"Neil Green" <nrgreenNOT@[EMAIL PROTECTED]
> wrote in message
news:4822ae62$0$30465$afc38c87@[EMAIL PROTECTED]
>
> "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.
It could provide additional stiffness and mass, as well as better
distribution of the highs.
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