Home Theater Forum and Systems banner
1 - 20 of 30 Posts

·
Registered
Joined
·
93 Posts
Discussion Starter · #1 ·
I have an art dual mic preamp with an onkyo sound card and I am lost as to how I should be setting this up?





Do I need to run an RCA cable from the "RCA IN" on the sound card to a 1/4" mono TS adapter into the preamp? Should I plug the cable into the Left input or right input? or should the cables go into the monitor output? If so left or right? Then do I run RCA cables from the sound card to the proccessor? Or should I be using the mic and headphones input out put?

Also what gain should I be setting the dials on?

Sorry for the noob questions, but I am stumped.
 

·
Premium Member
Joined
·
6,711 Posts
The USB Dual Pre is a soundcard itself, so you would not need the Onkyo with it. Turn the monitor mix knob all the way to the right, to "computer", that way the monitor outputs will have the signal generated by REW on them. REW generates the same signal on left and right, so you can use either monitor output or one channel of the headphone output, they all carry the same signal. If you have a line level source (such as an SPL meter) you would need the gain of the USB Pre input turned around to 0dB (which is unity gain), if you have a mic of some sort the gain will need adjusting according to the mic.

If you are using an SPL meter as the source you could also use the Onkyo on its own, with the SPL meter connecetd to the R channel on the line in and the line out R channel connected to an input on the receiver.
 

·
Registered
Joined
·
93 Posts
Discussion Starter · #3 ·
The USB Dual Pre is a soundcard itself, so you would not need the Onkyo with it. Turn the monitor mix knob all the way to the right, to "computer", that way the monitor outputs will have the signal generated by REW on them. REW generates the same signal on left and right, so you can use either monitor output or one channel of the headphone output, they all carry the same signal. If you have a line level source (such as an SPL meter) you would need the gain of the USB Pre input turned around to 0dB (which is unity gain), if you have a mic of some sort the gain will need adjusting according to the mic.

If you are using an SPL meter as the source you could also use the Onkyo on its own, with the SPL meter connecetd to the R channel on the line in and the line out R channel connected to an input on the receiver.
I am using a Calibrated Behringer ECM8000 "premium plus" microphone, but I also have an SPL meter comming soon.

Just to clarify, I would connect the USB dual pre with a 3.5mm Stereo Male To RCA Male Cable to the processor from either the headphone or either monitor outputs (in the monitor outputs use a 1/4" TS to RCA cable).

Could you tell me if the circled part in the pic below is the USB pre input or is that the monitor mix knob ?



How do I know what level the mic needs to be at?

Which input do I connect the mic to with the XLR cable? Would it be the right input?

And this is probably a dumb question , but will all the data taken by the mic be transferred through the USB bus to the PC? (I am guessing that it does)

Sorry for all the questions.
 

·
Premium Member
Joined
·
6,711 Posts
Just to clarify, I would connect the USB dual pre with a 3.5mm Stereo Male To RCA Male Cable to the processor from either the headphone or either monitor outputs (in the monitor outputs use a 1/4" TS to RCA cable).
Correct

Could you tell me if the circled part in the pic below is the USB pre input or is that the monitor mix knob ?
That is the monitor mix knob

How do I know what level the mic needs to be at?
You would adjust the mic gain during the REW level setting, with a signal playing through your speakers or sub, per the REW instructions.

Which input do I connect the mic to with the XLR cable? Would it be the right input?
Yes, use the right input

And this is probably a dumb question , but will all the data taken by the mic be transferred through the USB bus to the PC? (I am guessing that it does)
Yes it will

Sorry for all the questions.
No apology required, if there were no questions there wouldn't be a forum :)
 

·
Registered
Joined
·
93 Posts
Discussion Starter · #6 ·
Ok, it looks like I have got this setup. However I am trying to calibrate the sound card and this is the graph I am getting. Does this look right?




