Hello there.
I am a user of a 12" EDGE SPL122-e6 sub powered by a Crown XLS 2502 amp on bridge mode. The way I have them set up is this:
-low-pass filter up to 80Hz
-signal coming from a digital equalizer, some frequencies are lowered, some are boosted (very important! ex: 32Hz -5dB bc. of room resonant frequency, 38Hz boosted to 5dB)
-subwoofer box tuned to around 27Hz
The problem is that every time I turn the system loud and some parts of a song have around 38Hz playing through, the subwoofer seems to be bottoming out, even though it never gets hot or never smells. How do I know it never smells or gets hot? Well, when playing 32Hz and lower, it plays just fine and no noises can be heard. I even have sub 30 Hz frequencies boosted up to 3-5dB (21-29Hz) and has no problem playing them, not even at very high volume. The reason, I think, may be because the box is so low tuned, frequencies way higher than the tune frequency (in this case 38Hz) cause the sub to move quite a lot to the point where it actually starts bottoming out. It does that, although I don't think that's the most power the subwoofer can handle. Most people supply up to 5000w to these in a car which is mind-blowing, but I guess they have lower tuned boxes as well.
I have the sub for almost a year I think, there's never been anything wrong with it. I don't think there are coil problems or anything that can redeem it damaged.
Any thoughts on this? I'd really appreciate it.
Don't bother sending rude comments as I won't be taking them into consideration.
Here's how it looks in action:
Thanks!
I am a user of a 12" EDGE SPL122-e6 sub powered by a Crown XLS 2502 amp on bridge mode. The way I have them set up is this:
-low-pass filter up to 80Hz
-signal coming from a digital equalizer, some frequencies are lowered, some are boosted (very important! ex: 32Hz -5dB bc. of room resonant frequency, 38Hz boosted to 5dB)
-subwoofer box tuned to around 27Hz
The problem is that every time I turn the system loud and some parts of a song have around 38Hz playing through, the subwoofer seems to be bottoming out, even though it never gets hot or never smells. How do I know it never smells or gets hot? Well, when playing 32Hz and lower, it plays just fine and no noises can be heard. I even have sub 30 Hz frequencies boosted up to 3-5dB (21-29Hz) and has no problem playing them, not even at very high volume. The reason, I think, may be because the box is so low tuned, frequencies way higher than the tune frequency (in this case 38Hz) cause the sub to move quite a lot to the point where it actually starts bottoming out. It does that, although I don't think that's the most power the subwoofer can handle. Most people supply up to 5000w to these in a car which is mind-blowing, but I guess they have lower tuned boxes as well.
I have the sub for almost a year I think, there's never been anything wrong with it. I don't think there are coil problems or anything that can redeem it damaged.
Any thoughts on this? I'd really appreciate it.
Don't bother sending rude comments as I won't be taking them into consideration.
Here's how it looks in action:
Thanks!
Are you assuming it's bottoming because of distorted sound or because of visible excursion? I can't tell from your description.
I assume your voice coils are in series, for a 4 ohm bridged load?
Did you run simulations for port air velocity?
Did you confirm your port tuning frequency with measurements or were they just calculated?
Are you using a high-pass filter on the amp?
Have you turned off your EQ to see if the behavior is similar around 38 Hz? (though obviously at lower level without the EQ, if the loss of control around that frequency is related to the box, that basic characteristic should still be there without EQ)
I assume your voice coils are in series, for a 4 ohm bridged load?
Did you run simulations for port air velocity?
Did you confirm your port tuning frequency with measurements or were they just calculated?
Are you using a high-pass filter on the amp?
Have you turned off your EQ to see if the behavior is similar around 38 Hz? (though obviously at lower level without the EQ, if the loss of control around that frequency is related to the box, that basic characteristic should still be there without EQ)
in my Hypexed sub I made a ‘rather high’ high pass, at somewhere like 25-27 Hz, with more than 48 dB/octave. This prevents any problem with my speaker.
it allows a very tight control.
I'm assuming it's bottoming out because of the excursion at 38-ish Hz. But it's bottoming out strictly from a mechanical stand point, not cause of too much power being fed to it. As I said earlier, it can take all the power the amplifier feeds it at lower frequencies just fine.
Yes, the voice coils are in series, 2+2ohms.
I didn't run any simulations for the air velocity and the port tune is strictly just an asumation. It's most likely around 27 hz, as the air velocity is most pronounced at that frequency.
The amp has built-in filters and I have put a low-pass filter on the sub.
Without the EQ it will most likely won't act the same, as the bottoming out at 38Hz is because of the 4-5db boost I set on the EQ.
As I said in the post, the sub seems like it's got no enclosure beyond 33Hz or so, because of the low tune of the box. It has lots of excursions, but really emitting some clicky sounds at 38Hz which are noticeable in songs with less highs.
