"Arny Krueger" <arnyk@[EMAIL PROTECTED]
> wrote in message
news:jr-dnfzQKrU8LLzVnZ2dnUVZ_u6dnZ2d@[EMAIL PROTECTED]
> "Neil Green" <nrgreenNOT@[EMAIL PROTECTED]
> wrote in
> message
> news:48215c65$0$1021$afc38c87@[EMAIL PROTECTED]
>> "Arny Krueger" <arnyk@[EMAIL PROTECTED]
> wrote in message
>> news:Gc2dnWSGua6_1b3VnZ2dnUVZ_q-jnZ2d@[EMAIL PROTECTED]
>>> "Neil Green" <nrgreenNOT@[EMAIL PROTECTED]
> wrote in
>>> message
>>> news:481f9e14$0$17508$afc38c87@[EMAIL PROTECTED]
>>>
>>>> My son bought some 6" Kenwood speakers from a
>>>> local
>>>> shop, not cheapies, and we installed them on the
>>>> rear
>>>> parcel shelf of his car on Sunday.
>>>
>>> A sort of a classic kind of installation.
>>>
>>>> If we crank the volume (to around 75%) and bass
>>>> up
>>>> the
>>>> distortion is really severe.
>>>
>>>
>>> Either the amplifier is clipping or the speakers
>>> are
>>> running out of stroke, or there is some kind of
>>> parasitic vibration.
>>>
>>> What can you tell us that will help us decide
>>> which
>>> one it is?
>>
>> Nothing really, I have little knowledge of these
>> things, but the distortion is coming from the
>> speakers
>> themselves in the form of a coarse vibration so I
>> doubt it has anything to do with the amplifier.
>>
>>>
>>>> You can see the cones bouncing up and down
>>>
>>> That's normal, to a point.
>>>
>>>> and they
>>>> make a vibrating sound which is very unpleasant
>>>> so
>>>> he
>>>> has to either lower the volume of reduce the bass
>>>> to
>>>> eliminate this noise.
>>>
>>> Sounds like a parasitic vibration, possibly caused
>>> by bad mechanical installation.
>>
>> They are screwed down tight to the steel parcel
>> shelf
>> using a small amount of 1.6mm double sided tape at
>> each fixing point, or which there are four for each
>> speaker.
>
> You mean screw + tape, right?
Yes.
>
>> I can't see how they could vibrate against the
>> body.
>
> Maybe the shelf itself, or a stiff covering...
The distortion is definately coming from the speaker
itself.
>
>>>> What I'd like to know is if this effect is just a
>>>> limitation of 6" speakers
>
>>> While 6" speakers are not the be-all or end-all, a
>>> pair of good ones can be pretty impressive in the
>>> small confines of a car. BTW, they are probably 6
>>> 1/2", as that is a near standard size.
>>>
>>>> or whether the speakers themselves aren't up to
>>>> par
>>>
>>> Without more details, how would anybody know?
>>> Model
>>> number????
>
>> Kenwood KFC - M1628A
>
> I get 6.25 inch nominal diameter.
>
> They are a $50/pair class 3-way, which I would not
> expect too much of.
$150 in Oz.
>
>> Not top of the range, but not rubbish, or so the
>> salesman assured my son.
>
> I would say, towards the bottom of the market
> segment.
Maybe.
It wouldn't be the first time a salesman has ripped
someone off.
>
>>>> or if there's any way of
>>>> reducing this distortion to acceptable levels.
>>>
>>> Turn them down. ;-)
>
>> Looks like he will.
>
> Rarely fails! ;-)
>
>>>> Would housing the speakers in boxes placed above
>>>> the
>>>> shelf help?
>
>>> Probably not. The trunk makes up a wonderful large
>>> enclosure for trapping the back wave of the right
>>> speaker drivers. With the right speakers, it can
>>> work very well.
>
> I notice that Kenwood recommends using an angled
> adaptor with these speakers, in a rear parcel shelf
> application:
>
> http://india.kenwood.com/products/car/speakers/kfc-m1628a/features.html
I can easily make such a beast, but I doubt it will
reduce the distortion.
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