My cousin dropped his Velodyne DLS-4000R sub off with me to fix/replace the malfunctioning plate amp, but upon inspection of everything it looks like the entire surround is cracked right at the edge of the speaker cone.
I'm familiar with replacing foam surrounds on old speakers where they've begun to rot and crumble, so this isn't a 'how do I' post but rather a why post (and in turn, how do I prevent a repeat occurrence). The sub was made in 2010 and the surround looks to be in good health otherwise. The crack/break is almost all the way around the cone just at the point where the cone meets the surround. My only guess is that too much excursion caused stress right at the cone edge, which resulted in the break. Is there any best method to prevent a repeat crack?
I'm familiar with replacing foam surrounds on old speakers where they've begun to rot and crumble, so this isn't a 'how do I' post but rather a why post (and in turn, how do I prevent a repeat occurrence). The sub was made in 2010 and the surround looks to be in good health otherwise. The crack/break is almost all the way around the cone just at the point where the cone meets the surround. My only guess is that too much excursion caused stress right at the cone edge, which resulted in the break. Is there any best method to prevent a repeat crack?
It is wiser to contact Velodyne and report this incident.
If it is a serious company, you may get a speaker replacement for free.
If it is a serious company, you may get a speaker replacement for free.
Coil tests fine (dc resistance), but I'll give it a smell too. I'll contact velodyne, but I'm also curious what exactly would cause this. Is my initial assumption correct?
Sometimes the adhesives used to attach the surround are too hard and form a sharp edge which cuts the foam surround and sometimes the type of adhesive used can accelerate the decomposition of the foam causing premature failure, get in touch with Velodyne they might have had a bad batch.
Really though, they only warranty their product for two years so in the end I will likely be the cheaper repair option.
it sounds like the driver was really pushing hard and the edge stressed the cone. Even at modest levels, with lots of displacement, it's not uncommon to have a sudden bounce from the sub(s) (yes, with digital as well as vinyl)- there's all manner of weird stuff on recordings, and we do tend to listen to a variety, so the solution is that way too much=just enough. The short term solution is to re-surround it (with foam) if the coil isn't stinky. Longer term, is likely an increase in displacement. I have a modest apartment, but my 12" / 15" active/passive radiator systems (1 per channel) will see those passives jump sometimes on seemingly benign content. They're tuned to an overdamped 11 Hz or so if memory serves, so there shouldn't be much of anything down there.... but there is, sometimes.
Voice coil smells like fresh factory rubber/glue smell still (I'm likely the first to open this box since factory assembly). Absolutely no burnt/melted smell going on (I assume that's what I should be smelling for).
Tomorrow I'll phone Velodyne. I doubt I'll get far with them other than reporting a problem they might have had four years ago, but it can't hurt.
I'm leaning toward getting a rubber surround replacement and erring on the shy side for the amp replacement wattage to help prevent any problems of unloading. We'll see, if after the surround fix the T/S parameters suggest that this box sealed instead of it's current ported state, I may frankenstein something together that'll prevent it from unloading into dangerous excursion.
Tomorrow I'll phone Velodyne. I doubt I'll get far with them other than reporting a problem they might have had four years ago, but it can't hurt.
I'm leaning toward getting a rubber surround replacement and erring on the shy side for the amp replacement wattage to help prevent any problems of unloading. We'll see, if after the surround fix the T/S parameters suggest that this box sealed instead of it's current ported state, I may frankenstein something together that'll prevent it from unloading into dangerous excursion.
A 35/40 Hz highpass before the amp input might be cheap safety.
Not much music below that anyway, and if the box is ported it unloads the speaker below a certain frequency what is dangerous.
Not much music below that anyway, and if the box is ported it unloads the speaker below a certain frequency what is dangerous.
Yeah, Velodyne just told me 'thank you for letting us know' and that I'd need to ship the entire box and driver to them before they are able to determine it's actually a manufacturing defect. Way cheaper to fix it myself even if they end up finding it's their fault.
So now the question is: should I use a rubber surround to prevent any further problems or stick with foam to maintain similar T/S characteristics? I'm not even sure how much the surround material changes the T/S specs. Thoughts?
So now the question is: should I use a rubber surround to prevent any further problems or stick with foam to maintain similar T/S characteristics? I'm not even sure how much the surround material changes the T/S specs. Thoughts?
In my experience, the spider has more effect on setting the T/S parameters than the cone surround. Since we are talking about a high excursion rolled foam surround any similarly compliant rubber surround should not change things very much – not enough to be audible anyway. Now if we were talking about high efficiency drivers with stiff cloth surrounds, that’s another story.
EDIT: I've replaced the foam surround on my Tang Band W8-740C woofers with butyl rubber and the T/S parameters shifted less than 3%.
EDIT: I've replaced the foam surround on my Tang Band W8-740C woofers with butyl rubber and the T/S parameters shifted less than 3%.
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