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Discussion Starter · #1 ·
I have the following rig that I would like to use to measure the response of the Audioengine A5 powered monitors.

1. Dayton EMM-6 Electret Measurement Microphone (downloaded the calibration file)
2. Presonus Inspire 1394 Firewire Audio Interface with phantom power
3. Powebook G4 running Leopard and REW
4. Audioengine A5 powered speakers.

I connected the rig as follows:

PowerBook Audio out--->Audioengine A5 Right channel input...........EMM-6 Microphone placed in front of Right speaker--->Presonus Inspire---->Firewire of PowerBook.

(Audio out from Powerbook to a splitter and connected only the right output to the Audiengine A5 input. Placed the EMM-6 mic a meter away from the right speaker and hooked it up to Presonus Inspire which was connected to the Powerbook via Firewire cable.)

REW/Settings:
Soundcard: 44.1Khz,

Input Device and Input: chose 'Inspire'
Input channel: Right

Mic/Meter: Browse: imported EMM-6 calibration file

I wanted to do a preliminary measurement without calibration. However that failed miserably.:crying:

Also tried by using connecting the Inspire 'Audio Out Rt channel ' to 'Audio In' and choosing 'Default In' under Settings.

So far I have not been able to get any tracings, even though speakers gave out the pink noise and scared everyone else in the house silly!

So we are halfway there!

I will retry once again, but in the mean time I welcome the suggestions of the nice experienced folk on this forum :D

Cheers :bigsmile:
 

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Welcome to the Forum, Hobbs!

1. Dayton EMM-6 Electret Measurement Microphone (downloaded the calibration file)
2. Presonus Inspire 1394 Firewire Audio Interface with phantom power
You got the EMM-6 calibration file – that’s good. Did you perform the soundcard calibration routine?


(Audio out from Powerbook to a splitter and connected only the right output to the Audiengine A5 input. Placed the EMM-6 mic a meter away from the right speaker and hooked it up to Presonus Inspire which was connected to the Powerbook via Firewire cable.)
So you’re using the computer’s audio output, while the mic is connected to the interface?

I suggest reviewing the REW Cabling and Connection Basics thread (scroll down to the section titled “REW connections using an ECM8000 microphone and an external USB soundcard with integral microphone preamp with phantom power“).

Also, the REW Help Files.


Regards,
Wayne
 

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Discussion Starter · #3 ·
Welcome to the Forum, Hobbs!

You got the EMM-6 calibration file – that’s good. Did you perform the soundcard calibration routine?


So you’re using the computer’s audio output, while the mic is connected to the interface?

I suggest reviewing the REW Cabling and Connection Basics thread (scroll down to the section titled “REW connections using an ECM8000 microphone and an external USB soundcard with integral microphone preamp with phantom power“).

Also, the REW Help Files.


Regards,
Wayne
Thanks for the prompt response!

Regarding question 1: No, I have not done the calibration yet (still a little foggy on how to do it despite the excellent tutorials). Also I don't have an SPL meter.

A quick question (before I review more stuff you kindly referred me to). Should I use the Presonus Inspire as both Output and Input? So go from Presonus right Out to the Monitor speaker Right in (?).


Looks like you guys will morph me into a hometheatre/speaker building geek!! :bigsmile:


Cheers.
 

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Discussion Starter · #4 ·
I realized where I made the snafu.

I will use the diagram accompanying 'REW connections using an ECM8000 microphone and an external USB soundcard with integral microphone preamp with phantom power' to have another go at measuring the speakers.

Thanks once again.
 

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Regarding question 1: No, I have not done the calibration yet (still a little foggy on how to do it despite the excellent tutorials).
Loop a cable between the sound card’s line input and output. (Don’t use the mic input; unbalanced connections are fine.) In REW, Click on the “Settings” icon, “Soundcard” tab,” then the Measure” icon.


Also I don't have an SPL meter.
You’ll need to get one. Part of setting up REW is the “Calibration” routine (“Settings,” “Mic/Meter” tab). This tells REW where 75 dB is, giving it a reference for the graphs it will generate. Otherwise, the program has no idea “where” 75 dB is (or any other value).

The only concern I have for you is the firewire connection, rather than the usual USB. Try and see how it works. If you can generate a calibration file, you should be in business.

Regards,
Wayne
 

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Discussion Starter · #6 ·
Loop a cable between the sound card’s line input and output. (Don’t use the mic input; unbalanced connections are fine.) In REW, Click on the “Settings” icon, “Soundcard” tab,” then the Measure” icon.


You’ll need to get one. Part of setting up REW is the “Calibration” routine (“Settings,” “Mic/Meter” tab). This tells REW where 75 dB is, giving it a reference for the graphs it will generate. Otherwise, the program has no idea “where” 75 dB is (or any other value).

The only concern I have for you is the firewire connection, rather than the usual USB. Try and see how it works. If you can generate a calibration file, you should be in business.

Regards,
Wayne
Thank you once again for your helpful suggestions.

The Presonus hook up diagram shows both the front and back of the audio interface. The back shows RCA outputs (hooked up to the monitors) as well as RCA inputs (hooked up to a turntable / keyboard). If I gather what you are saying correctly, I would bridge the 'out' to the 'in' (e.g. Right 'out' to Right 'in') for calibrating the Inspire.

For what it is worth, under 'Settings' in REW, I can select the Inspire for both Input as well as Output (after I do the same under Audio/Midi set up in Os X). Wish me luck!

If that works, I should then be able to proceed further!

