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Retain oem amp or run speakers from HU for best result?

Discussion in 'In-Car Entertainment' started by A4 stu, Aug 6, 2013.

  1. A4 stu
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    A4 stu Member

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    [Aug 6, 2013]
    My rear speakers have always been much quieter than the fronts. They are run from the standard oem rear amp. I always assumed that it was just the little amp doing the best it could with the low voltage input it was getting from my upgaded HU rear RCA out.

    Today, I spliced a high 2 low converter into the HU rear speaker wires and converted them into a low voltage signal which I fed into the standard Audi wiring for the amp and BOOM! Much more volume and power. The volume was equalised from front to rear. Prior to this I had to fade to the rears by about 30-40% before I could hear them at all!

    So it seems that HU output converted down is more than the 2v the rear RCA puts out? If the HU is putting out 4x50w max, what voltage is it reduced to with a high 2 low converter?

    i still have the factory speakers but will probably now upgrade them. If I do, would I be better retaining the Audi amp to use with the new speakers, or run new speaker cable to the rear and drive them direct from the HU?

    Stu.
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  3. dualmono21
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    dualmono21 Well-Known Member

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    [Aug 7, 2013]
    without getting too technical the headunit does put out 4 x 50 but thats maximum which is basically advertising bull****
    when you convert that to real power its more like 4 x 18 wrms at the very most if your lucky

    all the convertor has done is give you more signal input into the amplifier ... hence it sounds louder ... it will also probably distort the sound at loud volume
    the proper way would be to adjust the gain control on the amplifier itself , but having never had one apart i couldnt even tell you if they have a gain control on them , i suspect there is but it will be inside the amplifier and supposedly not meant to be touched

    use the seperate amplifier it will allways sound better than a headunit speaker output
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  4. A4 stu
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    A4 stu Member

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    [Aug 7, 2013]
    The amp is tiny. I have had the rear speaker out to look at it and I'm surprised it makes any noise at all.

    I've always thought any amp was better than a head unit output but I think I am tempted to hook the rears up direct to the head unit just to see if I can hear a difference at all.

    I wonder what voltage the factory amp pulls through the factory wiring? Maybe I could replace the Audi amp with something better. If I used an amp that needed the same size fuse as the one Audi put in the fuse box, it should be safe to use the factory wiring?

    Stu.
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  5. dualmono21
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    dualmono21 Well-Known Member

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    [Aug 8, 2013]
    the headunit amplifier is simply a tiny ic chip ... they cant physcially make them any smaller because of the heat issues
    the amplifier in the rear will be far far better than the ic one in the head unit

    the fuse protects the wiring , not the amplifier ideally you would need to know the diamater of the factory wiring for that particular cable and the length and the current draw of the amplifier you intend using ... or alternatively add your own wiring , its not difficult to do
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  6. StuBill
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    StuBill New Member

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    [Aug 8, 2013]
    I would hazard a guess that if you found an amp that would safely run off the stock power wiring without frying your car, it would not produce any/much more power than the stock amp already in there. Also, depending what vintage of A4 you have, you may still need to provide a 12v ignition switched supply to the new amp (if your stock amp is switched by the CAN BUS).
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  7. dualmono21
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    dualmono21 Well-Known Member

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    [Aug 8, 2013]
    the newer amps are generally class d now they are more efficient ..ie require less power to make more power
    the downside is they dont sound as good as the older class a/b amplifiers
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