My amp clipping led goes on on bass sections - can I avoid it without turning the volume down?

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Morris - 12 Mar 2008 16:53 GMT

Hello all,

I've found this newsgroup on google search so I'm posting a question
here.

I've recently connected an amplifier to my car's front speakers and
although it pushed the clipping threshold higher (louder) I was hoping
still something could be made about it.

I've bought a pair of Infinity 16 cm speakers (60W RMS each) and
connected it to some JVC head unit. The head unit produces 19W RMS
power on each channel, and some distortion appeared heard at volume 30
(of 50) .

So after digging through Internet resources I've learnt that most
probably my speaker is underpowered and the distortion is actually
generated by the head unit itself.

I've bought an old second hand ampliflier - dual channel Legacy
branded - which is supposed to produce 2x100W of RMS power.

I've connected everything and although it is working and the sound is
louder, if I set my balance to more bass the clipping LED blinks with
each bass kick. At the same time distortion is heard in the speaker.

So I started wondering - is there actually a way of pushing the head
unit volume close to it's peak without any distortions? Or what can I
do?

I look forward to your replies and in the meantime I'll keep driggin
through wikipedia and different forums.

Regards,
Morris

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GregS - 12 Mar 2008 17:04 GMT

>Hello all,
>
[quoted text clipped - 27 lines]
>I look forward to your replies and in the meantime I'll keep driggin
>through wikipedia and different forums.

With HU alone the distortion is probably the HU but its not entirely clear.
The volume control is just a attenuator and does not indicate where
clipping will occur. Its possible the "Legacy" only puts out 2X50 watts,
so the power increase is minimal. The only way to be sure is get
another amp with good specs and more power and see how that
acts. Going from 19W to 50 watts is barely noticable. Up to 100 watts
should be very noticable but not even twice as loud. You need 10 times
the power to play twice as loud, but more power enables you to help avoid
clipping.

greg

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Morris - 12 Mar 2008 17:50 GMT

> In article <ca172123-2662-4d79-b415-36fa9a6e8...@s13g2000prd.googlegroups.com>, Morris <mauryc...@orange.pl> wrote:
>
[quoted text clipped - 41 lines]
>
> greg- Hide quoted text -

Would it be safe to power a 60W speaker with a 200W amp channel
provided the signal isn't clipped?

Thanks,
Morris

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ScottM - 13 Mar 2008 03:50 GMT

>> In article
>> <ca172123-2662-4d79-b415-36fa9a6e8...@s13g2000prd.googlegroups.com>,
[quoted text clipped - 49 lines]
> Thanks,
> Morris

YES, in fact it is safer than cranking up that cheap amp to the max. Amps
that are maxed out like to throw out uncontrolled voltage which will fry a
speaker.
if the "clipping" light is on the amp it has nothing to do with the head
unit. You are either over driving the amps inputs or outputs, or both. Most
likely the light is for output I would guess. Either way its not the head
unit, its the under powered amp. The more power the better. Oh, and you
can't trust a cheap amps power rating. Also when compairing look to see if
it tells you at what voltage it is rated at. 200w at 12 volts is a lot
better than 200w at say 16 volts. The one rated at 12 volts will most likely
have more power at 16, get my drift? Similar to the commment before, I think
you have to double the power to get 1db or some crazy thing like that. I
don't remember exactly but it was very suprizing the first time I heard it.

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I. Care - 13 Mar 2008 05:16 GMT

> I think
> you have to double the power to get 1db or some crazy thing like that. I
> don't remember exactly but it was very suprizing the first time I heard it.

2x power = 3db just noticeable.

10x power = 10db

So if your system was putting out 100db of sound and you wanted to
increase it to 120db (a 20db increase) you would need 100x the power.

the formula is (hope this comes out graphically correct in this post)

P1
10X LOG ------ = xdb
P2

For a more detailed discussion and explaination for the difference in db
calculations between power (watts) and voltage see here:

http://www.analogrules.com/dbwatts.html

For lots of neat calculations, just enter the data and read the results
go here:

http://www.calculatoredge.com/electronics/decibel.htm

Note this is a db calculation page under Electronics. There are lots
more on other pages.

I. Care
Address fake until the SPAM goes away ;-}

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Morris - 14 Mar 2008 12:17 GMT

> In article <ca172123-2662-4d79-b415-36fa9a6e8...@s13g2000prd.googlegroups.com>, Morris <mauryc...@orange.pl> wrote:
>
[quoted text clipped - 43 lines]
>
> - Show quoted text -

Ok - that's what I'm gonna do next then - I've just purchased another
second hand amp - this time it being the Audiobahn A4002T or something
like that, I've read quite a number reviews where people were praising
it. It's supposed to output the same wattage - 2x100 RMS at 4 Ohms and
I will check how it sounds soon.

Also another question appeared. At the moment my car is pretty messed
up - the speaker lies on the floor and the amp sits on the passenger
seat. I've only got one speaker hooked up to the amp (with a thick
wire speaker), the other one is connected straight to the HU using
original speaker wire. Now what will happen is - at certain volume if
I put balance only on the amped speaker - the clipping LED is off -
now if I move balance do play equally on both speakers without
adjusting the volume, again the LED will kick in every now an then (in
line with the bass kicks) Is that okay?

Also - maybe someone did it before and instead of me checking
different configurations for front speakers there is a certain
configuration proved to work?

Front speakers I'm using are Infinity 6012i
The Headunit is JVC KD-PDR31

ANd why did I at all thought of adding an amplifier to the system?
Cause I've replaced the original speakers with Infinity ones, as they
were knackered and had one or two holes, at the same tim bought a new
HeadUnit as the old one didn't have CD functionality. And after
realising that distortion heard at the speakers at certain volume most
probably originates from underpowering them - I decided to add an amp
as I haven't got rear speakers and haven't really made up my mind if I
want to have them as all the forum say to avoid mounting them on a
rear shelf. And since I've added an amp with the 'clipping' LED I
understood that it's definitely not the speaker's distortion, but the
signal comes distorted, so hopefully if the signal was OK the speaker
would play it clearly.

So am I going the right way or did I miss something and could the
reason be somewhere else?

Thanks,
Morris

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Adcom - 14 Mar 2008 19:22 GMT

Turn the gains down. They're not volume knobs.

Signature

Adcom
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