Cheers and many many thanks!
 

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If I gather what you are saying correctly, I would bridge the 'out' to the 'in' (e.g. Right 'out' to Right 'in') for calibrating the Inspire.
Correct. :T


For what it is worth, under 'Settings' in REW, I can select the Inspire for both Input as well as Output (after I do the same under Audio/Midi set up in Os X).
Yeah, if you can see the sound card in the Input and Output Device windows, you should be golden.

You can probably get around not having an SPL meter by setting the volume of your speakers to a comfortable level, then running the “Calibrate SPL” routine (“Settings,” Mic/Meter”) tab as if you did. Just keep in mind that the vertical axis SPL markings in the graphs you generate will have no bearing. :)

Regards,
Wayne
 

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Discussion Starter · #9 ·
Here are the results of my calibration:
Sample rate: 44100Hz
-3dB points: 997.9Hz, 1.001kHz
Input device: No device selected
Input: No input selected
Channel: Right
Input volume: no control
Input RMS target: -24.0dB
Actual RMS at 1kHz: -24.6dB
Output device: No device selected
Output: No output selected
Sweep level: -24.0dB
20Hz .. 20kHz flatness: +3.3, -62.8dB

What does this mean?


 

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Discussion Starter · #10 ·
Repeated the calibration after changing the setting to include the following:
Sample rate: 44100Hz
-3dB points: 999.3Hz, 1.002kHz
Input device: Inspire1394 (0772)
Input: No input selected
Channel: Right
Input volume: no control
Input RMS target: -24.0dB
Actual RMS at 1kHz: -24.1dB
Output device: Java Sound Audio Engine
Output: No output selected
Sweep level: -24.0dB
20Hz .. 20kHz flatness: +11.6, -105.1dB

What is going on?
 

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There is a known issue with using Firewire connected soundcards on a Mac, where Mac's Java implementation doesn't give access to the incoming sound stream from firewire connected soundcards. Your cal file could be explained by REW not getting any input.

Do the VU meteres move as you have REW play tones?
 

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Discussion Starter · #12 ·
There is a known issue with using Firewire connected soundcards on a Mac, where Mac's Java implementation doesn't give access to the incoming sound stream from firewire connected soundcards. Your cal file could be explained by REW not getting any input.

Do the VU meteres move as you have REW play tones?
The VU meters show signal while the calibration is in progress. At the end of the calibration, this warning shows up:

"Impulse peak is not where it should be, the measurement may have been corrupted.

Check the impulse Response and the Captured Data plots."
 

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Hmmm, the input VU meters? Or just the output one... can you post a screenshot?
 

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I don't know much about the Presonus, but looking at the sweeps and the VU meters I have bad feeling that the only input REW is getting is an internal feedback loop in the computer/soundcard... i.e. the soundcard is sending back upstream that which it is outputting... somewhere there should be a control to turn this off... I'm not sure if it's one of your mute buttons in the skin you showed or if it's elsewhere...
 

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Discussion Starter · #16 ·
I tried engaging Mixer Bypass. The curves still look the same
Mixer Bypass: When the Mixer Bypass is engaged, all of its controls are bypassed, input channels
1-4 are bypassed, and the software playback channel will be routed straight to the outputs of the
INSPIRE 1394. Only the software playback channel will be heard. When the Mixer Bypass is
disengaged, the Monitor Mixer will return to the settings it held before the Mixer Bypass was
engaged.
 

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I still think it's the Mac/Java/Firewire problem... but if you want to push forward...
Post another screenshot of the VU meters from REW with the tone running in this mixer bypass mode.
Disconnect the loopback cable and run the test again. Post that screenshot.
Connect the output of the soundcard to your AVR and output a test tone from REW. Do you get sound?
Connect the input of the soundcard to a mic and set REW to listen with the VU meters. Tap on the microphone. Do the VU Meters move?
Why is the output volume in your OS audio setup set to -104dB? Does that have any affect?
It looks like (in your original screenshots) you've muted all 4 inputs... how can the soundcard get input that way?
 

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Discussion Starter · #18 ·
I still think it's the Mac/Java/Firewire problem... but if you want to push forward...
Post another screenshot of the VU meters from REW with the tone running in this mixer bypass mode.
Disconnect the loopback cable and run the test again. Post that screenshot.
Connect the output of the soundcard to your AVR and output a test tone from REW. Do you get sound?
Connect the input of the soundcard to a mic and set REW to listen with the VU meters. Tap on the microphone. Do the VU Meters move?
Why is the output volume in your OS audio setup set to -104dB? Does that have any affect?
It looks like (in your original screenshots) you've muted all 4 inputs... how can the soundcard get input that way?
I tried with and without muting, muting only Channels 1, 2 and 3; with and without Mixer Bypass. Got the same results. Changing the output volume in the Audio Setup had no effect, but the Input did affect the VU meters. I also ran the sound from the Inspire directly into my powered speakers and was able to get a sound.
What I have not tried is to see if the VU meters register a sound with the microphone. Will do that later today and post back.

I will also try using the Mac's built in sound card (and see if that can be calibrated) and use the Inspire to only provide phantom power to the mike.

Finally, I will test this also on a newer Intel iMac.

Thank you for all the feedback and helpful suggestions.

Appreciate it very much.

Cheers
 

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I guess the Powerbook is PowerPC based? REW V4 doesn't work on PowerPC. V3.29 does though, so it is possible to measure with V3.29 and then analyse the results by loading the measurement into V4.
 
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