How to measure my system and room

murphy11 · « **Reply #20 on:** 10 Dec 2013, 03:11 pm »

Quick update. I can't figure out how to make a loopback connection on my internal laptop soundcard. I have 3 different laptops I can use with REW (2 Dells and a Lenovo) and 2 computers use 'Realtek Hi Def Audio' sound. Guessing maybe some physical connection is made between headphone out and mic in but I cannot find anywhere a description of specifics on how to make the loopback and cabling if any is required.

I posted in the REW forum and am waiting or an answer there but figured I'd post here in case anyone can provide an answer.

Ethan Winer · « **Reply #21 on:** 10 Dec 2013, 05:30 pm »

Don't worry about the loop-back. It's not needed.

--Ethan

Vedder323 · « **Reply #22 on:** 10 Dec 2013, 05:35 pm »

yeah, Ethan is spot on, dont need it man

murphy11 · « **Reply #23 on:** 10 Dec 2013, 10:47 pm »

Thanks. A few 'issues' I had previously were:

1) REW 5.0 randomly would find or not recognize the UMM-6 mike. I read that the latest beta 5.0 REW is compatible with USB mikes and the UMM-6 USB is listed so I downloaded that version and it automitically recognized the connected UMM-6 on startup and asked for the cal file. REW beta auto populated the soundcard input fields with what look like the proper settings.

2) I would constantly get error\warnings that the volume (it think) levels were too low and I needed to adjust. I would set the volume all the way up on my computer and the message would still display. If you look at my graph, I think the DB levels were low. Maybe REW beta and calculating the SPL using the UMM-6 will allow the volume and levels to measure properly.

Also, I just noticed that beta REW when it picked up the UMM-6 also enabled a REW setting 'control input/mixer volume' and that setting was not available\editable before using 2011 release v 5.0. If I have volume problems tomorrow maybe I will fool around 'input volume' setting to see what happens.

3) I'm wondering if using the dragonly USB DAC -> amp -> speakers is somehow affecting the levels and warning messages when trying to run REW. I just realized I can plug my cable adapter to the laptop headphone out and get sound\music out to my speakers. Tomorrow when I measure I will try using the dragonfly and not using the dragonfly to see if there is a difference.

Finally, and sorry for the long post but the vocals sound very recessed and the soundfield is very narrow. My source is the laptop sitting 18" behind and between the 2 speakers. Vocals now sound like they are literally coming from the laptop to such an extent that I put my ear to the laptop to check but the music IS coming from the speakers. Kind of weird and I think something is wrong but maybe it will all get resolved tomorrow when I remeasure.

murphy11 · « **Reply #24 on:** 11 Dec 2013, 05:28 pm »

Made some progress today. My work laptop was kind of flaky so I installed the UMM-6 on my personal laptop, set mic and speakers within windows to 100% and then installed latest beta REW 5.0 1 build 17 I think and levels were low. The input was -90. Somehow the mike was muted

Unmuted and measurements look a lot different than before.

Turning the Onix mini strata amp levels up or down makes a big difference in overall response as does placement. I will play around with placements and settings and will post updates over the next few days.

murphy11 · « **Reply #25 on:** 12 Feb 2014, 08:03 pm »

I got REW and UMM6 figured out enough to have made at least 100+ measurements in the last few weeks. In my gallery is a pic of my best measurements so far taken yesterday. What do you guys think? Danny in the GR forum thinks maybe diffuser(s) on front wall might make things better. I took down the plasma shown in my gallery so there is room there to mount a QRD diffuser. I downloaded a calculator that shows how to make QRD diffusers and I'm toying with idea of building diffusers.

Vapor Audio · « **Reply #26 on:** 12 Feb 2014, 08:21 pm »

Decay times are also important for knowing what kind of treatment is needed, do you have a screenshot of that you could post?

murphy11 · « **Reply #27 on:** 12 Feb 2014, 08:46 pm »

Decay and waterfall posted to gallery. I'm pretty new to measuring so not sure if I captured what is needed. Thx for posting!

JRace · « **Reply #28 on:** 12 Feb 2014, 09:04 pm »

I looked at your graphs. Can you take one with both speakers getting a mono signal (taken from listening position)
so that we can see the repsonse of the speakers together.

And if able, can you draw out the floorplan, and or take a pic in room.

Based on what you have posted I would start with moving the speakers and re-mesuring. You may end up needing some bass traps.
You want both a flat freq response below 200Hz, and your watterfall should show fast decay with little to no energy after 300ms.

Not too bad to start with though.