Also , I can only get the sound card calibrated when I connect the loopback cable to the left input and left output. Would this then mean I would have to connect the mic to the left input?
 

·
Registered
Joined
·
678 Posts
Ok, it looks like I have got this setup. However I am trying to calibrate the sound card and this is the graph I am getting. Does this look right? ...
Yes, the dotted line looks right. Be sure to save the soundcard calibration when you are done.

... Also , I can only get the sound card calibrated when I connect the loopback cable to the left input and left output. Would this then mean I would have to connect the mic to the left input?
What happens when you connect the right output to the right input? Is there just no signal coming in? Or is something else happening?

Yes, you can use the left channel out to the receiver/system under test. And the left channel input to REW. Just be sure to check the Left radio button under the Input Channel in the Settings.

Bill
 

·
Registered
Joined
·
93 Posts
Discussion Starter · #8 ·
Yes, the dotted line looks right. Be sure to save the soundcard calibration when you are done.
 What is the other line? It does not look like the ones in the help stickies.



What happens when you connect the right output to the right input? Is there just no signal coming in? Or is something else happening?

Yes, you can use the left channel out to the receiver/system under test. And the left channel input to REW. Just be sure to check the Left radio button under the Input Channel in the Settings.

Bill
The preamp/soundcard is detecting a signal, but the REW software is not detecting any signal. I tried upping the DB on the preamp but nothing registers.
 

·
Registered
Joined
·
93 Posts
Discussion Starter · #9 ·
Ok, so I am trying to check levels and the mic is not putting out any signal, or should I say the REW software is not reading any kind of decibles at all. I have the mic connected to the left input and have the left input box checked. I am getting a sound comming from the subs, so any idea what I am doing wrong here? Does the Behringer ECM8000 mic measure SPL? or do I need a seperate SPL meter?
 

·
Registered
Joined
·
678 Posts
You only need a separate SPL meter to calibrate the absolute levels being read. Without an SPL meter, when it comes to the step of calibrating the levels, you can just enter 75dB as if that is the actual value.

Are you seeing sound input on either of the Left or Right channels when you perform the Check Levels step? Perhaps something in the system is confusing left and right, and the left input to the preamp is appearing as the right input in the computer.

If you are seeing no input on either side, and you are using an ECM8000 mic (or similar), these microphones require phantom power. Did you press in the Phantom Power button on the front of the preamp?

Bill

P.S. The solid line in your graph is the filter target you have chosen. On the filter graph, the target is what you set to compare your actual to what it should be in an ideal world, and calculate equalization filters. The default is a subwoofer filter with an 80Hz crossover, which is what I see looking at your graph.
 

·
Registered
Joined
·
93 Posts
Discussion Starter · #11 ·
You only need a separate SPL meter to calibrate the absolute levels being read. Without an SPL meter, when it comes to the step of calibrating the levels, you can just enter 75dB as if that is the actual value.
That is good to know, thanks.

Are you seeing sound input on either of the Left or Right channels when you perform the Check Levels step? Perhaps something in the system is confusing left and right, and the left input to the preamp is appearing as the right input in the computer.

If you are seeing no input on either side, and you are using an ECM8000 mic (or similar), these microphones require phantom power. Did you press in the Phantom Power button on the front of the preamp?

Bill
At the present time I am not seeing anything. I did just try to calibrate the SPL on the main page and I finnaly got the mic to receive a signal, however it is 2 o'clock in the morning here and I can't complete the calibration for fear of waking the wife. So I will have to continue this tomorow.

P.S. The solid line in your graph is the filter target you have chosen. On the filter graph, the target is what you set to compare your actual to what it should be in an ideal world, and calculate equalization filters. The default is a subwoofer filter with an 80Hz crossover, which is what I see looking at your graph.
I am going to have to do some more reading I think. Thanks for your help and everybody elses.

I knew I would be a pain.:hissyfit:
 

·
Registered
Joined
·
93 Posts
Discussion Starter · #12 ·
Ok, I have been checking everything and I have been able to get a signal by turning the Db dial on the USB dual pro soundcard/preamp. The only thing is that it is at max and still has a few Db's for the right and left to be exactly level with the the out column on the REW software.

The software is telling that their is no problem and to continue, so am I ok so far?
 

·
Registered
Joined
·
678 Posts
You are fine. You don't need to have the input even with the output level: more important is that it is not too loud (greater than -12dB) where clipping could become an issue during the sweep, and hopefully so low (less than -24dB) that signal-to-noise ratio becomes an issue.
 

·
Registered
Joined
·
93 Posts
Discussion Starter · #14 ·
You are fine. You don't need to have the input even with the output level: more important is that it is not too loud (greater than -12dB) where clipping could become an issue during the sweep, and hopefully so low (less than -24dB) that signal-to-noise ratio becomes an issue.
Thanks. It is pretty even so those things should not be an issue I think. The signal is not clipping which is good.
 

·
Registered
Joined
·
93 Posts
Discussion Starter · #17 · (Edited)
Yes.

If you bought an individually calibrated mic, such as offered by Cross-Spectrum Labs, it would come with its own calibration file on disk. But, as you are in Japan, I imagine you bought a mic from a retailer, and the best available file is the generic one that you have already found.

Bill
Actually, I bought it from Cross spectrum labs with the "premium + calibration" package. I was wondering what that disk was for, now I know!:whistling:

I had a friend of mine give me advise on what stuff to get , I just did not know what to do with it. LOL

Here is my first graph.

 

·
Registered
Joined
·
199 Posts
I can't get the waterfall graph to work? How do you get that going?
Take a measurement of the subwoofer or speakers (one at a time), then under the waterfall tab click "Generate Waterfall." Then set the graph limits to the frequencies you want to look at. Click on the little picture of the floppy disk in the bottom left hand corner of the graph (right by the two arrows) to save it as a jpeg. That way you won't have to take a screenshot of your desktop.

The output below 10Hz is probably a measurement anomaly, for what its worth. I wouldn't bother measuring from below 15Hz or so. Can you take a measurement from 15-200Hz?

Is that measurement just the subwoofer(s), or the speakers crossed over to the subs? If the latter, what is your crossover frequency? I ask because trying a different crossover or messing with phase might get rid of the null at 55Hz. Otherwise try re-positioning the subwoofer in the room.
 

·
Registered
Joined
·
93 Posts
Discussion Starter · #20 ·
Take a measurement of the subwoofer or speakers (one at a time), then under the waterfall tab click "Generate Waterfall." Then set the graph limits to the frequencies you want to look at. Click on the little picture of the floppy disk in the bottom left hand corner of the graph (right by the two arrows) to save it as a jpeg. That way you won't have to take a screenshot of your desktop.
 Ok, I will give that a try. Thanks.

The output below 10Hz is probably a measurement anomaly, for what its worth. I wouldn't bother measuring from below 15Hz or so. Can you take a measurement from 15-200Hz?
I don't know if it is an anomaly, b/c I was curious as to that myself. The subs are Seaton Sounds Submersives which are know to have flat in room response down to 7-8 hz in some rooms and I can say that the windows in the room ,glasswear plates and and anything else shakes violently without any audible noise, which I can only guess is sub 20hz content. The windows visibly shake violently for the first 5 or so seconds at the start of the the 1M sweep and I don't start hearing sound until about the 9 second mark of the 21 sec sweep, so much so I am a little afraid to try anything at higher Db's .


Is that measurement just the subwoofer(s), or the speakers crossed over to the subs? If the latter, what is your crossover frequency? I ask because trying a different crossover or messing with phase might get rid of the null at 55Hz. Otherwise try re-positioning the subwoofer in the room.
It is just my subs at the moment. How do I mess with the phase, sorry this is all just so new to me.:sweat:
 
1 - 20 of 30 Posts
Top