# Room Measurments with REW Noob



## The_Nephilim (Mar 3, 2010)

Hey All,

I just tested my room with my new Umik I bought. Now It seems the room is pretty bad in the sub 200hz department.. I read the guide but I only went to 20K on the one graph. I can make new measurements tomorrow probally for now I will post what I have and see what the experts have to say..

The Room is 19' x 12' x 8' LxWxH. I have a DIY sub with a Mach 5 IXL 18.4 driver with a iNuke 3000DSP in a 12cu. ft. box with a 17hz tune..

















View attachment neph 3 umik.mdat










































I have real bad speakers and was going to build some new speakers from DIY Sound group.. I made the measuremnts to see where I need to improve and from what I can tell I need some helb with the Sub and the Highs seem to drop off real bad..

I was wondering what room treatments or what I can currently do to clean up the below 300hz..


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## willis7469 (Jan 31, 2014)

Are you going to use a minidsp or some correction? Minidsp is a great choice. If not, your only options are phase/placement to address any anomalies. You’re going to want to rescale the graph to 45-105db(60db window) as it’s a generally accepted standard. Actually the full range sweep looks pretty decent to my eye except one huge discrepancy. I’m not sure how a 12cuft tuned to 17hz is on its face at 30hz. Plz correct me if I’m wrong but that driver is designed for car audio, no? Usually their fs is around 30hz and I’m curious how you modeled this driver for the enclosure. Do you have a high pass engaged on the inuke maybe? It looks like a filter at 30hz with a steep slope. If this is for movies, you are missing out!
Edit:

Ok. So I went and looked, but when I click t/s parameters I see nothing. ??? Anyway, I probably underestimated this driver, but definitely check the amp settings. You should be getting response much lower than 30hz.


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## The_Nephilim (Mar 3, 2010)

IXL-18.4

Thiele-Small parameters:

Fs = 17.7 Hz
Re = 3.4 ohms[dc]
Le = 6.09 mH
Qt = 0.37
Qes = 0.39
Qms = 5.59
Mms = 434.34 grams
Rms = 8.69 kg/s
Cms = 0.184 mm/N
Vas = 274.1 liters
Sd= 1029.22 cm^2
Bl = 20.51 Tm
Lp(2.83V/1m) = 91.60 dB

I do believe the IXL 18.4 is for HT use.. I had gotten the design from the guy at Mach 5 he designed the box I just used that as it was perfect for me at the time..

I am a total noob and do not know what I need to get the readings fixed.. I will recheck the PEQ on the iNuke as I was in there messing around and might have killed the 30hz by mistake..

As for the Mini DSP will that correct some issues I have?? I will check the 30hz problem now.. but I followed this guide to set the inuke below 20hz:


http://www.avsforum.com/forum/155-diy-speakers-subs/1461489-how-extend-high-pass-filter-below-20hz-dcx2496.html

It does go down low just not to sure why it dipped in the 30hz range there??


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## willis7469 (Jan 31, 2014)

I think the minidsp has a lot of potential to fix your issues but placement is the first thing to address, and really, I don’t see anything really terrible other than that weird roll off at 30. Curious what you find in the settings.


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## The_Nephilim (Mar 3, 2010)

Well I checked the settings in the iNuke I did not find anything that looked like it would make that dip..

I am unsure what is going on, but could it be a blown speaker or the iNuke itself going bad?? I did another reading and it looked the same with the dip in the 20's??

I sure hope it is just a placement issue but it is in the right rear corner woofer facing into the room??


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## The_Nephilim (Mar 3, 2010)

Well I done a bit of reading and placement seems to be the best bang for the buck. But the only problem the subwoofer is a monster and weighs a ton.. I will need help moving it..

I was wondering if the speakerside should face into the room or at the rear wall?? I could try moving it myself to a more frontal position??

Not sure what to do but I know I need to do something.. Will go read some more threads here and there but hopefully I can get this solved..


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## The_Nephilim (Mar 3, 2010)

Well I turned the subwoofer to face the rear wall and back a bit to about 6" from the wall.. It did not help the Null was still there..

OK I just tested the mic on my PC it seems to be working just fine. I think there might be something wrong with the speaker itself..

