First equalization and having trouble.. anyone help please

[thewire]

I setup my MP3+ USB external sound card and saved the file, setup my RS digital SPL meter with the subwoofer at 75, then I turned up the volume on the Crystal Acoustics subwoofer a few dB to 85 and took a measurement. I did not check the C weighting because I had the RS meter file loaded. I added some filters to what REW suggested and optimized the peak and gain. This is location in my room that gives the most overall smooth response. I was not able to measure with a crossover since my receiver is being repaired. I moved the crossover up on the graph. I measured after applying the filters without adjusting subwoofer volume on my HD-DVD copy of DVE with limited bandwidth pink noise to be 64dB. The limited bandwidth pink noise is -3dB less than my other speakers which measure at 67dB after I have calibrated them using the full bandwidth to set them to 75dB. I have read that the subwoofer is -3 less on the disc. The speakers are set to small. Am I done or is there something that would require being done differently?

[thewire]

I measured tons of various settings out of the player using the spectrograph. I have measured so many things since I started using REW I can't remember what all I meausured anymore. Anyway.. The settings are correct but I had to switch my auto HDMI out to PCM. I raised the subwoofer volume a few dB to match and lowered the rest, but I used REW to do this (looking at RS SPL meter) with filters after, and it sounds amazing. It works for DVD now also. Thanks again.

[JohnM]

Probably easier to use RTA mode when measuring pink noise, that way the ideal response is flat rather than rolling off at 3dB per octave. Did you have averaging on for your measurements? Exponential averaging works well with noise measurements.

[thewire]

I think I forgot that averaging needed to be turned on before the measurements. I did try that but for the above measurements it was off since I did not have it on before taking any. I will try again with the RTA mode. What is a good average to apply?

edit: Does it matter the SPL cal file was loaded? This is with the line-in directly from my XA2.

[thewire]

I read in the help file that the cal is applied. It looks very similar to what I measured with the meter and I thought I was on the right track to measuring bass management directly from the player to confirm it. This was one I measured with the mic and the subwoofer and mains playing together. It is the full bandwidth pink noise on DVE and levels are set the same. I have since moved the subwoofer location.

[thewire]

This is Pink PN at a -16 sweep with my mains (light color) using a Y-cable and then the next measurement is the subwoofer included in a second Y-cable. If I measure this with my mic from the XA2 what is it I am looking for to be sure they are good. A flat looking meaurement at -20dBFS?



This is a RT60 I did of a sweep meaurement of my mains with 1/3 octave bands and EDT at -16 if anyone was interested.

[thewire]

With REW SPL meter cal file loaded...

Band limited pink noise for the subwoofer in DVE = 75dB (RS digital meter at 80 C weighting) in REW or 67dB C weighting on a RS digital meter set to 70.

Pink noise at -30Db FS in REW = 75dB on a (RS digital meter at 80 C weighting) in REW and 67dB on the RS digital meter set to 70.

Band limited pink noise for other channels in DVE = 67dB (RS digital meter at 80 C weighting) in REW or 60dB on a RS digital Meter set to 60.

Pink Noise in REW at -20dB FS = 85 in REW or 77dB on RS digital SPL meter at the same setting

Therefore in DVE my subwoofer should measure at 67dB on my RS SPL meter at 70 and should measure 75dB in REW at 80. My mains should measure at 67dB on my RS SPL meter (set to 70 C weighting) and 75dB in REW set to 80. No 3dB difference that I see going on.

I setup my mains and subwoofer using the limited bandwidth pink noise similar in REW and my full bandwidth pink noise pan around the room is at like 77dB. My mains ended up at -8 when set to small for the DVD side. It wants me to raise the volume on an AVR.

I wonder why is there no Full bandwidth Pink Noise in REW and what is it on DVE for. I also am curious hy is it louder. Could be something to do with a dial norm on an AVR maybe.

[Wayne A. Pflughaupt]

thewire wrote:

Am I done or is there something that would require being done differently?

I’d move the Target up to about 80 dB or a bit more. As it is now, assuming you have a PEQ, you’ve cut you sub’s level nearly 20 dB. That’s way too much.

Also your sub seems to be strong on the top end and weak on the bottom end, which is not good. At least that’s what it shows in its present location. Speaking of...

This is location in my room that gives the most overall smooth response.

