Using RTA to position subs/mains

**jdeanmc** · **05-29-09, 11:52 AM**

Thanks Bruce,
something simple here is what i think ive been missing,as im always turning the volume up and down!!!
As its much easier for me to adjust the subs volume over the mains,should i first cut off subs and choose to use mains in the check level routine to establish the avr volume?then turn on subs and get them up to that level using the sub gain and sub level in avr?
Dean

**brucek** · **05-29-09, 01:24 PM**

Depends on what range you're measuring.

If you're measuring the sub only, or the sub plus mains, or the mains only up to 200Hz, then use the subwoofer test signal in REW. The only time the mains test signal is used is when you are measuring full range.

To set the levels of the mains and subs before testing, use your receiver test tones.

brucek

**jdeanmc** · **05-29-09, 02:13 PM**

I havent been doing this,ive done everything from REW,maybe that will make my difference.
One more bonehead question,when i click "set target level"under target setting tab,where does it "see"the level?at what freq?it seems after i hit this button,sometimes i can look at the graph and it will be at 80 hz ,sometimes its the max spl(20-25hz)in other words if it says target level for this channel is 78.4 db,what exactly is 78.4 db?an average,a particular freq?a maximum spl?
Dean

**brucek** · **05-29-09, 02:34 PM**

Quote:

when i click "set target level"under target setting tab,where does it "see"the level?at what freq?

You can manually set the target level with the thumbwheels provided or you can run the Set Target Level routine that sets it automatically.

The target level routine positions the measurement trace with respect to the target line to create optimum filters (after a band limited pink noise is generated at the sweep level).

If you're creating filters and you don't like the trace position with respect to the target line that the auto method produced, you can adjust it manually.

brucek

**jdeanmc** · **05-29-09, 03:00 PM**

Thanks Bruce,
this is starting to sink in ( i think)
My problem thus far,getting the subs and mains to blend,is that ive been constantly changing the mains volume while trying to eq subs!!!
All your recent comments and guidance have sort of cleared this up.
I think you've answered all my questions
Now i need to find the time to put all this in practice and see where i go from here.
Thanks Again for your patience and expertise.
Dean

**weverb** · **05-29-09, 05:54 PM**

Dean,

Looks like brucek has got you going. I would not worry about REW until you can get your mains and surrounds balanced at 75dB at the listening position using the receiver's test tones. Remember to then add the MBM first and finally the Ho. Also make sure of your procedure of turning the MBM off and the Ho xo to bypass when you start adding the main sub. Try to keep your receiver's sub setting to 0dB and use the knobs on the subs mostly. You should only be "touching" the receiver at this point to start and stop the test tones. After you have everything "playing" at 75dB at the listening position, then start measuring with REW. I am sure you are going to find that you will have to raise the Ho knob a little more after applying your filters. Don't get too hung up on the 75dB mark though. Make sure to also listen to some reference material. Case in point, my subs only reach 74dB (versus 75dB for the mains) when I play my test tones and show to be 8-10dB higher than the mains when I graph them in REW.

Go figure. It sounds good to me and that's what is most important. Not the look of the graph.

Good Luck!

**jdeanmc** · **05-29-09, 07:03 PM**

maybe thats due to the calibration file when using rew and nothing when doing test tones/meter?
Anyway YES,between you and Bruce,i think i have a pretty good handle on what i need to do.I thought i did before but i havent run test tones before rew,so basically i was trying to look at the graph and trying to get everything to proper levels?i dont have enough experience with that obviously.
I cant wait to give this a go and see what kind of gains i get.
Thanks for all your input
No thanks thought for getting me spending hours looking through the "build your own ib thread"i am intrigued though!!!Maybe at a later date.
Thanks again
Dean

**weverb** · **05-29-09, 10:08 PM**

Quote:

jdeanmc wrote:

No thanks thought for getting me spending hours looking through the "build your own ib thread"i am intrigued though!!!Maybe at a later date.

I have already thought about your room and how an IB would do.