I moved it around the null should have responded some way as placement seems to fix some issues..

I really have no idea what is wrong I just wait for someone to chime in and maybe has an idea what is wrong..


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## SeismicHT (Nov 15, 2017)

Take the sub outdoors. Sweep it out in the open. No room affecting it. If you get the same or similar curve my thought is that sub it tuned around 28-32 hz. Take it outside and do a measurement. Middle of driveway with nothing around maybe. If that drop is gone it’s a really bad room null. It really looks like it drops off from a high tune though. Make sure you sweep inside with only the one sub. Ensure no other sources are present. 


Sent from my iPad using Tapatalk Pro


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## The_Nephilim (Mar 3, 2010)

Well that is the thing the sub is very heavy and I really don't feel like moving it outside if possible..


Thing is this sub is supposed to have a 17hz tune maybe I am not totally getting it but is this not a HT Sub?? Maybe it is not even a IXL 18.4??

I have to think that could be possible too?? If it was a Mach 5 IXL 18.4 would it be stamped on there somewhere??


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## SeismicHT (Nov 15, 2017)

You either have a HPF engaged or that box is tuned to 30 Hz, be it by design or build flaw. The rise below 20 is room gain, the content itself in free air would continue to fall off. If you don’t want to take it outdoors, then the safe assumption is the box build or a filter. 


Sent from my iPhone using Tapatalk Pro


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## The_Nephilim (Mar 3, 2010)

Well I tested just the sub from 10-200Hz. I ran REW with the Umik Pointed at the Subwoofer about 6" and the correct calibration file loaded and got the following reading, this was with no filters or EQ in the iNuke:











I did set the HPF filter on the iNuke but I read a guide on How to set it below 20Hz it should be set to 16Hz?? the above graph does look like the Sub is working as it should?


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## The_Nephilim (Mar 3, 2010)

OK I ran some more tests to day. this is the lates w/Front L/R + Sub graph.. I did the test from 2 - 20KHz but modeled the JPG for the sub Only..

AS you will see I still get a null from around 20-26hz?? I am unsure what is going on there as the separate sub test showed the sub is working at least I think it is Working Properly just that void there when doing the full test..

Does the above graph the post above this one show that the subwoofer is tuned at 17Hz ??


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## The_Nephilim (Mar 3, 2010)

OK I was making some mistakes with setting up REW.. I do believe I corrected them and have some new mdats.. I took 2 measurements and made notes in the files I saved..

One measurement was at listening position and SUB ONLY.. the 2nd was taken at 3feet from speaker center cone with the mic..

I made a mistake with the Mic setting I was setting the mic gain too 81 and it needed to be at like 10 or under.. I thought the laptop had Win 10 but it has Win 7 so I goofed there probally why they read so high..

I corrected that and here is a SPL Graph with the new measurements. they look similar but not as high DB wise..











here are the 2 mdat files incase anyone wants a more detailed look:
https://1drv.ms/u/s!AgDOJnMP-19IqSO0RBRxsnLpx4Yd


EDIT: I was rereading the faq and guide I was able to get Asio working last night. In the Guide it states to test the Speaker front L w/Sub?? Is that still how I should do it for a Full range reading??


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## The_Nephilim (Mar 3, 2010)

I had made some adjustments in the PEQ and came to a better graph.. here it is:












Now I read some of the guides especially this one:

http://www.hometheatershack.com/for...target-levels-hard-knee-house-curve-long.html


I followed along and did as he described there to use a 1.6 smoothing and EQ it. From what I can tell I have an improvement from where I started.. I think the Subwoofer is about as good as I can get it from all I see and read..

Now should I bother measuring the other speakers in my system or would that be pointless as I plan on building some DIY Speakers??

Now a Couple of the measurements I had some configuration issues but currently I have Asio4all working on the laptop. I can now test all 8 channels.. I have a 7.1 system.. 

The One thing I don't get yet in the setup guide it states I should be able to set the AVR to 7.1 channel input which when I do I hear no sound.. I have to set it to TV on the AVR.

I am curious to know why I can not use the 7.1 channel input like when I run my SACD/DDVD-Audio Player Denon 1930ci?? Is this mode not the same they talk about in the setup guide that I set on my AVR Marantz 4001..


