REW JPEG

5569 Views 46 Replies 7 Participants Last post by JohnM, Dec 26, 2011

Sweetmeat

Discussion Starter · Nov 23, 2011

Hello all.

I'm having a bit of a hard time with REW.

To this point, I have calibrated my sound card and SPL, then made a measurement of my sub from 0 - 200 hz.

I'm posting the measurement to see if this looks anything like what it should look like.

I've read, re-read and re-read the REW help and believe that I have followed the instructions completely, but I still feel like I'm missing something. For example, shouldn't my SPL need to be used for taking measurements?

When taking the measurement, my cables are hooked up the same way as the picture on the Equaliser Connections page, except I'm not using a BFD. Take out the BFD from the picture, and I have it setup exactly as the picture shows.

I did not, however, use that same connection while calibrating my sound card and SPL. I simply plugged one end of the RCA into the radio shack adapter and plugged that into my Line in on my sound card. The other end of the same RCA was plugged in to a separate radio shack adapter which was plugged in to the headphones jack on my sound card. This connection left one unused RCA input on each of the adapters.

Thanks in advance for your help.

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Sweetmeat

Discussion Starter · #2 · Nov 23, 2011

Or...

How about this picture?

I changed how my cables are connected, which matches more closely to what's on the Connections (not EQ connections) page within help. The difference between that picture and my setup is that I have a cable from the line out (headphones) from the soundcard going directly to the sub and not the AVR.

This one looks a little more like what I expected. Do you think it looks more like an un-EQ'd sub would look like? This is for a PB12 Plus.

And how in the world is this software getting ANY measurements? Is it reading information from the SPL that I have hooked into the line-in on the soundcard? I thought I would need to enter measurements into this software, so if I don't, I'm very happy - but obviously a little confused.

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Dr. Spankenstein

· #3 · Nov 23, 2011

You are correct in that the SPL meter is acting as your microphone to take the measurements. The response (in SPL) is shown in your second graph above.

It's a little hard to determine what's going on as the levels don't seem to be calibrated correctly as your target level in the both graphs is around 60dB when it should be 75dB. You have the option to calibrate your SPL meter by using the REW sub calibration pink noise. You should set your receiver volume at whatever it takes to make the SPL meter read approx 75dB. Having the volume set to this target dB helps keep the signal from going into the noise floor (the base ambient noise in your room).

You're on your way, you just need to get some more parameters straight before you gather a meaningful graph.

Sweetmeat

Discussion Starter · #4 · Nov 23, 2011

Dr. Spankenstein said:
You are correct in that the SPL meter is acting as your microphone to take the measurements. The response (in SPL) is shown in your second graph above.

It's a little hard to determine what's going on as the levels don't seem to be calibrated correctly as your target level in the both graphs is around 60dB when it should be 75dB. You have the option to calibrate your SPL meter by using the REW sub calibration pink noise. You should set your receiver volume at whatever it takes to make the SPL meter read approx 75dB. Having the volume set to this target dB helps keep the signal from going into the noise floor (the base ambient noise in your room).

You're on your way, you just need to get some more parameters straight before you gather a meaningful graph.

Hey, thanks for responding!

Right now I just have the sound card line out cord connected directly to the input on the sub, and the sub's volume is turned all of the way up (range from -100 to 0, and it's on 0).

I'll connect it directly to my AVR tonight and set the crossover for all other speakers to 200 (since I'm measuring only up to 200), turn up the AVR's volume until the SPL is 75 and then remeasure.

I have already done the sound card and SPL calibrations.

Thanks again for your help!

Dr. Spankenstein

· #5 · Nov 23, 2011

Yikes!

First things first: Turn down the sensitivity (volume) on the sub. You don't want to blow it when the first signal comes through... Start somewhere below the halfway point.

Yes, please utilize the AVR when doing these measurements as it's the only way that you'll derive any meaningful results.

