New Headunit Fitted - Some Component Issues

Hi guys,

I grabbed a new Headunit as connectivity for the iPod was an issue and te OEM RCD 300 is rubbish in that department. I got a Alpine CDE W203Ri, as sat nav and DVD aint my bag. I went with a set of Alpine SPG 17CS components as well, but I'm having major sound issues.

The clarity of the system has come up wonders, but the front sub/mid element of the components is awful. I am driving them from the HU itself so far, but the original midrange is in which splits to run up to the tweeter.

I want to know what is the best way of solving this...gutted that buying components hasn't worked for a change, but I think its something to do with the OEM crossover for the midrange?

I do have a Kicker Comp 15" sub and 4 channel Kicker Impulse IX404 40w. I know its under powered to run the sub, but it kicks loud enough now that I have a daughter in the car most of the time, although I still need to find a good place to put the grounding cable. Would you recommend running the sub with one set of channels and powering the front components with the other side? OR would you continue to power the components with the HU given that its a 50w RMS output and the components are 70w RMS??

The max out on that unit is 50 watts, likely the RMS is closer to 20.

I agree that the OE crossover is likely the problem. However you're still under powering the speakers.

dood, are you saying you are mixing the stock mid, with aftermarker woofer and tweet??

which crossover?? not to mention deck power is only enough for stock speakers to sound any good.

dTEA said:

OR would you continue to power the components with the HU given that its a 50w RMS output and the components are 70w RMS??

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Dude.. your head unit is not 50Wrms x 4... its 50 max which is probably 22Wrms x 4..

cheers guys, you are right about the RMS power...and yes they are under powered by a long shot...got the 4 channel amp that could resolve that but then i'd be mixing the fade up due to only one pre-out.

The main thing was the OEM crossovers...so cheers for that...but the installers didnt realise that the wiring colouring changes when going into the door so had pos to neg and vice versa. Sounds a lot more convincing now even off the headunit, but an inline amp was not much diff at all, and at the time of testing that it was still wired pos to neg.

its your car but the alpine headunit doesnt look good for the car for some reason it looks very cheap. i would suggest you to get a single din adaoter from the dealers and stick a single din unit if you dont want a screen like most people do have.

ill smallz

You didn't run new wires for the speakers? I would have, electrical interference in VWs is crazy without running your own wires. You would sound better if you cut out the mid stock speakers completely if you only bought two way components. Those are designed to cover the whole frequency range of sound, and you're throwing different ohm, different power rated speakers into the mix. Your components didn't come with their own crossovers? You are also severely underpowering the speakers which could lead to long-term damage. The same goes for your sub. You think it hits good now but if you powered it correctly it would hit cleaner, not necessarily louder. The best ground I could find in the trunk is in that side latch near the floor on either side, they are tie downs for whatever you put in the trunk. If you unscrew one of the screws it touches grounded metal.

You might also want to double check how your power wire is ran, it needs to be on the opposite side of the RCAs you used to get your amp signal.

Your best bet now would be to cut the midrange speaker out of the mix completely (Assuming you bought a complete set of two-way components) and powering them with a two channel amp (Assuming you didnt change the rear speakers). If you are getting and buzzing or interference you need to run your own speaker wires to the doors.

illsmallz said:

its your car but the alpine headunit doesnt look good for the car for some reason it looks very cheap. i would suggest you to get a single din adaoter from the dealers and stick a single din unit if you dont want a screen like most people do have.

ill smallz

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Each to their own on this...I didn't want a single DIN just for ease of use when driving...and the screen's are redundant for me.


Bigbadvoodooguru
Cheers for the advice..all makes a lot of sense, and one the main reason's for not using own wiring is I now don't trust the installers that carried out the work...they even managed to wire the components using neg to pos! They eventually conceded that for now the mid range is powered direct from the headunit bypassing the VW crossover leaving the components on their own crossover but currently powered by the HU. One thing that did keep happening when they tried to use an inline amp on the components was it cutting out at high volume...was this a byproduct of pos to neg wiring? or just a nasty inline amp...it was a 150w blaupunkt

Man that config is just too screwed up to even diagnose.. remove those stock mids from the equation and come back for fresh advice.

