2-Channel vs 4-channel amp

[andycph]

Hi guys, need your advice here.

I have Infinity reference 6.5" component up front and driving them with
Rockgord Punch100Z2 2-channel amp (25W RMS x2). Speakers are rated at
90W RMS. Think I'm underpowering them,, is that why they sound ****ty
with almost no bass?

I'm thinking of upgrading the amp, but I need your advice as to whether
I should get a 2-channel amp or a 4-channel amp to drive both front and
rear (JBL coaxial 60W RMS). Seems it makes no sense to drive the rear
with amp when I have just placed a 10 ohm resistor to level down the
rear for better staging. Is it better to use all the power up front when
I can get 80-100W with a 2-channel amp then to use a 4-channel amp with
40-50W going to all 4 speakers and then wasting the power to level it
down.....
--
andycph
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[andycph]

thanks guys for all the advice.

i think quite a number of people agree that using the HU to power the
rear fill speakers is good enuf. i'm using my HU rated at 25W RMS to
power them, and I thought they were already overpowered, that's why I
have to put the resistors in line, and even then, I'm fading front by
5.

anyway, just bought a soundstream picasso amplifier (60W RMS) to replace
my RF Punch (25W). Hope this helps!
--
andycph
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[Daniel Snooks]

andycph wrote
> thanks guys for all the advice.
>
> i think quite a number of people agree that using the HU to power the
> rear fill speakers is good enuf. i'm using my HU rated at 25W RMS to
> power them, and I thought they were already overpowered, that's why I
> have to put the resistors in line, and even then, I'm fading front by
> 5.

Take the resistors out, and just keep fading front until you are happy. Do
you have capacitors to highpass the rear speakers? IIRC something ~100microF
should work nicely.

--
Regards,
Dan Snooks

[Daniel Snooks]

andycph wrote
> no, i dont have them. i've been wondering why is there a need to
> high-pass the rear?

The speakers can't reproduce really low frequencies anyways (at any useable
volume), so why ask them to try? If you are worried about getting midbass
from the rears high-pass them way up between 250 and 500Hz.

> Cancellation?

Not so much as giving the head unit a break from trying to amplify the low
frequency signals that the speakers can't really do anything with.

> Shouldn't I low pass instead to
> squeeze out more of the mid-bass from the rear coaxials?

If you low-pass them under the mid-bass range, you won't hear anything from
them.

> BTW, what about the front comps? Should I high-pass them?

Yes. Typically between 80 - 125Hz. The actual crossover point depends on a
lot of factors (which are all boiled down to: What sounds best to you?)

>The Picasso
> 2-channel amp has this bass-boost which I'm thinking of using them to
> boost bass from the front comps to get better bass in the front instead
> of having bass coming from the rear which is what is happening now, at
> least for the lower frequencies.

Probably not a good idea. Bass boost functions usually affect signal down in
the 40 - 60Hz range, and you don't want the comps trying to play that low.
If you high-pass the fronts, you should notice a distinct improvement in
"direction" of the bass. The comps will sing better if they aren't being
muddied with the low stuff that they can't handle properly.

(that is some atrocious grammar and sentence structure, but I can't seem to
think of any better way to say what I mean. Perhaps working the night shift
is eating my brain)

--
Regards,
Dan Snooks

[andycph]

Thanks dan and all for the advice. think i got the idea now. let's say
i'm going to be pretty busy this coming weekend!

btw, u guys heard of the Alto Mobile subwoofer that's reportedly 3"
think? Looks real cool!

http://tinyurl.com/m3vr
--
andycph
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