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## The_Nephilim (Mar 3, 2010)

OK Moving on I made some more measurements just a minute ago and mostly it was for measuring for the distance setting which I was able to do.. I was able to see what the distance was and set the Reference Speaker that was closest to the mik..

But I imagine these are good for regular measuring. The measurements are made at Main Listening Position and at 75DB SPL Reading..

I double checked the levels and set them as I think I finally figured out how to set it up correctly..

From what I was able to discover setting the levels the AVR is supposed to set the Main Volume Automatically but with my receiver I have to adjust the Main Volume to get it set.. 

So the Problem I am having is trying to figure out what to set the Main Volume Level at.. I seen some say to set the MVL at ZERO but that seems way too loud..

Soon I am getting a new AVR With Audyssey and that should not matter anymore as the newer AVR Play the Pink Noise at a Set level..

Here is the mdat in case anybody wants a peak.. Remember these are the speakers I will be replacing.. Right now I tuned up the sub a bit and it goes down to 16hz preet loud now..

Now sure what else to do with REW and this post seems a bit slow so hopefully I can get the new AVR in January and get the new speakers started in Feb... Still trying to decide what DIY Speakers to get.. I am thinking maybe those bookshelves I saw a DIY Group..


https://1drv.ms/u/s!AgDOJnMP-19IqSb1VyjwaeQfb8gh


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## The_Nephilim (Mar 3, 2010)

Hi All,

I was wondering if anybody still visits here in the REW section of the Forums.. Been kinda quiet here last week or so..

OR is it because of the Holiday..?


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

Sorry Gerald, but for some reason I don't think I was getting an e-mail notification for your thread.

In any event, your last graph looks pretty good. :T

Regards,
Wayne


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## The_Nephilim (Mar 3, 2010)

So do you think I will need any room treatments?? did you see the sub measurements I took?

In the MLP there was a dip but when I measured from about 1foot away from the subwoofer it looked fine, Do you think there is some sort of cancelation thing going on with my sub..

I did try and move the sub I even turned it 180 facing the rear wall about 1 foot.. IT still looked the same with the dip..


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

If you’re talking about the dip seen in Post #13, it’s caused by the sub’s interaction with the room. A different location might take care of it. Typically best response is achieved with the sub in a corner with uninterrupted walls in both directions (i.e. no open doorways). Typically there will be a peak in response, but that is easily dealt with via parametric EQ.

Just noticed your pictures from the first page of the thread. I’m shocked that such an impressive sub is dead in the water below 30 Hz. What happened to the 17 Hz tuning?

Regards, 
Wayne


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## The_Nephilim (Mar 3, 2010)

Wayne A. Pflughaupt said:


> If you’re talking about the dip seen in Post #13, it’s caused by the sub’s interaction with the room. A different location might take care of it. Typically best response is achieved with the sub in a corner with uninterrupted walls in both directions (i.e. no open doorways). Typically there will be a peak in response, but that is easily dealt with via parametric EQ.
> 
> Just noticed your pictures from the first page of the thread. I’m shocked that such an impressive sub is dead in the water below 30 Hz. What happened to the 17 Hz tuning?
> 
> ...


Well that is exactly what I been trying to determine with the sub.. Either the sub is broke or it is not the sub I thought it was..

I really do not know what to do.. The sub is supposed to be a Mach 5 IXL 18.4 with a 17hz tune.. I do not believe there is any markings on the sub itself so either the sub is broke or it is a fake..


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

Does the driver have dual voice coils? If so maybe you have the polarity off on one of them?

Also, a low pass filter might be engaged with the amp or equalizer?

Regards, 
Wayne


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## The_Nephilim (Mar 3, 2010)

This is the original, single voice-coil 4 ohm version, Thiele-Small parameters:

Fs = 17.7 Hz
Re = 3.4 ohms[dc]
Le = 6.09 mH
Qt = 0.37
Qes = 0.39
Qms = 5.59
Mms = 434.34 grams
Rms = 8.69 kg/s
Cms = 0.184 mm/N
Vas = 274.1 liters
Sd= 1029.22 cm^2
Bl = 20.51 Tm
Lp(2.83V/1m) = 91.60 dB
Xmax = 22mm

Power Handling: 800 Watts
SPL (2.83v/1m): 89.2 db
Impedance: 4 Ohm (SVC)

Recommended Enclosure Sizes:
Sealed: 4.6 cubic feet
Ported: 7 cubic feet @ 19Hz 
EBS: 12.4 cubic feet @ 15Hz


I just looked at a link that had this info and a picture of that driver he had for sale it looks just like the one I have so it is the correct driver I think..

