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post #811 of 1088 Old 12-10-2013, 09:39 AM
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Man, when do you think you'll be able to get your measurements and testing rigs fixed? This has been going on for a long time now, and seems like every new measurement there's some reason it's not accurate. frown.gif
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post #812 of 1088 Old 12-10-2013, 09:46 AM - Thread Starter
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No kidding. That was with the old rig that includes behringer mic and mobile pre. The new HDMI computer and mic was not available. I still got that same response with the HDMI mic and computer. It still drops off like a tapped horn but rises below 4.5 hz or so. Could my wall be causing a dip because it does rise after the dip which is why it is confusing. The good thing is I still get 3 hz content but just 10 dBs lower than 10hz, Running the subs hot of course which i don't want to do. Well, not 10 dBs. The behringer mic and UMM6 give me the same results whether HDMI or not, the HDMI gives me ability to run any speaker at will which is highly recommended. Thanks for the help. It is a good thing I have headroom to spare!
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post #813 of 1088 Old 12-10-2013, 09:59 AM
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If two entirely different rigs, one analog and one digital measure pretty much the same response, it's probably a good guess that's your response no?

Under 5Hz neither mic is calibrated for- does your correction file have data down there?
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post #814 of 1088 Old 12-10-2013, 10:07 AM - Thread Starter
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I agree guys. It seems under 6-7hz changes with each measurement, whether analog or digital. The cal files go to 4-5 hz.
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post #815 of 1088 Old 12-10-2013, 11:41 AM
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Without this:

69264badf6325bc44a24c81106fa043d.jpg

You'll have us and yourself scratching heads for eternity.

The purple trace is the entire signal chain cumulative roll off, measured, which can vary wildly depending on what's in-line. It also helps to note what's in line on your measurements so that over the years it's not impossible to tell what the measurement includes.

0e953b43c907625d8e1309ce47877659.jpg
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post #816 of 1088 Old 12-10-2013, 12:47 PM - Thread Starter
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I can tell you ever I started doing spec lab graphs my normal response graphs low end have been all over the place. I have no idea why, even before I changed the subs. The digital response was UMM6 to computer, computer to SR8100 via HDMI. These were the two responses one right after the other:

DIGITAL

sub_zps36d209ab.jpg

sub1_zps1e1a7557.jpg

Last night I tried the behringer and mobile pre again and got this:

calibrated EMC 8000 to mobile pre to computer to SR8100 via analog:

ib_zps88410fee.jpg

AND this from before

ib_zps00c80772.jpg

Talk about different, will the real low end please stand up!
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post #817 of 1088 Old 12-10-2013, 12:50 PM - Thread Starter
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Guys, tell me what to do or just enjoy the bass but the problem with that is I need a baseline to EQ and boost. All I know is running the subs 3 dBs hot seems more powerful than running the others 10 dBs hot.
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post #818 of 1088 Old 12-10-2013, 12:54 PM - Thread Starter
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I have used the EMC 8000 calibrated by cross spectrums to 4.6hz or so and mobile pre since the DTS-10's. Processors and amps have changed within the chain.
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post #819 of 1088 Old 12-10-2013, 01:00 PM
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I don't know what we can do. You should be able to run a sweep now, later, tomorrow, the next day... and get the same, correct result over and over.

There won't be drastic differences if something significant hasn't changed. So that tells me in each of the very different graphs something has changed.

We have no way of knowing what that was.

You need to start from scratch with everything, reset to zero. Document every measurement in the notes area with signal chain and measurement rig and settings.

I would want to measure something that has a known response at this point. Like a driver close-mic. Get to the point where you can repeat the measurement setup and reading process to get the same result every time, know exactly how the final response is composed (calibration and correction) and have it consistently measure a known response so you have a baseline.

When your response changes you should be able to say, I know exactly why that is so different. I changed this, and it's exactly as I would expect.
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post #820 of 1088 Old 12-10-2013, 01:13 PM
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The other half is measuring your signal chain piece by piece. This has to be analog of course. I believe you did a loopback of the MobilePre and got a result matching that of one posted on HTS. So that's a start. Get that nailed, then add the receiver into the chain.

Measure the LFE pre out and the L channel pre out (so you can measure without LPF). Compare and see if roll-off is different for each. Now send the signal to the receiver via HDMI and compare those two preouts to the analog-in loopback. More data that will help us understand the chain and measurement corrections that may be good or bad assumptions.

