Tweet
Hi all,
I read this over at John Krutke's blog, and it piqued my interest in testing some of my drivers.
I don't have a measurement mic, just a tripod/SPL meter, warble tones, LCR/multimeter, and computer-based tone generator.
Can someone tell me, should I be doing this with, or without the crossover in place? What is a reasonable level to test at? 2.83V OK?
I don't want to ruin any tweeters...
regards,
Thanh.
I read this over at John Krutke's blog, and it piqued my interest in testing some of my drivers.
I don't have a measurement mic, just a tripod/SPL meter, warble tones, LCR/multimeter, and computer-based tone generator.
Can someone tell me, should I be doing this with, or without the crossover in place? What is a reasonable level to test at? 2.83V OK?
I don't want to ruin any tweeters...
regards,
Thanh.
Testing with ears...
On the subject of testing tweeters, those without the ability to see an impedance curve or a harmonic distortion sweep to confirm performance can still find rubbing voice coils by ear. Generally, rubbing voice coils will be difficult to hear with music other than some edginess and ear fatigue. Testing with music, performance issues aren't really clear except for a realization that something's just not right. But with a swept sine wave, it will stand out as a sudden change in tone from smooth to buzz at certain frequencies. Software signal generators are all over the internet, just do a search. It has to be a sweep, not discrete tones or warbles. For tweeters, I recommend a slow sweep from 10kHz to about 400 Hz, starting at a low level, then at a higher level but not enough to exceed Xmax at 400 Hz. (the sound of a tweeter exceeding xmax is unique in itself) Note that this isn't going to find all quality control issues, just the ones that are bad enough to have a rubbing voice coil. You can use a similar sine wave sweep on woofers, just go down to 20 Hz or so. When a woofer is mounted in an enclosure, this is also handy to find mounting flange gaps that cause rattling. These like to hide in the midbass, 150 - 250 Hz. I don't always use a sealing gasket, but this tells me if I do indeed need to add a gasket or sealant. I recommend this testing by ear even for those who have a full set of testing programs. It's a quick easy hookup and sweep that takes no time. I do it all the time.
On the subject of testing tweeters, those without the ability to see an impedance curve or a harmonic distortion sweep to confirm performance can still find rubbing voice coils by ear. Generally, rubbing voice coils will be difficult to hear with music other than some edginess and ear fatigue. Testing with music, performance issues aren't really clear except for a realization that something's just not right. But with a swept sine wave, it will stand out as a sudden change in tone from smooth to buzz at certain frequencies. Software signal generators are all over the internet, just do a search. It has to be a sweep, not discrete tones or warbles. For tweeters, I recommend a slow sweep from 10kHz to about 400 Hz, starting at a low level, then at a higher level but not enough to exceed Xmax at 400 Hz. (the sound of a tweeter exceeding xmax is unique in itself) Note that this isn't going to find all quality control issues, just the ones that are bad enough to have a rubbing voice coil. You can use a similar sine wave sweep on woofers, just go down to 20 Hz or so. When a woofer is mounted in an enclosure, this is also handy to find mounting flange gaps that cause rattling. These like to hide in the midbass, 150 - 250 Hz. I don't always use a sealing gasket, but this tells me if I do indeed need to add a gasket or sealant. I recommend this testing by ear even for those who have a full set of testing programs. It's a quick easy hookup and sweep that takes no time. I do it all the time.
Comment