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First Measurement!

27K views 205 replies 12 participants last post by  jtalden 
#1 ·
So proud that I finally did my first measurement tonight. :)
How does it look guys?

SETTINGS:
- Marantz SR5005 processor with settings: mode LFE (so not the LFE+MAIN setting), LPF LFE 120Hz, crossover 80Hz, all speakers set on SMALL
- Teufel Theater 8 5.1 surround set http://www.areadvd.de/hardware/teufeltheater8.shtml
- acoustic room profesionally treated with a lot of big basstraps, 6 types of different big diffusers and a Sombra-D ceiling.

I have bought a Behringer FBQ1000 (same as DSP1124) which is now in bypass mode. Looks like there s some work to do for me in the low frequencies. Should I first start to play with settings like LFE mode and crossover freq in my AVR or skip this and go right to my Behringer?

For your info: my subwoofer phase is already set properly. Move my subwoofer or main speakers is not possible anymore (only a few cm)
 

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#3 ·
Here s some more interesting information (I think).
You see 11 measurements here:

1. crossover 40
2. crossover 60
3. crossover 80
4. crossover 90
5. crossover 100
6. crossover 110
7. crossover 120
8. crossover 150
9. crossover 200
10. crossover 250
11. crossover 250, main speakers disconnected

I think (and correct me if I m wrong) that I can draw the conclusion from this that my low frequencies comming from my subwoofer has problems at:
a. 20-30Hz range
b. 37-44Hz range
c. 54Hz dip
d. 58-69Hz range
e. 75Hz dip
 

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#5 ·
The MDATs you attatched require that that REW be on the PC

Just post/upload JPEGs of your graphs as others on the forum do and it will be that much easier for others to see what's going on in your room, and/or make reccomendations without having to install REW first.
 
#6 ·
There is nothing wrong with attaching the measurement files, it's actually more useful for someone else to analyze. It's up to whoever is posting.

What are you measruing with? It looks like you are using a mic without calibrating SPL. Have you made a soundcard calibration and do you have a .cal for your microphone?

Have you tried taking sweeps at multiple listening points?

I see you have your speakers set to small for trying those different crossover points, which is correct, but I'm not seeing as much of a difference in the crossover region for all of those different settings. That being said, your sub's phase setting could need to be adjusted for each different Xover point that you try. The sub by itself isn't too shabby, I would probably pick the 60Hz Xover setting and start playing with some EQ.
 
#10 ·
I m using a cross spectrum calibrated ECM8000 and loaded the narrow_band_response_0_degree.frd file. The ECM8000 is placed at listening/ear position in an exactly horizontal position. My Tascam 122 MKII soundcard is calibrated.

I have not tried multiple listening positions; first things first and see what s going on at this position. There seems something 'wrong' with the crossover freq control of mt AVR/subwoofer and I want to figure out first what is going on here before trying other positions.
 
#8 ·
It seems to me that your cross-over frequencies ( within the AVR ) aren't really working as expected .

ie; Usually as one lowers the crossover frequency, one expects to see some leveling of the mid-bass frequencies such as that 90 to 140hz hump ( this is assuming both your subs & speakers are effected equally by the crossover ) .

:sn:
 

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#9 · (Edited)
thxz for your reply EarlK.

I don t understand (yet) what you exactly mean. The red line is with the 250 crossover so in this case the red line untill approx 200Hz is ONLY the subwoofer right? With the 40Hz crossover everything from lets say approx 60Hz or so are my main speakers also correct? I see big differences in the red and aqua lines but you say that something is not right. I don t understand what you mean exactly.

The next information might be important too:
My subwoofer has a setting called 'THX SWITCH'. I can set this on 'FULL RANGE' and 'VARIABLE FREQUENCY CONTROL'. My manual says the following about this:
FULL RANGE: thx setting for all surround modes
VARIABLE FREQUENCY CONTROL: only when running the subwoofer in conjunction with a conventional stereo amplifier.

