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Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 170

post #5071 of 9585
I've had pretty good success with a 'half' DBA which is two subs on the front wall and two on the rear wall at the 25/75% of width points in a number of theaters. The rear pair is delayed relative to the front pair.

Results from my demo room, unsmoothed before any EQ (given that the response is consistent across seats I can basically EQ the system as I please). Each line on the graph is the response at each of the three seats in the theater. You see the lack of any of the typical room mode peaks and dips below 70Hz.

Gear mentioned in this thread:

post #5072 of 9585
That is a nice curve, Nyal. So, are the four subs really mounted halfway between floor and ceiling? The drawback of the model is that it would be difficult to implement in non-dedicated rooms, IMO.
post #5073 of 9585
Quote:
Originally Posted by Brian Fineberg View Post

well right now i am only concerned about measuring my sub...so I reran with sub only...here is the result:


What kind of sub is this?

Check its free field response. In order to do so make a near field measurement: Put the mic very close to the speaker diaphragm (<10% of the speaker radius). Make sure to turn down the level of the test signal so neither the mic nor the mic preamp input clips. Also make sure the diaphragm doesn't hit the mic during measurement. Post that graph.
post #5074 of 9585
Quote:
Originally Posted by AustinJerry View Post

That is a nice curve, Nyal. So, are the four subs really mounted halfway between floor and ceiling?

Subs on the floor can work ok but one will only get the full benefits when number of sources, placement, delay and room requirements are met.
Quote:
Originally Posted by AustinJerry View Post

The drawback of the model is that it would be difficult to implement in non-dedicated rooms, IMO.

In-wall subs are way less obtrusive than any of those tiny black boxes discussed earlier in this thread.
Edited by markus767 - 10/9/13 at 11:42pm
post #5075 of 9585
Quote:
Originally Posted by AustinJerry View Post

Sorry to have to say this, but that is a terrible graph. I still think you are doing something wrong with taking the measurements, because your sub response can't be that bad.

Back to the previous graph. It didn't look right either. We need to zero in on what is wrong with your REW measurement technique or we won't make any forward progress. Did you read the Guide, and are you following it step-by-step when you are setting up REW and taking your measurements?
Yea i followed it to the t

Connected the avr to aux left with cable 1 with the y splitter innone end

Turned the speaker amp off for sub only

Audyseey off stereo setting

All the settings in REW as shown. Calibrated the mic against the spl meter

Reading was 80db. Idk im stumped.

Should i try hooking up directly to the sub amp?
Edited by Brian Fineberg - 10/10/13 at 4:29am
post #5076 of 9585
Quote:
Originally Posted by markus767 View Post

What kind of sub is this?

Check its free field response. In order to do so make a near field measurement: Put the mic very close to the speaker diaphragm (<10% of the speaker radius). Make sure to turn down the level of the test signal so neither the mic nor the mic preamp input clips. Also make sure the diaphragm doesn't hit the mic during measurement. Post that graph.
Psa xv15. More than capable. I KNOW the response is not what the graph shows. So whats wrong
post #5077 of 9585
Im frustrated to say the least. I appreciate the help here

EDIT:

ok I think i just realized I didnt do the MAc workaround...i.e. with the usb mic...I will try that tonight and see if it makes a difference
Edited by Brian Fineberg - 10/10/13 at 7:51am
post #5078 of 9585
ok think I got it!!!

post #5079 of 9585
Quote:
Originally Posted by Brian Fineberg View Post

ok think I got it!!!


Wow nice. Way smoother then my response.
post #5080 of 9585
Quote:
Originally Posted by Sean Spamilton View Post

Wow nice. Way smoother then my response.

thanks! i will be EQ with miniDSP tonight (it is being delivered today) so maybe it can be even flatter wink.gif

next hurdle...measuring the mains...and trying to find the optimum x-over...thanks for all the help in here...this is exciting haha
post #5081 of 9585
Quote:
Originally Posted by Brian Fineberg View Post

ok think I got it!!!


Well, I must say this graph is slightly different than the previous one. wink.gif And a lot better too! It seems like you have made a breakthrough WRT your REW procedures, so that is good. Keep sharing the measurements--it is interesting observing your progress. As a fellow PSB owner, I am interested in the measurements of the mains as well.
post #5082 of 9585
Quote:
Originally Posted by AustinJerry View Post

Well, I must say this graph is slightly different than the previous one. wink.gif And a lot better too! It seems like you have made a breakthrough WRT your REW procedures, so that is good. Keep sharing the measurements--it is interesting observing your progress. As a fellow PSB owner, I am interested in the measurements of the mains as well.

will do! now that I fixed the "bug" at least for the time being...the mains are up next...I also am interested in the full spectrum measurement...and maybe I can start working on reflective points etc. but so far after generating waterfall my ringing is pretty suffice as well...


again thanks for your patience with me..and help. I will continue to post as I get results.