If you’re going to equalize the sub, then you need a different approach. You don’t have to worry about finding the location with the smoothest response, because the EQ is going to take care of that. So, you want the location that gets you the best output and extension, and response that is “equalizable” (i.e. no more than about a 15 dB spread between the worst peaks and depressions). If you haven’t, I’d try a corner, if you have one available. Hopefully that will get you extension closer to 20 Hz, and get your overall response strong on the bottom end and weaker on the top, which is typically what you want.

Hopefully someone else will chime in about your other questions.

Regards,
Wayne

[thewire]

Here are different variations with the subwoofer in the right corner without filters or eq.

Subwoofer set to THX (no volume control), then set to an 85 target and a 75 target at a -12dB FS sweep.



Subwoofer set to THX at a 85dB target at -20dB FS. This is exactly the level I would listen to similar with DVE and a 75dB target at -30dB FS.

Did it work? What could I do now?




edit: Can't I improve lower extention also by stacking them on eachother?

[Wayne A. Pflughaupt]

edit: Can't I improve lower extention also by stacking them on eachother?

There are two subs? Did I miss that somewhere?

What’s wrong with your crossover? The sub isn’t supposed to be flat out to 250 Hz...

Regards,
Wayne

[Blaser]

thewire wrote:

I setup my MP3+ USB external sound card and saved the file, setup my RS digital SPL meter with the subwoofer at 75, then I turned up the volume on the Crystal Acoustics subwoofer a few dB to 85 and took a measurement.

Why?

I did not check the C weighting because I had the RS meter file loaded. I added some filters to what REW suggested and optimized the peak and gain. This is location in my room that gives the most overall smooth response. I was not able to measure with a crossover since my receiver is being repaired.

So you don't have an AVR in the loop? Are you using computer to BFD to sub?

I moved the crossover up on the graph.

Why?

I measured after applying the filters without adjusting subwoofer volume on my HD-DVD copy of DVE with limited bandwidth pink noise to be 64dB.

I understood you are using REW, Why are you mixing with DVE now? Limited bandwidth can yield different results from full bandwidth... But again why aren't you using REW sin sweep from say 10 to 200 Hz to test subwoofer FR?
I think either you or me are missing something. Sorry for my questions, but if you reply to them we can try to figure out what the required is.

[thewire]

I use the bass management in my player. For testing with REW, I hook the output of the BFD directly to my subwoofer input. My receiver blew up when I fed a signal from my XA2 (pink noise) after turning up the speaker levels in it to match the subwoofer without eq. Levels were at 0 and I played pink noise in the XA2 and the reciever blew up and without any speakers hooked to the amplifiers. I use analog out to seperates. It is on repair and I will get it back soon. Since my subwoofer was playing -2dB bellow reference for me, I turned up the volume. My AVR quit working a day or so before my BFD arrived.

I thought getting an additional subwoofer might help since even if they do fix my receiver (or I get a new one instead that does 15+ for subwoofer) that I will not be able to boost the LFE input with bass management enabled because my receiver defaults back to 10+ for analog because the speakers are set to large. An additonal subwoofer would allow +5dB boost I need for having my speakers set to small in the XA2 and possibly extened the lower extention in a vertical stack array. That is why I asked about a second subwoofer. I added two additonal filters to the topmost graph on this thread other than what REW had recommended. The large cut was -17.5dB.

edit: yes I use the computer-BFD-subwoofer for setup.

[Wayne A. Pflughaupt]

Okay then, getting back to your question:

Did it work? What could I do now?

That null is a big problem. Are there any openings in either of the walls close to the corner were the sub is?

Regards,
Wayne

[thewire]

The other locations anywhere in the front of the room have the null also. I had bags of playsand stacked up ready for use and my builder took them and used them for paving steps bcause nobody wanted to purchase more sand or would help carry it down the hill. They took my leftover and tossed it. The 3/4 plywood stage is filled with some pink insulation. If sand will help the null, I could give it a try but it would be some trouble to accomplish. I have seen that being done before so I might have the motivation to do it. I'm not sure if that is what causes it.



The two lower corners in the rear I have not tested since adding more room treatments. The other side similar to the one shown has the entrance door next to it. This is where I origanally placed the subwoofer (pictured) using a crawl test, before there was any framing, located in this corner. I had compllaints in the back row that it was boomy there and the room treatment phase then began. I have not tested the location.



