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miniDSP Low cost, modular Digital Signal Processor (DSP) kits for the DIYer from miniDSP.

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Old 27th September 2017, 12:16 AM   #1
HiFiNutNut is offline HiFiNutNut  Australia
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Join Date: May 2004
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Default UMIK-1 measurements look incorrect - soundcard problem?

I have bought a UMIK-1 mic and have just used it for the first time. It was connected to a HP laptop with HP Realtek High Definition Audio driver. All effects and EQ were off. Measurement software is REW. The earphone output of the laptop was connected to the preamplifier line input.

Measurements of my DIY speakers show frequency response starts to rise from 1kHz and when reaching 20kHz it is 10dB higher! My DIY speakers were previously measured flat using a calibrated ECM8000 mic and an USB soundcard for PA use ($300).

To verify the result I used the UMIK-1 to measure a commercial loudspeaker Paradigm Studio Reference 20 V5. The frequency response showed the same, almost overlapping my DIY speakers from 200Hz to 20kHz.

So I suspect that the measurements are far from correct. When I played music I noticed that it was heavy on the treble and thin on the midrange.

The MiniDSP site doesn't provide any information on how to calibrate a soundcard if that is possible.

How do you solve this problem?
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Old 27th September 2017, 12:48 AM   #2
ttan98 is offline ttan98  Australia
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I just got this microphone from Minidsp and use it with REW, I didn't have any problem, check the following:
1. Frequency sweep from 20 hz to 20,000Hz
2. use the equalization txt supplied with the microphone
3. from REW preference make sure, input and output are correct
output device:speakers; input device:Umik
output:default; input:default
4. Using Pink noise to set output to sufficient level refer to Minidsp Umik's document

I get useful measurements compared to my previous sound and microphone combo.
All the best.
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Old 27th September 2017, 03:33 AM   #3
HiFiNutNut is offline HiFiNutNut  Australia
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Hi ttan98, Thanks a million.

I tried starting it again clean from REW and checked the output device, etc. are correct like what you suggested. I got more meaningful measurements.

In any case, do most laptop internal soundcards have flat response?
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Old 27th September 2017, 03:42 AM   #4
ttan98 is offline ttan98  Australia
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Quote:
Originally Posted by HiFiNutNut View Post
Hi ttan98, Thanks a million.

I tried starting it again clean from REW and checked the output device, etc. are correct like what you suggested. I got more meaningful measurements.

In any case, do most laptop internal soundcards have flat response?
It is stated in the REW manual if you use USB input no need to calibrate the sound card, it assumes the freq. resp. from sound card output is flat in majority of cases is correct.
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Old 28th September 2017, 01:03 AM   #5
HiFiNutNut is offline HiFiNutNut  Australia
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I am still not 100% sure about the accuracy of the measurements with UMIK-1 and REW.

They show my speakers have a rising treble of 2-3dB and also a rapid roll-off after 10kHz and more than 6dB down at 20kHz. Since my speakers were measured the same as a pair of commercial speakers, does it mean the commercial speakers have the same frequency response faults? It is unlikely.

I then based on the measurements and changed the tone controls to make the speakers flat (based on UMIK-1 and REW), and the music became a little bit too soft.

If I played music through the laptop via a commercial receiver (Cambridge Audio 650R) and Paradigm Studio 20 V5 speakers the music sounded thin and treble heavy. This suggests that the soundcard may be inaccurate.
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Old 29th September 2017, 06:21 AM   #6
ttan98 is offline ttan98  Australia
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Did you use the txt file supplied with the umik mic? This is to equalise the mic input, to check this put a tick in the box for mic under the Freq. Resp. Curve display. In Few. It should look relatively flat.
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Old 29th September 2017, 09:35 PM   #7
HiFiNutNut is offline HiFiNutNut  Australia
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I did use the umik mic calibration file.

I thought of a new idea. When I have time, instead of using the laptop earphone out, I will use my external USB soundcard that is accurate and see if I can get better frequency response curves with the UMIK mic. I thought the culprit was the laptop soundcard.
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Old 7th October 2017, 01:55 PM   #8
Ivo is offline Ivo  Netherlands
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You can also export the measurement sweep as a sound file and play it directly from your receiver (does it stream?). Otherwise burn it on CD. You can let REW wait for the measurement sweep.

I have had accurate and repeatable measurements from the headphone outputs of an Asus EEE netbook and various "grown up" laptops using windows and linux. As long as there is no system EQ turned on, it is always accurate. Most use the same chip building blocks anyway. I later turned to an HDMI connection between laptop and AV receiver to go digital, it didn't make a difference. Now I use the streaming option, saves the hassle of rolling out a cable. My life is less cluttered but measurement results are the same. :-)
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Old 7th October 2017, 03:37 PM   #9
DonVK is offline DonVK  Canada
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Quote:
Originally Posted by HiFiNutNut View Post
I did use the umik mic calibration file.

I thought of a new idea. When I have time, instead of using the laptop earphone out, I will use my external USB soundcard that is accurate and see if I can get better frequency response curves with the UMIK mic. I thought the culprit was the laptop soundcard.
Are you measuring with the mic @0deg or @90deg? with the appropriate calibration file (there are 2 .txt files.
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Old 5th April 2018, 11:49 AM   #10
Sergi4 is offline Sergi4
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Quote:
Originally Posted by HiFiNutNut View Post
I have bought a UMIK-1 mic and have just used it for the first time. It was connected to a HP laptop with HP Realtek High Definition Audio driver. All effects and EQ were off. Measurement software is REW. The earphone output of the laptop was connected to the preamplifier line input.

Measurements of my DIY speakers show frequency response starts to rise from 1kHz and when reaching 20kHz it is 10dB higher! My DIY speakers were previously measured flat using a calibrated ECM8000 mic and an USB soundcard for PA use ($300).

To verify the result I used the UMIK-1 to measure a commercial loudspeaker Paradigm Studio Reference 20 V5. The frequency response showed the same, almost overlapping my DIY speakers from 200Hz to 20kHz.

So I suspect that the measurements are far from correct. When I played music I noticed that it was heavy on the treble and thin on the midrange.

The MiniDSP site doesn't provide any information on how to calibrate a soundcard if that is possible.

How do you solve this problem?
There is not any soundcard in play or to calibrate if the UMIK-1 is USB (mine is). The signal is digitized into the mic itself.
The only negative role your soundcard could be playing is to take out the swap signal to your speakers without a flat response. Then yes, it could be fooling you. There are several cheap DAC's that could help you if that's the problem:
INTERFACE, USB/AUDIO, UCA222 UCA222 By BEHRINGER: Amazon.es: Electronica
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