The Limit Prot LED on my RCF Art-321A speaker remains on upon power up. The speaker also pops upon powering down. What do you think it could be? Thanks

I would reccommend opening it up and taking a look inside. It should be easy to work out how to open it up. Once opened, check for any signs of damage or burning around the power supply unit. To find out what all of this means, simply search up what you're having trouble with on YouTube. Check to see if any of the capacitors are damaged. However, The most common reason for your problem would be damaged soldering, cracked soldering, or a weak solder connection. If you ?nkw anyone (friends or family) that are good at electronics and soldering etc, be sure to ask them to check it out too

Audio Equipment: Is the loud popping sound when you plug/unplug your speakers bad for them?
Most speaker cones are driven from a power amplifier.. The pop - like you said - is a transient spike. But the important thing here is that it gets amplified up through the pre-amp and into the power amp.. Speakers usually move in the ol' in-out fashion with respect the the voltage at the input.. and a big spike could loosen the cone from its suspension mechanism.. The higher the power and the more delicate the cone - the more the danger to the speakers ( what is normal for a woofer cone, could end blowing up a tweeter cone) . For e.g. In live events, where high output PA speakers are used, this is a very serious issue - because such a spike could throw the speaker cone out of its place, and it wouldn't work from that point on. For this reason, some high end audio equipment have a limiter at the output, that prevents signal from exceeding a certain predefined limit. So any occuring transients would never hit the cone at a level that is unhealthy to them.

Most home audio equipment tends to operate at lower levels. That being said, there is still some damage inflicted on the speakers - just maybe not of the same magnitude.. especially the smaller ones.

If your system has a remote control, it might be wise to hit a mute button just before you change to another input... or maybe find a way to turn off just the speakers (if separately powered) before you interchange the connection

At this point it sounds like you've done all you can do by yourself. Time to take it to the shop.

The amplifier is unable to achieve DC balance. This will require servicing. Could be a bad capcitor in the power supply.

Bass cancellation can occur if the polarity of one cable is reversed? Positive at the amp MUST go to the positive at the speakerS else one speaker will be pushing & the other pulling & the low frequencies get cancelled. You may also hear some strange imaging effects as you walk around the room - a bit like stereo from a mono setup.... check your cables :-)

The part number can probably be obtained from RCF directely as the speaker may be specially made for them. The specs are:

15" high power woofer, 64mm edge wound aluminium coil

email them to request part number at:

e-mail: [email protected]

Best to leave the limiter on unless you want to blow the amp and require repairs. Limiters protect the amp and also sometimes the speakers. The limiters reduce the gain when the amp reaches the maximum swing. If the gain were not reduced the amp would "flattop" which results in the circuitry saturating and massive distortion and if this condition is sustained, components can overheat or short out requiring repair. The LED MAY be just an indicator of clipping rather than an indicator of on/off. I downloaded the manual and what I have just said is CORRECT. The LED is a clipping indicator.

There is a caution regarding this amp and the sequence to turn power on. This amp does NOT have good speaker protection and you have to have the gain control down when turning on. The limiter, if you leave it on, might help protect your speakers when powering on. Most good power amps have circuitry to disconnect the speakers while amplifier is powering up and becoming stable, this one does not, so heed the warning and for certain leave the limiter ON... It just might save the amp and your speakers.

Yep, chalk that one up to poor design...The amplifiers are going out of balance during power up and down. Two seconds is pretty long... Try turning down the gain during power on and see if that affects it.

The pop on turning off is normal... None of these have speaker disconnecting hardware that is necessary for very high power amps. The biggies have hardware that checks amplifier is balanced before connecting the speakers and a relay also cuts the speakers immediatley on power down. As power goes up and down the circuitry comes to equilibrium and until it does, strange things happen.

I would investigate the CONDITION of the filter caps for the main power because if they age to a higher internal resistance that COULD cause the high freq oscillation on power up... Two seconds is MUCH too long.

There should also be some non-electrolytic caps NEAR the power output transistors to handle high frequency supply power bypassing.

Check the power bypasses that service the preamp stages. Look for pregnant electrolytic caps that have failed.

Ultimately, you MAY need an oscilloscope to isolate the high freq problem.

The power amp has failled and is driving DC current to the speaker. This can destroy the speaker. It is LIKELY that one or more transistors in the power amp and possibly other components have failed.

The unit will have to be serviced by an electronics repair facility. It takes test equipment to weed out all the failed parts, and it is likely there are several since when one fails it often burns up others. Likely one of teh power transistors or the amplifier "stick" has shorted. I would guess the parts will cost under $25 but finding which are bad can be labor intensive.

In the meantime DO NOT power the unit or you may destroy the voice coil of the speaker.

This often normal to get a pop as the power goes down. The amplifier goes out of balance as the power drops and it drives current into the speakers. This is a design problem and most amps don't even TRY to avoid it. Very large amps have relays that disconnect the speakers an instant before the power collapses to protect the speakers.