First room measurement..advice needed from newby - Home Theater Forum and Systems - HomeTheaterShack.com

Reply
 
Thread Tools
post #1 of 16 Old 10-12-10, 03:33 AM Thread Starter
Shackster
 
Join Date: Sep 2010
Location: Germany, Düsseldorf
Posts: 14
First room measurement..advice needed from newby

Hello,

finally managed to take some first measurements, enclosed my results, using REW and the radioshack SPL,
with dolby sorround giving the sweep on all speakers

First room measurement..advice needed from newby-oct-11thdolby.jpg

same volume settings etc. with thx

First room measurement..advice needed from newby-oct-11th-thx.jpg

and the waterfall

First room measurement..advice needed from newby-oct-11th-dolby-waterfall.jpg


would be greatful for tips which ones (peak at 30hz, low at 35 Hz) to treat, would a helmholtz do the job, do they work for lows at well ?
How do you measure a typical cinema setup, using fronts/sub only or using all speakers? Quite suprised I get so different results on the bass level switching between dolby and thx...

Regards

Daniel
Daniel0012 is offline  
Sponsored Links
Advertisement
 
post #2 of 16 Old 10-12-10, 07:02 AM
HTS Senior Moderator
 
bpape's Avatar
Bryan Pape
 
Join Date: Sep 2006
Location: Wildwood, MO (St. Loui
Posts: 5,288
Send a message via AIM to bpape Send a message via Skype™ to bpape
Re: First room measurement..advice needed from newby

Not perfect but I've seen a lot worse.

30 and 35Hz are going to be very difficult to deal with via treatment. I'd suggest working with mic position to see if you can help with small seating position changes. If you can't, or another problem them pops up, I'd consider using the RTA function of REW to play with sub position to try to smooth it out.

Bryan

I am serious... and don't call me Shirley.

Bryan Pape
Lead Acoustician/Owner
Sensible Sound Solutions
bpape is offline  
post #3 of 16 Old 10-12-10, 07:51 AM Thread Starter
Shackster
 
Join Date: Sep 2010
Location: Germany, Düsseldorf
Posts: 14
Re: First room measurement..advice needed from newby

Thanks Brian,
good to get some expert judgement on how to focus before building lots of resonators and stuff, will try playing around with sub position first, any hints where a good position might be? Between the fronts wont work due to size and the the thing is heavy ;-) Will a sub equalizer/BFD do a good job, they seem a comparable cheap solution ?

Regards

Kino.pdf
Daniel0012 is offline  
 
post #4 of 16 Old 10-12-10, 08:11 AM
HTS Senior Moderator
 
bpape's Avatar
Bryan Pape
 
Join Date: Sep 2006
Location: Wildwood, MO (St. Loui
Posts: 5,288
Send a message via AIM to bpape Send a message via Skype™ to bpape
Re: First room measurement..advice needed from newby

I'd play with seating position first if possible.

Experimentation is best for sub positioning and you can use the RTA function in REW to help you.

EQ may be needed but only after exhausting seating and sub positioning. 35hz and down is very hard to do even with tuned absorbers as many times, when tuned that low, they can cause their own problems.

I'd also recommend doubling or tripling the thickness of the absorbers on the rear wall behind your seating. 5cm isn't enough to approach the deeper bass. Its' still not going to go to 35hz fully but it may help a bit and will definitely help with other things.

Bryan

I am serious... and don't call me Shirley.

Bryan Pape
Lead Acoustician/Owner
Sensible Sound Solutions
bpape is offline  
post #5 of 16 Old 10-12-10, 11:52 AM
Senior Shackster
 
MatrixDweller's Avatar
Zip
 
Join Date: Jul 2007
Location: Canada
Posts: 969
Re: First room measurement..advice needed from newby

I found that when I moved my sub around it changed where the dips were, although they still existed. So you might be able to move your sub into a position so that the dip occurs at a lower frequency that is not as audible or to a higher frequency where it is more treatable.

Most people tend to recommend super chunks in corners and as thick as possible. That will help with the waterfall graph's representation of room decay and might alleviate some of the frequency anomalies. The end result is to minimize the room's colorization of the sound. Of course your speakers and/or AVR will have their own colorization. You could add in EQ to tackle things once you've made some improvements to the room.
MatrixDweller is offline  
post #6 of 16 Old 10-12-10, 01:57 PM
Senior Shackster
 
marty1's Avatar
 
Join Date: Jun 2010
Location: United Kingdom dagenham
Posts: 347
Re: First room measurement..advice needed from newby

I have spent a lot of time trying to get as flatter response as possible, I have managed to get a fairly good response from subwoofer, the upper frequencies I am yet to tackle with room treatment.

I would advise picking where you would like to sit first, ideally away from walls and the centre of the room. Put the mic there and measure the sub in every possible position with any eq on amp or sub switched off, unplug the speakers and measure just the subs response alone in each position. Set the sweep from 10hz-200hz, 512k.

Compare your results and look for the best result, as close to flat as possible. Once you have that position sorted out start adjusting subs phase and peq (if available) to tweak any peaks, dips in the lower hz levels are pretty much only dealt with by sub placement so just try and bring the peaks down.

