Playing with REW

[dvenardos]

REW is so :cool:
I have a pair of bass traps coming next week so I wanted to get a baseline measurement. I am running the Strata Minis with an Outlaw LFM-1EX with the crossover set at 40 hz. Having the powered woofers on the Minis really gives you a lot of flexibility and I adjusted the phase and crossover on the Minis woofers to get a better frequency response. Attached is my Graph raw and smooth. I see now why I am always turning down the LFE channel with that big peak at 18hz, that is also probably the one that is giving me grief with my neighbors windows.

[Josuah]

So are you going to buy a PEQ unit?

[dvenardos]

So are you going to buy a PEQ unit?

No, I am working on acoustic treatments right now, don't plan on using PEQ unless there is something really bad I can't fix.

[bunnyma357]

REW is so :cool:
I have a pair of bass traps coming next week so I wanted to get a baseline measurement. I am running the Strata Minis with an Outlaw LFM-1EX with the crossover set at 40 hz. Having the powered woofers on the Minis really gives you a lot of flexibility and I adjusted the phase and crossover on the Minis woofers to get a better frequency response. Attached is my Graph raw and smooth. I see now why I am always turning down the LFE channel with that big peak at 18hz, that is also probably the one that is giving me grief with my neighbors windows.

I found the room treatments didn't have as big an impact on Frequency Response as I would have thought - the big difference I was hearing could be seen in the Spectral Decay graph, where the sound didn't bounce all over the room. I've since added a PEQ (Behringer FBD-1124) to address some of the Frquency Response issues - mainly the mode at around 43Hz. Link to charts:

http://av123forum.com/showpost.php?p=654494&postcount=208

Jim C

[dvenardos]

I found the room treatments didn't have as big an impact on Frequency Response as I would have thought - the big difference I was hearing could be seen in the Spectral Decay graph, where the sound didn't bounce all over the room. I've since added a PEQ (Behringer FBD-1124) to address some of the Frquency Response issues - mainly the mode at around 43Hz. Link to charts:

http://av123forum.com/showpost.php?p=654494&postcount=208

Thanks, I don't know what I am supposed to be looking for in spectral decay graphs, but I do see that big bump at 43Hz. :dizzy:
Does that explain why my frequency response graph goes all over the place at the higher frequencies (not shown in posted graph)? I haven't bothered to figure it out yet because I can't do anything about those frequencies at this point.

I also have the option of pulling the port plug on my Outlaw and that raises the freq response from 16hz to 22hz.

[bunnyma357]

Thanks, I don't know what I am supposed to be looking for in spectral decay graphs, but I do see that big bump at 43Hz. :dizzy:
Does that explain why my frequency response graph goes all over the place at the higher frequencies (not shown in posted graph)? I haven't bothered to figure it out yet because I can't do anything about those frequencies at this point.

I also have the option of pulling the port plug on my Outlaw and that raises the freq response from 16hz to 22hz.

Each band of color is the level of the tones at 20ms intervals, so in the first graph you see that the tones are still bouncing around after 160ms (the pretty solid blue plot in the front)

On the second graph you see each plot is dropping much more every 20ms, so that by the last plot at 160ms most of the sound is below 48dB where in the first graph it was still at around 56dB.

Illustrates that a lot of the "smearing" reflections are actually being absorbed.

Jim C

[dvenardos]

Illustrates that a lot of the "smearing" reflections are actually being absorbed.

Thanks, that makes sense.
Looks like I have a huge amount of spectral decay.
edit: or I guess that would be a small amount of spectral decay as in a lot would be good?

[rumonkey2]

Cool thread dv...

I've been wanting to do REW. Just been putting it off for a few reasons.
Mainly, trying to find the time I can dedicate to "playing" with it & the learning curve. Plus, I need to get a soundcard for my laptop. It's one of those things I need to spend a whole day with +, and the timing has just not been right.
I still want to do it & get PEQ...just gotta focus my efforts!!:rolleyes::yes:

I imagine it will happen once I have SCAMPS!!!:fryingpan:

[dvenardos]

I've been wanting to do REW. Just been putting it off for a few reasons.
Mainly, trying to find the time I can dedicate to "playing" with it & the learning curve. Plus, I need to get a soundcard for my laptop. It's one of those things I need to spend a whole day with +, and the timing has just not been right.
I still want to do it & get PEQ...just gotta focus my efforts!!:rolleyes::yes

Yeah, it definitely takes a day playing around with it to get everything working right and figure out how to use it.
I went with this soundcard it is very flat down to 20 hz and has a correction file.

http://www.americanmusical.com/Item--i-BEH-UCA202-LIST

If you just want to do subwoofer calibration the ratshack meter is fine, but if you want to do full frequency analysis then this is the recommend meter:

http://www.americanmusical.com/Item--i-GAA-CM140

I pulled the port plug and although I lose a couple hz it gets rid of that 18hz peak. I think it is a much better looking graph and should fix my LFE problems.
The graph with two lines shows the before and after of pulling the port plug.

[Josuah]

Room treatments help with decay and flattening out your frequency response, but you're still going to need a PEQ for the sub. Room treatments first though. Remember you need really deep/thick treatments for the sub frequencies, and not only in the corners.

[rumonkey2]

Yeah, it definitely takes a day playing around with it to get everything working right and figure out how to use it.
I went with this soundcard it is very flat down to 20 hz and has a correction file.

http://www.americanmusical.com/Item--i-BEH-UCA202-LIST

If you just want to do subwoofer calibration the ratshack meter is fine, but if you want to do full frequency analysis then this is the recommend meter:

http://www.americanmusical.com/Item--i-GAA-CM140

I pulled the port plug and although I lose a couple hz it gets rid of that 18hz peak. I think it is a much better looking graph and should fix my LFE problems.
The graph with two lines shows the before and after of pulling the port plug.

Thank you for those links!! Gonna order this soundcard this week!!

[Josuah]

That Galaxy CM 140 only has a frequency range of 31.5Hz - 8kHz. That doesn't seem good....

I use a Behringer ECM8000. It's not great, but it's okay. And cheap.

[dvenardos]

That Galaxy CM 140 only has a frequency range of 31.5Hz - 8kHz. That doesn't seem good....

I use a Behringer ECM8000. It's not great, but it's okay. And cheap.

They have correction files for it. It is what they recommend if you don't already have a SPL meter.

http://www.hometheatershack.com/forums/rew-forum/16070-galaxy-cm-140-a.html

http://www.hometheatershack.com/forums/spl-meters-mics-calibration-sound-cards/16141-newbie-mike-versus-spl.html

Thank you for those links!! Gonna order this soundcard this week!!

I had them price match to B&H (was on sale for $25) when I ordered and got free shipping because I was ordering the SPL at the same time.

http://www.bhphotovideo.com/c/product/422094-REG/Behringer_U_CONTROL_UCA202_UCA202_USB_Audio_Interface.html

[dvenardos]

After an evening of listening it was apparent that I don't like the hopped up bass of a house curve. I lowered the level of the sub and powered woofers by ear. I will have to see what it looks like when I run measurements again, but appears that I really do like a flat frequency response.

[dane]

That Galaxy CM 140 only has a frequency range of 31.5Hz - 8kHz. That doesn't seem good....

I use a Behringer ECM8000. It's not great, but it's okay. And cheap.

So what's better than an ECM8000 that doesn't cost an arm and a leg?

curious,
..dane