Then you can add the amp into the loopback chain with and without receiver. (Using some sort of resistor on the amp output I would think?)

Now when you go back to digital measurements, HDMI and USB mic you can know what to expect. At this point you'll have to add in multiple sweeps of the various HDMI channel possibilities, understand how the receiver handles these and where it sends the signal. Again, playing with the various pre-outs.

Just gonna take some time to sort it all out and document everything so we all can wrap our heads around it and know exactly what's going on.
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post #821 of 1088 Old 12-10-2013, 01:14 PM - Thread Starter
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I am tempted to throw back in an Ada processor and see what happens. They were always flat to 5hz in the past but who knows if the gear was accurate back then, RS meter with c-weighting.
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post #822 of 1088 Old 12-10-2013, 01:16 PM
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At this point we need less variables, not more. biggrin.gif That's an experiment to hold until we have a good baseline.

Throw out all measurements from before this day, 12/10/13. Wipe the slate clean and let's get this done right once and for all. cool.gif
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post #823 of 1088 Old 12-10-2013, 01:17 PM - Thread Starter
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Quote:
Originally Posted by nfraso View Post

The other half is measuring your signal chain piece by piece. This has to be analog of course. I believe you did a loopback of the MobilePre and got a result matching that of one posted on HTS. So that's a start. Get that nailed, then add the receiver into the chain.

Measure the LFE pre out and the L channel pre out (so you can measure without LPF). Compare and see if roll-off is different for each. Now send the signal to the receiver via HDMI and compare those two preouts to the analog-in loopback. More data that will help us understand the chain and measurement corrections that may be good or bad assumptions.

Then you can add the amp into the loopback chain with and without receiver. (Using some sort of resistor on the amp output I would think?)

Now when you go back to digital measurements, HDMI and USB mic you can know what to expect. At this point you'll have to add in multiple sweeps of the various HDMI channel possibilities, understand how the receiver handles these and where it sends the signal. Again, playing with the various pre-outs.

Just gonna take some time to sort it all out and document everything so we all can wrap our heads around it and know exactly what's going on.

I tried the AVR loopback and everyone said it was wrong so that was the reason to go digital. Here it was

SR 8100

avr_zps023fb4df.jpg

My mobile pre

souncard_zps6c6e62ba.jpg
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post #824 of 1088 Old 12-10-2013, 01:19 PM
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Well we know it's wrong, but we still need to find out the why, correct it, and then get the real response.

Do it again and see if it's the same (analog), then repeat the measurement with HDMI source input and compare the two.
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post #825 of 1088 Old 12-10-2013, 01:22 PM
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Also, here's the loopback of the MobilePre that pbc did:



The response curve matches yours, but it should be smooth like his- so there's still something there to identify.
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post #826 of 1088 Old 12-10-2013, 01:25 PM - Thread Starter
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Could it be a bad cable or something, maybe a setting on REW? I will repeat the AVR and try an amp loopback as well. Can you give a step by step so I won't screw it up? Link?
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post #827 of 1088 Old 12-10-2013, 01:27 PM - Thread Starter
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Quote:
Originally Posted by nfraso View Post

Well we know it's wrong, but we still need to find out the why, correct it, and then get the real response.

Do it again and see if it's the same (analog), then repeat the measurement with HDMI source input and compare the two.
Quote:
Originally Posted by nfraso View Post

Well we know it's wrong, but we still need to find out the why, correct it, and then get the real response.

Do it again and see if it's the same (analog), then repeat the measurement with HDMI source input and compare the two.

I agree, I want some repeatable and accurate measurements of my room, I have put enough effort to get it right.
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post #828 of 1088 Old 12-10-2013, 01:27 PM
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Yeah check cables (twisted or otherwise), maybe nearby interference- if nothing, play with the latency setting:



