# First Measurement - Starting point for a work already in progress



## AGINHOUSE (Jan 28, 2014)

Good evening guys. Tonight I took my first REW measurement. I have been sitting on the fence for a while trying to make sure I read as much info as possible before getting started. 

Measurements are taken with a Macbook pro and a Dayton UMM-6. I have loaded the calibration from Dayton into REW and set the SPL levels with my Ratshack meter. 

My hopes are that I can use this preliminarily to get the best response as possible based on subwoofer placement. Once that is determined I will try to integrate the towers and blend as seamless as possible. From there I hope to receive recommendations based on the advice found here for room corrections, an equalizer or probably both...... 

Here is my first measurement, pretty painful to look at. 









My room is 18' long, 13' wide and 10' high(2340 cubic ft). I have dual SW-112 subwoofers currently sitting about 2'-3' apart in the front of the room. My listening position is about 8.5' from the front wall in the center of the room. What I have known, and confirmed tonight, is that bass is anemic from my main listening position. There is almost intolerable room gain towards the back of the room. I would post a copy of the REW simulation if could figure out how to do so.

I'm going to try and run cable this weekend and relocate one of my subs towards the back of the room. I'll take another measurement and post again once done.

Im hoping someone can take a quick look at this first measurement for me just to make sure Im not missing anything. Thanks in advance

Austin



View attachment Feb 6 - Sub Only.mdat


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## Phillips (Aug 12, 2011)

Have you tried switching the phase on one of the subs?

Find the best position for each sub and listening position (this comes first before any EQ, room acoustics).

Then measure each sub with the phase set to 0 on both.

Post the results.


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## AGINHOUSE (Jan 28, 2014)

Thanks for your response Phillips. I'll change phase on each and re-measure this evening.


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## Wayne A. Pflughaupt (Apr 13, 2006)

I don’t know much about Klipsch subs, but I’m sure a pair of 12-inchers will get lower than 70 Hz, even in a room as large as yours.

It sounds like you have the two subs more-or-less centered on the front wall? If so, move them to a corner. If you have a symmetrical room, you can put one in each front corner. If your room is asymmetrical, it would be best to stack them in the corner that has the longest uninterrupted length of wall (i.e., no openings). His should improve your extension significantly.

Regards, 
Wayne


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## Bowers (Mar 10, 2012)

You could also try to place the subs 1/4 of the width og youre room to either side. Against the wall your lookin at when playing music. And slightly move them towards you. Try getting the phase on the subs correct.


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## AGINHOUSE (Jan 28, 2014)

Thanks for the replies Gents. I have a hard time thinking as though I'm out of phase because I specifically changed to get the best sound when I initially set up my towers. That being said, I would have never guessed my response was that bad either. Def worth trying and I will post results this evening for your review. 

Always possible that one of my subs got bumped when the screen was being installed and knocked the phase switch, in effect that would have the subs cancelling each other out correct?

Its hard to see due to the low lighting but attached is a pic of my media room. this front wall is 13' wide with my towers flanking each side of my screen. The subs are just inside the table legs on each side. I will try to move them out and put each 1/4 width of the room as Bowers had recommended.


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## Bowers (Mar 10, 2012)

Hi. on picture 2 there. That thing in front of the sub on the right side, is that your legrest. My english is bad, i know. That is placed so near the sub, that the reflection from it will possably cancle out that sub, and it alsp looks that it will make trouble for the sub on the left side of the centerspeaker. Try taking that away, and do a new meassurement, and post the dat file...

I would also try to place the main L+R speaker eaven more into the room. Klipsch speakers like some air around them. 

Where is the backwall? Could you post å picture from your screen and towards where you are sitting?


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## AGINHOUSE (Jan 28, 2014)

Bowers, please see below pics of the rear if the room. Again, kind of hard to see due to the low lighting. Running more sweeps now....


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## tonyvdb (Sep 5, 2007)

Your first row looks like it about dead centre of the room is that correct?


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## Bowers (Mar 10, 2012)

just what I`m thinking myself.. If it is, try a sweep or two for the back row.


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## AGINHOUSE (Jan 28, 2014)

Yes the first row is dead center in the front of the room.I have made a bunch of sweeps this morning. Including this graph below. I moved one sub to the side in the front of the room and the second sub to the corresponding rear corner. Much smoother response. Your thoughts?









View attachment Feb 8 front rear.mdat


Still not exactly digging very deep......?


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## tonyvdb (Sep 5, 2007)

Sadly having the main listening position in the centre of the room makes it very difficult to get good results as that is where all of the reflections converge causing nulls and cancelation. Moving the subs around can help somewhat but treatment of the walls is the only real solution or move the front row back a few feet and get rid of or move the rear seating all the way back if it is not already.


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## AGINHOUSE (Jan 28, 2014)

I am sorry, I forgot to mention that I took a measurement in the back row. It was center line though. I will try again with the microphone off to one side.


