, just pulled out all my old gear. I can't find my ECM8000 cal file anywhere. I am on a new computer and must have lost it along the way. On the link above is a link to Sonnie's cal file, but for some reason I don't have access to it. Does anyone have another link or file they could send me?

I am sure there will be many questions to follow. If you are a praying person, pray for me and you. If not, I suggest the strongest drink you can find. My stupidity will be shortly forthcoming.
Thanks.
Roly

**Anthony** · **04-15-09, 01:39 PM**

Try this page:
http://www.hometheatershack.com/foru...oads-page.html

It has the most recent cal files. Good luck.

**rolyasm** · **04-15-09, 04:10 PM**

Okay, so I know have couches, some blinds, drapes, screen, etc. Here are the graphs of my sub with EQ (first) and without (second). Keep in mind I EQ'd these years ago when the room was basically empty.

**brucek** · **04-15-09, 04:16 PM**

Attaching an mdat file isn't something that most people would download and view.

If you want to show your measurement responses, attach a jpg of the graphs.

brucek

**rolyasm** · **04-15-09, 04:34 PM**

I have tried to save my measurements as pics but the only option it is giving me is .cal or .mdat. I tried to manually save as filename.jpeg, but REW saves it as filename.jpeg.mdat. I know this is simple, just not sure how to convert the file or save it correctly.

**rolyasm** · **04-15-09, 04:35 PM**

ah, never mind. Just looked under the "graph" tab and there it is... " save graph as jpeg"
thanks

**rolyasm** · **04-15-09, 05:13 PM**

So... Since I have 2 rows of seating, one on the riser and the other below and in front, AND I am not sure where my sweet spot will be, is it better to EQ it for a middle position between the two? I am going to start over since the graphs are so close and the response to the room seems to be quite different.

**brucek** · **04-15-09, 06:35 PM**

Next time you post, for a sub, use a graph scale of vertical = 45dB-105dB and horizontal = 15Hz-200Hz. The icon to change this is called Graph Limits and is located in the top right corner of REW.

Quote:

is it better to EQ it for a middle position between the two?

That's a personal choice. Many simply take several readings (up to 8) and press the Average button to create an average of all the readings you want included. Then they EQ the average plot.

brucek

PS. Stick to one thread. I renamed this one and deleted the other.....

**rolyasm** · **04-15-09, 07:08 PM**

thanks for deleting the ohter post.
I erased all of my settings on the BFD, I think, ( held down the reset button for awhile), then took these measurements at 2 positions: the first is front row center, the second is back row center. Interesting the difference. At 25 and 50 Hz, the graph is doing almost the exact opposite. My seating position in front is located directly in front of the subs. The rear of the couch is about 8 inches away from the 4 x 15" drivers. The seating position in the rear is on top of the riser/ sub box. I suppose this will make it very difficult to EQ. Would adding another sub at the front of the room (or somewhere else) be an option to smooth it out? Or should I just try to EQ it first and see what happens?

**salvasol** · **04-15-09, 07:21 PM**

Quote:

rolyasm wrote:

... Since I have 2 rows of seating, one on the riser and the other below and in front, AND I am not sure where my sweet spot will be, is it better to EQ it for a middle position between the two?

I used to have two row of seats, my favorite/sweet spot was the middle seat in the second row (better view) so I EQ'd that position, and because I had the option on my AVR I also EQ'd the middle seat in the front and saved them in different memories.

My suggestion ...first decide where you will seat and do the best you can with that place.

**brucek** · **04-15-09, 08:17 PM**

Are you able to move the subs you have to create an overall compromise in the plots. I wouldn't recommend adding another.

brucek

**rolyasm** · **04-15-09, 11:21 PM**

I can't move the subs. They are built into my riser. I know it limits the EQ capabilities, but man, they sure do shake the floor. I have heard that the best setup is 4 subwoofers, each opposing the other on all sides of the room. Never tried it, but that is what led me to the idea that maybe another sub would help out. thanks for the response.

**rolyasm** · **04-16-09, 08:30 PM**

So I think I have the sub Eq thing down, kinda. But I want to move onto the speakers. I have a 5 channel stereo capability, but can understand testing one speaker at a time, moving it, then testing again to see if I can find the smoothest response. Is there anything to do/know before I start testing each speaker individually. I read somewhere that you can only test the mains or use the main channels to test your other speakers. Did I read that correct and if so, why is that? I did a sweep of my room from 50-10k, just to see how it functioned, and will post that here. I see the whole graph is lower than intended. Are there specific vertical/horiz. you would like to see? Also, I had to put the 1/3 octave smoothing on, or it was really scratchy. Is that the way to do it, or am I starting out wrong? Thanks for a good nudge in the right direction.
roly

**brucek** · **04-16-09, 11:10 PM**

Since REW is a mono signal, you can't utilize any soundfields in your processor. You must use stereo mode only. This means the two mains and sub will be active, and none of the other speakers will be active.

