# Room Measurements. Sub + Sat



## Gson76 (Dec 18, 2006)

Hi moderators,

Is there any chance to let me post some of the plots of my room? (I think) I finally succeded to install all the needed software, make the mic corr etc. But, I can´t do it yet because I´m only at appr 5 posts...:wave: 

Thanks!
Martin


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## Wayne A. Pflughaupt (Apr 13, 2006)

You’ve passed five, Martin – go ahead and post your graphs! :T 

Regards,
Wayne


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## Gson76 (Dec 18, 2006)

Thanks!

Ok, here we go. REW rules, what a software, I´m truly impressed :clap: Please have understanding as it is my first time playing with REW. First pic shows the sub alone with LP filter active (24dB/oct) - exactly as I run it today. I´m not supprised as I can´t here much of the really low bass.








This is the sat's. (Pretty good extension for a 1,5 L cabinett with a 4" driver...) No HP filters. (I can't activate the HP filter in my receiver in Source Direct mode... So I allways run them full range as this is mode plays soooo much cleaner. I have tested the HP filter but I could´nt see much of a difference. It´s only a 6dB/oct HP filter fixed at 100Hz...








Both sub and sat. I´m worried about the 88Hz peak that (today) come both from the sat's (not much to do) and the sub.








Do I have to say that I need a 1124P fast? What do you say guys, can improvements be made? But I think that sub and sat will overlap quite alot without any sharper as a 12dB HP filter. Playing the sat's full range will cause phase problems between the sub and sat's - right?

I can´t do much how to place the speakers either (WAF). Speaker system KEF 2005.2 hooked up with Marantz SR5200. BTW, I can´t here any distorsion in the satellites even if I send signals full range to them. I never play very loud - live in a flat (with neighbours).

Love to hear from you:jump: 
/Martin


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## brucek (Apr 11, 2006)

A few questions....

Why are you measuring with a target at 60dB and not at 75dBSPL?

What is the solid black line on the chart located at 75dB?

Do you have the proper calibration file loaded for the specific microphone you are using?

Did you calibrate your soundcard?

brucek


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## Gson76 (Dec 18, 2006)

brucek said:


> A few questions....
> 
> 1. Why are you measuring with a target at 60dB and not at 75dBSPL?
> 
> ...


1. Don´t know why this was displayed...When I started REW recently the target was at 75dB.
2. That´s the corr line displayed, I think. That line came when I measured the sound card (SB24 Live).
3. I believe so. A pop-up window comes when I load REW.
4. Yes.


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## brucek (Apr 11, 2006)

> When I started REW recently the target was at 75dB.


Something went wrong for sure. Your target is at 60dB.

Try re-measuring at 75dB. 

brucek


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## Gson76 (Dec 18, 2006)

Brucek,

Ok I will do that when I find the time. But, do you think that it will matters (that much)?


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## Otto (May 18, 2006)

Gson76 said:


> Brucek,
> 
> Ok I will do that when I find the time. But, do you think that it will matters (that much)?


Hi, Martin,

It appears that, at this point, you are simply measuring your response before doing any processing. I don't think it matters what your target is for that step, but brucek is right that you will want to get that straightened out when you do the real measurement. Maybe I'm missing something else...

Did you get all the calibration stuff right? The cal of the SPL meter, etc.?

Can you increase output on your sub at all? It seems like your sub is quite a bit lower in output than your mains. Many of us shoot for the opposite of that. 

Good luck.


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## Gson76 (Dec 18, 2006)

Otto said:


> Hi, Martin,
> 
> It appears that, at this point, you are simply measuring your response before doing any processing. I don't think it matters what your target is for that step, but brucek is right that you will want to get that straightened out when you do the real measurement. Maybe I'm missing something else...
> 
> ...


Hi Otto,
What do you mean? (in red). Sorry, but I don´t understand.
I´m not sure that I got the cal of the SPL meter correct. But, a cal pop-up window comes when I start REW. (The response of the SB24 was relatively flat when I did the measure, before I did the cal.) After the cal a black line came:dontknow: 
Yes, I can increase the output if I want to, but I tried to get the "spikes" in the same level as the sat's. If I turn up the sub it sounds boomy. After I have cutted down the spikes I can increase sub.

//Martin


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## Otto (May 18, 2006)

Hi Martin,

I just mean that you are only measuring your response. And then we're just talking about it and analyzing it as humans. That target curve is where you want to end up after the BFD is done filtering, and will be used to determine such filters. When it comes time to set actually set filters, that target can be manipulated by you to get various results (you need a BFD to get anything actually done, but you can calculate the filters in REW before having the BFD, if you like). Since you're just measuring to see "where you are", the target is irrelevant and even could be removed from the graph. I think that's what's going on, anyway.

