Using RTA to position subs/mains

**jdeanmc** · **05-23-09, 04:25 PM**

Hey Guys,
If this isnt in the right area please let me know...
I have decided to start over with my setup.
Step one,i want to make sure ive got sub(s)in the best location for my room to get the best response.
Is using Rta in Rew my best bet for this?Put sub in lp and move the mic around to find smoothest response?then swap positions?
i have the HSU vtf mk3 ho and the MBM12.how do you do this with 2 subs?
Can i also us the Rta to get the mains in the best position.Toe in,distance apart,distance from wall etc...for the best soundstage?
Can someone please clue me in on the rta setup.ive looked through online help files,but dont see what i need,i did see a post from Brucek from 3/7/2009 on the subject(.RTA 1/24 octave.pink pn.fft 65536.average=2.window=rectangular.no bars.y axis=dbfs with scale -70 to 0)
Any thoughts?im i going about all this correctly?
Dean

**brucek** · **05-23-09, 07:16 PM**

Quote:

Is using Rta in Rew my best bet for this?Put sub in lp and move the mic around to find smoothest response?then swap positions?

Yep.

Quote:

have the HSU vtf mk3 ho and the MBM12.how do you do this with 2 subs?

A lot of trial and error if you aren't planning on co-locating them.

Quote:

Can i also us the Rta to get the mains in the best position.Toe in,distance apart,distance from wall etc...for the best soundstage?

You can give it a shot, but again the problem with two mains will make it difficult. The RTA is certainly useful at the listening position to adjust the subs phase control when you have the sub and mains playing to obtain the smoothest crossover region.

Quote:

Can someone please clue me in on the rta setup.ive looked through online help files

Follow the info below on using the RTA:

To use the RTA feature of REW, you must first setup the levels as if you were about to make a standard response measurement.

This involves running the Check Levels routine for the mic at the listening position to 75dB and the Calibrate routine. You can even run a measure to have a reference.

Then, select the Spectrum tab in REW and setup the controls as shown in the picture below.

Then, select the REW Generator and select Pink PN and start the signal using the play button.

Press the Red record button on the Spectrum page.

You can monitor your Input Level on the Spectrum page in the bottom left hand corner.

If it reads clip at any time (because you're moving the mic around when using the RTA), then simply turn down the REW input level a bit.

Below shows a response measure I took (that gets transferred to the RTA graph), and the black line is the RTA itself. Now I'm ready to move the mic around and watch the black line change.

brucek

**Wayne A. Pflughaupt** · **05-23-09, 07:28 PM**

Quote:

i have the HSU vtf mk3 ho and the MBM12.how do you do this with 2 subs?

No different, since the two function to cover the entire low end: put them both at the listening position for testing, then put them both in the location with best response.

Quote:

Can i also us the Rta to get the mains in the best position.Toe in,distance apart,distance from wall etc...for the best soundstage?

Not sure there's a definitive answer for this - others may want to chime in with their thoughts. My thinking is that REW won't do anything to help determine the best soundstage, since it's a mono signal. That's something you'll just have to do by ear.

As far as determining the best position from walls, etc. REW can help there. Smooth your RTA reading to 1/3 octave (hopefully you can do that with the RTA? I've never used it full range) and look for the larger peaks or dips in response below 500 Hz or so (which is about the frequency that the room really starts to influence things). See if re-positioning can minimizing the peaks and dips, but not at the expense of placement for the best soundstage.

Regards,
Wayne

**weverb** · **05-23-09, 09:08 PM**

Hey Dean,

We have not heard from you in awhile. Maybe post a full range graph of your current set-up and list some of things you are not happy with. Wayne and brucek are great at reading the graphs and making suggestions for improvement. Another option you may want to start researching is sound treatment panels. I have noticed an actual improvement in my current set-up with just a few diy panels.

