Active 2-Way - Intermittent Sound Cuts Out From Mid Bass Woofer

[audiohauz]

Hello,

IÂ’m a mobile DJ, Trying to troubleshoot a problem with my one RCF Art 422a,
12in LF / 2in HF active 2-way speaker.

After pumping music through it, for about 5-10 minutes at a pretty high volume (not clipping), the low frequencies cut out for 10-20 seconds then come back on. It seems that at the peaks of the music ( kick drum heavy sounds ) it cuts the LF woofer, IÂ’ll then turn down the music, wait a bit and it comes back on. The internal Xover is 1300Hz and IÂ’m assuming all that IÂ’m hearing is 1300Hz and up coming out of the 2in driver.

I brought it to my authorized repair shop a couple of times but they had limited time to fully inspect. I donÂ’t have an extra set to use for my gigs so I needed it back by the weekend. When I am using the speaker paired with the Rcf sub705, the speaker works fine. I use the subs xover to send
80Hz and up to the pair of 422Â’s. Only when I use the 422Â’s alone this sound cutting out would happen. When used alone, it would work as normal to start, but when the event moves along and I begin to push music louder, the lows eventually cut out having to then lower the gain of the speaker and within seconds it would eventually come back. It would only continue this process if I turn the gain back up.

The speaker and driver were tested and are fine. It was cleaned internally and the heat sinks tightened.
Components were tested, as was told to me. Culprit could not be found. I am hoping to get any advice of where to look for the problem or if anyone has come across a similar situation.

Much appreciated

[Enzo]

There is no real way to test parts on the bench for "shutting down after they warm up 10 minutes". All a shop can do is test them statically for function.

Same with the woofer, no way to test for this cold, you need to drive it hard for 10 minutes.

As far as I know, there are separate amps in there for woofer and tweeter. It sounds like your woofer amp is overheating. It could be as simple as a bias adjustment ...assuming one exists on this amp. The sheet calls it a digital amp, and a lot of those are not adjustable.

[J M Fahey]

Enzo points at the problem that some extreme tests can not realistically be made at a Service Shop.
Can they drive amp and speaker full blast and beyond for 1 hour?
Because although you say problem appears after 10 minutes full blast, you have already been using it for at least an hour, if not more, so you are not starting with a "cold" amp/speaker by any means, but a thoroughly warmed up one.
In any case, be glad that modern high quality speakers such as RCF, a very respected brand, added lots of protective circuits to their products.
"Cutting off" tells you something: cabinet is being abused, period.
Any other brand would simply kill the speaker or worse.

So it works fine (the way you use it) by adding a subwoofer?
Then by all means please use it always.
A bass drum kick is a very strong and difficult waveform, and can easily clog a 12" speaker; sending it to a subwoofer is the right thing to do.

[nevetslab]

Enzo points at the problem that some extreme tests can not realistically be made at a Service Shop.
Can they drive amp and speaker full blast and beyond for 1 hour?
Because although you say problem appears after 10 minutes full blast, you have already been using it for at least an hour, if not more, so you are not starting with a "cold" amp/speaker by any means, but a thoroughly warmed up one.
In any case, be glad that modern high quality speakers such as RCF, a very respected brand, added lots of protective circuits to their products.
"Cutting off" tells you something: cabinet is being abused, period.
Any other brand would simply kill the speaker or worse.

So it works fine (the way you use it) by adding a subwoofer?
Then by all means please use it always.
A bass drum kick is a very strong and difficult waveform, and can easily clog a 12" speaker; sending it to a subwoofer is the right thing to do.

While it sounds like you're dealing with an automatic resetting thermal switch, just where that part is placed within the amplifier / signal processing assembly of this speaker is another matter. I've never been inside one of these, and at first glance, you may be in for real challenge, having serviced some other similar products. Some are so densely packed, I passed on them, deferring them to factory service. I'm guessing this is Class D Switching amp for both LF & HF, and has a switching power supply to run everything.

The good news is, while it is a discontinued product, it's expensive enough that service should be available for it, and it may be a common ailment. I'd contact the factory and also do some further search to see if what you're experiencing may be a product defect that has a correction for it.

[audiohauz]

I emailed RCF, just waiting for a reply. Thankfully they are pretty local here in NJ. The speakers are just about 10 years old, have never abused them or pushed them to their limits. Worst case, I found the amp module for $399. They’re great speakers with neo magnets before they switched to ceramic/ferrite I believe. They’re not building them like these anymore, at least for the Art series. I appreciate the feedback and I’ll keep you posted.

[g1]

So you have a pair of them, and if you swap them around, the same one cuts out?

[audiohauz]

So you have a pair of them, and if you swap them around, the same one cuts out?

Good question. Was planning on it. Will try this out and post