Hartke LX8500 cutting out

[Oddacious]

I cranked to compression as the documentation states that it is designed to protect the speaker from transient spikes. Again, I would never play with it dialed in this way, I was testing to see if full compression would stop the amp power section from cutting out. Im going to test and check the resistance values under the same load tomorrow and see if the cab drops below 3ohms.

 

[agedhorse]

Hold on a second, before testing things, please let us know how you propose. What you just said above doesn't make sense... you can't check resistance values under the same load since the resistance IS the load that you are measuring.

 

[Oddacious]

I might be thinking about this incorrectly, but I was going to measure the voltage and current, chart it, and calculate the resistance using resistance=voltage/current.

 

[agedhorse]

That will work but be careful.

 

[Oddacious]

And, I figured out what's been causing this phenomenon, it is somewhere in the crossover. I have been skeptical about the crossover with the shunts, and a total cabinet load of 5 ohms while the woofer is 4ohms. I am guessing that the crossover is shunting the 8ohm tweeter, and running the two speakers in a series. So, at a feed signal of 1500hz+, the woofer isn't getting any power because its choked, and the crossover is pushing the load to the tweeter via the high pass, perhaps at a little over 1 ohm? Again, I could only produce this issue with the treble on the active bass eq maxed, and the treble on the amp maxed.

So I bypassed the crossover and wired the amp directly to the 12" woofer at 4ohms, and voila, no issues. I have the treble pegged on both the bass active preamp as well as the amp eq, the gain at 10. Now, the gain still lights up red when I'm plucking, but no cutting out, no fan kicking on, and I can get pretty loud with it, but am not wanting to blow the driver.

Thank you all for your input and patience, I've definitely learned quite a bit

 

[agedhorse]

Hold on a minute… it’s common to use a pair of resistors along with the high pass filter as a pad.

All you have done is identify that SOMETHING within the crossover or tweeter is responsible, but not WHAT is actually the cause.

Have you measured the DCR of the tweeter to rule out a shorted voice coil?

It’s possibly a number of things, some not obvious.

 

[wave rider]

I remembered an issue about some amps going into protection due to the Avatar crossover. I tried searching for the thread and found a few referencing the problem but not an exact diagnosis as to why. @agedhorse was in a few of those threads too.

Feeling weak on the Google-fu…

 

[agedhorse]

I remembered an issue about some amps going into protection due to the Avatar crossover. I tried searching for the thread and found a few referencing the problem but not an exact diagnosis as to why. @agedhorse was in a few of those threads too.

Feeling weak on the Google-fu…

Yes, that is why I brought up the subject of illegal loads, and the need to correctly identify the actual cause. In some cases it could be due to an open tweeter (though I don't think that's the cause here).

There are multiple potential causes, often it's not as easy as it seems once you understand how many class D amps work. The same (or similar) issue can occur with conventional class AB amps, but the result tends to be catastrophic failure if the cause is a leading PF load.

 

[DWBass]

And bring down that compressor knob. Should not have to have it all the way up. That will severely cut your signal as well. Dialed in at noon should suffice.