I just installed a rockford amp and sub. When it's on, I only get all pass or high pass on my amp and no low pass. Where is the best place to tap into the mach 460 for a low frequency?
If when you have it on full pass and no low frequency gets through then technically you still have high pass working. If this is the case then tapping into a low pass wire (near impossible) won't help. Two potential problems! (that are likely, it may be neither of these)
1) the amp is broken - do you have warranty??
2) the deck is broken and is not transfering these frequencies to the amp. - my money is on this one!!
Like I said, it may not be either of these. Check them out though cause they are relatively easy to check.