What's throwing off the equation here is you have two crossovers powered off the same signal, which is vastly underpowered to begin with. Ideally you want to have a head unit with 6 preouts, 4 of them are speakers, two are sub (you only really need 1 for the sub).

You put the amp using pre-outs (read: RCA's) right after the head unit, then you run speaker-level out wires to all the doors. Those wires eventually connect and power a crossover, which then uses high pass and low pass filters (For a two way) to "redirect" the high frequency sounds to the tweeter, and the lower frequency sounds to the larger woofer. Theres some overlap in the frequencies usually.

Now, I don't know what stock ohm ratings are on the GTIs, but I'll be willing to bet they are different than the aftermarket components you bought. Ohm ratings are the resistance load the speaker provides. In layman's terms, ohm rating in combination with your amp power rating (watts) results in how "loud" the actual speaker is. You can see how a different ohm rating would mess up the "loudness" aspect of the speakers, and that is not taking into account the max wattage your speakers can handle before blowing. What I'm saying is, you might get an extremely loud midrange that is out of proportion to your tweeters and low woofer, which will sound even stranger because you are actually broadcasting those sound frequencies TWICE.

I suggest you:
1) remove the midrange speaker from the equation... it will sound better (A good two way aftermarket speaker setup, despite losing the 3-way and the positional advantage, will probably still sound better than the stock system)
2) you need more power to your speakers. If you are getting a very tinny sound and it seems you are missing all your midranges and lows, its because the tweeter takes very little power to run, whereas you are vastly underpowering the main woofer. In effect you're getting a tweeter running at 100% volume and a woofer at 40% (random number). I suggest (Since you are just running front speakers) a 2 channel amp. If your head unit does NOT have pre outs for the speakers, then you have what is termed "speaker-level outs" coming out of the head unit. This is an AMPED signal coming out of the head unit. You need to take these speaker level outs, find the FRONT right (+ and -) and the FRONT left (+ and -) and run it to the amp's SPEAKER LEVEL in's. Thats a way of letting the amp know, "hey, this signal is already amped... chill". It won't be as good sound quality as a preout, but it'll do. Finally. I don't know if the stock GTI system has an amp, but I'm pretty sure in an OEM system the crossovers are stored in the amp itself (It was that way on my brothers MK4). You DO NOT want to run your wires through that amp anymore. Else you'll be cutting frequencies out twice.

Example: (I actually don't have firsthand knowledge of the GTI amped system, but this is how a generic no-crossover-in-the-door oem system works)

head unit --- amp (crossover) <(splits into two wires here) === tweeter ---- woofer
If you tap the wires after the amp, youll have two wires going to the doors, one carrying woofer only signal, the other tweeter only. So you see, if tap only one of those for signal, you just lost the other side.

If you do use an amp, you will probably have to run your own wires through the door, unless you feel like hacking up your GTI amp harness. You only need 1 wire (double stranded) because you are putting the crossover inside the door.

Someone tell me if I'm wrong, I might very well be concerning the GTI sound system. My experience with the MKIV monsoon system shows the system is set up this way. I don't have premium audio in my Rabbit, and I don't think I have a non-headunit amp either.

Concerning the 150W blaupunkt amp, was it a mono, or 2 channel amp? If you just used it on one speaker, 150W I would estimate is about 70 watts RMS which matches one of your two-way components pretty well. You might want to double check the RMS rating on your speakers, thats the only number you really care about.

Cutting out on high volume could mean several things, if you are amping an already amped and filtered (crossover-ed) signal then you could be losing major sound quality and who knows what else. Best advice: Take the head unit out, install the amp connected to the front speaker outs (preamp or speaker-level outs... reference above), run a temporary wire to the crossover from the amp, connect tweeter and woofer, test sound system, faded full forward. Front-to-back fade should still work. I would also do it with a 300 watt amp or so, 70watt RMS x 2 (IF your speakers really are 70watt RMS. If theyre 70W peak then that power would blow them). It should sound beautiful. You can then compare it by taking the amp out, and connecting the head unit speaker level outs to the crossover. No messups on + and - here. If it sounds beautiful, then you know what you need to do.

bigbadvoodooguru said:

Now, I don't know what stock ohm ratings are on the GTIs, but I'll be willing to bet they are different than the aftermarket components you bought.