**jdeanmc** · **05-30-09, 10:04 AM**

As i said i am intrigued with this.
At some point this may be a possibility.My Ht room backs up to a basement garage,so i could do something on the back wall,however,with my luck,the back wall would surely be the worst place for the sub.I dont really have options otherwise.
I'll make do for now and try to get the best out of what ive got,if i can get this thing sounded well enough to suite me, the next step is a projector.maybe then i can entertain the idea of cutting an Ib into a wall.
Thanks
Dean

**jdeanmc** · **06-01-09, 05:13 PM**

Hey guys,
i finally got a chance to rerun REW.
i first ran test tones to get everyhthing to 75 db
Graphs are...
1.1st measurement
2.then moved subs around to get as smooth as i could(this seems to be as good as it gets)
3.subs only.1 filter 21hz gain -8 bw 15
4.subs only 2 filters 21hz and 61.2 hz gain -1 bw 12
5.subs and mains
6.subs and mains phase set to reverse in avr
7. full range smoothed 1/3
i did cut the 61.2 hz filter after adding the mains and the "hump" reappeared so i cut it back on.it does seem to help.
after i ran test tones, to get to 75db,my avr volume was at -6.5.
i never touched it again.my rew settings were as follows...
wave volume -.398
output volume 0.200
input volume 1.000
sweep level -12
these seem strange,i had to turn the thumbwheel down to get to 75 db,i did calibrate the meter.
I havent played much source material(i ran straight upstairs to post this)but i will say what i did play so far sounds better than i've ever gotten yet.the subs do seem to have some life to them and they sound like the do blend with the mains better than they ever have.
how does all this look?
Dean

**weverb** · **06-01-09, 10:05 PM**

Sorry I did not respond sooner Dean. Couple questions for you before I comment.

1. What xo setting are you using for the lfe channel? 80, 90 100Hz.?
2. What xo setting are you using for the Ho?
3. Have you tried graphing just the MBM with your current settings?
4. Have you tried graphing just the Ho with your current settings?
5. Have you tried graphing just your mains with your current settings?

**jdeanmc** · **06-02-09, 12:49 AM**

Hi Weverb,
my xover is set to 80 hz.in the avr,i think i have the HO set to @ 45 hz xover "in"no turbo in mo mode
i have not graphted ho,mbm or mains alone,sounds like a good idea.
my graph looks terrible,i know.the 55 to 150 and 30 to 50 regions look way too low however me and my wife just watched taken.i have seen it before,it was her first,i can say it sounded much,much better than the first time i watched it,she commented that she thought she was about to have an anxiety attack!!!this was strictly because of the soundtrack.i have had better looking graphs but nothing has sounded close to this yet.i think its because im finally getting the mains and subs to play together(thanks brucek and you)now if i can just get everything fine tuned,maybe ill be set.come on with the suggestions
Thanks Dean

**weverb** · **06-02-09, 06:07 PM**

Sorry for the delay Dean.

Your 30Hz. does not look too bad until you applied your filter at 21Hz (second graph versus third). It looks like you have more than one filter being applied there. I would double check that and try different filter settings so that you don't pull that 30Hz. area down so much.

As for the other area, did you try different phase settings on the MBM? Have you tried it without the MBM and only the Ho? I assume the Ho is in max output mode and not max extension mode.

I was asking about the different xo settings and graphs because you can graph them alone and see where the correct xo point should be. You may be able to have a lower xo between your mains and Ho and not need the MBM.

At least give it a look and listen if you have not already.

**jdeanmc** · **06-02-09, 07:13 PM**

Quote:

weverb wrote:

Sorry for the delay Dean.

Your 30Hz. does not look too bad until you applied your filter at 21Hz (second graph versus third). It looks like you have more than one filter being applied there. I would double check that and try different filter settings so that you don't pull that 30Hz. area down so much.

As for the other area, did you try different phase settings on the MBM? Have you tried it without the MBM and only the Ho? I assume the Ho is in max output mode and not max extension mode.

I was asking about the different xo settings and graphs because you can graph them alone and see where the correct xo point should be. You may be able to have a lower xo between your mains and Ho and not need the MBM.

At least give it a look and listen if you have not already.

My 21 hz filter has a pretty wide bandwidth?also the second graphs has the target line at 75 hz third has a 80 hz target(applied house curve,i think)maybe thats why the 30 hz looks different.
So you'd like to see the ho,mbm and mains seperately?i'll try to get graphs on this.
I moved subs around slightly,but if need be i can start over and do the rta "crawl"i could also try to co-locate the subs,the only time they have been close is both next to each other behind the sofa.