I see what you mean, but if I do that, I kind of lose the purpose of having a sub playing music. Most songs have lots of frequencies between 40-60 Hz which are mostly getting picked up by the sub alone. Over 60 Hz the sub low pass filter meets the speakers high pass filter and then the speakers start to pick up the rest of the job.
Oh, and by the way, the intercalation of the two curves is really important. I once tried rising the high pass on the speakers so that they would pick up the frequencies around 80 Hz and up, but it just didn't sound well. It seemed like there was a blank space at around 59-70 Hz. The sub box being so low tuned doesn't perform as well at higher frequencies such as 60, 70 as below 50. In adition, there's room acoustic problems. That's why we have more speakers being put in more places other than just in one place, in order to compensate for the loss of bass in one or the other place.
You seem to be implying that the thermal power handling is the end of the story, but it's not. The box design influences actual power handling in practice, since excursion limits can easily be exceeded before thermal limits with a box design that doesn't suit the end use.
If you run simulations that plot excursion vs. frequency, you will also see that driver excursion is lower at the port tuning frequency (Fb), and then increases at frequencies above it and below it. As frequency increases more, excursion goes through a local peak then starts to decrease. That's just the way a ported box works. Here's a plot for a ported box tuned to 24 Hz (not your driver):
Let's make it a round 6 dB, because that's an easier number. 6 dB of boost requires 2x the excursion vs. no boost.
Given your responses above, it sounds like you may just not be happy with the performance of the current tuning.
Or there could be an issue with the driver's design where it's inherently mechanically noisy. Some high excursion woofers just are.
There's also the chance that the driver has a problem that is making it noisier than it should be, but not in a catastrophic failure kind of way.
Happen to know the volume and port length of the enclosure? With the box design and the parameters of the driver (available online) we could run a sim and get a very rough idea of excursion, port velocity, etc.
The volume is 3.28 cubic ft and the port length is 1.75 ft. It is roughly 27Hz tune as that is where the woofer excursion is the least prominent.
Yeah, I think that the driver is prone to those clicking sounds at very high excursions.
If it's "clicking", check if the voice coil lead wires can hit the back of the cone. That sort of thing is very audible and very annoying.
Chris
Chris
Considering the Fb of your design is 27 Hz, 38 Hz is likely at or near that point in the passband above 27 Hz where the driver hits maximum excursion for a given input voltage. If the driver's running out of excursion, then if you want the same or higher level of output, you'll need to use a more capable driver, or shift Fb upwards (decrease the length of the vent), or add another subwoofer, or use a higher order alignment like a tapped horn.
It could be anything. As I've previously intimated, sims are all well and good but do not account for 'music'. An amplifier is literally a multiplier. It will take the input signal at any given frequency and multiply it by 'x'. Even with hip-hop there's very little signal at 38hz and below. If, as hip-hop does, the track contains old samples you are likely multiplying rubbish, sub-bass rumble from an old analogue device.
Rather than use music, check your system using a frequency signal generator. You should also try a different amp as specs are never perfect.
I once had a sub with an 'apparently' mechanical click which vanished when I blocked the port. It turned out the driver's resistance dropped to less than 3 ohms at the tuning frequency of the port - the amp was having none of it. I've also had a cabinet with a mysterious port rattle - five different drivers and three different ports didn't cure the problem. Rebuilding the cabinet did not solve the problem either.
It's a mystery.
Rather than use music, check your system using a frequency signal generator. You should also try a different amp as specs are never perfect.
I once had a sub with an 'apparently' mechanical click which vanished when I blocked the port. It turned out the driver's resistance dropped to less than 3 ohms at the tuning frequency of the port - the amp was having none of it. I've also had a cabinet with a mysterious port rattle - five different drivers and three different ports didn't cure the problem. Rebuilding the cabinet did not solve the problem either.
It's a mystery.
Have you checked whether it is really the subwoofer making that clicking noise an not your digital EQ running out of headroom ?
Regards
Charles
Regards
Charles
His amplifier has a built-in, undefeatable subsonic filter (6dB/octave @ 20hz) which, thanks to OPs tuning and EQ, makes excursion below tuning lower than in the area immediately above it.
Based on my sim (which is imperfect given I don't know the Q of his filters or the exact dimensions of his port), his subwoofer's excursion hits quite a large peak at 38Hz. This leads me to strongly suspect his subwoofer is exceeding XMAX at relatively low power at the trouble frequency (38Hz).
Based on my sim (which is imperfect given I don't know the Q of his filters or the exact dimensions of his port), his subwoofer's excursion hits quite a large peak at 38Hz. This leads me to strongly suspect his subwoofer is exceeding XMAX at relatively low power at the trouble frequency (38Hz).