New to REW, few questions to get me started.

[sirquack]

Hello everyone, I've been lurking around for some time and have a few questions. I work in IT, so I'm suprised I've had so much problems getting everything to work, but I think I'm getting close now. I built a HTPC back some time ago for my HT. It has an Nvidia based motherboard with on board Realtek AC97 Audio. I think the problem I was having in the past was going through the beginning setup/calibration was that I had my SPDIF coax still hooked up at the same time.

I've unhooked the SPDIF for now, and have everything working I think. I've been through all the setup/calibration steps, using the "speakers" button for setting everything up to 75dB. I've just started to take some initial measurements. Per the instructions, it says to start with the sub. When I do my first sweep from 20 to 200 it completes but I get a message saying the readings were at -70dbfs or something like that and to check connections, levels, etc... The graph completes and looks pretty good, but it is way low on the graph from where the target 75dB is located?

I've checked the XP sound controls and WAVE is maxed, Master Volume is half way. I had to ADD "Fronts" and "Sub" levels otherwise I was not getting any sound to the AVR. Not sure this is correct? Am I supposed to use SPDIF, I would think not otherwise the instructions would not say to hook RCA's left/right to the AVR from the Output on the soundcard.

Any help would be appreciated.

http://porterplex.googlepages.com

[Mitch G]

Do you have the line-in (microphone) turned on and set to a high value?

Also, were you able to do the sound card calibration (where you loopback the signal)?
I found doing this step first would help me debug problems.

You might want to post your graph(s) since that may help show something. Be sure to check the sticky thread on how to post graphs.

BTW, that's a great looking theater. You IT guys make that kind of money?
(I'm in telecom. )


Mitch

[brucek]

When I do my first sweep from 20 to 200 it completes but I get a message saying the readings were at -70dbfs or something like that and to check connections, levels, etc

If you heard the sweep and had set it to ~75dB on your RS meter and then got a -70dbfs level, then your input level is bad.

Be sure the cable from the RS meter is connected to the LINE_IN right channel of the soundcard using a stereo jack?

Be sure the input level is set correctly by using the SET INPUT level....

brucek

[sirquack]

Thanks Mitch,

I think the program automatically mutes everything except WAVE and MASTER if you pick "Line In" and "Speaker" from the REW main screen in the lower left. I tried that, I also tried unchecking Mute for Line In, Mic, Synth, etc.. and cranking those levels up and nothing, until I went into the sound properties and added the levels for "front" and "sub" in Windows. The soundcard test worked fine and I didn't have any errors.

Before, when I had my SPDIF Coax hooked up from the pc to receiver the sound was being routed throught that, not the left/right RCA cables that I had hooked up to an extra Audio In connection. When it was that way, I did get an error during the soundcard test, something about the 1KHZ signal was not detected. That seems to be fixed now.

My goal in all of this is to graph my room response, add additional bass traps and reflection treatments, and also play around with various sub placements in the room to get as flat response as possible. Prior to finding this tool, I used the RealTraps CD to manually graph my room before/after the bass traps and I did see some dramatic improvements. This application you can just sit back and watch it plot your graph for you, much faster.

[sirquack]

Hi Bruce,

On the back of my HTPC, there is an Input, Output, Mic, Sub, Surrounds, and Rear jacks, and SPDIF. I have the RS meter hook to the "right" channel of my "Y" cable, the other end is the 3.5mm jack which is hooked to the "Input" on the motherboards soundcard. Then I have the same thing going from the "Output" 3.5mm jack to the left/right RCA audio inputs on my AVR. For now I'm using and extra one "VHS-1" since it was free, but I've tried others and get the same results.

I've gone step by step through all the measurements, per the Help File (F1) and everything seems to be accurate. I'll have to give it some more attention in the next few days, as I'm done for the night.

Thanks for everyones help...

[sirquack]

Here is what the jacks look like on the back of the motherboard, it is an 8channel on board card.

[brucek]

You have the same motherboard and on-board soundcard that I do, so I know that it should work.
Since you've successfully looped the in to out with the soundcard calibration test, then we know the card works.

Can you show us a picture of your mixer windows setting.

Also go to control panel and start up the RealTek mixer called Sound Effect Manager and check settings there. i.e. SPDIF off, 2 channel speakers, sound effects off...........

brucek

[sirquack]

Thanks Bruce,

I'll try to check a little later today. If I recall correctly the windows standard volume controls are Volume Control, Wave, SW Synth, CD Player, SPDIF, and Line In for the Playback controls, and for the Recording side just Line In is showing up as selected. To get it to somewhat work last night I had to add the front/subwoofer controls in the Playback screen.

Also, I have gone into the Realtek mixer, the EQ stuff is turned off, SPDIF is now off Line In is set to IN and Line Out is set to Out. Pretty much everything is the default settings from the installation, I've never used the mixer.

Prior to running through the measurments, I ran my Denon 2805s test tones and adjusted everything to 75dB using my RS meter. All speakers are set to small, with a crossover of 80hz. I'll try to get some screen shots/information asap...

