Just an update for this for those who were asking about the pre out.
I finally managed to test the system properly today after a few issues which turned out to be a blown hertz bass speaker. For the test I used a couple of other 6.5 drivers which arent as good as the HV165L but I just protected them by upping the high pass freq level. Replacements are on route and I'll then be able to run a HPF between 60 - 70Hz
Note to others... dont try giving your new speakers over 150w of full range frequency :)
Anyway... I also borrowed a cheap 10" sub enclosure until the custom one arrives.
The result... amazing!!
The bass is now really punchy and crisp. Previously I was just running all OEM cabin speakers and an Infinity basslink active sub that was tapped off the rear channels. It sounded good but this is leagues ahead.
My friend has a £4k system in his golf and this sounds nearly as good as that (he is running multiple amps and rainbow speakers etc)
For about £800 with bits off ebay im dead chuffed
Im currently running it from the Audiocontrol LC2i which is a 2ch-in 4ch-out hi-low converter. This also has their 'bass roll off' compensation circuit but TBH im not sure the RCD510 actually rolls the bass off so i've got this turned off at the moment. I'll test more with proper instruments when its all 100% installed with the replacement speakers and proper sub enclosure.
I did try it with my LC6i aswell and it sounded just as good. This doesnt have the bass compensation but like I say, im not sure this is even needed now so I'm not missing anything and I only need 2 channels anyway so the LC6i is for sale for definite.
The Audiocontrol LOCs can give up to 9.5v pre out but i found this a bit too much actually so have them turned down a bit to give a 4v pre out (checked with multimeter). This is the usual pre out voltage of decent aftermarket headunits anyway and you can then use the gain / input sensitivity on the amps to fine tune the levels.
I actually need to reinstall the autoleads one that i have laying around aswell and test the voltage output and sound from that.
In terms of installation... if your just adding a sub but keeping the cabin speakers running from the headunit you need to tap into the rear speaker output from the back of the headunit (but obviously dont cut it completely as then you will have no rear speaker output). Then run this feed to the LOC (line out converter) of your choice and then run the pre out to the amp of your choice and in turn to the sub. This way you then have a bit of sub control by fading your headunit forwards and backwards.
If your upgrading the front speakers and running them off a new amp then cut the front speaker output from the back of the OEM headunit and run these to the LOC. If your using the LC2i or LC6i this will then give you a pre out for the front speakers AND a pre out for the sub. You will then need either 1x4ch amp or 2x2ch amps or 1x2ch and 1xmono amps so you can amplify the fronts and the sub.
Hope that helps people.