Don't set your AVR crossover to 200. You want to use the normal crossover setting you will be using during listening. You'll want to see if there are any issues in the frequency response in the crossover region as well, as these may interfere with the integration of your sub to your mains.

Just make sure the PC volume is set to max. Make sure that all processing is OFF in the AVR (no Audyssey or MCCAC. Use some manner of "direct" or "pure" mode and an analog input.

That should get you on track to take some valid measurements (when taken from your main listening position.) These will show potential issues (peaks or nulls) that can be addressed via a combination of subwoofer placement, room treatments and/or EQ.

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Sweetmeat

Discussion Starter · #6 · Nov 28, 2011

Dr. Spankenstein said:
Yikes!

First things first: Turn down the sensitivity (volume) on the sub. You don't want to blow it when the first signal comes through... Start somewhere below the halfway point.

Yes, please utilize the AVR when doing these measurements as it's the only way that you'll derive any meaningful results.

Don't set your AVR crossover to 200. You want to use the normal crossover setting you will be using during listening. You'll want to see if there are any issues in the frequency response in the crossover region as well, as these may interfere with the integration of your sub to your mains.

Just make sure the PC volume is set to max. Make sure that all processing is OFF in the AVR (no Audyssey or MCCAC. Use some manner of "direct" or "pure" mode and an analog input.

That should get you on track to take some valid measurements (when taken from your main listening position.) These will show potential issues (peaks or nulls) that can be addressed via a combination of subwoofer placement, room treatments and/or EQ.

Thanks for your reply. I finally found some quiet time today to try your suggestion, but it didn't completely work.

Here are the things that I did:
1) Hooked up the cables as depicted on connections page (without an EQ) within REW help.
2) The cable output cable from the soundcard was put into the right channel on my AVR's AUX input
3) Lowered my sub's volume to 50%
4) Set my AVR's input to Pure Direct
5) Turned up the volume to -10 db
6) Performed a measurement

At this point, my sub was not working at all - only the main speakers. Since I was trying to calibrate my sub and I couldn't figure out why my sub wasn't working with the main speakers, I changed my setup to go directly to the sub (again). I've asked some people on a different website if they know why I'm not getting sound through my sub during REW measurements when the connections are directly to my AVR (Yamaha RX-A3000). I'm waiting to hear back from them.

I'd like to know if I'm able to change the level on the measurement tab without having to first recalibrate using that level. I'm asking because all of my calibrations used a level of -12, but I kept getting a clipping error that said to turn down the volume or the level. I tried turning the volume down in small increments and remeasured and continued getting the same message. Once I turned my volume back to where I began and turned down the level, I didn't get the clipping message. So lowering the level resolved the problem, but I'm not sure if I needed to recalibrate using my new level to make everything in synch.

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Sweetmeat

Discussion Starter · #7 · Nov 29, 2011

Sweetmeat said:
Thanks for your reply. I finally found some quiet time today to try your suggestion, but it didn't completely work.

Here are the things that I did:
1) Hooked up the cables as depicted on connections page (without an EQ) within REW help.
2) The cable output cable from the soundcard was put into the right channel on my AVR's AUX input
3) Lowered my sub's volume to 50%
4) Set my AVR's input to Pure Direct
5) Turned up the volume to -10 db
6) Performed a measurement

At this point, my sub was not working at all - only the main speakers. Since I was trying to calibrate my sub and I couldn't figure out why my sub wasn't working with the main speakers, I changed my setup to go directly to the sub (again). I've asked some people on a different website if they know why I'm not getting sound through my sub during REW measurements when the connections are directly to my AVR (Yamaha RX-A3000). I'm waiting to hear back from them.

I'd like to know if I'm able to change the level on the measurement tab without having to first recalibrate using that level. I'm asking because all of my calibrations used a level of -12, but I kept getting a clipping error that said to turn down the volume or the level. I tried turning the volume down in small increments and remeasured and continued getting the same message. Once I turned my volume back to where I began and turned down the level, I didn't get the clipping message. So lowering the level resolved the problem, but I'm not sure if I needed to recalibrate using my new level to make everything in synch.

