First Sub measurements, What does it say?

**playitbyearmusic** · **03-03-09, 06:38 PM**

Hey Room,

After months of preparing for this day, it has finally come. The first measurements of my KRK V12S Sub. Mains are KRK's V*'s Series 1. Room dimensions are 14' x 13' x 8'. Early reflection points (left and right walls), ceiling & front wall covered with 2' x 4' x 4" thick OC 703 plain. All four corners of room (ceiling to floor) 6" OC 705 FRK paper facing into room. Floor is Red Oak hardwood. Here are some pics of measurements. Can someone tell me am I on the right track, do I need EQ, should I use more absorption, etc. What does this graph say? This measurement has no smoothing. This is raw data. When 1/3 smoothing is applied, boost at 45 Hz, after that not spiky at all. Name: 80-90hz sub xover.jpg
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Name: 80-90hz sub xover.jpg
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**Wayne A. Pflughaupt** · **03-03-09, 08:20 PM**

Yeah, you need EQ to bring down that peaking area between 35-80 Hz. Alternately, you might try some different locations.

Regards,
Wayne

**NCDave** · **03-03-09, 08:33 PM**

Do you have a double-crossover applied? The specs on that sub are better than what you are showing. If you already are crossing over in the AVR, don't do it again on the sub. Turn the sub crossover all the way up. The rolloff looks like it's starting too soon. Is it set lower than 80Hz in the AVR?

Your plot makes your sub look like a one-note-wonder. I'm not familiar with that sub (I just looked it up), but it's not supposed to look that bad.

Your room and sub location could be contributing a lot to building the mountain in the plot. At the same time, your extension looks pretty poor. Clearly, the present sub location is not helping the response in the room at all. Are there other sub locations you could try?

I'd think I'd try to get more output on the sides of the mountain before resorting to chopping the top of the mountain with a lot of EQ.

**Wayne A. Pflughaupt** · **03-03-09, 08:38 PM**

Quote:

At the same time, your extension looks pretty poor.

This is not a home theater sub, so it's doubtful it was designed to dig deep.

Regards,
Wayne

**playitbyearmusic** · **03-03-09, 08:53 PM**

No AVR. This is a home studio. Other placement possibilities is under the listening position table but wouldn't that cause waves to build up under the table? Right corner of room is also another place for possible placement, however I would be blocking the vocal booth. I'm also going under advisement from several adds that the sub shouldn't b placed behind the listening position. It should be either left of, right of, or in the middle of the mains. Is this true? Also, believe it or not, no one note bass. I hear notes in basslines very well!! I'm gonna try other placement possibilities. Will post results tomorrow. Please look out for future measurements, Will b back tomorrow. Gonna try all around the room and see what sounds the best and looks the best. Thanks you guys for input.

PlayItByEar!!

**Wayne A. Pflughaupt** · **03-03-09, 10:29 PM**

Quote:

playitbyearmusic wrote:

I'm also going under advisement from several adds that the sub shouldn't b placed behind the listening position. It should be either left of, right of, or in the middle of the mains. Is this true?

Probably should ask that on a Forum for home studio enthusiasts - most of us here, our knowledge of them is minimal.

Be looking forward to seeing your next graph.

Regards,
Wayne

**DrWho** · **03-05-09, 11:58 PM**

Can you first post a response without the xover engaged (or turned up as high as it will go)?

It's looking to me like your sub might be employing an EBS alignment and definitely has a highpass filter for controlling excursion below the tuning point. If this is the case, then you'll probably want to use a low shelf filter to lift the response below 40Hz.

You'll also want to measure just the mains alone and then a 3rd measurement of the mains + sub. The goal is to line up the xovers such that 6dB of summation at the acoustical xover point results in a flat passband.

**Ricci** · **03-06-09, 03:10 PM**

I'd try playing around with different positions in room. Also the room length of 14' combined with nearly the same width of 13' will likely cause some strong resonances and nulls. Possibly the big pile up around 40-50hz is attributable to this.

**playitbyearmusic** · **03-07-09, 05:50 PM**

Sup Dr. Who,
I'm in studio now running more tests. So your saying measure the sub with low pass filter to max? Sub is KRK V12 S. Frequency response is 39Hz - 130Hz. Open low pass to allow the whole 39 - 130 through?

