[themuffinman]

Finally got my cabinet built. 25x25x25 cube with two EX PR-18's with 1600 grams mass on each one. Amp is Crown XS900. Using a minidsp with a bi-quad programmed high pass filter at 13hz.

Got everything hooked up and playing a bass test tone at 24hz quarter volume. Sub sonds terrible. Scraping noise, like it's semi blown.

Killed the signal. Slightly pushing in on the cone produces a terrible scrapping sound. Turned it off. Got up this morning and the cone is locked now. Doesn't want to move.

How is this even possible? It is nothing I did as the sub barely got like 3-400 watts and theoretically if I had turned the volume up it wouldn't have bottomed out via calculations in winISD.


Thoughts??

 

[Moonfly]

Sounds like the VC is scraping to me. I would say this needs to go back and be replaced. First port of call should be Mach really IMO.

 

[themuffinman]

No I agree with you. I will email/call them on Monday. I just wanted to make sure I wasn't crazy or anything.

 

[Moonfly]

Well given what you say it sounds like something in the suspension has failed, or the VC assembly has a manufacturing fault, and the VC is scraping in the gap for what ever reason. That could lead to a short and seizure of the motor I guess, which would also add up with what you seemed to experience. With low power input and no burning smell, I think a burnt motor could be ruled out, and a blown driver will usually rattle rather than scrap and seize up.

I can only think of a manufacturing fault being to blame.

 

[themuffinman]

Mark sent me a quick reply even though it's saturday. Top notch customer service.

He said it is most likely from the magnets shifting during shipping due to such a heavy driver. Glad it wasn't something I did!

 

[Moonfly]

I think he should probably work on trying to figure out a way to secure that then. A driver works quite hard during its life and magnets that could move would be a concern.

 

[Binary]

i don't see how it could be the magnets moving during shipping. They are aligned to each other, and glued in place. There should be no way that they can move, and if they do. Its a major QC issue. not a minor one.

The Pi is almost impossible to bottom out to begin with, it has a very stiff suspension vs the xmax available. It can do 34mm, but you'd need like 3000+ watts to get it there in a 14 cubic foot box tuned for 15hz. and a high pass at 13hz.

This is definitely manufacturer side, but not for the reason the he explained to you. I don't like that explanation. at all.

 

[Moonfly]

My bet would be a manufacturing error with the VC in the gap, possibly too tight and scraping as a result, or not machined quite right. I know AE had a similar issue with a small number of drivers, apparently due to poor employees.

 

[themuffinman]

Maybe it is just one bad sub. Mistakes happen and they are taking care of it. I'm not too worried about it. I'm more worried about getting the sub out without the hurricane nuts breaking lose and spinning.

 

[sub_crazy]

I'm more worried about getting the sub out without the hurricane nuts breaking lose and spinning.

That's why I stopped using hurricane and t-nuts, not enough benefit for the potential problems.

 

[GranteedEV]

That's why I stopped using hurricane and t-nuts, not enough benefit for the potential problems.

What do you use then?

 

[sub_crazy]

I just screw directly into the wood. It works a great with ply wood and good enough for MDF. If your not going to take your screws in and out then screwing directly into the wood is just as good, just use a good speaker gasket.

 

[sub_crazy]

As an example, I secured 2 LMS 18's into 13ply baltic birch using just the wood screws supplied by TC Sounds. Those heavy beasts were in very tight.

 

[themuffinman]

I was able to get it out. 2 broke free of the gorilla glue. Perhaps they pushed out a little bit from the glue expanding though.

 

[themuffinman]

Sad day for these two UXL-18's. Thanks a lot UPS...

 

[sub_crazy]

Wow, UPS really went to town on those, they must have been playing truck soccer with the boxes.

I personally never use UPS anymore, too much damage over the years.

Sorry to see they did you like that.

 

[Mike P.]

Ouch!

 

[Moonfly]

I would be letting Mach know whats happening to their products.

 

[themuffinman]

I have sent them emails. They are aware of UPS. Hopefully they can recoup from UPS insurance...And Hopefully I can get a driver.

 

[Ricci]

Sorry to hear about your subs. Thanks for the pics though. Man those got trashed. That pole is shifted bad. Mach5 must beef up their packaging on these even if they have to pass some extra cost on to the end consumer.