I am replacing my 4 door speakers and adding an amp to my 2G MDX. I wasn't planning to run wires to the new speakers directly but rather connect the output of my aftermarket amp to the stock wires leading to 4 door speakers. I cut the output of the stock amp to the 4 door speakers and connected the outputs of the aftermarket amp. Simple enough right... Not quite.

Besides the front door stock speakers, the stock tweeters are connected from the same wire in parallel. The impedance of the stock door speakers is 2 ohms. The impedance of the tweeters is 4 ohms however, based on this thread the tweeter have capacitor to filter the high frequencies that increases the impedance to 6 ohms.

My new speakers are 4 ohms. My aftermarket amps is stable at 2 and 4 ohms. If I keep using the stock wire into my new speakers connecting the tweeter and the speakers in parallel, the total impedance (TI) would be calculated as follow:

1/ TI = 1/4 ohms + 1/6 ohms
1/TI = 5/12 ohms
TI = 12/5 ohms ~= 2.4 ohms

The total impedance on each of the two front channels would be 2.4 ohms which would be ok with my amp.

Do you see any issues with my set up?
Do you thing I should disconnect the stock tweeters since the new speaker are coaxial?
Do you think I should wire the speaker directly from the new amp?

Thanks

 

This one: Do you think I should wire the speaker directly from the new amp?

 

Tweeters
You need to try them both ways to see which sounds best to you... With tweeter or without.

Speaker Wires
It's not worth the extra hassle to run your own speaker wires in lew of the stock speaker wires. The difference would be minimal. Only distinguishable in a side to side comparison. However, if you're not happy with the way the system sounds then by all means change to a lower guage wire.

 

I have had mixed results with coaxs and tweeters in stock locations. It could very well be that they mate well together but don't be surprised if you end up disconnecting the tweeter or replacing it to get it to sound right.
You never told us how much wattage the new amp runs but I will always recommend new direct wiring in all aftermarket set ups because I'm from the school (old) of doing it all up front so you never have to wonder about those sort of things being an issue. I know that anything above 75 watts RMS per channel is a significant increase in power over the OEM amp so this should be taken into consideration as the existing 20-22 gauge speaker wire is not going to be optimal...maybe tweeters as they require less power but even that's a stretch.

 

The amp is doing 75 W RMS per channel although the speaker only support 60 W RMS. I did some more research and found that it is a pain in the neck to run additional wire thru the existing loom tubing that goes to each door. The only way would be to run in adjacent to the loom tube and maybe drilling which would be not ideal for me. As @01acls mentioned, other people also mentioned the sound difference would be negligible. If it wasn't that hard, at least for me, to run new wire to the door, I would definitely run the wires directly.

Going back to the original question, I ended up disconnecting the tweeter (after finding how easy it was to disconnect them) because the sound was leaning too much on the high side specially when the volume was high ( > 25 out of 40).

 

How is the imaging with just coax's running? Sound stage?

 

Sorry for the late reply. After using the new install for a couple of months, it sounds pretty good. Imaging is very good. It feels better overall than the stock speakers IMO. I am very satisfied with the install.