If you read through all the REW instructions, it goes through all the steps to get the system calibrated. Usually, we go at a target of about 75 dB. Once you get everything calibrated, there's a button called "Set Target Level". This will set that overall target based on the output from the sub before EQ. It usually ends up in the mid-70s. You can move it around if you want, but REW does a pretty good job of getting everything right on its own.

As to the cal file for the SPL meter, I'm not quite sure if it's right. If the mostly-flat black line in your picture is your SPL meter cal, I don't think it's right. You would know if you loaded the cal file. It's something that's available here on HTS. Find your meter and load it up under the "File" menu in REW. My apologies if you already did this, but I'm pretty sure there's more of a dip at the low end for the RS SPL meters than your black line shows. Actually, looking back again, I think you may have done the cal for the soundcard. The SPL meter cal is separate.

Unless your sub's volume level is high already, I would probably turn it up before doing the real REW mesaurement. If you get spikes like those in your mains, that's OK. We're going to tame those with the BFD. Plus, your sub level is quite a bit lower than your mains. How does it sound now from your point of view?


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## Gson76 (Dec 18, 2006)

Otto said:


> Hi Martin,
> 
> I just mean that you are only measuring your response. And then we're just talking about it and analyzing it as humans. That target curve is where you want to end up after the BFD is done filtering, and will be used to determine such filters. When it comes time to set actually set filters, that target can be manipulated by you to get various results (you need a BFD to get anything actually done, but you can calculate the filters in REW before having the BFD, if you like). Since you're just measuring to see "where you are", the target is irrelevant and even could be removed from the graph. I think that's what's going on, anyway.
> 
> ...


Otto,
Thank you for your input, it starts to clear up a little bit in my brain...
Your right, the black line is the sound card cal :duh: I have not done any cal of my JTS-1357 digital SPL meter since I can´t find any corr file to this unit. I have read that it´s relative flat, but it will shurely drop around 2 dB at 20Hz???

If I had turned up the sub any higher REW had informed me that the signal had clipped. I tried this. 
I don´t understand how I can tame the spikes in my mains since I only will hook up the BFD to my sub?

The sound is ok on certain music, but if the music contain a lot of bass of a specified tone, it will sound boomy. When it sounds boomy I decrease the sub and ofcourse it starts to sound a little bit thin :sad2: Can´t wait to get the BFD anylonger. The sad thing is that I can´t find a new one :explode: 

BTW, I have left the Sound Direct mode and hooked up the speakers as a normal setup. I.e the 5 sat's are running as "small" (-6dB 100Hz) and the sub is connected from the sub-out with the comfortable option to in/decrease the sub from the listening positon.

BR/Martin


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## Gson76 (Dec 18, 2006)

brucek said:


> A few questions....
> Why are you measuring with a target at 60dB and not at 75dBSPL?
> What is the solid black line on the chart located at 75dB?
> Do you have the proper calibration file loaded for the specific microphone you are using?
> ...


Hi Brucek,
Soundcard calibrated and file is loaded when starting REW. C-weighting active on meter, no futher calibration needed on JTS-1357 dig. SPL meter... Target set to ~70-75dB. (If it´s higher it starts to shake and make noises which probably will affect the measured data).
BTW, I bought a brand new FBQ-2496 yesterday :bigsmile: It was time to walk the long line  
Sub alone without any PEQ.








After setted around 10 filters I got this look. Now I´m getting somewhere :T The FBQ is awsome :heartbeat: I´m addicted big time :T 








Now adding the satelites (stereo) and 4 more filters :whistling: I´m sure you could have done this by 6-8 filters, but hey I´m new and I have 20 filters/channel :innocent: The overall sound is much better. The bass is cleaner, almost as the sub is not activated, it´s scary. Below pic is the result, but I increased the sub by 3-4 dB after this setting. I believe I´m aiming for a house curve as well.


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## brucek (Apr 11, 2006)

Looks good Gson76. 

Hopefully the JTS-1357 digital SPL meter has the same output characteristics as the CM140 and as such doesn't require a calibration file. You do have to have the C-Weight box checked though as the meter would have a C-weight output like the CM140.

I'm sure it sounds a lot better than the original plot you show....

brucek


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## Malice (May 1, 2006)

I'm curious about how the sub on its own with filters produces a SPL of 65db at 30Hz, the satellites on their own produce diddley squat at 30Hz, and yet combined with 4 more filters you have a 30Hz SPL of nearly 80db. I hope you're not boosting your lower frequencies by 15db as you could run into headroom problems when running movies for real.