**playitbyearmusic** · **03-07-09, 05:56 PM**

Yeah, thanks. I was thinking that too. My room is treated with OC 703 and 705 FRK. The only wall not treated is the real wall (behind the listening position). Do you think some treatment on the rear wall will help any or not. I still have 6 broadband absorbers left to make. Even my ceiling is treated.I tried speaker placement and the only spot I get the best results is either under the listening position table or to the left of it. Gonna run a test now with low pass wide open. Be right back..

**playitbyearmusic** · **03-07-09, 06:10 PM**

Okay. Here are some posts with Phase 0', low pass fully open (39 - 130) 81 db SPL.

**playitbyearmusic** · **03-07-09, 06:21 PM**

low Pass fully open close in corner.mdat

3ft to left of listen fully open.mdat

Here are the o' phase, fully open low pass (39 - 130), 81 db SPL. Somebody, talk to me. What do I need to do. Is this response okay ovearall in regards to smoothness from 40 Hz to 100 Hz? I know there's variations in amplitude but is it pretty smooth? I'm measuring a studio, not home theater. According to Ethan Winer, he states that it's allright to use a little EQ for correction as long as its below 60HZ. True or not.? I know because of the size of my room I'm not gonna get the best frequency response, however, the room sounds so much better with the additives I've put in the room. Someone, help me get this response as smooth as possible., please.

Thanks to all,
PlayItByEar

**playitbyearmusic** · **03-07-09, 06:26 PM**

low Pass fully open close in corner.mdat

3ft to left of listen fully open.mdatWhat am I doing wrong? Pictures wont open..

**DrWho** · **03-07-09, 07:33 PM**

Quote:

playitbyearmusic wrote:

Sup Dr. Who,
I'm in studio now running more tests. So your saying measure the sub with low pass filter to max? Sub is KRK V12 S. Frequency response is 39Hz - 130Hz. Open low pass to allow the whole 39 - 130 through?

Yes.

Post one plot with just the subwoofer with no xover.
Post another plot with just the mains alone.
And finally post a plot with the mains+sub (with no xovers).

Btw, that "frequency response" doesn't have a tolerance on it, in which case it's usually assumed to be a 10dB window, which would fall in line with the guess I'm making about its alignment.

Also, can you display your screenshots without any smoothing applied? It will be easier to identify room effects that way.

**thewire** · **03-08-09, 11:29 AM**

When you measure make sure that you measure from 0Hz - 200Hz. Try placing some further distance from yourself and the mic also if possible, and check for some noise in the room.

**playitbyearmusic** · **03-09-09, 07:57 PM**

Okay, Playitbyear is back,

Here are some measurements of Sub only, no Xover, 0Hz - 200Hz, Phase 0', several positions within my 14' x 13' x 8' home studio with 75% of walls and ceiling covered with OC 703 & 705 FRK in corners of room. I know you said post sub, mains, and sub + mains but was anxious of feedback about my sub KRK V12 S.

Name: 12" from bass trap left rear corner.jpg
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Name: 12" from bass trap left rear corner.jpg
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Name: left rear corner of sub in middle of bass trap.jpg
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Name: 2 ft from center of bass trap.jpg
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Name: sub no x pushed back 6 - 8".jpg
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Name: sub only no xover i think the best.jpg
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Name: 6" from middle of bass trap.jpg
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Name: sub no x 38% 3ft.jpg
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Name: 5 ft left 1 foot back list.jpg
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Name: sub no x pushed back to wall 4ft left.jpg
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Tell me something. What am I looking like? Good, Bad, all right? What needs to be done. Help. Ready to start making some money. all criticism and suggestions welcome.
Thanks in advance. Hold mouse over pic for position of sub when measured. All measurements are no xover, sub only, measured at 0Hz - 200Hz, low pass opened all the way. 39Hz - 130Hz.

PlayItByEar

**brucek** · **03-09-09, 08:33 PM**

REW tip: Use the MEASURED tab to compare graphs. It's very difficult to compare when they're all on different plots.

brucek

**playitbyearmusic** · **03-09-09, 08:36 PM**

Thanks Brucek, Here it is.

Name: measured tab no smoothing.jpg
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**playitbyearmusic** · **03-09-09, 08:39 PM**

And here's measured tab w/ seperated traces.

Name: measured tab seperated traces.jpg
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**brucek** · **03-09-09, 09:53 PM**

As suspected, they aren't different enough to matter.........

brucek

**thewire** · **03-09-09, 10:31 PM**

playitbyearmusic, does your voice sound natural when walking from outside the HT room to inside it? We don't want to add too much absorption making the room sound unnatural. This was been a real problem with home theaters in the last five years but it is getting better. I'm sorry but I can't tell what the graphs are saying.

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