Next there is the 'FREQUENCY' knob on my subwoofer. My manual says about this:
Controls the crossover frequency between the subwoofer and the front speakers. This control is not active when setting the 'THX SWITCH' on THX MODE. When running the thx front/center speakers and subwoofer in stereo mode, set this control to 80Hz.

I have my settings as follows: THX SWITCH on VARIABLE FREQUENCY CONTROL and FREQUENCY KNOB all the way to the right which is 240Hz.

Could I be doing something wrong here?

You can find the manual of my speaker system here:
http://www.google.nl/url?sa=t&rct=j...PONfrqbWvOh8x5tsQ&sig2=pH1tMvlj-d8bj7451pmi0g.
On page 7 there is information about the subwoofer.

EDIT:
My phase control knob of my subwoofer ONLY works when setting the THX SWITCH on FULL RANGE so that s why I have it set on FULL RANGE. The manual of the subwoofer says the following about the PHASE KNOB:
This control is not active in THX MODE (thx switch) as the phase is controlled by the AVR.
 
#11 ·
What you are doing should work but is clearly not what was meant by the manufacturer. They meant for you to use the switch on "full range" as crossovers etc. are in your AVR. The "phase" would be controlled by the distance you set for the sub compared to the other speakers in the AVR--as well as the FBQ assuming it has delay functionality.

If it were me I would do that (switch on full range) and stick with 80Hz crossover. After setting level I'd play with subwoofer distance until the crossover region looked OK, then put that FBQ in there and start tweaking.
 
#12 ·
What you are doing should work but is clearly not what was meant by the manufacturer.
But the question is WHY it does not work. I hope EarlK has some idea.

They meant for you to use the switch on "full range" as crossovers etc. are in your AVR.
That seems odd. Phase (=delay) is a setting that s generally set in a subwoofer (correct me if I m wrong).

The "phase" would be controlled by the distance you set for the sub compared to the other speakers in the AVR--as well as the FBQ assuming it has delay functionality.
Normally a distance is set by the AVR (via Audessey) and after that you 'fine-tune' the phase(delay) with the phase setting of a subwoofer. At least, this is what I thought.
 
#13 ·
But the question is WHY it does not work. I hope EarlK has some idea.

That seems odd. Phase (=delay) is a setting that s generally set in a subwoofer (correct me if I m wrong).

Normally a distance is set by the AVR (via Audessey) and after that you 'fine-tune' the phase(delay) with the phase setting of a subwoofer. At least, this is what I thought.
I do care why things don't work, but usually find it expedient to move on to figuring out what does work, and when I do figure out what works I magically stop worrying so much about what didn't work.

Phase/delay is normally set in the subwoofer for a two-channel system. However since the relative arrival times of the sounds are important to creating the surround effects, multichannel AVRs have the capability to delay each channel individually (which is precisely what the distance settings for the speakers do). It's been this way for quite a while now (decades). Your subwoofer's switch is basically intended to be a switch between using it with a two-channel rig and using it in a multichannel system. While it's possible to make it work in a nonstandard fashion, I'd start with the simplest setup which happily coincides with the way the manufacturer intended it to be used in your type of system. I don't really find it odd. It's different from systems I have owned, but then I have never owned any THX certified gear either--and I don't really care where things happen as long as that which needs to happen, happens!

Maybe Audyssey is better (I don't know-- I just got my first AVR with Audyssey and have not yet switched it in) but in my experience automagic setups are not very good--they just don't always make sense in terms of the small/large settings and distance settings. I just use an SPL meter and a tape measure (though perhaps I should listen to each and assess how it sounds... that might be an interesting experiment). Anyway it's very common to manually adjust the relative distances between the speakers (which I mean to include the sub here) to achieve a desired effect -- for example to compensate for the acoustic delay of a horn subwoofer.
 
#15 ·
THX said:
But the question is WHY it does not work. I hope EarlK has some idea.