Dean

**weverb** · **06-02-09, 07:20 PM**

Quote:

jdeanmc wrote:

My 21 hz filter has a pretty wide bandwidth?also the second graphs has the target line at 75 hz third has a 80 hz target(applied house curve,i think)maybe thats why the 30 hz looks different.

You are right.

On my part.

Quote:

jdeanmc wrote:

So you'd like to see the ho,mbm and mains seperately?i'll try to get graphs on this.

What we are trying to do is blend the Ho and MBM better to reduce/eliminate that dip at 30-45Hz. Same goes for that MBM to main transition. Have you tried adjusting the xo knob on the Ho to see what happens?

**weverb** · **06-02-09, 07:32 PM**

Also try that last graph with a target of 72dB versus 75dB and see what it looks like. 72dB seems to split the difference of your mains better.

**jdeanmc** · **06-02-09, 11:49 PM**

I have played with the Ho,s crossover,ive moved it from about 40hz to 55 hz,this seems to be as good as it gets,ive contemplated trying to get rta running and moving subs to make sure they are in the best locations,i dont think ill gain much with,phase,distance settings(ive played with these at every possible setting)
i do see your point about losing the mbm,ill give that a try.
any other suggestions before i disconnect subs and start with the moving?
Thanks for all the attention
Dean

**jdeanmc** · **06-04-09, 12:01 AM**

to whom it may concern.
1st graph mains only.
red-left only.green right only.blue-both mains to 200 hz
next graph same but full range
does it not look like left and right are out of phase?

**jdeanmc** · **06-04-09, 12:08 AM**

subs only
light purple-HO only 48 hx crossover
dark purple-MBM only
blue-both subs

**jdeanmc** · **06-04-09, 12:21 AM**

subs and mains
first to 200 hz unsmoothed
next to 3k hz smoothed by 1/3
im not quite there yet,but ive considered...
$3-$400 each for adcom or yamaha amps(wayne,you,ve cleared me up on that)
$1200 to $1300 to upgrade to klipsch rf-7 fronts PLUS $400 to $500 for rc-7 center.
$1300 to $1600 for sub upgrade
or getting Weverb,Brucek,Wayne to fly to huntsville international airport(HSV)picking you guys up(its only 10 mins away)spending an evening getting me the best out of what i have,feeding you filet's(big green egg style)and sending you back home!!!
What would be the cost???
Please help
i have become obssessed with this!!!!
Dean

**brucek** · **06-04-09, 07:57 AM**

Those plots look quite good now. Hopefully, it sounds good too.

brucek

**weverb** · **06-04-09, 08:45 AM**

Quote:

jdeanmc wrote:

im not quite there yet,but ive considered...
or getting Weverb,Brucek,Wayne to fly to huntsville international airport(HSV)picking you guys up(its only 10 mins away)spending an evening getting me the best out of what i have,feeding you filet's(big green egg style)and sending you back home!!!
What would be the cost???

Dean that is funny. Atlanta is only about 6 hours from home!

I have to agree with brucek. That last plot is looking good. I know you listed a bunch of possible upgrades, but I think there is one route you missed. You already started some. I think sound panels will help a lot more in your room. You have very reflective walls with all that wood paneling. You really could use a lot more treatment. I would look at diy or at ATS to help keep the cost way down.

http://www.atsacoustics.com/

I noticed a huge difference in my room with the little sound treatments I have done. brucek posted about another really cool feature in REW called Energy Time plots (ETC). It will help show you if you have addressed all your reflection points. Here is the post I am referring to:

http://www.hometheatershack.com/foru...tml#post170156

Besides the reflection points, you have a lot of corners in that room. Bass trapping is going to help the bass a lot. You can get very creative to help make any type of treatment blend in the room.

If you are not ready or the WAF prohibits sound panels, you can start adding another MBM to help smooth things out. What's most important though is how it sounds to you. Don't get too caught up in how the graph looks. Worry more about how it sounds. I would spend some more time listening/watching some reference material and really pay attention to see if any thing is lacking or is too much. You should feel

with the headway you have made so far.