This guide by pbc used your model MobilePre: http://www.hometheatershack.com/forums/spl-meters-mics-calibration-sound-cards/53169-mobilepre-usb-setup-troubleshooting-thread.html
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post #829 of 1088 Old 12-10-2013, 01:29 PM - Thread Starter
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Awesome link, I will perform a step by step from it. Does it include amp and AVR or do I need to look further?
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post #830 of 1088 Old 12-10-2013, 01:31 PM
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No, but the same principles apply as it's also a loopback, you're just adding the AVR or amp into the chain that's already set up- nothing else should change really.
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post #831 of 1088 Old 12-10-2013, 01:37 PM - Thread Starter
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Let me make sure everything is clear for hookup of the processor and amp. The mic is not needed for any of this since I am not measuring my room. I will disconnect the mic. Usually the output on the soundcard goes to the analog 1 to my SR 8100, so the input on my mobile pre will come from the LFE out rather than the mic? For the amp I run the what output of the amp to the input of the mic? What do I select on REW for input, still mobile pre?
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post #832 of 1088 Old 12-10-2013, 01:45 PM
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Correct, I would do both LFE out and L channel out. For the amp you use an output that's currently going to your driver. You'll need to rig something up, I'm not sure if anyone has an easy write-up for that. I would think you need a voltage divider to drop it down to something your MobilePre input can handle, then maybe a resistor to simulate the same load?
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post #833 of 1088 Old 12-10-2013, 01:55 PM - Thread Starter
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Quote:
Originally Posted by nfraso View Post

Correct, I would do both LFE out and L channel out. For the amp you use an output that's currently going to your driver. You'll need to rig something up, I'm not sure if anyone has an easy write-up for that. I would think you need a voltage divider to drop it down to something your MobilePre input can handle, then maybe a resistor to simulate the same load?

The clone has both xlr inputs and outputs but that might be for daisy chaining. I wonder if a xlr out to 1/4 to the mobile pre would work?
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post #834 of 1088 Old 12-10-2013, 01:56 PM
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Quote:
Originally Posted by MKtheater View Post

The clone has both xlr inputs and outputs but that might be for daisy chaining. I wonder if a xlr out to 1/4 to the mobile pre would work?

Yes, I would assume XLR out just passes through what it receives so you don't have to use splitters. You'd definitely want to use the same output your drivers see.
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post #835 of 1088 Old 12-10-2013, 01:58 PM - Thread Starter
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Quote:
Originally Posted by nfraso View Post

Yes, I would assume XLR out just passes through what it receives so you don't have to use splitters. You'd definitely want to use the same output your drivers see.

I could always wire 1/4 plug at the end of speaker cable but I have a feeling something will blow up.
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post #836 of 1088 Old 12-10-2013, 02:05 PM
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Quote:
Originally Posted by MKtheater View Post

I could always wire 1/4 plug at the end of speaker cable but I have a feeling something will blow up.

Only one way to find out. biggrin.gif

That's the idea, but yeah you'll need a voltage divider to get the output somewhere around 1V I'm guessing for the MobilePre input.
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post #837 of 1088 Old 12-10-2013, 02:20 PM - Thread Starter
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Also, the SR 8100 does not have preouts so I need to do the same thing for the left channel if need be.
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post #838 of 1088 Old 12-10-2013, 03:00 PM
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I think it's also worthwhile to completely get rid of your old REW installation (after backing up all measurements somewhere), make sure it's uninstalled, and then reinstall with standard settings. You said in the other thread that you have a new laptop with HDMI out? Perfect timing!

There is absolutely no reason why measurements should vary at all, as nfraso said, if nothing else changes.
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post #839 of 1088 Old 12-10-2013, 04:39 PM
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Quote:
Originally Posted by MKtheater View Post

I could always wire 1/4 plug at the end of speaker cable but I have a feeling something will blow up.

Do it.

All loopbacks feed voltage into the SC (or whatever interface you use). Your AVR SW out sends a couple of volts and you have no problem running a loopback with that.

Just start with reducing the AVR MVL to about -20dB lower than you normally set it to for measuring and the clones gain knob all the way off, then add a click at a time until you get signal at the right level.

I guarantee it will work. Worse case, nothing will suffer any damage, just make sure the gain is DOWN and ease it up.
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post #840 of 1088 Old 12-10-2013, 04:46 PM
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Quote:
Originally Posted by nube View Post

I think it's also worthwhile to completely get rid of your old REW installation (after backing up all measurements somewhere), make sure it's uninstalled, and then reinstall with standard settings. You said in the other thread that you have a new laptop with HDMI out? Perfect timing!

There is absolutely no reason why measurements should vary at all, as nfraso said, if nothing else changes.

Yes, there is a case where the ULF portion can disappear and the result shows a huge early roll off.

Some AVRs will hesitate until a bit after the signal goes through when you've just switched from say, the BR player input to the input you use for measuring. Since the sweep starts at the low end, that portion of the sweep never gets passed to the computer.

The easy way to avoid that problem is to burn the first sweep (just hit cancel after it starts) and try again any time you've just switched from one AVR input to the input you run the sweep through.
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