It is a Single voice coil. I was just thinking is it possible I wired the Speakon connector wrong? 

*EDIT: I just checked the wire on the cabinet and the speakon connector it appears to be wired properly.. I just have to pull the driver off to make sure I have the positive and negative correct.. *

here is a Picture of the drive I have:




the below link is how to set the inuke to 16hz with the HPF. I think the LPF is OFF??


http://www.avsforum.com/forum/155-d...tend-high-pass-filter-below-20hz-dcx2496.html


Thank you for helping me


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

Is that your sub – dual drivers?

Yes, I meant hi-pass filter, sorry. Frankly, with the capability of that sub, I don’t see a reason for a HP. I’d suggest bypassing it for the time being so we can make sure it’s not the problem.

Regards, 
Wayne


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## The_Nephilim (Mar 3, 2010)

Well when I bought it I was a Noob big time and sold the other driver OOPPPS!! Well I will get two next time out 

I will remove the Filter and see what happens.. so I will take a measurement from the MLP with the Subwoofer..

I will do that tomorrow as I have some things currently going on.. I did hook the sub back up and it was definitely hooked up correctly.. I am going to install some T-Nuts on the sub tomorrow also so I can check the polarity of the wiring to the driver..


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## The_Nephilim (Mar 3, 2010)

Well I did not get to check the sub earlier but I will try and get some Sunday.. IF I still get that dip with the HPF Off what would that indicate?


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

Good question. Do you have another amp you can try?

Regards, 
Wayne


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## The_Nephilim (Mar 3, 2010)

Wayne A. Pflughaupt said:


> Good question. Do you have another amp you can try?
> 
> Regards,
> Wayne


No I do not.. so maybe the amp could be faulty?? I did try both channels and it did the same thing it had that dip..


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

Maybe you could get an amp from a place like Guitar Center for a test, and then return it?

Regards, 
Wayne


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

Also, could it be something in your receiver? Do you have an old active sub you could try for comparison? You are using the receiver's sub output, right?

Regards,
Wayne


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## The_Nephilim (Mar 3, 2010)

Wayne A. Pflughaupt said:


> Also, could it be something in your receiver? Do you have an old active sub you could try for comparison? You are using the receiver's sub output, right?
> 
> Regards,
> Wayne


Yes I will try and see If I can rent an amp at Guitar Center or something.. Yes I am using the Subwoofer Output on my Receiver.. No I gave my old active sub to my niece..


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## The_Nephilim (Mar 3, 2010)

Well I was trying to get a sub measurement tonight altho I could not get it to isolate the sub to do a measurement ONLY on the sub. not sure what happened there but maybe a misconfigured REW??

I did get a measurement with the front speaker and sub from the Main Listening Position.. I still had the dip 

Not sure what is going on but I completely took off the HPF and all the PEQ and such on the amp. I tried reconfiguring REW and I am not sure what is going on with that but could it be possible the UMIK is defective??

here is the graph:












Here is the Box I found these after some looking around.. It states for the 18.2.2 but It also works fine for the 18.4 IXL.. This box was built by the guy from Mach 5..






















*EDIT: I did think of a trick I could try with REW.. Since the dip is at like 22hz get rew to generate that tone and check with an SPL meter built into rew and see if the dip is really there.. I am listening to the SUB and it sounds fine but I guess if I don't hear the tone that could indicate a problem.. still unsure why that dip is there in my measurement it sure ddoesn't sound like it when watching a movie or music..*


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

Well at least response is getting down to 20 Hz now. So here was a HP engaged?

As far as the dip at 22, that’s going to be an issue of the room and placement, primarily the latter. As long as you’re testing with tones , do them at 20 Hz and 30 Hz as well as 22. If they seem louder, that would confirm the dip at 22 Hz.