OT: what PSB's do you own?
post #5083 of 9585

Just a quick tip.  Make sure you disengage bass management (i.e. set your mains to large) when you measure the LCR responses without sub.  This way you'll get a true picture of their full range in room response.  It looks like your sub response might also have the crossover engaged (deep falloff beginning at 70Hz) so you might want to measure its full response again (and plot out to 200-300Hz).

post #5084 of 9585
Quote:
Originally Posted by jkasanic View Post

Just a quick tip.  Make sure you disengage bass management (i.e. set your mains to large) when you measure the LCR responses without sub.  This way you'll get a true picture of their full range in room response.  It looks like your sub response might also have the crossover engaged (deep falloff beginning at 70Hz) so you might want to measure its full response again (and plot out to 200-300Hz).

ok. yes with stereo it enables the speaker crossover (at 80hz)....so how should I do that? set it at its highest possible setting in the AVR?
post #5085 of 9585

I'm not familiar with your sub and not sure if this is the easiest way but make sure it's in a mode that defeats the internal crossover or at least sets it to the highest value possible.  Then raise the crossover in the AVR and take your normal measurement.

post #5086 of 9585
Quote:
Originally Posted by jkasanic View Post

I'm not familiar with your sub and not sure if this is the easiest way but make sure it's in a mode that defeats the internal crossover or at least sets it to the highest value possible.  Then raise the crossover in the AVR and take your normal measurement.

ok wel its disabled in the sub, so ill try the avr.

question...while this worked perfectly..when I try to measure the output at say 12hz...it makes the results not work...any reason for this?
post #5087 of 9585
What smoothing factor do speaker manufactures use for their freq response spec in their glossy brochures?
Have they agreed to use the same smoothing factor? e.g. B&W and Kef both use same smoothing factor in their brochures?
post #5088 of 9585
Quote:
Originally Posted by Brian Fineberg View Post
 
question...while this worked perfectly..when I try to measure the output at say 12hz...it makes the results not work...any reason for this?

 

Sorry, I'm not sure I understand the question?  Are you saying that if you start your sweep in REW from 12Hz that the measurement fails?

post #5089 of 9585
Quote:
Originally Posted by jkasanic View Post

Sorry, I'm not sure I understand the question?  Are you saying that if you start your sweep in REW from 12Hz that the measurement fails?

correct and to be honest I was in a rush...so I didnt even see what the warning (the pop up that said the results will be skewed) said because i was so happy the 15hz and up sweep worked...I immediatly went back to 15hz...and it worked again...maybe I need to turn the gain on the AVR up a tad?

also , ...I just realized I put the xover at 70 last night while trying to figure REW out...you can see that dropoff clearly on the graph...so its good to know its graphing properly!
post #5090 of 9585
Quote:
Originally Posted by Brian Fineberg View Post

ok think I got it!!!


Wow looks nice! What was the Mac workaround you mentioned? I will be hoping to take my first measurements tonight with my Mac smile.gif
post #5091 of 9585
Quote:
Originally Posted by jlpowell84 View Post

Wow looks nice! What was the Mac workaround you mentioned? I will be hoping to take my first measurements tonight with my Mac smile.gif

http://johnr.hifizine.com/2013/02/room-eq-wizard-on-the-mac-an-input-workaround/
post #5092 of 9585
Hey guys,
An update on the 'grand experiment' with XT32/Pro and Trinnov. I'd finally blocked out some time this week to do my Trinnov cal and post results (as well as comparisons to an MCACC run I did on my old Pioneer SC-27). Then my wife called the carpet cleaners as part of the baby stuff....and the carpet folks promptly moved my two front L/R Mythos ST speakers, rendering pretty much all my calibration work moot. Unfortunately while I was properly OCD about measuring the mic from my MLP and writing down the dimensions from specific L/W/H points, I hadn't taken measurements of where my mains were or had recent pictures. And those pesky carpet folks did such a good job this morning that it's almost impossible to see the indentation marks of my speaker spikes. And now they're on blocks mad.gif....

Thus, rather than relying on "close enough" memory within 3 or 4 inches, I've decided to do a fresh Audyssey Pro 8 to 12 position cal and re-reposition my mains. OTOH, that opens up opportunity: I can do RTA of the mains and optimize their position pre-Audyssey, which I didn't really do on my last Audyssey cal in the days of ignorance (read: pre-REW circa 12/2012). I'd had OmniMic, but since my post-Audyssey runs were generally smoothish FR, and I liked the sound, I didn't see a need to re-invent the wheel and fine-tune individual speakers with Audyssey more as "icing on the cake". That was my dirty secret: individual mains weren't optimized pre-calibration, just jointly post-cal, due to "room compromises". But we can do better... tongue.gif

So....I guess this is a good thing. I'm going to move my fronts more in line (read: closer) to my center, which will bring their physical distances into line. My center's been about 2 ft closer on the Audyssey distance settings than my mains, since I had to move the center onto a stand for better upper bass response that was slighty outside of our entertainment center that my mains have flanked. And while I might have to give up some of the "best practice" conventional axis placement, it will be interesting to see if it improves my crossover splice region, relative to a distance tweak, and that annoying 150-200 Hz dip on the powered Mythos mains and center I've had to battle over time. I can always go back to my older, more toed-in and angled placement as a rough fallback, particularly if I find that the sound dispersion is narrower than in my established setup, but there's nothing wrong with starting over with the great set of tools that REW gives us. Plus when I get to Trinnov, you get into remapping, which at least theoretically moves speakers closer to "best practice" music vs. movie angled placements of speakers.

