Question about bi-amping w/ C400.4.

kstrike155

Hello everyone,

I will soon be buying a 2007 Audi A4 without the Bose system. I am planning on tapping into the pre-amp outputs on the back of the radio (yes, it has pre-amps surprisingly) and running the following system that I ripped out of my Mustang that I'm selling:

MMC6500s up front.
Stock in the rear using stock amp.
C400.4 bi-amping the 6500s.
C500.1
JL Audio 10W3V3 in a sealed enclosure.

So my question is:
In the Mustang I remember having to turn down the crossovers for the tweeters -3dB as they were just a bit too bright. With the Pre-EQ on the C400.4 I won't have this capability (will I?). How do they sound when bi-amping using the pre-EQ?

Thanks,
Brian

PoweredByDodge

when you bi-amp, all you have to do to achieve a -3b drop on your tweeters is to turn the gain down (on the channels that feed the tweeters) a little bit. the -3db switch on your old crossovers didn't do anything except cut down the power going to the tweeters (through the use of big 'sand block' wirewound resistors [in ceramic]).

as far as using the pre-outs on the bose deck... i believe all the bose products are pre-amp out of the head with mini amplifiers built into the speaker casings.

if you want to use an aftermarket head to power aftermarket speakers, all you have to do is cut the pre-amp wires and use them as if they were speaker wires (up to about 20 watts and then you exceed the current carrying capability of the very skinny pre-amp wires).

if you want to use the stock head unit as a pre-amp for an external amplifier (with aftermarket speakers), then cut the pre-amp wires at the back of the head unit, patch in, and run them as RCA's to your new amplifier. then run new speaker cable from the new amplifier to the new speakers.

kstrike155

PoweredByDodge wrote: »

when you bi-amp, all you have to do to achieve a -3b drop on your tweeters is to turn the gain down (on the channels that feed the tweeters) a little bit. the -3db switch on your old crossovers didn't do anything except cut down the power going to the tweeters (through the use of big 'sand block' wirewound resistors [in ceramic]).

as far as using the pre-outs on the bose deck... i believe all the bose products are pre-amp out of the head with mini amplifiers built into the speaker casings.

if you want to use an aftermarket head to power aftermarket speakers, all you have to do is cut the pre-amp wires and use them as if they were speaker wires (up to about 20 watts and then you exceed the current carrying capability of the very skinny pre-amp wires).

if you want to use the stock head unit as a pre-amp for an external amplifier (with aftermarket speakers), then cut the pre-amp wires at the back of the head unit, patch in, and run them as RCA's to your new amplifier. then run new speaker cable from the new amplifier to the new speakers.

Wow I'm an idiot, I didn't even think of the separate gain controls. I was still thinking of a single gain for each set!

Anyway, the Bose system in the 2007 A4s use separate amps (as opposed to the mini-amps they used to use). I don't have the Bose system but the head unit is exactly the same. I won't be changing out the HU on this car, as I want to keep all of my factory options and I don't want to change the looks, so what I will be doing is what you described in the second section.

The unit has pre-amp outs which I will be patching into, and I will run RCAs to my C400.4. I will then piggyback off of the C400.4 to the C500.1 and set my crossover somewhere around 80Hz. The filter on the C400.4 I want to set around 60Hz. I will then run two sets of speaker cables to each of my components up front, and leave all of the factory rear speakers and whatnot hooked up as rear fill when necessary.

Thanks,
Brian