Ditton 66 problem

[Nikivuk]

Two days ago I noticed that both bass drivers have a slight distortion, or is it some kind of resonance, exclusively at 250hz.
Does anybody encountered a similar problem?

I excluded the signal source as a possible cause, or cabinet itself, crossover, cables.
I'll check the amplifier tomorrow, that's the only thing left.
For now, I've solved the problem by reducing the input level on power amp (luxman m03).
That distortion, if I can call it distortion, is virtually inaudible when listening to music, I only noticed it when I tested the speakers with those samples of frequencies, but I was shocked to hear it on both bass drivers.

Thanks in advance for any idea.
Sorry for my bad english.

[Pharos]

First guess, coil binding in gap.

[walpurgis]

First guess, coil binding in gap.

Likely. The weight of the cones may have caused the suspension to sag slightly, resulting in the coils being at a slight angle relative to the magnet pole piece permitting rubbing. A simple 180 degree rotation of the drivers can sometimes cure this, but there are other options.

[Nikivuk]

That's it. When I gently push the cone outward distortion stops.
Somebody told me that 180 rotation can not give result immediately, is that true?

[Audio Al]

It wont happen instantly and will take time to sag the other way , Give it some time and see what happens

[Ian7633]

I had a similar problem with my MS Signifer's 12" drivers. I turned them 180 degrees and the distortion stopped after a day or two.

[Nikivuk]

Ok, 180 degree rotation done, now I have to wait.
Thank you all.
I will let you know how it turned out, it might be useful to someone.

[Nikivuk]

Guys, is there any other way to speed up this thing?

[Puffin]

Time Moves Faster Upstairs

https://www.insidescience.org/news/time-moves-faster-upstairs

[Nikivuk]

Nice system you have there