I assume that the presence of that large peak ( between 90 to 140 hz ) can be attributed to getting too much overlap between your sub-woofer & your main speakers .

Reduce the overlap sufficiently , and I assume that the offending peak will disappear .

You can reduce the overlap by implementing Johns suggestion ( by running subs via the standard arrangement ) or ( with the present setup ) by lowering the low-pass frequency on the sub-woofer to something much lower ( & then keeping the mains set to "small" , but maybe hipassed at 100hz ) . You'll need to experiment to see what works best . You might also want to stuff any ports ( if they exist ) on your main speakers .

The point is; there are a few ways to minimize over-lap between mains & subs / / use REW to discover what all the possibilities are ( by measuring each scenario ) . Don't be afraid to turn some knobs, make a measurement with REW to "discover" the results and then log your findings ( either on paper using hand written notes or committed to Word on your computer ) . Once everything is logged for reference, it becomes much easier to choose the best scenario .

:sn:
 
#18 ·
You can reduce the overlap by implementing Johns suggestion ( by running subs via the standard arrangement )
? What do you mean with this (Johns) suggestion exactly? I don t understand.

or ( with the present setup ) by lowering the low-pass frequency on the sub-woofer to something much lower ( & then keeping the mains set to "small" , but maybe hipassed at 100hz )
But the low pass freq. on the subwoofer is not active when I will put my subwoofer in FULL RANGE mode (see my reply to aackthpt two posts back)

You might also want to stuff any ports ( if they exist ) on your main speakers .
no ports on my mains :)

The point is; there are a few ways to minimize over-lap between mains & subs / / use REW to discover what all the possibilities are ( by measuring each scenario ) . Don't be afraid to turn some knobs, make a measurement with REW to "discover" the results and then log your findings ( either on paper using hand written notes or committed to Word on your computer ) . Once everything is logged for reference, it becomes much easier to choose the best scenario
ok thxz
 
#19 ·
THX said:
? What do you mean with this (Johns) suggestion exactly? I don t understand.
- I assume that John meant that you should go back to using a typical Bass Management implementation ( as is typically found within an AVR for running Subwoofers with Mains speakers ) .
- This is the scenario where the AVR applies (if you decide to choose 80hz as acrossoer point ) an 80hz HighPass filter to the Mains and an 80hz LowPass filter to the subs .
- I would call this approach, a "symmetrical" arrangement to bass management . It minimizes overlap at the expense of some flexibility .

- Currently ( from what I understand ), your arrangement is asymmetrical ( in that it allows you to choose 2 different frequency points for either of the HiPass or LowPass filters . )

- It is this arrangement ( & it's misuse ) that has caused ( I'm speculating ) the big hump between 90 & 140hz .

:sn:
 
#21 ·
I cannot set frequency points of the HiPass and LowPass filters. At least, I don t think I can. In my avr I can only set a crossover frequency (40, 60, 80, 90, 100, 110, 120, 150, 200 and 250). A crossover freq. is nothing more then my avr sending everything below eg. 60Hz to the subwoofer and everything above 60Hz to the main (with a rolloff). I have also a setting called LPF of LFE. I have set this on 120Hz. I think this applies to only the LFE signal (in a 5.1 track) and that this means that the subwoofer plays all the frequencies up to 120Hz from the .1 signal.
 
