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Discussion Starter #1
Hi all,

I am new to this and I just spend 4 hrs to try to follow the doc but I cannot even pass the Soundcard and mic cal part yet. There are differet situations that the docs did not mentioned clear based each needs. Can someone confirm my connection is right for sound card and mic cal process ? Please help me started.. My ultimate goal is to dial my subs (running stereo) for my 2 channel music need. Thanks.

I started by following the connection document and my first question is confusion of the connection with my SB Live 24 external. Is the line in plug at rear is where I should plug in my 3.5mm adapter (Splitter to RCA) or should I use the plug labeled mic/in in the front of the SB ? I use the front speakers L/R plug on my SB (not sub nor rear speakers L/R plugs) as the output for this setup and it is connecting L (white RCA plug) to my left channel in my preamp . Am I did this right ?

In the doc for sound card calibration, it only started connect the output directly to the input, I assuming it is still using the whole connection setup in place, ie. going throught both 3.5mm to RCA splitter/adapter ? the my CM-140 still connecting at the left (the white RCA plug on the 3.5mm adapter) on the input side (I am using the line-in plug at the back), I also has the splitted output connected to my preamp of the left channel. Basically following the connection diagram.

At this stage, I just want to get my SB and Mic cal first before I mixed my BDF 1124P into the picture.
Did I do this right ? When I click measure button, I balance the line in/mic in input to match the output as directed by REW, then next again, the measure head room windows pops up with "ready to measure bar". However there is no 1K tone heard from my system even I crank up my preamp vol to mid level..
The measure bar in that window does not move at all seem like is waiting for some tone or something to start.

What did I do wrong ?

Thanks in advance..:wits-end:
 

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I have the same soundcard. Did you try and measure more than once? Sometimes if I use the RTA/Generator or cancel a measurement, the next one will not work, but will work if I just measure again. If it is soundcard related you may need to restart REW. That would be in the case some driver settings may have been changed during the setup proccess, or maybe the USB connection became loose for a very short time. Is there a message that appears when you start to measure, but nothing happens?
 

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Is the line in plug at rear is where I should plug in my 3.5mm adapter (Splitter to RCA) or should I use the plug labeled mic/in in the front of the SB ?
The line-in jack on the SoundBlaster is where a 3.5mm splitter will plug into. The splitter breaks the stereo jack into its left and right channels. You will be using the right channel exclusively for REW. The left channel will be unused.

I use the front speakers L/R plug on my SB (not sub nor rear speakers L/R plugs) as the output for this setup and it is connecting L (white RCA plug) to my left channel in my preamp . Am I did this right ?
The front jack on the SoundBlaster is the where another 3.5mm splitter will plug into. The splitter breaks the stereo jack into its left and right channels. You will be using the right channel exclusively for REW. The left channel will be unused.

In the doc for sound card calibration, it only started connect the output directly to the input, I assuming it is still using the whole connection setup in place, ie. going throught both 3.5mm to RCA splitter/adapter ?
The first order of business before you do any connecting of mics or receivers, you must preform the soundcard calibration. It requires a single RCA cable between the right channel line-in and the right channel line-out. As I said above, the left channel is never used. You always select the right channel on the REW settings page, and you never select the 'Use Left channel as calibration reference.
Once the soundcard calibration is complete and checked fro accuracy, you remove the loopback RCA cable so the mic and receiver can be connected.

The CM-140 is connected to the line-in right channel and the line-out right channel is connected to the AUX or CD input of your receiver or preamp with a splitter so that left and right channels can be driven. The receiver is placed in stereo mode with soundfields off, and mains speakers of the receiver are disconnected to test the sub.

Show me your soundcard calibration file graph before going any further in testing..........

brucek

P.S. I'm moving this thread to the REW forum.
 

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I started by following the connection document and my first question is confusion of the connection with my SB Live 24 external. Is the line in plug at rear is where I should plug in my 3.5mm adapter (Splitter to RCA) or should I use the plug labeled mic/in in the front of the SB ? I use the front speakers L/R plug on my SB (not sub nor rear speakers L/R plugs) as the output for this setup and it is connecting L (white RCA plug) to my left channel in my preamp . Am I did this right ?
Yes that is correct. Use the line out right analog connection. Be sure that the soundblaster enhancements (such as bass boost) are disabled in the creative console, or windows sounds mixer window. If you are using Vista that will require some extra setup so let us know.
 