Regards
Marty

P.S. When you Measure speakers aswell set amp to stereo not dolby surround as it overcomplicates measurements, do not worry about rears just try and get 2 front mains and sub perfected first

Last edited by marty1; 10-12-10 at 02:05 PM.
marty1 is offline  
post #7 of 16 Old 10-13-10, 06:20 AM
Senior Shackster
lesmor
 
Join Date: Dec 2009
Posts: 153
Re: First room measurement..advice needed from newby

As a novice I concentrated too much on the sub and graphs in one seating position
Perhaps there should be a room/seating/ sub setup guide . as I too found you should try and find the flattest seating position.
I positioned sub as best I could , then I run a line down the centre lenght of the room taking readings with the meter up and down the line until I found the best/ flattest seating position.
You could then try and fine tune by moving sub slightly . I didnt need to.

As always every room will be different but there has to be a better way then lugging subs around doing your back in.
Far easier to move the meter
lesmor is offline  
post #8 of 16 Old 10-13-10, 07:04 AM Thread Starter
Shackster
 
Join Date: Sep 2010
Location: Germany, Düsseldorf
Posts: 14
Re: First room measurement..advice needed from newby

Thanks guys, this has been tremendously helpful so far, especially the hint just connecting the sw and runnung up 200hz helped a lot.

problem is, the sw ist just fine were it was, assuming i will run it up to 80 hz anyway (few other otions to place it anyway, bit too bulky)

First room measurement..advice needed from newby-sw-only.jpg

problem are the fronts, these seem to drive most resonances, and there's just no other way to place them

First room measurement..advice needed from newby-fronts-only.jpg

well, altoghether looks a lot better then before playing a bit around with positions and sw settings, plus some thicker panels for the back already ordered but haven't arrived yet, I hope that will do the yob, what do you think

First room measurement..advice needed from newby-oct-13th.jpg


txs again

Daniel


btw.: great fun, playing around with REW, still the impact of running thx, dolby etc. keeps me quite frustrated, all of them at least on my receiver don't seem to change things for better
Daniel0012 is offline  
post #9 of 16 Old 10-13-10, 04:23 PM
Senior Shackster
 
marty1's Avatar
 
Join Date: Jun 2010
Location: United Kingdom dagenham
Posts: 347
Re: First room measurement..advice needed from newby

Try using 1/3 octave smoothing and click on measured at the top of rew graph, I think it makes the response a bit clearer.

Again measure with your amps sound settings set to stereo, not surround, with any eq on your amp or your sub switched off.

It is important you get everything correctly balanced before adding any eq.

Do a measurement for sub and speakers combined, phase on sub set at 0, then move phase dial 1 step measure again then move it again and again until the dial has done a complete 360, then compare the results, that dip around 50hz you have is more than likely a phase issue so this again will allow you to determine the best position for the phase dial.

Just out of curiousity, do you have your amps crossover set at 80hz, the subs crossover fully open and speakers set to small?

Last edited by marty1; 10-13-10 at 04:40 PM.
marty1 is offline  
post #10 of 16 Old 10-14-10, 02:25 AM Thread Starter
Shackster
 
Join Date: Sep 2010
Location: Germany, Düsseldorf
Posts: 14
Thumbs up Re: First room measurement..advice needed from newby

Thanks Marty for taking care of this

enclosed the smoothed graph


First room measurement..advice needed from newby-oct-13th-13.jpg

will try that, haven't changed the phase yet, will try if that further improves.

I have the SW open for the measurement only since I do all the digital processing on the BD-Player and run the Amplifier pure analog via Ext-in when watching movies (I don't use the amplifiers digital section) In my normal setup I have the fronts on large (The Logans go down well w´below 30 HZ) and the other speakers on small, SW crossover at 80Hz. Thus the 100hz distortin should dissapear, but cant really measure that.

Can you use REW for pure recording as well without using it as a signal? then I could try the setup with a test-dvd I have at hands using the BD-Player.

BTW, I will try not to use any EQ, I am more of an analog guy, believe in good analag equipment, even if its old stuff. So I really would like to smooth this out with room acoustics and placement, still some free space on the wall to add more foam ;-)

If the drop at 100hz stays, do you think a helmholtz or plate resonator would be an option?

Txs again

Daniel
Daniel0012 is offline  
Reply

Bookmarks

Tags
measurement..advice , needed , newby , room

Quick Reply
Message:
Options

Register Now




PLEASE COMPLETE ALL REQUIRED FIELDS BELOW... THANKS!

REQUIRED FIELDS ON THIS PAGE
YOU MUST COMPLETE ALL OF THESE

Username
Password
Confirm Password
Email Address
Confirm Email Address
Random Question
Random Question #2




User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
PLEASE READ BELOW PRIOR TO ENTERING AN EMAIL ADDRESS!

ATTENTION!

YOU MUST ACTIVATE YOUR ACCOUNT!

Activation requires you reply to an email we will send you after you register... if you do not reply to this email, you will not be able to view certain areas of the forum or certain images... nor will you be able download software.

AN INVALID EMAIL ADDRESS WILL CAUSE YOUR ACCOUNT TO BE DELETED!

See our banned email list here: Banned Email List

We DO NOT respond to spamcop, boxtrapper and spamblocker emails... please add @hometheatershack DOT com to your whitelist prior to registering or you will get nowhere on your registration.


Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML is not allowed!
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


For the best viewing experience please update your browser to Google Chrome