This one seems to have more low-end to it. https://www.youtube.com/watch?v=b3FIDW5_BqQ
IMHO, setting the limiters is gonna depend on what sort of music the system is to reproduce. If its the sound of a drum kit, 140v peaks would appear to be fine. There's no sustained power, so all there is to be worried about is peak excursion.
If its something like the link from sine143, you're gonna need to set limiters much lower, since the thermal power handling will give out way before mechanical.
A good peak/rms limiter will make sure you never damage your drivers, but I've no idea if they're expensive or not...
Try corner-loading the test-labhorn. That'll provide loading similar to more horns playing.
Chris
IMHO, setting the limiters is gonna depend on what sort of music the system is to reproduce. If its the sound of a drum kit, 140v peaks would appear to be fine. There's no sustained power, so all there is to be worried about is peak excursion.
If its something like the link from sine143, you're gonna need to set limiters much lower, since the thermal power handling will give out way before mechanical.
A good peak/rms limiter will make sure you never damage your drivers, but I've no idea if they're expensive or not...
Try corner-loading the test-labhorn. That'll provide loading similar to more horns playing.
Chris
I've thought that driver manufacturers should start measuing RMS power handling based on more modern music, which a great deal of the time contains pretty much sine wave bass lines.
Tapping on peak limiters with Led Zeppelin isn't quite the same as tapping on limiters with Gucci Mane. Something like sine waves at 5 cycle steps and then rating the drivers at whatever power level causes the voice coil temperature to approach the thermal limits of the glue / former.
Especially for drivers intended for cars, because that's pretty much what people are going to play through them, and then get confused when a 750w amp ends up roasting two 1000wrms drivers without getting anywhere near xlim.
As far as the op, I'd agree with Art, it's most likely the spider-former joint tapping the edge of the coil gap.
Tapping on peak limiters with Led Zeppelin isn't quite the same as tapping on limiters with Gucci Mane. Something like sine waves at 5 cycle steps and then rating the drivers at whatever power level causes the voice coil temperature to approach the thermal limits of the glue / former.
Especially for drivers intended for cars, because that's pretty much what people are going to play through them, and then get confused when a 750w amp ends up roasting two 1000wrms drivers without getting anywhere near xlim.
As far as the op, I'd agree with Art, it's most likely the spider-former joint tapping the edge of the coil gap.
Hi, replying to several comments.....
sine143, 4 labhorns. the Kaiju vid was plenty loaded with 38hz....my crossover started walking off the amp stack at only about 4v rms at amp! (5.7vp)
38hz is the impedance minimum (5.4 ohms) on a single Lab12 in the labhorn (by my measurements). So at 50v peak or 35vrms, I get that would be about 6.5 amp through the 26 gauge coil .....this song is perfect for smoked labhorn BBQ ...
50vrms would probably make direct cooked BBQ !
mRgSr, that's the kind of thing I'm wondering about.
Chris, both vids really push 38hz out...the vid you linked starts right out with it...
In the past, I had a pair of corner stacked labhorns in a fairly large 39'x23' rec room. They pointed into the corner which provided a quasi mouth extension in addition to the gains from 1/4 space loading. Nose tickling bass 30 feet away!!
Thx all,
and to all......
OK .... there seem to be 3 knock possibilities...
1. coil hits plate
2. spider striking magnet structure
3. coil/former cocking inside magnet
1. Coil hitting plate started out as my assumption, but in looking closely at the driver, and feeling just how much pressure it takes to get the former to touch the back plate, I'm leaning to a combination of 2. and 3.
Because it's pretty clear the spider is in a race with the coil to hit something first.
It looks like the first thing the spider could hit is the basket about 1" in from the spiders outer perimeter. The basket steps up/dn there and has a perforated band going around inside it, right up to its lip.
On the driver I have torn apart, the perforated band isn't uniformly aligned below the basket lip. It is about 3mm too high in one spot, and my guess is this is the first place the spider would hit. This would cause the coil to tilt in the magnet gap too.
Dunno if this is it, but it does seem more likely than the coil hitting....
sine143, 4 labhorns. the Kaiju vid was plenty loaded with 38hz....my crossover started walking off the amp stack at only about 4v rms at amp! (5.7vp)
38hz is the impedance minimum (5.4 ohms) on a single Lab12 in the labhorn (by my measurements). So at 50v peak or 35vrms, I get that would be about 6.5 amp through the 26 gauge coil .....this song is perfect for smoked labhorn BBQ ...
50vrms would probably make direct cooked BBQ !
mRgSr, that's the kind of thing I'm wondering about.
Chris, both vids really push 38hz out...the vid you linked starts right out with it...
In the past, I had a pair of corner stacked labhorns in a fairly large 39'x23' rec room. They pointed into the corner which provided a quasi mouth extension in addition to the gains from 1/4 space loading. Nose tickling bass 30 feet away!!
Thx all,
and to all......
OK .... there seem to be 3 knock possibilities...
1. coil hits plate
2. spider striking magnet structure
3. coil/former cocking inside magnet
1. Coil hitting plate started out as my assumption, but in looking closely at the driver, and feeling just how much pressure it takes to get the former to touch the back plate, I'm leaning to a combination of 2. and 3.
Because it's pretty clear the spider is in a race with the coil to hit something first.
It looks like the first thing the spider could hit is the basket about 1" in from the spiders outer perimeter. The basket steps up/dn there and has a perforated band going around inside it, right up to its lip.
On the driver I have torn apart, the perforated band isn't uniformly aligned below the basket lip. It is about 3mm too high in one spot, and my guess is this is the first place the spider would hit. This would cause the coil to tilt in the magnet gap too.
Dunno if this is it, but it does seem more likely than the coil hitting....
Mark,
No, the distortion test with Smaart requires sine wave tones. The distortion is there on your kick drum hit, but harmonics from drum sounds sound like drums. You could use the spectrograph to compare what the crossover output looks like on the kick hit compared to what the mic output looks like, I'll bet you will see a lot of harmonic content not in the recording well below 140v peaks.
Drum hits are also not a symmetrical waveform, you might not hear the "clunk" if you reverse polarity of the speaker or the signal.
At any rate, you won't be running just kick drums, I'd set the peak limit no more than 80 volts, the drivers will be well above X max through most of their range at that level.
Art
Thank you Art,
When i get the time and weather to test outside, I'll try the spectrograph.
It will be interesting to compare the peak impulse distortion against the usual sine distortion.
I tried reversing polarity, clunk remains....
I think it's about time to back down to some reasonable setting like the 80v you suggest.....and let this go.
I hate over analyze anything, especially a drum hit on one flipping song. (which btw, Joe Walsh, Ordinary Average Guy... great test track)
When i get the time and weather to test outside, I'll try the spectrograph.
It will be interesting to compare the peak impulse distortion against the usual sine distortion.
I tried reversing polarity, clunk remains....
I think it's about time to back down to some reasonable setting like the 80v you suggest.....and let this go.
I hate over analyze anything, especially a drum hit on one flipping song. (which btw, Joe Walsh, Ordinary Average Guy... great test track)
Probably a good idea.
Hey, if you want to bump some backplates, try "Andrea Zonn - Better be Home Soon"
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