"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?
> I can't see how they could vibrate against the body.
Maybe the shelf itself, or a stiff covering...
>>> 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.
> 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.
>>> 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
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