US Amp MD 43 and figuring 80Hz location

[Iluv2zmzm]

i have the Rainbow 265Kicks which need to be run at 80 Hz/ 12 db high pass but problem is amp only list 40 Hz and 1Khz, so right now i have it set in the middle...

how can i tell for sure if that is 80 Hz?? dont want to ruin my speakers and want to make sure i get the most out of them that i should be...

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[NewToTheGrounds 10+ year member]

bump

 

[docutech 10+ year member]

Interesting question...

Would playing a 80hz tone while adjusting the knob work? //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[squeak9798 5,000+ posts]

Interesting question...
Would playing a 80hz tone while adjusting the knob work? //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

In conjunction with a DMM yes, it would.

Most (but not all) crossovers define the crossover frequency at the point where the signal is down -3db.

Turn the crossover on the amplifier either off or to it's lowest setting (and turn off any xovers in the headunit).

Grab a DMM and set it to measure AC Voltage. Connect the DMM to the speaker outputs on the amplifier.

Play an 80hz tone and turn the volume up until the voltage reads 1.414V

Turn the crossover knob on the amplifier until the voltage decreases to 1.0V.

For inquiring minds;

Voltage difference in dB = 20*Log(Voltage2/Voltage1)

db = 20*log(1/1.414) = -3.01db

Though; Don't bother with exact crossover frequencies. I'm guessing the reason you're set on using that xover frequency is because it states to use an 80hz 12db/oct highpass filter in the owner's manual. Realistically, the BEST thing you can do is simply grab some music you're familiar with and listen to the music at your typically listening level with the xover set to various positions throughout it's range and find the positioning that minimizes distortion while still providing adequate midbass presences and the best blending with the subbass (assuming you currently have a subwoofer installed). Exact frequencies aren't important....all that matters is how it sounds....and the "best" setting will be different for every car/installation/system.