**jdeanmc** · **05-26-09, 10:17 AM**

I will try to get graphs up.
Its not that my setup doesnt sound good,it does.I just want more than good!!!
I still feel like im lacking that "room filling"low end,ive got descent bass,but no "pressure"
I can cut the HO off and there is really no audible difference whether its off or on.seems like the mbm does all the heavy lifting.
I did (for some reason)gut my mains and noticed that 2 screws on each woofer was pulled through.The woofers werent "sealed"to the cabinet.i fixed this and do notice a great deal of improvement in "clarity"now i want to start over and make sure im getting all i can from subs,location,setup etc...
I do have panels in the first reflection points and a few on the back wall.
I had considered adding another Ho but after speaking with Pete at HSU,he stated i should have plenty of sub for my size room?
I will try to get graphs up in a day or two.
Thanks for all the help.
Dean

**weverb** · **05-26-09, 10:33 AM**

Quote:

jdeanmc wrote:

I still feel like im lacking that "room filling"low end,ive got descent bass,but no "pressure"
I can cut the HO off and there is really no audible difference whether its off or on.seems like the mbm does all the heavy lifting.

Hey Dean,

Can you post a layout and give us more details on your room. "Pressure" is going to be very difficult unless you have a "sealed" room. Mine opens to other areas of the house. No matter how many drivers I add, I will never pressurize my space.

**jdeanmc** · **05-26-09, 10:49 AM**

This would be the latest room layout i have on my computer however,things have changed.The Ho is now on the right wall almost below the first reflection panel.I have also moved and added panels.I now have 2 on each side wall.
The room is a basement room that does close off from upstairs.
Maybe trying to "pressurize"my room was a bad choice of words.I actually just feel the low end is still a little weak.maybe i need a "steeper" house curve?
I do feel like a problem is the "blend"between the mains and the subs.Ie.i set up the subs with rew and get "wall rattling"low end then after i add mains and actually watch a movie there is no "wall rattling"low end.same for music,i can crank the sub level(in the avr) from 0 db to 6.0 db and dont notice much difference.
Its like when i watch a movie or listen to music at normal level,the low-end disappears.like the mains overpower the subs??
This is what im trying to improve on.
Dean

**weverb** · **05-26-09, 11:05 AM**

Quote:

jdeanmc wrote:

Its like when i watch a movie or listen to music at normal level,the low-end disappears.like the mains overpower the subs??
This is what im trying to improve on.
Dean

Gotcha. We will have to wait and see your graphs. I am sure Wayne and brucek will be a big help then. I would just read Wayne's house curve post again and try his suggestion of playing something like 30Hz. and comparing it to something near your crossover point (like 90 or 100Hz.) and see if they "sound" like the same volume. That should help with your house curve.

**jdeanmc** · **05-27-09, 01:26 AM**

o.k here is the mess im dealing with..
i set the subs only,check levels ,set target levels,have filters at ...
21 hz gain -16 bw 14
30.85 hz gain -6 bw 8
52.16 hz gain -12 bw 11
looked pretty good i thought.i have to set the avr volume to -18.5 to get to the proper level(at -18.5 with the mains added will run you outta the room,if not the house!!!)
then when i add the mains,set target level,check levels,i have to set the avr volume to -32
next is with the sub level maxed out
what am i missing?
makes since that when i set sub levels properly,then add mains and have to drop avr level so much here lies my problem.
i have got much better results than this before but the problem is the same.mains overpower the subs.
HELP.......
Dean

**robbo266317** · **05-27-09, 04:15 AM**

the dip between 80 Hz & 90 Hz doesn't look right. It's not evident in the sub only graph?
Have you tried inverting the phase of the subs?

**brucek** · **05-27-09, 06:58 AM**

Quote:

the problem is the same.mains overpower the subs.

Why not simply reduce the level of the mains?

brucek

**weverb** · **05-27-09, 08:30 AM**

Another question for you Dean. When you play your receiver's test tones, what reading do you get for your subs versus the mains? I would assume 75dB for the mains. Also, did you play just the MBM and set it to 75dB and then just the HO (and set it to 75dB)?

I would look at your phase setting on the MBM and the play with your crossover some. Try moving the MBM to one side of the couch versus behind it. Let's see if we can fix that dip. Also, what xo setting do you have on the HO? Your blend of the could be better.

What about trying both subs behind the couch? I have seen people have good results with them both back there.

**jdeanmc** · **05-27-09, 09:33 AM**

Quote:

robbo266317 wrote:

the dip between 80 Hz & 90 Hz doesn't look right. It's not evident in the sub only graph?
Have you tried inverting the phase of the subs?

