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Hi Sikus, You were right!

I have not considered the fact that the REW output file uses the current regional locale for it's decimal separator. Now the tool is updated and should work better.
I will upload the tool somewhere later tonight (gitub has disabled hosting executables).

Per Ivar
 

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Not sure if I'm on the right thread but for REW if I use only an spl meter what kind if info can I get on the sub?
 

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Hello Folks and Thank You for the tips. I am a small studio owner searching for the most effective way to calibrate my studio monitors to my room. Short of the expensive treatment option. I look forward to browsing through the forum and discovering new tips and ideas.
 

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One thing I've come across is that upon initial measurement it gives me the signal too low at -90.3 db over and over again no matter how much I boost reference mic input or master volume. This of course after setting soundcard preferences to match my setup and checking to make sure the speakers (rather than subwoofer) was selected. "Check levels"...level is low -129.4. It isn't low I'm sure, it doesn't seem to be responding to the dbx reference mic set at the listener position.
 

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Discussion Starter #47
One thing I've come across is that upon initial measurement it gives me the signal too low at -90.3 db over and over again no matter how much I boost reference mic input or master volume.
That indicates REW isn't getting a signal to measure. Could be that in the soundcard preferences REW has been told to use the other channel, or you are on a Mac and using a Firewire or multichannel USB card (in which case you need to check the sticky thread on getting around Java problems on OS X), or a wiring problem etc. In any event best starting a separate thread and including information about your setup rather than posting in the REW tips thread, I'll remove the posts from this thread in due course.
 

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Got it John, Thank You! Yes a Mac. I'll look into it further here in a bit. I briefly went over some of the help menu but apparently missed it. Not uncommon these days! :foottap:
 

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Hi Guys.
I am new here so please excuse me if this tip was mentioned in a different thread (but thread with tips for REW is here). Please also excuse my english :)

My tip is for quick calibration of the SPL in REW with digital multimeter and microphone with known sensitivity in V/Pa (and cable of course). Calibration enables you to measure characteristics in absolute values and for example measure the loudspeakers distortion acording to SPL...

1) Run REW generator, set frequency 100 Hz (area where almost each digital multimeter has maximum accuracy), level as desired and mic gain as desired
2) Measure the voltage level at the output (or input of the microphone)
3) Calculate the SPL corresponding to measured voltage as follows:
Equivavelnt SPL = 20*log(Voltage measured/mic sensitivity) + 94 dB

example:
SPL = 20*log(1.6 Volts / 0.010 V/Pa) + 94 dB = 138 dB

4) set the generator to 1 kHz (frequency where all curves are overlaping) and keep it runing
5) run the SPL meter and start calibration, chose "use the external signal"
6) into the field for SPL readout type the calculated level, e.g. 138 dB and confirm finish

Now you can measure in absolute values, because this calibration is used for all the measurements!

PS: I have noticed that digital level in dBFS are different in some application even if the electrical level is the same (asio and java drivers give the same values)....
 

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I have been using Holmimpulse in the past and just got REW a few days ago. Wow! What an amazing program! The setup was flawless and very easy - I got from install to measurements with a UMM-6 mic literally in minutes. I am starting to work on getting CSD plots and decay data but not sure how to setup the parameters to enable a good measurement as I seem to be measuring the room decay of several hundred milliseconds. How do I set the gating to enable looking at just stuff before 3 to 5 milliseconds? Sorry if this question has already been covered elsewhere.
Thanks,
xrk971
 

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Hi xrk!
Try the IR windows icon (on the top between info and SPL meter). You can also change the default window lengths (and also Analysis dafaults) under Preferences - Analysis. There you can set up your favorite setup (window type and length, smoothing and many more)!

Enjoy :)
 

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OK, thanks. How far away from the driver should the mic be for a CSD measurement and what gate settings do you typically use?
 

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Discussion Starter #54
I am starting to work on getting CSD plots and decay data but not sure how to setup the parameters to enable a good measurement as I seem to be measuring the room decay of several hundred milliseconds. How do I set the gating to enable looking at just stuff before 3 to 5 milliseconds?
Show the controls for the waterfall graph by clicking the gear icon at the top right of the graph, then set the Time Range, Window and Rise Time to suit the range you are interested in - e.g. 10 ms for time range and window and 1 ms for rise time are reasonable starting points if looking at driver behaviour.
 

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Thanks for the steps on how to do this. Do you have a recommendation for distance mic needs to be away from cone surface?
 

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OK, thanks. How far away from the driver should the mic be for a CSD measurement and what gate settings do you typically use?
Sorry for my misunderstanding, JohnM was right :). Regarding the measurement distance - If you want to measure the whole loudspeaker, you should be in the "free field", which is further than the biggest dimension of the baffle (typically the diagonal)...
But for special purposes, as analysing the speaker at particular point, you can be closer.

PS: the CSD Mode tick in the "Graph control" can be handy, but I belive that you have spotted that already.
 

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Forgive this beginner question but can REW be run with my Oppo 105 player connected directly to my amps or does it have to be through a prepro? Thanks.

Matt
 

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Discussion Starter #58
Forgive this beginner question but can REW be run with my Oppo 105 player connected directly to my amps
Yes, it could be run that way, the audio output from the computer would need to be connected to one of the Oppo's inputs so either via HDMI or a coaxial or optical digital audio connection.
 

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Yes, it could be run that way, the audio output from the computer would need to be connected to one of the Oppo's inputs so either via HDMI or a coaxial or optical digital audio connection.
Thanks John. I tried hooking up my front channels directly to my 2channel amp and the results sounded really nice but when I hooked up the rest of my 7.1 system directly to my other amp, the results were not that good. I will probably just go back to the way I had things which is through my Emotiva UMC-200 prepro.

The main thing I am interested in with REW is looking at the frequency response of my dual subs. They sound really good right now but I have always been curious as to what is actually going on with them and my room. Thanks for the reply.

Matt
 

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Hello , i,m also new here and hope i,m not asking for help in the wrong forum, i do apologize if thats so .
I have a Anthem D2v 3D running with the Arc room correction and 2 Danley DTS,10s connect to the Anthem via xls and then fed to 2 Behringer EP 4000 amps ,sounds good in music and movies.Arc does try to get the curve flat for the 2 subs but there is a big dip at around 45 Hz and it is this i would like to correct.
I have a new DSP 1124P ,a M audio midisport,and a Galaxy CM-140 and a HiTeC X-Mystique 7.1 Gold sound card. Never tried to get these in the chain .
There is so much information to read up on that it is a bit confusing at times ,i am no expert and would like to know the easiest way to let Rew trim my 2 subs to sound even better.
I would be very grateful if anyone could give me some advise.
Thanks so much .:help:
 
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