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## Gson76 (Dec 18, 2006)

Malice said:


> I'm curious about how the sub on its own with filters produces a SPL of 65db at 30Hz, the satellites on their own produce diddley squat at 30Hz, and yet combined with 4 more filters you have a 30Hz SPL of nearly 80db. I hope you're not boosting your lower frequencies by 15db as you could run into headroom problems when running movies for real.


Hi Malice,
I was able raise the total output of my sub with almost 15dB because of all the filter cutting of my nasty peaks. As you can see on the graphs, this did alot of good stuff with the bottom end plus that the sub does´nt sound near as boomy as before :T (I did a slight filter increase at 25,3 and 47-49Hz, thats all).

Have´nt listened so much after the installation of the BDF yet, but planning to do so during the weekend. I´ll see if this tweeking had a negativ effect on head room or not...

BR/Martin


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## tdamocles (Sep 23, 2006)

Gson76 said:


> I was able raise the total output of my sub with almost 15dB because of all the filter cutting of my nasty peaks.


Me thinks you should cut a little more to get that bottom up a little more and see how it sounds. Might as well....You got this far....Go for the gusto! By the way, what sub are you using? Extension below 20hz looks nice and flat....

I had the same problem as you. I corner loaded my sub and all it did was exaggerate 30hz and 55hz areas by at least 15db. I couldn't put the sub anywhere else because of room contraints.


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## MACCA350 (Apr 25, 2006)

tdamocles said:


> By the way, what sub are you using? Extension below 20hz looks nice and flat....


I was just wondering this, Gson76's profile says he is using the KEF 2005.2 speaker system, which uses this sub The Fq response stated on the sub is 30Hz-140Hz.

So my question is how can you get near flat response with this sub to 15Hz without increasing distortion or pushing the sub past its limits? Either the graphs are wrong or there is a lot of distortion at those frequencies. I would caution Gson76 against pushing your sub past its capabilities or you may end up with a new doorstop.

cheers


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## Gson76 (Dec 18, 2006)

MACCA350 said:


> I was just wondering this, Gson76's profile says he is using the KEF 2005.2 speaker system, which uses this sub The Fq response stated on the sub is 30Hz-140Hz.
> 
> So my question is how can you get near flat response with this sub to 15Hz without increasing distortion or pushing the sub past its limits? Either the graphs are wrong or there is a lot of distortion at those frequencies. I would caution Gson76 against pushing your sub past its capabilities or you may end up with a new doorstop.
> 
> cheers


I think the specification 30-140Hz is within a -6dB range... Which means that 25Hz is around -8dB and 20Hz at -11dB or something. This is only my thoughts though. I´ve been reading some tests were it had extension to around 15Hz. So, after I decreased all the peaks I was able to push up the bottom end beyond the specifications. This will ofcourse push the output limit potential, but I am never listening very loud. This tweek really works, the bottom end is beyond my imagination now and the sub is´nt even put in a corner :T 

Think of it like this. You cut as the green line and then increase the total output of the sub signal. This will push up the bottom end quite good :yes:


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## MACCA350 (Apr 25, 2006)

Gson76 said:


> I think the specification 30-140Hz is within a -6dB range... Which means that 25Hz is around -8dB and 20Hz at -11dB or something. This is only my thoughts though. I´ve been reading some tests were it had extension to around 15Hz. So, after I decreased all the peaks I was able to push up the bottom end beyond the specifications. This will ofcourse push the output limit potential, but I am never listening very loud. This tweek really works, the bottom end is beyond my imagination now and the sub is´nt even put in a corner :T
> 
> Think of it like this. You cut as the green line and then increase the total output of the sub signal. This will push up the bottom end quite good :yes:
> View attachment 1806


If you have the sub calibrated to the Dolby specs with this flat response, your asking it to produce 115db(at your listening position) when the peaks hit all the way down to below 15Hz. I'm sorry but no matter what you do you cant make a sub do more than it can without sacrificing something(ie distortion/bottoming out). Try playing WOTW chapter 4/5 you'll soon find the limit. Unless it has built in protection I'd use a subsonic filter somewhere below 30Hz so the sub doesn't pop on dynamic material. 

Even my 5.5K DD15 can't do 115db at 15Hz, the built in protection prevents it from even trying this. I'm not trying to be rude, I'm just trying to warn against the possibility of damaging your new equipment when the dynamics hit

cheers


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## Gson76 (Dec 18, 2006)

Thanks for the advice, but as I stated earlier, I never push my system very hard (have to respect my neighbours...) And I really love that nice subsonic wibes, but who knows I could end up with a melted amp in my subwoofer :blink: Additional to say; This is fun now, but maybe I will change my EQ-settings in a near future ?


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