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## Phillips (Aug 12, 2011)

Use the RTA in REW for each at a time, and move the mic around to see if extension/response improves.

What is the specs of the subs?

Have you tried the phase?

What size drivers are the subs?


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## AGINHOUSE (Jan 28, 2014)

Phillips, I tried the phase last night and switched to 180 and it just made the response quieter. 

The drivers are 12". Here are the specs.


FREQUENCY RESPONSE:	26Hz-120Hz ± 3dB
MAX ACOUSTIC OUTPUT:	116dB @ 30Hz
AMPLIFIER:	BASH® Digital Hybrid
AMPLIFIER POWER:	FTC Rated Power: 300 watts continuous @ <2% THD / Dynamic Power*: 600 watts
DRIVE COMPONENTS:	12" (30.5cm) Active non-resonant Woven Fiberglass driver
ENCLOSURE TYPE:	Bass-reflex via front-firing slot port
INPUTS:	L/R Line-level RCA jacks, L/R High-level speaker binding posts, WA port
OUTPUTS:	None
HEIGHT:	16" (40.6cm)
WIDTH:	14.5" (36.8cm)
DEPTH:	19" (48.3cm)
WEIGHT:	46lbs (20.9kg)
FINISHES:	Black pica
VOLTAGE:	100-120V / 220-240V~50/60Hz 3.15A (Auto-voltage switching) with 1 Watt standby


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## Wayne A. Pflughaupt (Apr 13, 2006)

AGINHOUSE said:


> Still not exactly digging very deep......?


For sure. Did you by chance take separate measurements? That might be instructive.

Regards, 
Wayne


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## Phillips (Aug 12, 2011)

> Use the RTA in REW for each at a time, and move the mic around to see if extension/response improves.


Please do this



> What is the specs of the subs?


With these specs with 2 26hz should be easy.



> Have you tried the phase?


Ok if you did this with *one at a time* leave at 0 degrees

What do the mains measure, matter of interest?


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## Phillips (Aug 12, 2011)

> It sounds like you have the two subs more-or-less centered on the front wall? If so, move them to a corner. If you have a symmetrical room, you can put one in each front corner. If your room is asymmetrical, it would be best to stack them in the corner that has the longest uninterrupted length of wall (i.e., no openings). His should improve your extension significantly.


Sorry Wayne to jump in here.

Have you tried this what Wayne has suggested?

Try moving the mains in, then put the subs on the outside of the mains (corner loading). 

Generally speaking use the 3rd rule for starters.

Measuring one at a time is your best starter, RTA is a quick way to measure for positioning for sub/s etc and listening position, then fine tune with the sweep (normal measurement).


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## AGINHOUSE (Jan 28, 2014)

Good morning guys, I apologize for the delayed response. 

Yes Wayne, I took quite a few measurements. Here are a few. 








View attachment Feb 8 pos3 stkd.mdat
This is the subs stacked along the longest uninterrupted wall








View attachment Feb 8 stacked front.mdat
This is the subs stacked on the front wall one third of the way across








View attachment Feb 8 pos2 phase0.mdat
This is the subs split apart. One on each side equal widths apart. 

Im sorry Phillips, Im unable to corner load the sub in the front of the room because that would relocate my towers to be in front of the projection screen. 
Im don't follow regarding your instructions regarding RTA. Is there somewhere I can read about this? If so I'll try to study up and analyze for you based on my room. 

I hate to be waisting everyone's time here but, Im beginning to feel as though Im just doing something wrong? Could it be my calibration file? I have verified the spl levels in REW with my SPL meter.....? 

View attachment calibration1381251.txt


Phillips, would you like me to turn my sub off and take a bass sweep with my mains? or do you want subs and mains together in a bass sweep?


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## JohnM (Apr 11, 2006)

The feb 8 pos 3 stkd and feb 8 stacked front measurements are not valid, if you look at the impulse responses you will see two peaks about 1.1 seconds apart, perhaps some strange buffering behaviour in line in/soundflower/OS X/Java. Best to keep an eye on the impulse response after each measurement and discard any that look like those.


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## AGINHOUSE (Jan 28, 2014)

JohnM said:


> The feb 8 pos 3 stkd and feb 8 stacked front measurements are not valid, if you look at the impulse responses you will see two peaks about 1.1 seconds apart, perhaps some strange buffering behaviour in line in/soundflower/OS X/Java. Best to keep an eye on the impulse response after each measurement and discard any that look like those.


John, I am getting quite a few graphs that look fairly close to these two.....Please explain to me again how you recognized that they were invalid? Could what ever has caused this to be part of the reasoning that my sub response looks so uniformly bad?

Edit: I have been running the laptop headphone jack out with a cord that is 3.5mm to RCA. I have use female/female connectors to another RCA cable to extend the length, then directly into my stereo "CD" input. 
Does anyone see any flaws with this basic connection?