JohnR · « **Reply #29 on:** 12 Feb 2014, 09:24 pm »

One quick suggestion: rather than taking a screenshot, press on the "camera" button and REW will export just the graph to an image file.

murphy11 · « **Reply #30 on:** 12 Feb 2014, 10:33 pm »

Thanks for the suggestions. I will take another measurement with both speakers and post the result. Didn't know about camera feature of REW; will export images to capture more of the graphs. I've been so focused on getting each speaker as flat as possible through placement, haven't really focused on much else.

murphy11 · « **Reply #31 on:** 12 Feb 2014, 11:43 pm »

Added pics of the room to a new gallery including descriptions. Will take REW measurements and upload later tonight.

Vapor Audio · « **Reply #32 on:** 12 Feb 2014, 11:58 pm »

Looking at that Decay, that room looks really live ... midrange through 1500hz just isn't dying out. At least from that I'd say a lot of absorption is needed all over the room. RT60 is also helpful.

Bass doesn't look too bad, bump at 58hz and a suckout at 85hz, but I've definitely seen worse. The big suckout at 200hz is most likely floor bounce, don't worry about that. Mainly it's the herky-jerky midrange that's going to cause problems.

murphy11 · « **Reply #33 on:** 13 Feb 2014, 12:16 am »

Replaced screen shots in measurements with REW camera grabs and added RT60 data. Will measure mono signal with thru both speakers later if that would help. I did that a few weeks ago and Danny said he saw comb filtering in the plot (didn't know what that meant at the time)

murphy11 · « **Reply #34 on:** 13 Feb 2014, 08:09 pm »

Uploaded some measurements of mono signal thru both speakers. It also occurred to me I can move my couch back or forward instead of tweaking speaker placement. All measurements so far are approx 4' from listening position to front of speaker.

JRace · « **Reply #35 on:** 13 Feb 2014, 08:51 pm »

Please upload a graph, both speakers mono, from 10 Hz - 200 Hz, no smoothing.

Above 200Hz smoothing (1/3) is ok, but below that we want to see more resolution.

Also measure at current listening position, then at the max distance you could move the couch, then a third roughly half way between.
(all from 10-200, no smoothing)

This will help determine where the bass repsonse in your room is the most flat.

murphy11 · « **Reply #36 on:** 14 Feb 2014, 12:48 am »

I took 5 mono measurements moving backwards from original position. The back 2 unsmoothed 20-200 were less smooth than closer three. I uploaded an unsmoothed pic of three measurements and another with 1/3 smoothing from 20-20,00. The difference in distance of the 5 measurements was 33" from closest to furthest back.

murphy11 · « **Reply #37 on:** 15 Feb 2014, 03:39 pm »

I can't leave well enough alone

so I moved speakers again and have new measurements. Rather than ask for help on a specific measurement maybe I can ask a few higher level\principal questions.

1) In my smoothed 200-20k pic in my gallery. I see a huge dip in the top end from what I think is comb filtering. Makes sense because the speakers were not equidistant to the mike. Should I be worried by that huge dip when I won't be playing a mono signal but exclusively stereo? I have taken new measurements in mono and gotten rid of that dip and have measurements pretty flat on top end to 6K before roll off. Is that 'better' than huge dip measurement pictured?

2) My left and right bass measurements are not in sync but I can tweak both speaker amp levels to get 'relatively flat bass' I think bass is somewhat non-directional so should I be not be too worried about left and right bass measurements not being tightly in sync?

This time when measuring I tried focusing first on getting rid of the huge mono dip on the high end and then it seems fairly easy to get bass tweaked. If i do it the opposite there is almost always a huge dip on top when measured in mono. Just not totally sure in what order to attack the problem because everything seems to affect everything else and with all of the settings on the ONIX mini strata speakers it feels like sometimes I'm chasing my tail.

JohnR · « **Reply #38 on:** 16 Feb 2014, 10:44 am »

Hi, I think I would measure each speaker individually. You will unavoidably get interference affects (above a few hundred Hz) from measuring two together.

Other than the hole presumably due to interference between left and right, your measurements look quite good to me... what is it you are wanting to improve? (Sorry if you already said...)

murphy11 · « **Reply #39 on:** 16 Feb 2014, 04:21 pm »

Hi John,

Good question about what I am trying to improve. Not really sure because I have never measured before and don't know how to interpret results and whether it can get better. My earliest measurements sounded better to me than anything I had ever heard before from my system.

My wife is away this weekend and I will try a few more things to see if I can see measurements that look better. Thanks for saying that earlier measurements were good or good enough. My ears told me the same thing, just trying to get an idea if it could get significantly better.