Vancev Posted November 1, 2019 Report Share Posted November 1, 2019 Hi! This is my first post and my first car audio system so please be patient with me. So In my truck i have a kenwood 7706s head unit with 4 volt preamp output a Rockford prime 1200 class d monoblock amp and a pair of ct sounds bio 2.0s. Wired in at 2 ohms. So my issue is no matter what I do I cant seem to exceed half the rated rms of the amp which is 800 @ 2 ohms. I had the same issue with my Rockford 500 and assumed it was just to small for the job. So general notes are truck has 160amp alternator and doesnt dip below 14.3v on 40hz tone. 2 gauge power and ground wire. The ground is .2 ohms from the amp back to the negative terminal and the truck had the big 3 done. I checked the amp with a Fluke oscilloscope and its clipping so my question is why? I have tried various media types from bluetooth to USB thinking it's a signal issue and completely reset all the settings more times than I can count. Link to comment Share on other sites More sharing options...
Mike4068 Posted November 1, 2019 Report Share Posted November 1, 2019 How do you know that you are only getting half the rated power? I've never seen a rf not do over rated. Link to comment Share on other sites More sharing options...
Vancev Posted November 1, 2019 Author Report Share Posted November 1, 2019 I used a fluke multimeter to measure the output voltage and a Kline amp clamp to check the amps. And I have been told that Rockford is a great brand and I doubt that I have had 2 bad ones. So I'm sure its something I'm doing. But I'm not sure what I got wrong. I should note that its clipping at half power.. the power is there but I just cant seem to use but half of it Link to comment Share on other sites More sharing options...
CrackFactory Posted November 1, 2019 Report Share Posted November 1, 2019 This is probably due to impedance rise. Link to comment Share on other sites More sharing options...
Vancev Posted November 1, 2019 Author Report Share Posted November 1, 2019 Would you mind helping me understand this? Google gives me a bland explanation not particularly aimed at the subject Link to comment Share on other sites More sharing options...
CrackFactory Posted November 1, 2019 Report Share Posted November 1, 2019 The subwoofer changes impedance depending on frequency as it's playing. So the amp doesn't always see 2 ohms. This will reduce amplifier output. To calculate your impedance divide the voltage you measured from the Fluke by the amperage from the Kline. Try measuring at different frequencies and you can make a graph. That would be your impedance curve. Link to comment Share on other sites More sharing options...
Vancev Posted November 1, 2019 Author Report Share Posted November 1, 2019 Ahh I see! I'll start working on that tomorrow after work. And thank you for the insight! Link to comment Share on other sites More sharing options...
Mike4068 Posted November 1, 2019 Report Share Posted November 1, 2019 What is your subwoofer level set to on the hu? Link to comment Share on other sites More sharing options...
Vancev Posted November 1, 2019 Author Report Share Posted November 1, 2019 Everything is set to zero when I'm setting up the amp. So eq and sub on the hu Link to comment Share on other sites More sharing options...
Mike4068 Posted November 1, 2019 Report Share Posted November 1, 2019 That's why. Set eq to flat. Sub level to max. Link to comment Share on other sites More sharing options...
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