I currently have 1 rca connected (front output on h.u.) however since I used to have a sub I still have another rca run so I could easily connect it to the rear output on the h.u and channel 3&4 on the amp.

I have two sets of cables coming out of the amp going ot the crossovers. At the amp they are twissted together. My biggest issues was figuring out which speaker wire belonged to which speaker since the crossover will send power to tweeters and mids even if you disconnect one of them from the amp. Now that you pointed out the diagram I need to follow as I had suspect I see if I pull the two middle jumpers on the crossover this will create the bi -wire configuration and thus it shouldn't send the signal to all speakers and I can then determine which cable goes to which speaker. Hope you can follow that...it's hard to explain without actually looking at what I'm talking about.

 

ok i just read what I typed and it doesn't make much sense I will try to draw a diagram, I need to install visio so it should be a fun looking mspaint diagram

 

It makes sense to me.

Essentially, you need to keep the signals separate from the amp, through the crossovers, and to the tweeter and woofer. Removing the jumper will ensure this happens at the crossovers and tweeters.

As for the head unit to amp connection, the easiest way is simply to use the Front left and right RCA connector and connect it to the amp channels 1&2. Then switch the "Channel 3&4 Input" switch to "1&2". see page 6 (page 4 of the pdf) of the amp manual here http://mobile.jlaudio.com/pdfs/G-Series/G4500_MAN.pdf Keep the subwoofer wires in place in case you want to add a subwoofer at a later stage.

Connect the tweeter wires to the Channel 1&2 outputs of the amp and set the "Filter Mode" switch to HP and the dial to the maximum of 200Hz

Connect the woofer wires to the Channel 3&4 outputs of the amp, and set the "Filter Mode" switch to "Off"

You'll need to adjust the "Input Sens" dials to get a nice balance of sound (probably best to have the tweeters set a bit lower than the woofers) but essentially it's best to use your ears on this one.

Hope that makes sense.

EDIT: The system as I describe is mentioned on page 11 (page 6 of the pdf) under the heading "Bi-Amplified System with one G4500" and part "A) No User Adjustability".

 

There is another way to do this, but it's a bit more complicated. It's what NS alluded to above. That is, a full active setup.

Here, the crossover facilities in the head unit are used to split the signal between high and low frequencies. high frequencies are sent to the "front" channels and low frequencies to the "rear" channels. Have a read og the HU manual on how to set things up on the head unit itself.

What you would do is reconnect the "subwoofer" RCAs to the "rear" RCAs on the head unit. These would then be connected to channels 3&4 on the amp. You'd need to set the filter switch to off for all channels.

You would then remove the Alpine crossovers completely and connect the tweeters directly to the 1&2 outputs from the amp and the woofers directly to the 3&4 outputs.

The general idea is that the HU crossovers are better than the Alpine ones, and you have more control over the settings and levels direct from the head unit.

However, I remain a bit sceptical as to the benefits of doing this in a noisy car like the S2000. It also takes a good deal of expertise to get this set up correctly. If NS wants to help you out with thise, then great, but I'd not recommend doing it yourself.

My bi-amped system sounds fantastic as it is.

 

That's what the PM I sent him was about. He lives <20mi from me


Full active, once set up, makes a huge difference in sound. Even in a noisy environment such as the S. I have the stock plastics behind the seat gutted for my HD roll bar, and I still wouldn't run anything but active.

Amp has more control over each speaker, and therefore each speaker is more effective and clear - even in a noisy environment.

 

Cool thanks guys! I like the idea of using the h.u. as well since it has some very nice xover features and I can adjust it easily. Perhaps though the combination is good too. Priority #1 is identifying which speaker wire is which....NS I will reply back to your pm's and see if we can get something on the calendar...thanks for all your help guys!

 

No worries. Easiest way to identify speaker wires is to just plug one wire in it at a time, along with a low level signal.

NS, one question, how doe the amp have "more control" over each speaker? Is it just a question of only having to work with a limited frequency range, sort of like I suggested by using the HP filter for the tweeters? i.e. filter out the low frequencies before they get to the amp section?

 

That does have some play...

but think more along the lines of 'damping'. A speaker is a microphone is a speaker (etc) . The movement of the speaker from the music sends signals back through the speaker wires to the amplifier. The amplifier's ability to eliminate that signal is referred to as the amplifier's 'damping factor'. Now, while it's debatable just how much damping factor is needed to be effective, it is indisputable that damping of some kind is needed.

Anything between the amplifier and speaker hinders the ability of that amplifier to properly dampen the feedback from the speaker.

This is why bi-amping (as you've done) is an improvement on a straight passive system - in a passive build, the feedback from one speaker interferes with the other speaker where they intermingle to return to the amplifier. The amplifier, at this point, also has no control over what each speaker is doing.

When bi-amping, there is more control - but introducing a passive xover mutes some of that direct control. I personally prefer nothing between each speaker and it's respective amplifier output.

Of course, the biggest boon to running full active is that by opening the door to the various xover points of an active system, a whole range of other higher quality, more efficient, and less expensive speakers becomes available.

 

fyi I also have a mic that i can plug in to automatically tune my h.u. I've used it before and it works great!

 

That's fair enough, but surely has little relevance here where the passive crossover is properly matched to the woofer and tweeter? That's essentially why, when I discussed it with my very expert installer, he advised against a full active setup, especially given the environment. In his opinion, the gains would be minor.

However, if josser has a friendly helping hand to rewire and do the setup, then go for it