OK, I've found out how to disable my EQ in order to get measurements with my front speakers and sub - however I don't believe things are correct.

When I make my connections, I hear TONS of static coming from my front speakers and when I take the measurments I only hear the static and I'm not able to get the pressure level above 60db's - even when I turn my AVR's volume up to -10 (which is really loud). Is this normal?

Sweetmeat

Discussion Starter · #8 · Dec 1, 2011

Bump

EarlK

· #9 · Dec 1, 2011

> Plug a CD player ( or iPod ) into your AVRs aux input to prove to all of us that you can actually get music into & then out of your AVR over to your speakers ( focussing on the ones you want to measure ) .

> Then unplug the CD player & replace it with your computer, but this time use some tunes as a source ( played through either iTunes or WMP ) to confirm the same ( as above ) .

> Then ( & only then ) we can talk about what REW is ( or isn't doing ) for you !

:sn:

diffserv

· #10 · Dec 3, 2011

test

Sweetmeat

Discussion Starter · #11 · Dec 9, 2011 (Edited)

2

Ok, so my computer crashed and I had to buy a new one. I just reran all of the calibration steps on my new computer and here are my measurements. Please note that I'm still not able to get my SPL to 80 or more, because when I increase the volume or the level I keep getting clipping errors. Why do I keep getting that? Is there something wrong with my speakers, or have I not done something correctly in the REW setup?

When taking the 0-200 measurement, I had my L/R and sub ouput the signal, so all 3 are measured. I did not turn off the EQ in my AVR before I took those measurements. The crossover was set at 80.

:rofl:

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Wayne A. Pflughaupt

· #12 · Dec 9, 2011

We could tell a lot more about your sub response if you’d scale the graph for something like 45-105 dB vertical and 10-200 Hz horizontal. A huge 130 dB vertical scaling will make response as bad as the Grand Canyon look good!

Regards,
Wayne

Sweetmeat

Discussion Starter · #13 · Dec 9, 2011

Wayne A. Pflughaupt said:
We could tell a lot more about your sub response if you’d scale the graph for something like 45-105 dB vertical and 10-200 Hz horizontal. A huge 130 dB vertical scaling will make response as bad as the Grand Canyon look good!

Regards,
Wayne

You bet, I'll take a look tonight and find the way to do that. Thanks for the suggestion.

JohnM

· #14 · Dec 10, 2011

Sweetmeat said:
Please note that I'm still not able to get my SPL to 80 or more, because when I increase the volume or the level I keep getting clipping errors. Why do I keep getting that? Is there something wrong with my speakers, or have I not done something correctly in the REW setup?

Clipping is detected on the input, you need to reduce the input volume setting so that you do not get clipping any more. If you are using an RS SPL meter use the 80dB range when making your measurements and make sure the meter is not overloaded (needle pegged) during the measurement. If you change the RS meter range you will need to redo the SPL calibration to get correct trace levels.

Sweetmeat

Discussion Starter · #15 · Dec 10, 2011

JohnM said:
Clipping is detected on the input, you need to reduce the input volume setting so that you do not get clipping any more. If you are using an RS SPL meter use the 80dB range when making your measurements and make sure the meter is not overloaded (needle pegged) during the measurement. If you change the RS meter range you will need to redo the SPL calibration to get correct trace levels.

John, thanks for your response. I'd like to ask a few follow up questions.

"Clipping is detected on the input, you need to reduce the input volume setting so that you do not get clipping any more.". I'm assuming that you are saying to reduce the volume on my AVR to eliminate clipping. That's what I've done, but I don't know why I can't get 80db SPL before I start getting clipping errors. I'm using a RS digital SPL (they didn't have any analogues left).