Quick question: I've always done sine sweeps, but the RTA analysis is more "pink noise". In general, while we all love our nice, loud sine sweeps, it seems like at last for sub placement , you're not "too far off" with the pink noise in RTA. What is the impact for higher frequencies as far as being "close enough", say over 300 Hz? And if I follow correctly, you still need to do a 30-second or so "palate cleanser" between individual RTA measurements, correct?

One step backward, one and a half steps forward LOL...

Edit: it also seems that the binding posts on my $4K DefTech Mythos ST speakers may have broken. They're 5-way gold-plated posts, and I had my Blue Jeans Cable banana plugs fit snugly into them. Apparently when I unscrewed them, they were so snug that the hard-wired gold connector on the posts broken in two--the top half is on the Blue Jeans plugs, and the bottom half is still hard-connected to the base of the posts on the Mythos STs. There's a fastener attached to the posts, but it won't hold the plugs by itself. Arghhh.....I've left a VM with the customer support guy at DT, but any ideas?
Edited by sdrucker - 10/10/13 at 4:51pm
post #5093 of 9585
Quote:
Originally Posted by AustinJerry View Post

That is a nice curve, Nyal. So, are the four subs really mounted halfway between floor and ceiling? The drawback of the model is that it would be difficult to implement in non-dedicated rooms, IMO.

No these are on the floor.

As Markus said if you use inwall subs they can be discretely put where ever you want them even in non-dedicated rooms. JL, Artison and Triad make good in wall subs.
post #5094 of 9585
crossover



L R SW overlay full spec



L R SW together



sub w EQ


sub only

Edited by Brian Fineberg - 10/11/13 at 6:43am
post #5095 of 9585

Is the first sub only measurement with no EQ still crossing at 70hz?  Also, you should add titles to your graphs or show the legend especially when there is more than one response showing.

 

What's the difference between these two?

 

I assume this is L OR R + Sub:



And this L+Sub and R+Sub:


 

post #5096 of 9585
Quote:
Originally Posted by Brian Fineberg View Post



OT: what PSB's do you own?

Equally OT: Synchrony One's up front, Imagine B's for surrounds and wides, and Imagine Mini's for surround backs and heights.
post #5097 of 9585
Quote:
Originally Posted by jkasanic View Post

Is the first sub only measurement with no EQ still crossing at 70hz?  Also, you should add titles to your graphs or show the legend especially when there is more than one response showing.

What's the difference between these two?

I assume this is L OR R + Sub:





And this L+Sub and R+Sub:




 
Ok that makes sense. Yes you are correct in your comments except it is R L AND SUB

First sub only is no eq. Second is with eq
post #5098 of 9585
Quote:
Originally Posted by Brian Fineberg View Post
 
Ok that makes sense. Yes you are correct in your comments except it is R L AND SUB

First sub only is no eq. Second is with eq

 

Sorry Brian...it would probably be best if you just edited your post to correctly reflect what each FR plot represents.  I'm still confused by your response as R L AND SUB implies to me that you measured R+L+Sub but there are two response curves in the second plot?! :confused:  If you add a legend and give a more detailed title to the measurement as well as the graph then this would help us understand what exactly you are showing in your plots.

 

The main question on the first sub only plot (as well as the crossover plot as it appears to be the same) was whether or not you still had the crossover engaged for the sub?  Based on your sub post EQ plot(s), I'm guessing the answer is yes as well as the fact that you accidentally posted this response plot twice?  When posting the crossover, focus on the crossover region rather than showing a full range plot.

post #5099 of 9585
Gotcha! Again i tried to do it in a rush. Bad idea. Thanka for the feesback. I will properly post it later tonight. Thank you
post #5100 of 9585
Ok, I have the newest version of sound flower downloaded on a flash drive since I won't get internet hooked up until Tuesday at the new place. I will follow the guide to all the settings I read in the Mac guide link off of Jerry's beginner guide. If all goes as planned I will have some subwoofer measurements tonight!

Shout out to J_P_A for creating that illustrated setup guide!
Edited by jlpowell84 - 10/10/13 at 1:25pm
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AVS › AVS Forum › Audio › Audio theory, Setup and Chat › Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs