# calibrating a firewire external sound card?



## Guest (Dec 30, 2007)

Hi... I have a phonic Helix 24 MKII, 24 channel mixer that is ALSO a firewire 16 simutaneous track recording soundcard. It shows up in REW fine and iIcan do measurements, but I do not understand how to calibrate it since it does not have line in outs that go to the computer, only firewire ins/outs. I have the mic hooked up to ch 15/16. In REW it sees ch15/16 and it sees the correct main L/R out. How would I calibrate this set up?

Also i am using a SONY ECM-ms907 Stereo mic. Is there a cal file for this mic? Or Can I/How can I calibrate the mic also?

thanks... Jam


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

If this is what you have, you calibrate it just as the REW help files say: Feed one of the outputs into one of the inputs. Make sure any the EQ strip is set flat. 

Regards,
Wayne


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## Guest (Dec 31, 2007)

Wayne A. Pflughaupt said:


> If this is what you have, you calibrate it just as the REW help files say: Feed one of the outputs into one of the inputs. Make sure any the EQ strip is set flat.
> 
> Regards,
> Wayne


Yes that is it. But I am confused. This system sends the inputs signals through it's built-in firewire port, and receives signals from the computer via it's built-in firewire port not the 1/4" inputs/outputs. I must be missing something dumb here.

jam


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## Guest (Dec 31, 2007)

This is how I have the system hooked up. Let me know where I go all wrong.

laptop running REW Helix 15/16 input and Helix main L/R output show in REW default input outputs in REW. Firewire cable to the Helix. SONY ECM-907 stereo mic running to helix channel strips 15 and 16. Helix 1/4" main L/R outs running to power amp then to JBL jrx-100 15" and horn PA speakers. I can get the output volume set to 75db using the internal REW generated tones but the only way I can find to adjust input volume is by the pre amp gains on the helix mixer and even with them turned up all the way I am still at about -40db. SO I have to turn up the volume on the amp for the mains and it get WAY to loud. Where am I falling apart?

jam


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

That’s the correct connection scheme, but for measuring, not for calibrating the soundcard.

If you’re trying to calibrate the soundcard, you’ll need to loop a cable between the main output and the channel strip you intend to use, as indicated in Item #1 in the REW help files for Calibrating the Soundcard. 

There should not be a mic connected, or a connection to the sound system, until later when you’re ready to measure.

Regards,
Wayne


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

Also:


> Also i am using a SONY ECM-ms907 Stereo mic. Is there a cal file for this mic? Or Can I/How can I calibrate the mic also?


You can create your own calibration file, but you’ll need a frequency response graph of the mic in order to do it.

But one thing at a time. 

Regards,
Wayne


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## Guest (Dec 31, 2007)

Ok got it... I hate plugging directly from ins to outs. But THANKS! ...it worked. Next problem is still the same though. When I do a measurement it tells me that the input is too low so a ctrank up the amp and the sound is piercing but it says too low, reading is about -50 to -40. I still get readings but not sure if they mean anything because of this. I will upload my soundcard graph and new plot. For some reason I get an "error on page" when I try to add an atatchment using this computer. I turned off pop-up blocker, but that did not help. And, Yes after this it is on to the mic!

jam



Wayne A. Pflughaupt said:


> That’s the correct connection scheme, but for measuring, not for calibrating the soundcard.
> 
> If you’re trying to calibrate the soundcard, you’ll need to loop a cable between the main output and the channel strip you intend to use, as indicated in Item #1 in the REW help files for Calibrating the Soundcard.
> 
> ...


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

> Next problem is still the same though. When I do a measurement it tells me that the input is too low so a ctrank up the amp and the sound is piercing but it says too low, reading is about -50 to -40.


Why not increase the gain and/or input slider at the channel strip the mic is plugged into? 

Regards,
Wayne


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## Guest (Dec 31, 2007)

I can do that too. But my question is after i get all the calibration done setting the spl to read what my spl reads (75db) and setting the volumes etc etc. Why do i have to turn up the volume for the measurement to well into the 100db+ range... I am covering my ears even with ear plugs, when the test runs. I think that I still don hae thing set right... agreed?

jim


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## brucek (Apr 11, 2006)

> agreed?


Agreed........


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

Can you show us a screen shot of your Settings box, including your input and output levels? That’ll probably provide us with the clues we need.







​

Regards,
Wayne


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## AmyNelRN (Jan 22, 2013)

Did this problem ever get resolved for you? I am having the exact same problem. I'll start a new thread on it, but man.. is it loud in order to get any actual pick up of any sound and it's obvious that the settings just are missing something. Let me know what it is, if anyone knows. Bless you!- Amy


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