To measure a sub, disconnect the mains speakers. To measure the mains, turn off the sub.

If you wish to measure the rear speakers for example, connect them in place of the mains.

If you wish to measure the center speaker, connect it to the right or left main position and shut the other mains off.

When you measure the mains, use the usual vertical scale of 45dB-105dB, and use a horizontal scale of 15Hz-20000KHz (if you have a full range mic).

Yes, for full range plots, you need to turn on smoothing to hide the comb filtering (scratchy).......

brucek

**rolyasm** · **04-17-09, 08:56 AM**

Great, I actually think I understood everything you told me. I knew you would understand the "scratchy" description. I'm using a Behringer 2500 for the subs and an Atlantic Technology 7 channel for the speakers. I will use one RCA pre-out from a main channel on my processor and connect it to the rest, one at a time. I will turn off the amp each time prior to disconnecting/connecting to make sure I don't fry anything. To reiterate, I will disconnect all rca inputs on my amp, except one, the left or right channel, and move it to each amp input in sequence until I have a full measurement of all the speakers. Does this sound correct? thanks.
roly

**brucek** · **04-17-09, 09:03 AM**

Quote:

I will disconnect all rca inputs on my amp, except one, the left or right channel, and move it to each amp input in sequence until I have a full measurement of all the speakers. Does this sound correct?

Yep, but remember, in addition to this, you may want to test for interaction. It's fine to measure a single main, but with two mains running, there may be some negative interaction between them that you might want to be aware of. So, at the least, feed the two mains and take a measure.

Also, you want to see how the mains integrate with the sub(s), so you want to do a sub + mains measurement.

brucek

**rolyasm** · **04-17-09, 05:51 PM**

so this is the measurement of my mains and my sub. I had to keep going down on the measure level because clipping kept being detected. Anything you can deduce from this? Anything I should deduce from this graph? Is the next step to move my speakers around and see if I can reduce that nasty peak around 100 hz? Thanks.

**brucek** · **04-17-09, 06:04 PM**

Quote:

Anything you can deduce from this?

Yep, you have a nasty peak at 100Hz....

That's why it was clipping.

Anyway, I would start by adjusting the phase control of the sub(s) and see if you can get the peak down. I would also measure sub plus each main individually to see if there is a single culprit.

brucek

**rolyasm** · **04-17-09, 07:03 PM**

This is kind of strange. So I just did my last measurement that I posted. I went to eat, came back, turned everything back on, and now I can't get a descent output level. It is as if my soundcard has been muted partially. I am using the mobilepre usb. I went into my soundcard settings, and before when I checked the levels my "out" was around -15 and I could easily match the level of left to it. Now, I can only get the "out" to about -27, and I have increased all levels as high as I can. When I play music through my MobilePre, I have the volume up very high and the speaker volume is very low. I checked my DVD player, and it is loud as ever. I uninstalled an re-installed the drivers.
Also, where my gain on my sub amp was at 50%, now it is up all the way and barely making the spl meter hit 75. My volume on the receiver was at -23, now it is at -04. Any ideas?

**rolyasm** · **04-18-09, 03:43 PM**

I am not sure what I did different. but I finally got it working. I have a pretty big dip around 40hz. Just out of curiosity I put a 12" sub in the room. It seemed to help with the dip, but not sure if it is worth it. Here are the graphs with my riser sub only, and with the riser and 12".

**brucek** · **04-18-09, 03:54 PM**

Any sharp dips can be ignored, you won't notice them. The extra sub only eliminated the sharp dip...

I like the green plot better........

brucek

**rolyasm** · **04-18-09, 06:25 PM**

Since I can't move my subs, I know room treatments are recommended before EQ. Is it a trial and error thing, or how would I go about using room tx. to make this the best possible curve before I EQ? Do I just spend some money on bass traps and try them in different corners to see how it helps? Or should I just EQ it and call it good?

**brucek** · **04-18-09, 06:54 PM**

Quote:

I know room treatments are recommended before EQ

Treatment doesn't help a lot in the modal region. The traps have to be too large to be practical. It's movement or EQ. But there's really not a lot wrong with your response.

brucek

**rolyasm** · **04-18-09, 11:23 PM**

Great. I will just EQ it and be done with the bass. What is the modal region? I will post some full range graphs later. Do treatments often help at higher frequencies or when do people start implementing wall treatments? Does the response have to be really bad to make a difference?

**brucek** · **04-19-09, 08:35 AM**

Quote:

What is the modal region?

This would depend on the room, as it refers to the modal frequencies for the standing wave resonances set up between parallel surfaces in your room. There are axial modes (two surfaces), tangential modes, and oblique modes. Long story short - these cause the peaks and dips in your subwoofer response.

These types of acoustical questions are better asked in our acoustics forum section. We try and limit discussion here to REW specific questions.

brucek

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