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The tweet and the woofer are 3.4 ohms dead.
The mid is 4.2 ohms dead.

Bigbadvoodooguru

There is no amp at the back of the headunit, the OEM crossovers have been bypassed using the original OEM wire loom to carry the signal through to the door. Once in the door they have been cut and connected to the new 2 way component speakers. This leaves the OEM mid still powered but receiving the full range direct from the OEM speaker cabling...by my reckoning this means that the guy has cut the door speaker cable and spliced it into 2...taking one splice to the OEM mid and one to the component crossover that then splits again to the tweet and sub components. Does the VW wiring come in singularly from the headunit and then get split in the door at the OEM crossover thus sending the signal 3 ways to the OEM sub, mid and tweet?

The bluapunkt inline amp was 2 way...should have been no probs but like I say if the wiring is split and powering what is technically 2 sets of speakers then that would account for it, esp with the different OHM rating for each set

I am guessing that if the above is the only way the VW wiring comes through to the door, then the signal to the components will be even more messed up as the signal is being shared? Its like adding a loop from one speaker to another...watering down the signal as the power is sapped at two points i guess.

There is also unfortunately only 1 preout which can be switched to front or sub, but with an active crossover for the sub this could be a solution as the headunit actually 50watts max, so probs around the 25-30rms...the amp is 40watts rms. I also have a 2 channel 70watts RMS that could be used. However the 4 channel amp is underpowered for the components and definetly for the sub...something I am aware of but on a budget at the moment. The amp lives in the boot/trunk, so can be replaced at a later date when funds allow.

Thanks for the feedback and knowledge so far guys...i figure i'm gonna have to challenge the installer and probs get my money back and go elsewhere, or do what I should have done which is take my time and do it myself

Well if your headunit only has one preout, then you must be using the built-in amp in all head units. That means you're dealing with speaker level signal. Honestly dude its really easy to run wires into the doors, the rubber grommets either click out or pull out.

I don't know where the OEM crossovers are located, in the head unit or built into the under-seat amp (Assuming you have one). The monsoon audio in the MKIV has the crossovers in the amp. That means there are three signal wires and a ground going into each door, with the components already split up. If the crossover is built into each speaker (Highly possible) then there are only two wires, full signal and ground, coming into the door, and its split there.

The problem lies in the first situation, and you tap the remaining "wires". You'll either be getting a full tweeter, full mid, or full woofer signal.

Amp wise, you'd be better off just leaving the rear speakers unpowered for now. If the headunit is 50W max (Total?) then that means 12.5W per channel, depending on ohms. And thats peak. If you mean 50 watts per channel then thats 25-30W RMS per channel, which is still not enough. Your ultimate goal is to supply the front speakers with power close to its rated RMS. Thats the only way it will sound the way you want. How you do that depends on you.

I finally took a look at what amp you have in the back. Its a 40W x 4 RMS at 4 ohm rated amp, which you can bridge to 120W x 2 at 4 ohm if you wanted to power front speakers with it. That's not a bad amp. In fact, 40W RMS x 4 might do it if you pick a lower powered set of speakers in the 40-50W RMS range (Assuming theyre 4 ohm speakers). The amp also takes speaker level inputs (the only type of output you have from your head unit, no preouts). That means you take the 4 channels of signal coming out of your head unit, plug them into the 4 channel amp, then run wires or splice :cringe: into the stock harness, assuming the wires go where you think they go. Remember you want to preserve clean, full signal into each door, and then split it with your crossover. If you don't explicitly see that happening, then chances are its going somewhere, getting signal processed, and then going to the door.
Of course then you'd need a cheap mono amp that puts out enough to power your sub. Thats much cheaper used and I'd think well worth it. If you're going to upgrade audio you have to do it right, else you won't get the full effect of what you're paying for.