Distortion from Jamo D4 - problem cone?

The speaker info is telling you that a 400watt input is nominal or stable. and handle anything that can Peak up to 1200watt , the speaker can handle the 1200watt but not for long periods. Distortion will likely occur well before then anyway. On my home stereo, I have twin Marshalls which are 500 watt each going to JBL,s rated at 150 watt with 250 peak. The ratings are a bit different from manufacturer to manufacturer. Ive found the system is really powerful but there is very little to no distortion as the amp is not needed to be cranked up to get the volume I want. If you run an amp that is too big for the speakers, it will sound really loud for a while, then distortion happens then watch your speaker cones self destruct or the voice coils burn out. If you run an amp that is too small, you will need to turn it up more for the volume and then distortion sets in earlier, which is the biggest destroyer of any speaker.

It sounds like the cone is distorted. If it's a paper cone, it may have gotten wet. If it's a poly cone, it may have been exposed to too much heat (sunlight?).

Also check the wiring; anything loose may make a rattling sound.

Last, the problem may not be in the speaker at all - it may be a problem with the amp.

yes, but you would not get the same performance as you would if you gave them the suggested power. I have found that it is always better to use a more powerful amp than your subs are rated for (as long as it is clean, high quality, low distortion power). I have had the best luck with name brand amps (kicker,rockford fosgate,phoenix gold,etc...). I hope this will be helpful to you.

Possible this is a distortion from the Amplifier if the speakers are not damaged. however it is important to switch the speakers to confirm if the fault is relative to the particular channel in which case the amplifier is faulty. If not the speaker can be the culprit. All what is needed is to reduce the BASS level a bit lower when the volume is increased so as to allow the cross over to work. Also if teh cross- over network is faulty within the speaker the bass can vibrate on the tweeter.

A common reason for 'distortion' with all bass amps can be either that the screws holding the speaker unit to the cabinet have worked loose or that there has been a build up of dust particles in the corrugations around the edge of the speaker cone, which rattle especially on the lower notes.
The solution is simple - remove the front grille and check the screws are tight. Use a vacuum cleaner to remove dust from the rim of the speaker cone.

This is a problem I have had as well. Know that Yamaha and other manufacturers that give an 8 ohm minimum spec DO NOT reccomend hooking 4 ohm speakers up to their amplifiers. That being said, I have had no problems with the Behringer 1C on Onkyo, Sony and JVC amps. You *must* be careful to regulate your listening volume, and be aware that the distortion the amp produces into a 4 ohm load is much higher than with 8 ohms. You also take the risk of cooking your output transistors.
It is up to you to decide if the risk, the neccessary self imposed volume limiting and the added distortion are worth it.

Your amp is too much, or your gains and bass boost are set too high and the sub is distorting. Distortion happens when any of those three things are happening, basically your sub is no longer moving straight in and out and the cone is trying to compensate. This causes the cone to break away from the coil.

A receiver with the specs...

* "90 watts minimum continuous power per channel, 8 ohm loads, 2 channels driven from 20 Hz to 20 kHz, with a maximum total harmonic distortion of 0.08%"

(*) The only acceptable statement of its power bandwidth in the manual.

... when fed an undistorted audio signal, used properly and not driven abto clipping is not particularly dangerous to any reputable speaker.

Driving any amplifier, even a modest one, into high distortion is more dangerous to any speaker than a high-powered amp pumping pure undistorted power.

Choose any speakers but low efficiency models if you want loud and clean sound.

First, swap the speakers to see if it stays with the speaker or the amp channel.

Second, disregard the throretical ability of any speaker to handle any amplifier's maximum output. Amp ratings are at a certain power output with a certain amount of distortion. Turn the volume a click higher and power output might rise just a tad but distortion starts to go ballistic. Continue and you get total high current garbage. Clipping (high DC output) will kill any speaker.

Since it seems to go away, I doubt the speaker is damaged, unless torn speaker cone or burnt voice coil can self-repair in a few minutes every time.

Sounds like classic dry joint on speaker terminal ROTELS are well known for it,if you can use a soldering iron or know someone who can resolder the pins where these terminals are connected,always make sure amp is unplugged from wall socket before ...