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Advice/recommendations for a beginner

Discussion in 'In-Car Entertainment' started by Jay, Aug 27, 2006.

  1. Jay
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    Jay Member

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    Hi Guys,

    Just bought my first car A3 1.8T and my first head unit (fisher price:biggrin: )

    The factory fitted system included a tiny sub which didnt sound too bad but the head unit wouldn't play MP3's which is why I decided to replace. Now the sub no longer works which makes the system as a whole sound dull.

    I've been checking out package deals online but haven't a clue what to look for due to the range out there. All I know is that i'd like a 12" Sub and a decent amp.

    I mostly listen to DnB and Dub/dubstep (30Hz bass) and have a budget of around £250-£300.

    All the techincal talk on this forum has confused me even more.

    Can someone please help answer the following questions.

    1. Which box should I be looking at ported/sealed?
    2. What does tuning a box mean? I've read that people have their boxes tuned to e.g 30hz...is this to do with the filter on the amp? and will this still need to be done if I get a sub which is already boxed?
    3. I understand I need a monoblock amp? Any recomendations
    4. What should I look for in a sub? Ohms etcs... and any recommendations
    5. What is the function of a power cap and will I need one?
    6. The cd changer above the sub no longer works is there a way of connecting this to my new headunit (JVC KD-LHX552)? I forgot to take the cd magazine out before i removed the factory head unit!

    Also the new headunit has some feedback or a humming sound at low volumes and was told by the guy who installed it that it was a problem with A3's, is this true or was I fobbed off? the workaround he suggested was to run the back speakers off a separate amp. Its not really a problem as it disappears when i turn the volume past 10.

    Are there any recommended online stores I can check for package deals.

    Thanks in advance guys

    J
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  2. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    If you're going with a new sub then forget the OEM sub. The OEM sub powers the rear speakers as well so if the sub no longer works then neither will the rears. Just by pass the sub amp and run new peaker cable to the rears directly from the HU.
    A ported enclosure is usually bigger than a sealed one and is more efficient. But a sealed enclosure probably gives a bit more punch.
    Forget tuning the box unless you're making your own. You can tinker with the port so it resonates at different frequencies etc etc. It has nothing to do with the crossover settings on the amp.
    If you've only got £300 to spend on both the amp and enclosure/sub then you're not gonna have a huge choice of decent packages. You'll also need £40 worth of wiring so make sure this is included in the package if possible.
    Bass junkies have a lot of bargain sub/amp packages available.
    What to look for in a sub/amp? Power & power. 4ohm is the standard impedance for most amps bridged, but 2 ohm is more efficient, but the amp needs to be stable with a 2 ohm load. I'd stick with 4 ohm to make life easy.
    Sell the CD changer on ebay (£90-£100) it cannot be used with an aftermarket HU.
    There are issues with any Audi install but they can all be overcome, so yes he fobbed you off. It depends how he's connected the standard HU to the non standard wiring in the A3. If the sub doesn't work then I'm amazed you're getting anything from the rears. But your best bet is to bypass anything that came with the car, including the wiring, as it is really mickey mouse.
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  3. Jay
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    Jay Member

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    Thanks for your reply. Any chance i'll be able to get the cds out of the changer without connecting the old headunit?
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  4. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    I doubt it, the unit needs power in order to get the current CD back into the magazine.
    This may help, but I'm pretty sure the unit has to have power:
    [​IMG]
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  5. Jay
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    Jay Member

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    Thanks i'll give it a shot.
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  6. evomaster3000
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    evomaster3000 Member

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    Bit of simple advise, go for a sealed system, bass is punchier and just plain simplier. Here's a pic of my system, It's a bit more than £300 but not by a lot as most of it was secondhand and i built it all myself within 3 days.
    [​IMG]
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  7. Jay
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    Jay Member

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    The manual override didnt work so looks like i'll have to reconnect the old unit. Whilst I had my head in the boot i noticed that sub was actually working, even though I cant hear anything whilst driving.
    The buzzing/interference i mentioned is begining to annoy me a little so I decided to disconnect the sub and reconnect which surprisingly stopped it until i switched the head unit off and back on again.

    Just to elaborate on the wiring...The head unit was connected using the audi ISO connector. I managed to connect the new unit upfine but went back to the shop I purchased the iso connector from because of the back speakers not working and the unit not retaining its memory (clock and eq settings). The guy said something about cutting and connecting a permanent live to get the back speakers to work which he did for me. This is how the buzzing came about At least I know its something to do to the back speakers and the sub.
    Any suggestions on what i can do.

    thanks
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  8. Jay
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    Jay Member

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    Nice setup.

    I've just ordered the alpine R 1242 12" and M605 mono amp.

    I take it you dont have an Audi judging from your username and avatar but was wondering how hard it is to get the power cable from the battery to the boot. Is there an existing hole I can make use of or will I need to drill through?

    cheers
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  9. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    The buzzing is fairly normal and is due to the shyte Audi low level wiring to the rear amp, and the shyte rear amp. You could spend about a day fannying around with earth cables on the new HU to try and reduce it but TBH you'd be much better off by passing the rear amp and run new speaker wires from the rear speaker outs on the HU to the rear speakers. Isolate the old Audi speaker cable terminals with insulating tape so they don't short.
    The sub won't buzz as it's low frequency. You won't be able to hear the sub because your new HU has at least twice the power of the Audi HU (2x20w) so the cabin speakers will drown it out.
    PM me your email address and I'll send you the PDF on how to run Power through the bulkhead.
    Cheers, Andy
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  10. col6821
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    col6821 Member

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    Do you really need to run power through the bulkhead?? I ran the power for my amp from one of the 30A connectors under the drivers side dash (I am king of the bodge-it though, so this may well be wrong).
    Also take a switched live from the fusebox, AndyMac advised me to do this and it's easy! It was fuse 37 on my 2002 S3, now my HU comes on with the ignition and stays on until the key comes out, a la original Audi. I'm also powering my rear speakers from my amp, it seemed easier at the time.
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  11. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    Running it through the bulkhead is the only completely safe way to do it as the 30a connections under the dash are used for other electrical equipment drawing their own current. If you install a 300wrms amp it can easily draw an additional 20amps so you could find that your amp causes the fuse to blow on the ABS system or something fairly important. If it's a fairly small amp then you won't have a problem.
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  12. col6821
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    col6821 Member

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    Cheers AndyMac, think I'll review my installation.
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  13. Jay
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    Jay Member

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    I dont suppose you know how I can locate the wiring for the rear speakers? ALso where is the rear amp located?

    thanks
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  14. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    The wiring for the rears is attached to the rears and runs back to the sub. The sub amp is inside the sub and powers both the sub and the rears.
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