Nismo audio upgrade- critique my planned setup

2fast4thelaw

You have a little ground floor noise going on which is normal and to be expected. This is caused by a mismatch of gains or lack of balanced outputs between the headunit and the amplifier. (very few car audio head-units use balanced pre-outs - only the very high-end units) Since you cannot adjust the pre-out levels from your headunit the only way to reduce your floor noise is to use a pre-amplifier/line-driver to match the levels between these devices. You will never be able to get rid of all of it, only reduce it.

I also recommend stuffing your enclosure with about 2 to 3 pounds of poly-fill which will (I know it sounds strange) increase the volume of your enclosure by 10% to 15%. The polyfill will lower the FS (Lowest tuned frequency of the enclosure before -3db roll-off naturally occurs) Essentially the enclosure/driver work as if it were in a larger enclosure. This does come at a slight cost of efficiency though. With the amp you are using, you wont notice the loss.

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