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## Phillips (Aug 12, 2011)

> Im don't follow regarding your instructions regarding RTA. Is there somewhere I can read about this? If so I'll try to study up and analyze for you based on my room.


First of all get them measurements running ok, John is looking after this.

RTA is in the REW help files. RTA stands for Real Time Analyzer. This is useful for finding the best positioning for speakers, subs and listening positions. Then use the Sweep (that you are using currently) to fine tune.



> Phillips, would you like me to turn my sub off and take a bass sweep with my mains? or do you want subs and mains together in a bass sweep?


Once John and you get the measurements running ok if you are using RCA, instead of plugging the cabling into the Receiver try the sub/s input. 

Measure each main (Left and Right) + combined full range (all no bass management) and post to see there response. Will deal with crossover later.


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## AGINHOUSE (Jan 28, 2014)

Ok will do, Thanks Phillips. 

Week days are very busy for me. I'll take a few days and try to read over the RTA info and will be back on in a few days with more measurements


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## JohnM (Apr 11, 2006)

AGINHOUSE said:


> John, I am getting quite a few graphs that look fairly close to these two.....Please explain to me again how you recognized that they were invalid?


Look at the Impulse response plots, there should be one main peak, the bad responses have two:

A good impulse response:








A bad impulse response:








The oscillations in the frequency response plot also point to something being wrong in the measurement.


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## Wayne A. Pflughaupt (Apr 13, 2006)

AGINHOUSE said:


> Im sorry Phillips, Im unable to corner load the sub in the front of the room because that would relocate my towers to be in front of the projection screen.


It would be good to at least get a corner measurement, even if you can’t permanently locate the sub there. It would tell us for sure if we’re dealing with location difficulties, or a sub that has poor extension.

Regards, 
Wayne


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## AGINHOUSE (Jan 28, 2014)

Ok John, thank you for explaining. Does this lend itself to a bad sub or something in the way of the methods used to take the measurement? Do these just happen from time to time? Should I always measure twice to make sure they match?

Wayne, I'll see if I can get someone help me move the towers this weekend and take a measurement.....Would it make a difference if I just corner loaded in the rear of the room. I would think this would work just to make sure we are not dealing with poor sub extension? Your thoughts?


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## jtalden (Mar 12, 2009)

I would question if any of your current measurements are valid. None of the IRs appeared normal to me, but I may not have looked at all of them. Even if only some are wrong that is a major issue. I suggest you concentrate on getting consistently good measurements before anything else is considered.

Double check everything per the link to John Reekie's blog found here *OSX sticky thread* and review the comments from other Mac users.

I suggest you place the mic about 0.5 m to 1 m from a full range speaker (FL or FR). Use a normal volume level or a little lower to measure the full range (20-20k) with. I only suggest this as it should make it more obvious to determine if the measurement looks normal. Remeasuring with no changes will show if there is any issues. All measurements should overlay identically. 

The sample rate settings are apparently often a source of problems so pay particular attention there.


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## AGINHOUSE (Jan 28, 2014)

Sounds good. I'll try to review the OSX thread before I re-measure this weekend. Thanks


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## Wayne A. Pflughaupt (Apr 13, 2006)

AGINHOUSE said:


> Wayne, I'll see if I can get someone help me move the towers this weekend and take a measurement.....Would it make a difference if I just corner loaded in the rear of the room. I would think this would work just to make sure we are not dealing with poor sub extension? Your thoughts?


Sure, as long as the room is symmetrical it doesn’t matter which corner you use. If it’s easier to get the sub to a rear corner, then go for it!

Regards, 
Wayne


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## AGINHOUSE (Jan 28, 2014)

Everyone, I apologize for the delay in getting back on. I left town for vacation, got a new laptop and had a death in the family. It has been a very busy few weeks. 

I wasn't able to get the Mac to every work quite properly so I have started over with a PC. 

I hope these results look a bit better. They seem to atleast be valid. Your thoughts and comments are welcomed please. 

Here is my most recent measurement with the subs split in front and rear corners. I took the measurement multiple times and each response was identical. Thanks


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## 3GGG (Mar 1, 2013)

I had the exact same issue. On a mac any measurement below 100Hz was totally incorrect, huge dips and a lousy response. With a PC it worked and shows what i was expecting to see. Now you can play with placement to try and lessen the room modes.

Sorry to hear about the death in your family.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Yup, valid measurement indeed. :T That null at 70 Hz is going to be a problem. Different sub locations should make a difference.

Regards, 
Wayne


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## Phillips (Aug 12, 2011)

Measure each sub with the crossover disabled on the subs, then post the mdat file

Have you found that this is the best positions for the subs? If you haven't already try different postions.


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## AGINHOUSE (Jan 28, 2014)

Hi Phillips, this is the best position I have found for the subs based on my previous tests. Now, that doesn't mean I am settling. There may still be a better location that I have not yet been able to find. I will keep moving them around a bit. 

I will try to take another measurement this weekend and make sure there are not MCACC settings in the mix. Thanks

AG


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