#23 · (Edited)
I did some more testing this morning (not yet your suggestion Wayne but the suggestion from EarlK to turn on and off some knobs and change some settings and make measurements). All the 8 tests I did are with different settings in my AVR and on my subwoofer (not played with the crossover of my AVR this time). All test where done with AVR in mode STEREO and subwoofer distance in AVR on the same 4.30m. In my next reply I have made a Excel for the ones that have Excel so that the differences in measurements are easier to read. As attachtment on the bottom of this reply there is also the .mdat file so you guys can take a closer look at the graphs and compare them easier. I hope the differences I made in all settings are clear for your guys.


graph 1
AVR:
- speakers SMALL
- bass setting: mode LFE
- crossover: 80

SUBWOOFER:
- switch on VARIABLE FREQ. CONTROL
- VARIABLE FREQ. CONTROL knob active and on 240
- PHASE knob active and on 80%

graph 2
AVR:
- speakers LARGE
- bass setting: mode LFE
- crossover: NOT SELECTABLE with above settings

SUBWOOFER:
- switch on VARIABLE FREQ. CONTROL
- VARIABLE FREQ. CONTROL knob active and on 240
- PHASE knob active and on 80%

graph 3
AVR:
- speakers LARGE
- bass setting: mode LFE+MAIN
- crossover: 80

SUBWOOFER:
- switch on VARIABLE FREQ. CONTROL
- VARIABLE FREQ. CONTROL knob active and on 240
- PHASE knob active and on 80%

graph 4
AVR:
- speakers SMALL
- bass setting: mode LFE
- Crossover: 80

SUBWOOFER:
- switch on FULL RANGE
- VARIABLE FREQ. CONTROL knob not active
- PHASE knob not active

graph 5
AVR:
- speakers LARGE
- bass setting: mode LFE
- crossover: NOT SELECTABLE with above settings

SUBWOOFER:
- switch on FULL RANGE
- VARIABLE FREQ. CONTROL knob not active
- PHASE knob not active

graph 6
AVR:
- speakers LARGE
- bass setting: mode LFE+MAIN
- crossover: 80

SUBWOOFER:
- switch on FULL RANGE
- VARIABLE FREQ. CONTROL knob not active
- PHASE knob not active

graph 7
AVR:
- speakers SMALL
- bass setting: mode LFE+MAIN
- crossover: 80

SUBWOOFER:
- switch on VARIABLE FREQ. CONTROL
- VARIABLE FREQ. CONTROL knob active and on 240
- PHASE knob active and on 80%

graph 8
AVR:
- speakers SMALL
- bass setting: mode LFE+MAIN
- crossover: 80

SUBWOOFER:
- switch on FULL RANGE
- VARIABLE FREQ. CONTROL knob not active
- PHASE knob not active
 

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#27 · (Edited)
THX said:
<snip> All the 8 tests I did are with different settings in my AVR and on my subwoofer (not played with the crossover of my AVR this time). <snip>
I note that all eight of those approaches were pretty a failure at reducing the offending peak ( the one between 90 to 140hz caused I think by having too much signal overlap between your sub & mains ) .

Since you are spread-sheet savy / I suggest that you make up a SS of all the permutations & combinations that you have tried to date / and then log the results for reference .

Note : you have yet to try Johns ( aackthpt ) suggestion of running the system normally / ie; using the built in crossovers from the AVR .

Is there some reason you don't what to go down that road ?

:sn:
 
#29 ·
I note that all eight of those approaches were pretty a failure at reducing the offending peak ( the one between 90 to 140hz caused I think by having too much signal overlap between your sub & mains )
I did those tests to see what differences I would get in the results and not really to see if the bump would go away. After all these measurements I already learned a few things. One of the things I learned is that the setting in a AVR with the SMALL+LFE/MAIN combination gives the exact same result as setting your AVR to SMALL+only LFE. This is because the 'LFE mode' (it s called different on various AVRs) only has effect when you set your speakers to LARGE. That is also why GRAPH 1+GRAPH 7 and GRAPH 4+8 look the same (because the settings are not different from each other although you would assume they are different). I have also learned that setting my speakers on LARGE is not even a option. One can ONLY set speakers on LARGE if the speakers are truly full range and by this I mean capable of 20-20000Hz (so eg. the b&w 800D :)).