Randy

[brucek]

If I recall correctly the windows standard volume controls are Volume Control, Wave, SW Synth, CD Player, SPDIF, and Line In for the Playback controls, and for the Recording side just Line In is showing up as selected. To get it to somewhat work last night I had to add the front/subwoofer controls in the Playback screen.

Below is a graphic of my windows playback and recording mixer settings when REW is running.

See in the Recording mixer window, the LINE_IN is selected and REW has controlled its volume to 0.406....
In the Playback mixer window, the Master VOLUME and WAVE are unmuted and the volumes are controlled as shown.

Start REW and bring up the mixers and set them the same as this. You can play with the sliders and watch the volumes go up and down.

You have to select Recording and Playback separately of course. I just used photoshop to overlay both of them at the same time for demonstration purposes....

If the LINE_IN is selected and the Input volume is set to some decent value, then click the big square red button on the REW SPL meter (which turns it on and talk into your RS meter (it's a microphone) while set at 70dBSPL on its dial and the cable hooked up. THE SPL and VU meters in REW should jump up and down.



brucek

[sirquack]

Thanks Bruce for the help. Well I'm closer I think, I adjusted to your settings, however, as soon as I click the "Set Measurement Level" button, the figure jumps down to .50. Also, as soon as I click "Set Input Volume" button that jumps way down to like .15... Also, the measurement level starts at -20, if I bump that up I can get closer to your figures, if I leave it there I have to really crank up my master volume on the receiver to get to 75dB's on the meter...according to the pop up box I'm supposed to adjust my AV receiver volume control. By adjusting the volume on the windows volume control to .804 it sticks, however, then I run the Set Input Volume test and it drops to .14. This is fun and frustrating all at the same time, reminds me of my day job.

[brucek]

Sorry, when I said, "Start REW and bring up the mixers and set them the same as this, I didn't specifically mean the volume settings, I meant the same selections and check boxes.

You should set your levels to whatever works when you go through the calibration. (although I prefer a -12dB measurement level rather than -20dB)

The order for calibration after you have the soundcard calibration file complete and the meter calibration file loaded is:

Set Measurement Level
Set Input Volume
Calibrate SPL Meter
Set Target Level
Automatic Measurement.

brucek

[sirquack]

Ok, things seem to be working now...I'm at -15dB for my measurement level, .804 measurement output level, .179 for the input level. Have completed the steps in exact order and no errors. Just ran my first Sub Automatic Measurement with a target of 75dB's and it worked, Right now I'm moving the sub around a few inches at a time on my front stage to see where I can get the flatest graph...

Thanks so much..Randy

[sirquack]

Ok, here is my first graph after help from Bruce, thanks so much. It is with my sub positioned center of my front wall below the screen.

[brucek]

Without any equalization it's pretty good. Have you played with your phase control on the sub at all - you may be able to further smooth the 80Hz area with that.....

[sirquack]

I've been focusing on bass traps and first reflection points recently. So far the only bass traps I have are front corner superchunks. I plan to treat the rear corners as well as wall/ceiling corners. I have some graphs I plotted using the Real Traps CD from 20hz to 300hz in 1hz increments, and the superchunks made a big difference in flattening out the overall graph...

[sirquack]

Hey guys, me again. I've go a new graph for my sub I'll post soon, by moving it around a bit and flipping the phase switch, I've got a smoother graph than above.

One question I have is how do I test the other speakers? I've clicked on the left and right,etc. filter tabs but the sub is still active. I see there is a drop down with options like bass limited, subwoofer, etc., but can't figure out how to test my other speakers. Do I have to make adjustments to the cables? I also just discovered that I thought when I was doing a subwoofer test that it was just my subwoofer in the graph above, I just discovered sound was coming from my mains as well for the sweep. Is this how it works? I guess I assumed when you setup the sub first that only sound would come form the sub.

thanks, Randy
]

[brucek]

I've clicked on the left and right,etc. filter tabs but the sub is still active.

REW outputs a single mono analog signal to your receiver. How do you propose REW changes the speaker selection in your receiver?

If you want to select a different speakers then you will have to connect or disconnect the speaker(s) you want to test. REW can sweep any frequency you want and it provides a convenient set of tabs for you to store different speaker tests in. It also provides different target curves by selecting bass limited or sub or full range etc....

Generally we test and equalize the sub alone first. Then we add the mains to ensure they integrate well around the crossover frequency. If not you can adjust the phase to correct that.

brucek

[sirquack]

Ok, here is my first graph and recent second graph. I moved my sub to a different position, and my phase switch is at 180 now. It appears to be overall better than the first. I'm still confused on my comments above on how your supposed to measure the sub, left, right seperately according to the instructions? I'm getting sound through my mains when I use the sub tab and vice versa when I try to test my left or right speaker, I get sound from my sub and other main?

[brucek]

I'm getting sound through my mains when I use the sub tab and vice versa when I try to test my left or right speaker, I get sound from my sub and other main?

answered above

[sirquack]

Thanks again Bruce for your help, that makes sense. Just for kicks and giggles, I moved my mic around to the various seathing locations in my theater. As expected the graphs look very different for each location. I guess that is why people try to acoustically treat with bass traps and use EQ'ing to counteract for the nulls and peaks. Thanks again, Randy