Hello ! one channel to have any high frequency oscillations. After few sec after ON , LEDs TEMP & ACS and relay disconnecting speaker . Regards Jerzy Purtak

follow this instructions and fix it. God bless you
Instructions

1. • 1
     Plug one end of a shielded input cable into the mixer's main output, and the other end into the crossover's input. The cable connectors will be dictated by your particular mixer and crossover, and will be either standard 1/4" or 3-pin XLR connectors. Consult the owner's manual of all components for specific details and recommendations.
     
     
   • 2
     Plug another shielded input cable into the crossover "high" frequency output, and the other into the crossover's "low" frequency output.
     
     
   • 3
     Plug the cable coming from the crossover "high" output into the channel one input on the stereo power amp, and the cable from the crossover "low" output into the channel two input of the power amplifier.
     
     
   • 4
     Plug one end of the unshielded speaker cable into the power amp channel one speaker output, and the other end into the horn tweeter.
     
     
   • 5
     Plug one end of the second unshielded speaker cable into the power amp channel two speaker output, and the other end into the woofer. The connections are now complete.
     
     

There are LED's all over these and you don't say which are lit... If they are mute or solo LED check the switches for a solo button or mute that is set.

IF they are the output level LED's plug in a set of phones and crank the phone volume up to losten if there is feedback or oscillation that is causing this.

HUM PICKUP due to a ground loop could be causing this. Make sure that ANYTHING connected to the unit that is also powered receives pwer from the SAME receptacle. If you have devices that receive power from a different receptacle you MAY have a ground loop. Noise on power lines can DAMAGE the equipment due to excedding the common mode input and output capability of the unit.

Finally, a strong local radio transmitter MAY be interfering. Sometimes the interference can go backward into the output lines to trigger the indicators.

As a test, when event occurs again, start unplugging anything connected to the mixer and see if disconnecting anything stops the problem. If you can have the problem with ONLY the power connected, then check if you have inadvertently created a loop within the unit by your settings.

Please refer to the "signal flow" diagrams in your user manual to see the possible feedback paths you can cause a loop to form.

REMEMBER the oscillation MAY be occuring well above the frequency you can hear !!!!

If you have access to an oscilloscope that would see if there is an oscillation going on.

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.

There are a lot of reasons your amp could be "motorboating" That is the term given to a low frequency oscillation. Be it only a half second it is still an oscillation. Electrolytic bypass caps are suspect most of the time. I would highly doubt there is a feedback problem with the amplifier circuits due to the fact this probably just started happening. Grounding on power supply caps also can be a big suspect. There could be a cracked solder joint on one of those components that is causing a ground loop which in turn will cause your parasitic oscillation of a 0.5 Hz.

you are actually not bi-amping the unit, you are bridging the amp. this really only works as long as all channels produce equal power. next the bad news is that typically home stereo amps are not wired internally to bridge channels.

bi-amping a speaker refers to connecting on channel to the highs and on channel to the lows. the receiver would need to be be able to process the outputs via a crossover network to split the frequency range in half so the appropriate frequencies went to the correct speaker.

Hello michaelandta,

Check your filter settings on the front channels. It sounds like they may be set to "high pass" which would eliminate the bass frequencies. If you are using the amp to power normal speakers, it's usually best to set the filters for "full range". If the amp only has "low pass" and "high pass" settings, turn them both OFF.

Hope this helps.

That sound´s like overheat... chek if there is no short circuit in the output cables or if any speaker is damaged

Hope it helps

Hello rwalinske, The abbreviations "hpf" and "lpf" stand for High Pass Filter and Low Pass Filter. They do exactly what their names imply. They allow frequencies above or below a specific setting, while blocking or attentunating frequencies below or above the setting. There's also a "band pass filter" which allows frequencies within a specific range below the high setting and above the low setting. Finally there's a "subsonic" filter which blocks inaudible frequencies below the threshold of hearing. The hpf is generally used in speaker component systems to send the high frequencies to the tweeters. The lpf is normally used with subwoofer systems and is set to send frequencies below the setting to the subwoofer. While most amps will amplify a wide range of frequencies, they are more efficient when the range is limited depending on their intended use. For example, a typical 2-channel amp might have a frequency response of 20-20KHz. When used to drive a set of normal speakers, you would not use either the lpf or the hpf, but simply let it send all frequencies to the speakers. But when used to drive a subwoofer, and operated in "bridged" mode, the amp can put all of it's amplifying power into frequencies than can be used by a subwoofer if the lpf switch is turned on. Hope this helps.

It isn't getting a steady, usable source of power, you can try to diagnose this your self but it will be a power issue INSIDE the monitor within the circuit board