Loading Profile...
measurements different everytime
I bought a macbook pro just to use fuzzmeasure. Primary interest is to to determine loudspeakers in room frequency response. I am using a behringer mic and the art dual pre. The measurements I am getting is vastly different every time. can you verify I have connected everthing correctly?
output: headphone jack from macbook pro, headphone to rca connector and rca to preamp of my stereo system ( I connected L ch only)
input: mic to xlr L channel input of dual pre (gain set to 12 o clock), autocorrect: mic R channel output is connected to the xlr R channel ( gain of R ch is zero). Mix knob is set to preamp. the art dual is connected to macbook via usb.
playback setting: built in ch 1
recording: codec ch 1
autocorrect: playback & record ch2
Are these setting correct? The room is not noisy. Occasioinally, I can get a curve that mimic what i have on a velodyne bass sweep system ot similar to frequency sweep with Paa3 meter. With both device, I know I have a 5db peak at 25hz and a suckout at 40-50hz
Curve seems to be better with longer sweep time, 3sec vs 1sec.
Is the headphone output from macbook contributing to the variability? Mix knob on the dual pre should be set to preamp instead of computer. Is this correct.
many thanks in advance
output: headphone jack from macbook pro, headphone to rca connector and rca to preamp of my stereo system ( I connected L ch only)
input: mic to xlr L channel input of dual pre (gain set to 12 o clock), autocorrect: mic R channel output is connected to the xlr R channel ( gain of R ch is zero). Mix knob is set to preamp. the art dual is connected to macbook via usb.
playback setting: built in ch 1
recording: codec ch 1
autocorrect: playback & record ch2
Are these setting correct? The room is not noisy. Occasioinally, I can get a curve that mimic what i have on a velodyne bass sweep system ot similar to frequency sweep with Paa3 meter. With both device, I know I have a 5db peak at 25hz and a suckout at 40-50hz
Curve seems to be better with longer sweep time, 3sec vs 1sec.
Is the headphone output from macbook contributing to the variability? Mix knob on the dual pre should be set to preamp instead of computer. Is this correct.
many thanks in advance
I’m learning
1
person has this question
I have this question, too!
Tell me when someone answers.
The more people who ask this question, the more it gets noticed.
The more people who ask this question, the more it gets noticed.
Create a customer community for your own organization
Plans starting at $19/month
-
Inappropriate?When you get wide variances, either your connections are wrong, or your SNR is not good enough to give reliable graphs between runs.
If your graph looks approximately like what you'd expect (e.g. turning up the level on the subwoofer, or the mic input, should raise the overall graph level), then you don't have a connection issue. It sounds like you have that part working fine.
So now I have to ask about your sweep parameters. You mentioned that you increased your sweep duration to 3s. This will certainly help. Did you leave the 'full range' sweep option selected, or did you set a reduced frequency range? If you set a reduced frequency range, you'll have to set a very much longer sweep duration—potentially on the order of 30s—to mitigate SNR issues.
I highly recommend you run full-range sweeps if you can help it. Otherwise, just be sure to set really long duration limited range sweeps, and deal with the larger file sizes and increased memory usage. You can get around this issue by cropping your measurement to the analysis window, but you lose the ability to get distortion graphs.
Hope this helps! -
Inappropriate?Chris,
Many many thanks for the prompt reply and patience. I have repeatable measurements now. The problem was the phantom button in the back of the art dual pre. I just need to turn it on. The graph now fully duplicate what i have with PAA3 meter and velodyne bass sweep. The fuzz measure produce data that is higher in resolution and the data is more manipulatable.
When auto correct is not use, I have very similar curves with the mix button (art pre) set to computer or preamp. What should it be?
If I use auto correct, should i set the mix button to preamp or computer?
Thanks
I’m thankful
-
Inappropriate?The mix knob should always be turned to computer. Never, ever set it to preamp.
How do the graphs differ between correction enabled and correction disabled?
EMPLOYEE