I have switched the phase setting on both subs as well as played with the distance setting in the avr.this seems to be as good as it gets.
The thing is i can measure four or five times and this dip will only show maybe once or twice?the other times its gone?
Dean

**jdeanmc** · **05-27-09, 10:15 AM**

Quote:

brucek wrote:

Why not simply reduce the level of the mains?

brucek

This brings a whole new level of confusion to me(yes,something this simple)

i run ypao.yamaha's auto calibration.to set the levels,it matches the speakers levels with each other spot on,but i dont know what level it sets them to 75db?to keep it from messing with the sub levels(as per my avr salesperson)i first set the fronts to large,lfe to fronts,i guess telling the avr i have no subs,then run ypao to do its thing,auto eq,levels etc.then turn on subs,set fronts to small set lfe to swfr.
I know i make things too complicated!!!!.point is if i lower the level of the mains,i will then have to manually set the levels of all other speakers(6.1 system)
if i do this .should i first get the subs set with a 75db target level,then without touching the avr volume,set all other speakers levels with the avr test tones(assuing thats 75 db)and at what point(what freq)are the subs at 75 db target level(10 db house curve)????
Dean

**jdeanmc** · **05-27-09, 10:22 AM**

Quote:

weverb wrote:

Another question for you Dean. When you play your receiver's test tones, what reading do you get for your subs versus the mains? I would assume 75dB for the mains. Also, did you play just the MBM and set it to 75dB and then just the HO (and set it to 75dB)?

I would look at your phase setting on the MBM and the play with your crossover some. Try moving the MBM to one side of the couch versus behind it. Let's see if we can fix that dip. Also, what xo setting do you have on the HO? Your blend of the could be better.

What about trying both subs behind the couch? I have seen people have good results with them both back there.

I did just move the Ho from behind the couch and back to the current location.i felt that i had to have the level so low with it back there that maybe that was part of my problem?
i did measure both subs together,if i have a 10 db house curve should the level of the ho be higher than the mbm?if i ran the avr test tones to get 75 db on the mains should i be getting about 85 db on the subs?then doesnt the rat shack spl meter correction comes into play?
Sorry for making all this waaaay tooo complicated but im ready to jump into this with both feet and obsess till i put this to bed!!
Dean

**weverb** · **05-27-09, 10:30 AM**

Quote:

jdeanmc wrote:

I know i make things too complicated!!!!.point is if i lower the level of the mains,i will then have to manually set the levels of all other speakers(6.1 system)
if i do this .should i first get the subs set with a 75db target level,then without touching the avr volume,set all other speakers levels with the avr test tones(assuing thats 75 db)and at what point(what freq)are the subs at 75 db target level(10 db house curve)????
Dean

I would manually set the mains level to 75dB (set as "small")using the receivers test tones. Then do the same for the surround speakers. Once those sound level, I would turn the HO off and run the sub test tone and set the MBM to 75dB. After that, turn the MBM off and set the HO xo to bypass and set it to 75dB using the receiver's test tone. When you have these two set, turn the MBM back on, the HO xo on and check the level for the two together.

**weverb** · **05-27-09, 10:36 AM**

Quote:

jdeanmc wrote:

I did just move the Ho from behind the couch and back to the current location.i felt that i had to have the level so low with it back there that maybe that was part of my problem?
i did measure both subs together,if i have a 10 db house curve should the level of the ho be higher than the mbm?if i ran the avr test tones to get 75 db on the mains should i be getting about 85 db on the subs?then doesnt the rat shack spl meter correction comes into play?
Sorry for making all this waaaay tooo complicated but im ready to jump into this with both feet and obsess till i put this to bed!!
Dean

Let's just start simple and don't over think things. You need to start off with things balanced first. Are you able to test things now or are you at work?

**jdeanmc** · **05-27-09, 10:46 AM**

Quote:

weverb wrote:

Let's just start simple and don't over think things. You need to start off with things balanced first. Are you able to test things now or are you at work?

