Hello,
For measurement purposes I am considering the speaker cable as an extension of the amplifier outputs. We now know the noise and distortion results of the test setup including the input and output connections. We are good to go with what we have.
If you look at testing done over at Head-Fi you will see a headphone test enclosure that rests on a 1300 pound vibration isolation table.
If you look around here at ASR, @amirm does his headphone testing with the GRAS 45CA test fixture in the same room with the APx555 cooling fan. The test fixture is across the room and at a different elevation than the AP analyzer. The analyzer with cooling fan is in an enclosure that attenuates the cooling fan noise to a degree.
The thinking is also that the headphones will isolate the test microphones from the ambient noise to a degree, closed back headphones even more.
I live in a quiet residential area out in the woods. There is a well stuffed linen closet across the hall, stuffed with blankets, pillows, sheets, towels and 2 years supply of toilet tissue.
I will do some noise level measurements in the same room as the APx555 with cooling fan, measurements across the room from the analyzer and measurements across the hall in the linen closet.
Perhaps the isolation chamber on the 1300 pound isolation platform is over kill.
For solid measurements we need to confirm that ambient noise is 10dBs less than potential headphone 2nd and 3rd Harmonic Distortions.
Thanks DT
For measurement purposes I am considering the speaker cable as an extension of the amplifier outputs. We now know the noise and distortion results of the test setup including the input and output connections. We are good to go with what we have.
If you look at testing done over at Head-Fi you will see a headphone test enclosure that rests on a 1300 pound vibration isolation table.
If you look around here at ASR, @amirm does his headphone testing with the GRAS 45CA test fixture in the same room with the APx555 cooling fan. The test fixture is across the room and at a different elevation than the AP analyzer. The analyzer with cooling fan is in an enclosure that attenuates the cooling fan noise to a degree.
The thinking is also that the headphones will isolate the test microphones from the ambient noise to a degree, closed back headphones even more.
I live in a quiet residential area out in the woods. There is a well stuffed linen closet across the hall, stuffed with blankets, pillows, sheets, towels and 2 years supply of toilet tissue.
I will do some noise level measurements in the same room as the APx555 with cooling fan, measurements across the room from the analyzer and measurements across the hall in the linen closet.
Perhaps the isolation chamber on the 1300 pound isolation platform is over kill.
For solid measurements we need to confirm that ambient noise is 10dBs less than potential headphone 2nd and 3rd Harmonic Distortions.
Thanks DT