This is where the subwoofer was tested at the top of the thread with it located on the side of the room. I don't see a null at this location... so I thought it might have been a good location? Having a peak a few dB higher to eq is better than having a null right?

[Wayne A. Pflughaupt]

Good information, but I didn’t see an answer to my question in all that.

Try moving the sub away from the corner down the wall between 4 to 8 feet (i.e., it stays against the wall), taking measurements at 1-ft. increments. Sometimes you can find a spot that will eliminate a null like that, yet the sub will still be close enough to the corner to get the benefits of coupling. If that doesn’t help, do the same thing down the other wall.

Regards,
Wayne

[thewire]

Sorry I did not answer the question that well. I have tried this before on the wall by moving the mic in this thread and it looked like I was getting some valleys as a result. Second picture from the top.

right wall front and between right and center

I will try with the subwoofer located there instead to see what that is like.

[thewire]

Wow. I was doing this all wrong. I set REW to do pink noise as DVE does and even applied the boost to my subwoofer as I do for setup. The results look like when I had my AVR. The light green in the graph is my subwoofer facing away from the side wall moving in 1-ft each time the measurement becomes darker. The purple color is on the right platform when I run out of room on the floor. I did not change settings in REW as I moved it.



I tried again with the driver facing forward away from the front wall in the corner. I also stacked a trash can full of boat batteries as heavy of the subwoofer to see what difference that might make. It looks like the null is because of my floor which is acoustically inert. How about that second third or fourth subwoofer then?

[thewire]

Here is the corner with lots and lots of boost like my receiver used to do to the mains.







additional info: THX switch setting is now 72dB at -33dB FS in DVE on my SPL meter.

[thewire]

Was I supposed to recalibrate the SPL each time I moved the subwoofer? I don't see the lower extention in the corner..

[Wayne A. Pflughaupt]

I’m confused. I thought here you had already measured all over the room and found the best location. Why are you doing it all over again? Some of the graphs on the other thread, like this one are identical to what you’ve posted on this thread.

I’d say review your old thread, put the sub in the location that got the best response, and equalize.

Regards,
Wayne

[thewire]

I guess I was waiting to see if anyone was going to recommend raising the level on the subwoofer again like at the other forum.

Boomy subs == bad sound, corner loading your sub can cause this.. I think you should stay with 1 sub (maybe you need a bigger sub) multi subs will really complicate your situation right now.

What you reall should do is EQ your subwoofer. I have a BFD (feedback destroyer) that I run between my reciver and sub setup. It takes a bit to setup but is worth the time. Search around (here and goolge) there are some really good resources for EQing your sub. The EQ and test equipment will cost less that a 2nd sub an it will really imporve your sound.

When you kill the boom you can turn your current subwoofer up and it will sound alot better. If you EQ and find that you still don't have enough output then think about more output.

Have Fun!

[thewire]

This sounds good after three tries and while listening to sweeps and buzz rattle test in DVE. I demoed some material also. The subwoofer is in the center of the room again to reduce the null and some other issues I was having. It is with a standard house curve.

[Wayne A. Pflughaupt]

Excellent!

Regards,
Wayne

[thewire]

This thread already has some good info about my room. If nobody recommends otherwise I will just continue here for my second matching sub-woofer shipping soon.

[thewire]

Second equalization

I'm having some trouble. I get errors that say there is to much noise and the only noise is from my computer at the subwoofer. I thought it was bad with one sub but with two it is telling me it effects the measurement.

First I calibrated each sub to 72dB in REW then it gave me 85dB with both subs. I adjust the settings to standard settings -12dB sweep and turn my volume to half. The SPL meter was previously calibrated for 85dB.



Then I messed with some things to get close to 75dB.



I skip the error messages such as 29dB to low and get this.



How do I get past step 1? Are the measurements accurate if I am just turning down the sweep level and the output volume? When I measure with different settings instead and with an 85 target it says this (pictured bellow) when I measure but I can hear computer noise during the check levels. Is this going to be an accurate measurement if I have to turn down the volume on the computer so far? Measurements look like my old ones. Would having my AVR help solve anything besides just having the filter? That is still not yet fixed. I can't seem to get ET5 to work also it just gives me a very flat looking response every time and I have to turn down the output to about 4%. I have been using the THX optimizer to make each level 75dB and my surrounds only go to 75dB at the lowest setting so I really need to get this 75dB target working I think. Anyone have any suggestions?