I am at work,
I have a huge bump from 20-35 hz,that i now have eq'ed down with the bfd,should i bypass all my subs filters before i do this and set the subs at 75 with an uneq'ed measurement?
Dean

**weverb** · **05-27-09, 10:53 AM**

Quote:

jdeanmc wrote:

I am at work,
I have a huge bump from 20-35 hz,that i now have eq'ed down with the bfd,should i bypass all my subs filters before i do this and set the subs at 75 with an uneq'ed measurement?
Dean

Yes. Then you will redo the filters. After the new filters are applied, you may have to adjust the levels to get the subs back up to the 75dB reference level. Don't worry about the house curve yet. Once you get things balanced and hear it, then you can look into adding a house curve.

**jdeanmc** · **05-27-09, 11:26 AM**

Quote:

weverb wrote:

Yes. Then you will redo the filters. After the new filters are applied, you may have to adjust the levels to get the subs back up to the 75dB reference level. Don't worry about the house curve yet. Once you get things balanced and hear it, then you can look into adding a house curve.

Im liking this"lets start from the beginning thing"why haven't i thought of that!

I will try to do this tonight,however it may be a day or two.now that summer has started,it seems to be difficult to get the house quite enough to measure anything!!

So ill bypass filters,bypass the house curve,cut off subs,run receiver test tones to set all speakers levels to 75,then the ho,then the mbm,then both subs(i got the procedure on that down)get everything flat to 75 db and balanced.then run rew,get filters for subs so that they are as flat as possible,get their level back to 75 db after filters.then look at house curve.am i on the right track here??
Dean

**weverb** · **05-27-09, 11:52 AM**

Quote:

jdeanmc wrote:

am i on the right track here??

Sounds like it. I would still try other sub locations if you can. If you truly feel these are the best spots then don't worry about. Just use it as an excuse to purchase more subs to smooth things out!

Also, you may want to make multiple readings so we can see what you described about the dip.

**jdeanmc** · **05-27-09, 11:59 AM**

Quote:

weverb wrote:

Sounds like it. I would still try other sub locations if you can. If you truly feel these are the best spots then don't worry about. Just use it as an excuse to purchase more subs to smooth things out!

Also, you may want to make multiple readings so we can see what you described about the dip.

I will do this
Ill get all this going as soon as i can
BTW,i noticed a while back you sold some subs and mbm'sif you dont mind me asking, what are running now?
Dean

**weverb** · **05-27-09, 12:08 PM**

Quote:

jdeanmc wrote:

I will do this
Ill get all this going as soon as i can
BTW,i noticed a while back you sold some subs and mbm'sif you dont mind me asking, what are running now?
Dean

I am running two Fi IB318's in an infinite baffle set-up.

**jdeanmc** · **05-29-09, 10:15 AM**

i havent had a chance yet,to check my levels or take any measurements,however the last two nights i was able to go downstairs and watch some tv/listen to some music.
I turned off the BFD,cut off subs,set speakers to large and lfe to fronts.
WOW.this sounds very nice!this is what i want with the subs involved,the low end seamless with the midrange,these speakers do go low as well,not as low as the subs,but i wasnt missing much!!
I still notice that the highs seem to be weak,on music cymbal's seem like they're 10 feet behind the drums.I can turn the treble control from 0 db to 6 db(max)and dont really hear any difference?maybe its an eq thing with the ypao?
Anyway,i hope tonight or over the weekend to be able to rerun ypao,manually set levels to 75 db and start over with the subs.

One question...
when i set levels on the mains and surrounds,i want to make a mental note of the avr volume.then set subs at this same avr volume(in an attempt to get the subs/ mains to blend fairly well before i start playing with phase and filters etc...)then i want to use sub level(in avr)and gain on subs to get as smooth of a response as i can(without touching avr volume)then when i get response as smooth as i can without any eq filters,or house curve,ill post a graph.
Im thinking out loud,but when i get to the point of "level too low"do i use the sub out to raise level?(as i dont want to move the avr volume)???
Thanks Dean

**brucek** · **05-29-09, 11:15 AM**

The AVR volume is set during the Check Levels routine, so that the SPL level at the listening position is 75dBSPL. Then it isn't touched.

The REW input volume is now set to a level on REW's VU meters to be about -12dB.

Then the Calibrate routine is run and the REW internal SPL meter adjusted to 75dBSPL.

If you do that the level won't be low.

brucek

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