When all this information I can already forget the settings I used in GRAPH 2,3,5,6,7 and 8. This leaves settings 1 and 4 (remember I am NOT YET talking about the crossover setting in my AVR!). As you can see in my excel the differences between the settings used in Graph 1 and 4 are the settings on my subwoofer. Graph 1 looks better than Graph 4 as you can see but (I think; and this is what I want to know/have to find out yet) this is because in Graph 1 I have set my subwoofer on VARIABLE FREQUENCY control which means (according to my manual) that the PHASE KNOB of my subwoofer is active. I already had my phase setup correctly because I was always using this (VAR. FREQ. CONTROL) setting. In Graph 4 I ve put my switch on my subwoofer on FULL RANGE which means that the PHASE KNOB is NOT active anymore (according to my manual). This means I will have to do a new graph4-settings-measurement with first looking for the correct phase with the distance setting in my AVR. After finding the correct phase I will have to get the same graph as graph 1 if I am correct which also would mean that I understand my subwoofer settings (which is: switch on VAR. FREQ. CONTROL, VAR.FREQ.CONTROL KNOB on max (240) and PHASE KNOB on correct value is the exact same as switch on FULL RANGE so VAR.FREQ.CONTROL KNOB and PHASE KNOB not active).

Since you are spread-sheet savy / I suggest that you make up a SS of all the permutations & combinations that you have tried to date / and then log the results for reference .
I m not THAT good with excel m8 :)

Note : you have yet to try Johns ( aackthpt ) suggestion of running the system normally / ie; using the built in crossovers from the AVR .
will try that tonight

Is there some reason you don't what to go down that road ?
reason is that I first want to understand what all settings (not the crossover!) in my AVR and on my SUBWOOFER do so I can first config. this all the right way. Only after this I m going to look into crossover and after that eq. my subwoofer with my Behringer FBQ1000.
 
#31 ·
reason is that I first want to understand what all settings (not the crossover!) in my AVR and on my SUBWOOFER do so I can first config. this all the right way. Only after this I m going to look into crossover and after that eq. my subwoofer with my Behringer FBQ1000.
Earl, isn't he using the AVR crossovers whenever he's using the "full range" setting in the sub? Graph 4 or 8 would have been what I was suggesting, if I am reading his stuff right

UltraII, do you have only one seating position? For my setup it makes a huge difference whether I measure in the center (left-right) of the room or of center by ~18 inches. Response in the exact center is wonky and makes for sub setups that I don't like. But I have two chairs in the front row, if I measure from the center of one of them (the ~18 inches off center) the sound in the room is much more pleasant. So, you might try testing some other listening positions.

Signal coming out of the AVR is the most unadulterated signal we can verify, so that makes sense where to start. In response to your question, you can only capture one channel at a time with REW. You connect the output of your interface to the AVR as usual, and the input on the interface from the pre-out rather than the mic. You will have to do the sub pre-out and the left, or right, pre-out on separate runs, but it's totally repeatable so it will work fine.

Also, you _are_ running with Audyssey EQ off, yes?

After that your sweeps using the mic again but with sub only and main only is a good idea.

Another thing that is often done is to run sweeps with the mic up close (like less than 12 inches) away from the speaker or sub (best with gating, but you can get something close-ish without I think). That will help you know what the raw response is without much room influence. That would give you a better idea of whether the raw speaker response is causing any of the FR anomalies (at which point you should just probably go ahead and equalize them).

After that, you are probably into acoustics problems. A diagnostic you can do is, if your "bass traps" can be removed, put the mic in a corner and run sweeps without/with them in place. That will tell you real quick-like how effective they are. Can you outline what your "bass traps" are?
 
#30 ·
THX said:
<snip>I did those tests to see what differences I would get in the results and not really to see if the bump would go away.<snip>
Fair Enough !

If you want to further explore what how things change on your outputs from your AVR ( with different mode selections ) then do what was suggested by JohnM & John ( which is feed your AVR a test signal and then bring back the relevant output from your AVR into REW to "see" & log the frequency changes ) . It is about the same setup as doing a soundcard calibration / but now including the AVR in the test circuit loop .