JohnM

· #16 · Dec 10, 2011

Sweetmeat said:
I'm assuming that you are saying to reduce the volume on my AVR to eliminate clipping.

Nope, I'm saying reduce the input volume setting on your soundcard.

Sweetmeat

Discussion Starter · #17 · Dec 10, 2011

JohnM said:
Nope, I'm saying reduce the input volume setting on your soundcard.

Wow, I just noticed that the author of REW is helping me! I'm honored! Thank you!

Here's my new graph.

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Sweetmeat

Discussion Starter · #18 · Dec 12, 2011

I am getting so incredibly frustrated with working with this REW software.

For some reason, no matter what I try I can't get my SPL to be at 80db or above without getting a clipping error. In addition, once I finally get a measurement without a clipping message, when I remeasure again with the exact same settings I get different results and many times I'll get a clipping error.

For example, earlier today I finally got a measurement without a clipping error. My settings were as follows:
1) All speakers set to off except for the front speakers
2) Measuring 0 - 30Khz
3) AVR volume set to 053
4) REW level set to -16
5) Headphones on computer set to 10
6) AVR EQ set to through (off)

The result finally showed the SPL around 80db's so I was extremely happy.

I wanted to compare that measurement to a measurement with the EQ on, so I executed the measurement using the same settings except for turning on the AVR's EQ. When I did that, I kept getting clipping errors. I adjusted the internal level (headphones) level decrementally by 1 all the way to 1 and continued to get clipping errors. I then reset the headphones level to 10, and tried decrementing the level setting on the "measurement" page 1 db at a time until I reached -40db and continued getting the clipping error. I then tried multiple variations of changing the headphones level, "measurement" page level and the AVR volume until I could find a setting that didn't give me a clipping error. This resulted in having the volume so low that I could barely hear it, and my SPL meter wasn't even displaying the level when it was set to 60 (it's lowest setting).

After all of that, I reset everything back to the settings listed above and reran the measurement and started getting clipping errors. Why was I able to use those settings before without getting clipping errors and now I'm using those same settings and getting clipping errors?

I have no idea if this will ever work for me and I don't know what to do next. I don't even know if I'm setting this stuff up correctly, or if my laptop has the correct type of sound card that's needed for use with this software and I have no idea on how to know if it is correct or not. My new sound card has 2 lines (headphones and microphone).

I'm connecting the cable going to the AVR to the headphones jack and I'm connecting the SPL to the microphone jack. These connections are being made with adapters and the use of the loop back cable.

Here's the graph using the settings I listed above.

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Sweetmeat

Discussion Starter · #19 · Dec 12, 2011 (Edited)

10

Ok, so after my last post I decided to try it again and it seems like I'm getting some better results (at least better in that it's closer to what I expect).

I measured the following:
1) Front speakers only - no crossover (EQ on and off) 0-30Khz
2) Center speaker only - no crossover (EQ on and off) 0 - 20Khz (mistake, should have been 30Khz)
3) Rear speakers only - no crossover (EQ on and off) 0 - 20Khz (mistake, should have been 30Khz)
4) Sub only (EQ on and off) 0-200Hz
5) All speakers with sub (EQ on and off) 0-30Khz

Here are the measurements. One thing I noticed is that YPAO doesn't appear to be doing ANY EQ'ing on my sub. Very interesting.

Here are some additional settings I used:
Measurement Front speakers Center Speaker Surround Speaker Sub
Front speakers only Large None None None
Center speaker only Large and unplugged Large None None
Rear Speakers only Large and unplugged None Large None
Sub only Small and c/o at 200 None None Yes
All speakers Small and c/o at 60hz Small c/o at 80 hz Small c/o at 80hz Yes

SPL <-cable -> microphone jack
Headphones jack <- Cable -> AVR

Please provide any suggestions you have.

Thanks!

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Sweetmeat

Discussion Starter · #20 · Dec 12, 2011

bump

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