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Discussion Starter #5
I mugg around with it further and get the measure going. This time, the green horizon bar moved all the way to the about 90% and gives the following message " The highest level in measured measurement is just -44.3dbfs. Much lower than it should be. Check input channel selection is correct. I checked the connection and out SB control both input and output is not muted. So far, I have not heard any sweep tone generated from either my main speakers or sub. I tried on both main speaker and sub options does not make any diff. Please help.. Thanks.
 

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Wow, I finally got the flat response curve after a few changes. Bass start rolling off the horizontal line at 50hz and dropped off quite rapiodly after 30 and 20. Top start roll off after 20hz and end at 27hz. I have my cal file with me. I have to send this cal file off to you or post it here if you can point me how to attach the file for uploading to this site ? Now my next step is to cal the mic ? I have the mic in normal room (no nose) ranging at about 45 -50db with C weighting slow setting. When I click the cal mic on the top part of the main REW screen, the reading is much highter than actually on my mic reading. Now it asked me to adjust the default 75db in a pop up window to reflect my actual mic reading which is about 47. I then go back to the setting screen and click on the check level button. The direction for me is to set my Preamp vol to hit 75db which I can hear a lot of pops can cracks noise with the clipping on the main db reading on REW. I can adjust the input and output in the setting option to try to reach 75db. Am I doing the right thing ? Even I lower the input or output on REW, i can still here some pops sound (I have the using sub instead of main speaker option).

Please help again.. Million thanks.
 

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if you can point me how to attach the file for uploading to this site ?
See here.

When I click the cal mic on the top part of the main REW screen, the reading is much highter than actually on my mic reading.
The Calibrate mic routine is not done until the Check Levels routine is complete in the Settings screen.

brucek
 

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Ok. I am not sure I have done the check level and mic cal right. But I just followed direction to the best I can. Here are the first mic cal file loaded graph and the first right channel sweep measure files.

Am I doing it right? I am still not connecting my 1124P in the chain yet. What is my next step ? Thanks again..

right channel sweep.jpg

mic cal file loaded graph.jpg
 

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The soundcard cal is fine.

Hopefully, you have loaded the mic calibration file into REW from our download page.

A few problems.

Your response graph is in Linear rather than Logarithmic mode. Set the mode to LOG rather than LIN using the Freq Axis button in the top right corner of REW.

A good practice is to start with the sub alone with the mains shut off (disconnected), so you can see how the sub reacts with your room without any other influence. Then, when you have the sub located and/or EQ'd the best you can, add the mains and adjust the subs phase to get the best crossover transition. You still have your mains turned on.

Your response graphs target level is low. It should be 75dB. When you run the Check Levels routine, the receiver volume is adjusted so the real SPL meter reads 75dBSPL at the listening position. Once the Check Level routine is complete you run the Calibrate routine. This simply sets the REW internal SPL meter to the 75dB set at the listening position. It syncs the REW SPL readout with the real meter. Your target will be ~75dB now for your graphs. Yours is much lower.

So, let's see the response graph again....

brucek
 

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Discussion Starter #12
Hi Brucek,

I followed your advice and bypassed my main speakers including my preamp and go directly to one of my subs at at time. When I setup the level check, it keep clipping out when I try to match up the reading on my CM140 to 75hz. What do I need to do next ?

I also loaded the CM140 cal file downloaded from this site. Thanks again. .
 

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I followed your advice and bypassed my main speakers including my preamp and go directly to one of my subs at at time
No, you want to go through your preamp and have the standard crossover set that you normally use. You simply want the mains shut off.

When I setup the level check, it keep clipping out when I try to match up the reading on my CM140 to 75hz.
Don't understand?

brucek
 

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Discussion Starter #14
Brucek, what I mean is when I increase the gain on my preamp to get the vol. up to match the reading of my CM140, REW showed the the message "Clipping" on the top screen near the SPL display there. I also hear the sweeping tone is broken whenever see the "clipping" sign freshing. Do I incease the vol in the preamp or actually in the sub to match the SPL reading ? Please advise..

Thanks!
 

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when I increase the gain on my preamp to get the vol. up to match the reading of my CM140
Again, I'm confused at what you're doing.

1. Run the Check Levels routine using an REW sweep level of -12dB and adjust the preamp until the reading on the CM-140 is 75dB.

2. Adjust the REW input level for a level between -18dBRMS and -12dBRMS.

3. Run Calibrate and set the internal REW SPL meter to match it to the CM-140 (~75dB)....

brucek
 
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