Get Ready to Measure - The Measurement Chain
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9.3
The Measurement Chain
Before a measurement, please make sure that the full measurement chain is in place:
1. A PC/Laptop running HOLMFIR is connected to the DSPre via a USB cable
2. The DSPre is powered on
3. The amplifier(s) are connected to the DSPre and powered on
4. The speakers are connected to the amplifiers
5. The microphone is connected to the DSPre and powered on
9.4
Protect Your Ears
When measuring, HOLMFIR uses a frequency-sweep, which goes from 10 to 22050 Hz at
full amplitude from the computer. It is therefore important that you protect your ears
while measuring, since the high tones from 4000 to 22050 Hz might not sound loud, but
can damage your hearing, so please remember to protect your ears - hence the warning
pop-up when measuring:
9.5
DSPre Volume and Surroundings
Start with a DSPre volume at 15, then increase if record level is to low.
Some guidelines:
•
Near field (less than 10cm) use low volume to avoid clipping
•
Far field (further than 1m) use higher volume to get a better signal to noise ratio
•
Close windows and doors to the outside
•
Do not hesitate to make a new measurement, eg. if a large truck drove by or if your
neighbor slammed the door
HOLM Acoustics
HOLMFIR User Guide v0.4.4
