Sguirrelfeather
Senior VIP Member
Trying to help my tattoo artist with his setup and I'm not familiar enough with his amps to know if I'm screwing something up or if his amps are bad. He has two JL 500/1 slash amps. I know that means they're supposed to put out rated power into 1.5, 2, or 4 ohms, but is there anything odd about them? He had it already setup and wasn't 100% sure he had done it right, so I pulled the speaker wire, reset gain to lowest, and hooked up the DMM and o-scope. I turned the gain up until it read 31.6 volts, with the HU set to max volume he would be listening at. The o-scope showed MAJOR clipping at that level....rather than a flat line atop the wave, it actually dipped back down a little bit. I read the manual, just to be sure, and they recommended 31.9 volts I do believe, just like I had set it. Next thing I know, he's asking me why I had it so low. He said he had turned the gain much higher. So, I figured I would show him, and had him turn the gain knob to where he had it....pointed at the S in sensitivity. I hooked up the DMM. 61.1 volts!! He had that thing set to try to put out almost 1900 watts! Funny thing about that is the o-scope was a perfect sine wave.
So, color me confused. I started playing with the gain while watching the o-scope and DMM. When I dropped down below 39 volts or so, the flat tops started appearing. At 32.5 or so the flat tops began dipping down, and then became normal sine waves at about 25 volts. I honestly only checked the one amp, because after that I figured I needed to do some reading. Thus far, I have found nothing to explain this. Just for the heck of it, I hooked up the sub and played it at various voltages. As the o-scope would suggest, the sub sounded like crap at any voltage where the o-scope did not show a nice, pretty sine wave. And, it started sounding like crap above 45 volts...I'm thinking took much power for the subs. So, we settled on 40 volts for now, and I told him to not crank it up.
Also, I did check his RCA outputs and there was zero clipping all the way up to his max volume, so definitely none at his high listening volume. And, bass boost was off on amp, on HU, etc. Crossovers were set appropriately, good wiring, decent voltage (never went below 12...he has stock alternator), etc. I'm thinking there's something wrong with the amp, but since this is something I'm not used to, having the regulated power supply, I figured I would seek out some advice.
So, color me confused. I started playing with the gain while watching the o-scope and DMM. When I dropped down below 39 volts or so, the flat tops started appearing. At 32.5 or so the flat tops began dipping down, and then became normal sine waves at about 25 volts. I honestly only checked the one amp, because after that I figured I needed to do some reading. Thus far, I have found nothing to explain this. Just for the heck of it, I hooked up the sub and played it at various voltages. As the o-scope would suggest, the sub sounded like crap at any voltage where the o-scope did not show a nice, pretty sine wave. And, it started sounding like crap above 45 volts...I'm thinking took much power for the subs. So, we settled on 40 volts for now, and I told him to not crank it up.
Also, I did check his RCA outputs and there was zero clipping all the way up to his max volume, so definitely none at his high listening volume. And, bass boost was off on amp, on HU, etc. Crossovers were set appropriately, good wiring, decent voltage (never went below 12...he has stock alternator), etc. I'm thinking there's something wrong with the amp, but since this is something I'm not used to, having the regulated power supply, I figured I would seek out some advice.
