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Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 167

post #4981 of 9491
Quote:
Quote:
Originally Posted by Brian Fineberg View Post


Quote:
Originally Posted by Brian Fineberg View Post


Brian, what are these graphs?

Gear mentioned in this thread:

post #4982 of 9491
They are sub only. They are used to dhow the redponse im getting and how its nowhere near 75db. Why? No matter how loud the sweep is it wont go higher than what you see.

The first is the predicted after peq (only posted to show spl)
The second is with antimode in the signal change.
post #4983 of 9491
Why don't you post something more conventional, like a simple frequency sweep? I also didn't understand the result of the test I asked you to do. Did the REW SPL window show a level of 75dB when you ran the speaker test tones?
post #4984 of 9491
post #4985 of 9491

The Dell spec'd has HDMI 1.4a while the HP wasn't specific.  Some users have indicated they only have 2-channel HDMI with some laptops so you might want to double check this before purchasing.

post #4986 of 9491
Quote:
Originally Posted by AustinJerry View Post

Why don't you post something more conventional, like a simple frequency sweep? I also didn't understand the result of the test I asked you to do. Did the REW SPL window show a level of 75dB when you ran the speaker test tones?
Yes it showed 75.

I only am concerned with sub response at this time.

I managed to get it working. Thank you. Although the end of the sweep it says the signal is getting clipped. Is there a reason for this?
post #4987 of 9491
During the sweep you should see a level indicator. If the indicator reaches zero, the input was too high and the signal was clipped. Adjust the volume level on your AVR downwards slightly, re-run the sweep, and observe the input level. It should not reach zero. If it still does, lower AVR volume again, and repeat. Post your new measurement, please.
post #4988 of 9491
post #4989 of 9491
Nothing wrong with that measurement, Brian. You could make it visually more appealing by adjusting the vertical axis to say, 50-90d! So that the graph isn't way at the bottom. That is just cosmetic, however. The frequency response looks actually pretty good. Is the graph un-smoothed?
post #4990 of 9491
Great! Thanks!! Yes its unsmoothed

I will fix the verticle axis like you mentioned

Once i get the sub all set i will dive into the mains smile.gif
post #4991 of 9491
Quote:
Originally Posted by bao01 View Post

It is along the long wall.
That wasn't too hard. You might want to edit the post you directed me to, so that it lists 28.5 feet as the width of your room, not length.

Looking at a section of your measurement, notice there is a dip around 40Hz.



If I divide the speed of sound by the frequency of the dip I should get the width of your room.

1130 ÷ 40 = 28.3 (close enough to 28.5)

If you place one of your subs where that dip is deepest and do the same on the opposite side of the room, you'll not only minimize that 40Hz dip but also the 60Hz peak in the measurement above.
post #4992 of 9491
Quote:
Originally Posted by jkasanic View Post The Dell spec'd has HDMI 1.4a while the HP wasn't specific.  Some users have indicated they only have 2-channel HDMI with some laptops so you might want to double check this before purchasing.

Ah thank you how can I check that there HDMi is MCH

post #4993 of 9491
Quote:
Originally Posted by andyc56 View Post

It's worth mentioning the Pink PN (periodic noise) option too. Here's a quote from the latest PDF manual for beta 17.
Quote:
Originally Posted by REW Manual 

Pink and White Periodic Noise
Periodic Noise (PN) sequences are ideally suited for use with spectrum and real time analysers (RTA's). They contain every frequency the analyser can resolve in a sequence length that matches the length of the analyser's FFT. Their great benefit is that they produce the desired spectrum shape without requiring any averaging or windowing, so the analyser display reacts much more rapidly to changes in the system than it would if testing with Pink or White random noise, making them ideal for live adjustment of EQ filters. The PN sequences REW generates are optimised to have a crest factor (ratio of peak level to rms level) that does not exceed 6 dB.Use Pink PN when measuring with an RTA or White PN with a Spectrum analyser.
Excellent find. Considering it is sometimes easier to slide a sub around while staring at a RTA, rather than the usual move-measure-move-measure-move-measure technique, it is helpful to have signals that allow the analyzer to react much more rapidly to changes.
post #4994 of 9491
Quote:
Originally Posted by AustinJerry View Post

Neither. The graph you posted yesterday is considerably better, IMO. Don't you think so?

Edit: I suspect these are both without Audyssey, and the one yesterday was with Audyssey, which could account for yesterday's looking better.

Yes - both are without Audyssey.

The BLUE line is the two subs both along the long wall (28.4 ft) as per the pics in my gallery i.e. sitting next to the 802 Diamonds. This is the old configuration. It is the "No Audyssey" line in my very first REW graph i posted on Sunday which you commented on.

The RED line is my NEW configuration smile.gif per the Harmon white paper.
The sub next to the front left speaker is pretty much where it was in old configuration. It is almost centered along the 28.4 ft wall but not quite. It is off by 1.5 ft because the front left speaker is at dead center (14.2 ft). mad.gif
I moved the sub that was next to the front right speaker all the way to be BEHIND the MLP. It is dead center along the other 28.4 ft wall - centered at exactly 14.2 ft.
The MLP is not dead center i.e. it is not at 14.2 ft - it is about 4 ft to one side of dead center - Feri will make me move so MLP is right between the two subs smile.gif
Both subs are 12" from their walls (i think - i need to check this).
I need a diagram.

So, which graph is better?

thanks
Edited by bao01 - 10/7/13 at 10:37pm
post #4995 of 9491
Quote:
Originally Posted by sdurani View Post

That wasn't too hard. You might want to edit the post you directed me to, so that it lists 28.5 feet as the width of your room, not length.