:sn:
 
#33 ·
John said:
<snip> Earl, isn't he using the AVR crossovers whenever he's using the "full range" setting in the sub? Graph 4 or 8 would have been what I was suggesting, if I am reading his stuff right. <snip>
A careful reading of the user manual might clear up the question ( OTOH, answers should be forthcoming by executing some "loopback" measurements from the AVR's outputs // which Sanders seems willing to pursue with REWs help ) .

Either way ( IMHO ), it's up to every owner of an AVR to figure out how the equipment they bought actually works .

If that comprehension isn't possible through self-study, then there is always the HTS AVR ( receiver ) Forum



:sn:
 
#36 ·
Not sure yet how to do the measurements with my AVR. Am I correct that I disconnect my ECM8000 and turn off my amplifier and only have to turn on my AVR? And I connect the main LEFT or RIGHT front pre-out to the 1/4'' jack line in of the Tascam 122 MKII and that s it?
 
#37 ·
Sander said:
Am I correct that I disconnect my ECM8000 and turn off my amplifier and only have to turn on my AVR? And I connect the main LEFT or RIGHT front pre-out to the 1/4'' jack line in of the Tascam 122 MKII and that s it?

Yep ! It's a lot like doing a soundcard calibration but now including the AVRs' pre-amp within the loopback circuit ( just don't include amplifiers ) .

For the sake of safety ( & developing some "best practices" for loopback measurements ) , turn off the 48Volt phantom supply on your soundcard ( though I doubt that it's present on your line level input jack / at least it shouldn't be ) .

:sn:
 
#38 ·
Yes, you disconnect the mic altogether. If you use a separate amp from the AVR it can be off (in fact it will be disconnected from the AVR). The jacks on the front panel are not pre-outs, they are inputs to your AVR. Just send the signal to the AVR as you have been (perhaps let us know how). Have the AVR in a typical mode like "stereo". Connect the left or right pre-out to the jack line in of the Tascam for the main channel sweep. Switch that (on the AVR) to the sub-out rather than left or right out. Do "check levels" as usual. Run a sweep as usual. Output from the sub out should look like the picture in the link I posted.
 
#39 ·
Yes, you disconnect the mic altogether. If you use a separate amp from the AVR it can be off (in fact it will be disconnected from the AVR).
check

Just send the signal to the AVR as you have been (perhaps let us know how).
At this moment I have the Right RCA output of the Tascam (on the rear of the Tascam) connected to the Right+Left aux input of my AVR. Do I leave it this way?

Have the AVR in a typical mode like "stereo". Connect the left or right pre-out to the jack line in of the Tascam for the main channel sweep. Switch that (on the AVR) to the sub-out rather than left or right out. Do "check levels" as usual. Run a sweep as usual. Output from the sub out should look like the picture in the link I posted.
So I first run a measurement with the Left (or Right) pre-out of my AVR connected to the Jack Line In (Left or Right) of the Tascam and after that run a measurement with the Sub pre-out of my AVR connected to the Jack Line In (Left of Right) of the Tascam?
Correct?
 
#40 ·
At this moment I have the Right RCA output of the Tascam (on the rear of the Tascam) connected to the Right+Left aux input of my AVR. Do I leave it this way?

So I first run a measurement with the Left (or Right) pre-out of my AVR connected to the Jack Line In (Left or Right) of the Tascam and after that run a measurement with the Sub pre-out of my AVR connected to the Jack Line In (Left of Right) of the Tascam?
Correct?
You would be better off for our purposes only connecting to the right in jack or the left in jack depending which channel you are going to be measuring. You will get much better results with measurement of one channel playing at a time, or else you get confounding combining effects between the two channels. In actual fact it probably doesn't matter for this test of the AVR, but it will matter when you get back to tests using the speakers.

Second part is entirely correct on the [REW] input side.
 
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