Do you have the sub in a corner with uninterrupted walls in both directions? That typically gets the fewest nulls.

Regards,
Wayne


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## The_Nephilim (Mar 3, 2010)

Yes I did have the HPF on but it had the -4 shelf to go lower down to 16hz.. I guess either that trick did not work or I had it set wrong?? But it was a thread over at the other forums I think I linked it back a few pages..

I have the sub in the rear right wall facing into the room.. I tried facing the driver into the wall and the measurement was still the same.. Do you think I should move it to the front of the room??


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

Not sure what “in the wall” means, but if you have it in the middle of a wall that’s probably the worst thing you can do for both response and extension. Try a corner as described in my previous post.

Regards,
Wayne


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## The_Nephilim (Mar 3, 2010)

Wayne A. Pflughaupt said:


> Not sure what “in the wall” means, but if you have it in the middle of a wall that’s probably the worst thing you can do for both response and extension. Try a corner as described in my previous post.
> 
> Regards,
> Wayne


I stated "Into the Wall" meaning the driver was facing the wall.. Should I try and move it to the front of the room.. I have it in the rear right wall with the driver facing into the room.. it is an enclosed room with uninterrupted walls..

Not sure why there is a dip but I did move it and the dip was the same with no change..


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## The_Nephilim (Mar 3, 2010)

I am going to do the SubWoofer Crawl with Pink Noise and my RS SPL Meter. Hopefully it will reveal a better placement and IF I have to move it I need to get a longer SpeakOn cable..

I will do this tomorrow.. Thank you for all the help so far.


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## The_Nephilim (Mar 3, 2010)

I do have 1 question, when I do the subwoofer crawl am I supposed to set the subwoofer in the MLP??

If so that is going to be a bit hard as my subwoofer is VERY Heavy and I don't think I can put it on the sofa??


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

There’s no good reason to do the subwoofer crawl if you have REW. It’s not terribly reliable anyway. Your best bet is to put the sub at the listening position and use REW’s RTA function that shows a graph in real time. Then move the mic to any potential sub locations and see how the graph reads.

BTW, no need to put the sub on the sofa. It should be good enough to move the sofa and put the sub where you’d be siting.

Regards,
Wayne


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## The_Nephilim (Mar 3, 2010)

Well I may do this when my Brother inlaw comes over Saturday and he can help me move the sub and couch 

I was going to do the Subwoofer Crawl with the SPL Meter. would it still be better to do it with Rew??

If I did the subwoofer crawl with Rew do I run the sweeps from 10-600hz then see what the graph looks like with the mic in the new possible sub location around the room??


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

SPL meters only measure noise. The location that gets the highest SPL might merely be the location with the highest spike (i.e. peak, room mode) in the response curve. Plus, there could be a severe null to go along with it, which wouldn’t show up at all. 

What you want is the location with the least difference between peaks and troughs in response. REW will tell you that. Using the RTA is faster, but sweeps will work just fine.

Regards,
Wayne


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## The_Nephilim (Mar 3, 2010)

OK I will try to do the sweeps with REW.. I just hope they come over Saturday


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## The_Nephilim (Mar 3, 2010)

Hmmm, I went back and reread your posts and I see that RTA will be faster. I will try the RTA Method first I only have a few spots where the sub could possibly go so it should not take long to find the sweet spot hopefully..

If I don't get RTA to work I will just try the sweeps.. If I do the sweeps will running from 10-600hz be OK??


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## The_Nephilim (Mar 3, 2010)

OK I was gifted a Integra DTR-40.3 for Christmas, I know now it is an older amp but it suited my needs for now..

I did setup with Audyssey and that was great. my system never sounded better or more tuned then I ever had my old Marantz..

That made up to 8 different points of reference and I did 5. I did turn of the A-EQ and man what a difference it made. Audyssey actually seems to work Fantastic..

Now I am trying to decide what speakers to get or build.. I guess now to go off in a Speaker area and make some requests on what I should get according to what I would like to have..

So I am not going to do any more REW readings for now until I get the new speakers..

Thank you for the help everybody and hope we all have a Happy new year.. I know I had a very Merry Christmas .


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