Looking at a section of your measurement, notice there is a dip around 40Hz.



If I divide the speed of sound by the frequency of the dip I should get the width of your room.

1130 ÷ 40 = 28.3 (close enough to 28.5)

If you place one of your subs where that dip is deepest and do the same on the opposite side of the room, you'll not only minimize that 40Hz dip but also the 60Hz peak in the measurement above.

ok
maybe it is a terminology thing that i have mixed up.

I consider the LENGTH of the room the GREATER value. So for me 28.4 ft is greater than 22.2 ft so I call 28.4 the length and 22.2 the width.
The speakers are along one of the long (28.4 ft) walls. The sound from speakers would fire across 22.2 ft and hit other long wall.

I will try digest your math. I am not sure i am following but i am a novice.
post #4996 of 9491

I was a DELL fanboy - bought maybe three times from them over the years.
But I got tired of the lousy 1-800 support. It was getting to be like Comcast - the other evil empire.

So last time i tried HP and liked the experience.

I dont have HDMI so i just use my headphone jack split to red and white RCA connectors. Works fine (i think).
post #4997 of 9491
Quote:
Originally Posted by bao01 View Post

ok
maybe it is a terminology thing that i have mixed up.

I consider the LENGTH of the room the GREATER value. So for me 28.4 ft is greater than 22.2 ft so I call 28.4 the length and 22.2 the width.
The speakers are along one of the long (28.4 ft) walls. The sound from speakers would fire across 22.2 ft and hit other long wall.

I will try digest your math. I am not sure i am following but i am a novice.

See my post above for Jerry - the BLUE line is the old configuration. The RED line is the new config.

I just didn't want to tell anyone because i wanted it to be a double-blind-double test. smile.gif
post #4998 of 9491
Quote:
Originally Posted by bao01 View Post

which placement is better: RED or BLUE.

Wrong question. The best configuration is one that a) has the lowest point-to-point difference within the listening area and b) is correctable, i.e. minimum phase.

You need to take more measurements within the listening area. Regarding minimum phase please see http://www.hometheatershack.com/roomeq/wizardhelpv5/help_en-GB/html/minimumphase.html
post #4999 of 9491
Quote:
Originally Posted by bao01 View Post

I consider the LENGTH of the room the GREATER value. So for me 28.4 ft is greater than 22.2 ft so I call 28.4 the length and 22.2 the width.
"Width" is more commonly used to describe how wide something is (wide = left to right). Like the width of your soundstage from left to right. "Length" typically means how long something is (front to back). Like the length of a train from front to back. Just so we're on the same page and not confusing each other.
Quote:
Originally Posted by bao01 View Post

I will try digest your math. I am not sure i am following but i am a novice.
Don't worry about the math. I was just trying use a simple equation to show you that the peaks & dips in your measurements were tied (apparently quite closely) to your room dimensions. This makes it easier to use subwoofer placement to minimize those peaks & dips. And the more you can fix with placement, the less that has to be done with equalization later.

Are you willing to move your MLP to the midpoint of room width (14.2 ft from each side wall) in order to have a symmetrical soundstage?
post #5000 of 9491
Quote:
Originally Posted by sdurani View Post

Excellent find. Considering it is sometimes easier to slide a sub around while staring at a RTA, rather than the usual move-measure-move-measure-move-measure technique, it is helpful to have signals that allow the analyzer to react much more rapidly to changes.

Your ears and tweeters won't like the high frequency part of that signal smile.gif Anyway, if someone has some experience then he will be able to extract relevant information from lower resolution graphs, e.g. shorter FFT which results in a more responsive display.
post #5001 of 9491
Quote:
Originally Posted by markus767 View Post

Quote:
Originally Posted by sdurani View Post

Considering it is sometimes easier to slide a sub around while staring at a RTA...
Your ears and tweeters won't like the high frequency part of that signal...
I'll be wearing ear plugs and my sub doesn't have tweeters.
post #5002 of 9491
Quote:
Originally Posted by sdurani View Post

I'll be wearing ear plugs and my sub doesn't have tweeters.

You don't want to optimize the splice to your satellites?
post #5003 of 9491
Quote:
Originally Posted by markus767 View Post

You don't want to optimize the splice to your satellites?
Not with RTA. I've only used it for initial subwoofer placement (getting it in the ballpark).
post #5004 of 9491
Quote:
Originally Posted by wse View Post
 

Ah thank you how can I check that there HDMi is MCH

 

 

I don't know how you could test this before purchase.  Just make sure you can return it, should the multi-channel support be missing.  I am one who has a laptop with only 2-channel HDMI.  I think this is a limitation of older chipsets, and suspect that any current model will support multi-channel.

post #5005 of 9491
Quote:
Originally Posted by bao01 View Post


I dont have HDMI so i just use my headphone jack split to red and white RCA connectors. Works fine (i think).

 

This type of connection should work just fine.  It is described in the Guide as an alternative for users with laptops without HDMI connections.

post #5006 of 9491
are there any comparable alternatives to umik-1?
post #5007 of 9491

Dayton Audio UMM-6.

post #5008 of 9491
^
The lack of a loopback channel is a real downside of those USB mics. For example, one can't properly add curves or set delays.
post #5009 of 9491

The UMM-6 is a USB mic just like the UMIK-1.

post #5010 of 9491
Quote:
Originally Posted by Brian Fineberg View Post

are there any comparable alternatives to umik-1?

I don't know where you're located Brian, but know your in the PSB thread a lot, so thought maybe you're in Canada. If so, I can point you in the direction of where I just bought my UMM-6 usb from, only took about 3 days between order and arrival. Let me know smile.gif
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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