**Synthsayer** · **06-04-09, 09:34 AM**

TRY THIS, IT WORKED FOR ME: If your sub amp has a continuous or variable phase control set it to about 90 degrees, and then start adjusting in slightly increasing amounts. Most likely you will wind up with a setting around 135 degrees. This combines the 90 degree phase shift of the 1st order crossover and the natural ACOUSTIC PHASE differences between mains and subwoofer of approximately 45 degrees.
I have been working with subwoofer placement and phase alignment between main speakers and subwoofer for several years. Getting my system adjusted to where it sounds like all of the sound is coming from the fronts, center, and rear speakers with the sub really being almost inaudible until some strong low end kicks in has been a big challenge. But, after a lot of research, crawling around the room, and calculations, the system sounds very good.
Sure, people say to 'put the sub in your listening position, crawl around the room on your hands and knees until your hear the sub the way you think it sounds best' and bingo put the sub woofer in that spot and you're done. HA! Don't believe it for a moment. Not to mention the fact that my sub is a 3 cubic foot cabinet weighing 90 lbs. Sure, I can put that on my couch.???
Some people will say that bass signals below 300Hz are non-directional. But with Room Modes and other acoustic anomalies it is not always true. Give strong consideration to using bass traps in corners nearest the subwoofer, along walls, and other corners. This will make an incredible difference getting your system aligned without a bunch of moving the sub all over the room until your back gives out. For excellent videos of

making bass traps

check out this YouTube Site
Now it's time to get technical and bring up some relative factors that will impact your ability to properly place and 'phase align' your sub and main speakers.
You can see my post about considering the natural phase characteristics of the passive crossovers of the main speakers at this thread
To be brief and not overly technical the main point is this: Your powered subwoofer has no passive crossover components and likely uses a fourth order, 24db/octave Linkwitz/Riley active crossover which is 'in phase'.
Your main speakers may only have First Order 6db/octave PASSIVE Crossovers (Crossovers made with combinations of inductor coils and capacitors). This type crossover has a phase shift of 90 degrees. If you have more expensive high-end mains, then you may have 2nd, 3rd, or even 4th order PASSIVE Crossovers.
For this example I focus on 1st and second order PASSIVE crossovers since they are the most common.
Consider this: The sub amp contains the 24db Linkwitz/Riley ACTIVE crossover, phase inversion switch or continuous phase control, and maybe a parametric EQ. We consider the subwoofer's input and output to be 'in phase'. Say your main speakers have Passive first order crossovers. (The main part of the crossover we are concerned with is the Low Pass section). The 1st order crossover is 90 degrees 'out of phase' compared with the subwoofer.
If your subwoofer has no phase adjustment or only a phase reverse switch then you will have a tough time getting the phase problem solved and achieving the best sound reproduction. I am going to consult a friend who has done electronics design for Elan Home Systems to see if adding a small inductor in series with the subwoofer voice coil would solve the problem and post another reply.
The most important thing is to know the type of PASSIVE crossover used in your main speakers and whether they are 1st, 2nd, 3rd, or 4th order.

**JimP** · **06-04-09, 09:40 AM**

Dean,

Are you in Huntsville Alabama or Huntsville Texas? I'm in Wetumpka AL north of Montgomery.

Back to you problem. First, I went through the whole MBM thing with a Velodyne HGS15. Talk about struggling with it. I think part of the problem that you're experiencing may be in timing differences between the MBM-12 and your deep sub. I don't honestly believe that a phase adjustment does the same thing. At one time, I added a Behringer something in other (still have it in junk room) in order to play with trying to get the same amount of delay between the two subs (includes the mbm). It helped only a little. One thing I think we're overlooking is that depending on volume, your group delay changes and keeps you from keeping the mbm and sub properly time aligned and causes cancellations. You're also dealing with different slopes and their interactions. In my configuration, I guess I didn't really need the mbm as my sub was pretty good at mid bass. I wound up ebaying the mbm and went back to using just the sub. Since then, I bought a SVS PB Ultra 13 which knowing what I know now I might not have done. (If you're interested in a HGS15, let me know.)

If you're in Huntsville Alabama, I could drive up there to help, but if the problem is as I'm suggesting, its not really fixable with your current equipment configuration.

**weverb** · **06-04-09, 09:45 AM**

Quote:

Synthsayer wrote:

If your sub amp has a continuous or variable phase control set it to about 90 degrees, and then start adjusting in slightly increasing amounts. Most likely you will wind up with a setting around 135 degrees.

The HSU Ho sub only has a phase setting of 0 or 180 degrees. Nothing in between.

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