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From: D.Kreft on 16 Mar 2007 01:11
On Mar 15, 4:43 pm, "Lou3" <l...(a)poolgods.com> wrote:

> How would rate Rockford Fozgate and Infinity amps?

I have never been a fan of RF amplifiers (or any of their products,
for that matter). Back in the '90s, I had to deal with a lot of RF
Punch amps, all of which I was thoroughly unhappy with for multiple
reasons--the two biggest of which being price (the Punch amps were
*way* overpriced and were an exception to the "you get what you pay
for" rule of thumb), and overall sonic quality. The Precision Powers
that we sold consistent beat the snot out of them in every possible
regard...and I'm talking about keeping the rest of the system the same
and just swapping the Punch amps for their closest PPI counterparts.

But that was 10 years ago and from what I understand, PPI isn't what
it used to be, and given the state of the car audio industry as a
whole, I have serious reservations as to whether RF has gotten any
better. That's not to say that they haven't, mind you, just stating my
apprehension.

I don't know anything about the Infinity amps.

Personally, when I shop for such things, I try to zero in on companies
who focus more on technology and innovation than they do on bikinis,
chrome and marketing gimmicks. In my eyes, gimmicks just scream "Our
stuff sucks, so we're hoping that we can wow you with small shiny
objects and G-string bikinis." Personally, I have no need for a G-
string bikini or an amp that has a screaming human face or a spider
cast into its heatsink--what I do have use for is solid engineering
which leads to durability and exceptional value.

> After reading Crutchfield's advice to match the amp's power output to the
> speaker's power handling, I thought I needed an amp with at least 60W per
> channel to match the 60W RMS of my speakers. I guess I misunderstood that.

You don't so much want to match the amp to the speaker's power rating
because that implies that you should always try to apply the maximum
amount of power your speakers can handle. This may work for some
systems, but is not to say that it's what will work in your system.
Manufacturers like JL Audio provide a recommended power *range* that
you should aim for. Keep in mind also that there are two different
types of power handling: mechanical and thermal. The thermal rating is
a constant and is what you typically associate with a power rating--it
tells you how many Watts of power can be safely handled, beyond which
there is a risk of melting the voice coil and causing serious damage.

The mechanical power rating, however, depends upon the enclosure type.
A speaker rated to handle 300W RMS might very well self destruct if
you put it into an enclosure that is too large (e.g. infinite baffle)
because the "springy mass" of air behind the cone is too large and
"mushy" to keep the cone under control. Going the other way, it's also
power to put the driver in a smaller box and wind up having an
effective maximum mechanical power rating that far exceeds that of the
thermal rating.

What I'm getting at here is that you need to be careful about blanket
statements like this because that *can* (though not always) get you
into some trouble.

> Some places recommend a 4-channel amp for powering four door speakers, and
> others go with a 2-channel amp. Are there any real advantages to one or the
> other for powering four 2-way door speakers?

If you use a 4-channel amp on your mids-n-highs, you'll have finer,
easier control over the balance between front and rear--adjusting
relative levels becomes a simple matter of turning a screw (or maybe
adjusting the fader on your head unit if your system is so wired).
Adjusting front-rear fade with a simple two-channel amp normally
requires the installation of a small resistor network (an "L-pad") to
attenuate the rear speakers. It also means that all 4 channels would
run at 4 Ohms, meaning that the amp would have more dynamic headroom
and would run cooler than a 2-channel amp running 2-Ohms stereo.
However, it's also more expensive and usually takes up more space in
your car--a 2 channel amp can just as easily do the job while saving
you cash and vehicle real estate. Other than the adjustability factor,
though, I'm not convinced that there's really any terribly compelling
reason to use a 4-channel amp on your mids and tweets.

-dan

From: z28com on 16 Mar 2007 10:40

D.Kreft;670998 Wrote:
>
> Why do I share this story with you? Basically to point out that there
> are some not-so-subtle differences between amps, and that just
> because an amp may seem pretty expensive for the amount of power it's
> rated to deliver (IIRC, the PPI was about 2x the price of my
> Soundsteam), it can really pay off in terms of the enjoyment you can
> get out of the system. So buy the nicest small amp that you can
> afford--don't be suckered into buying a cheap-O amp because it has
> bigger numbers--you'll actually save more money in the long run if you
> *DO IT RIGHT THE FIRST TIME* and *DON'T HAVE TO KEEP UPGRADING*.
>
> -dan

WELL SAID!!!!

I have been trying to tell people this for years. I spent the first 10
years trying to save money by buying cheaper amps and speakers and it
just isn't worth it. I got tired of trading up.


--
z28com
From: lou0001 on 16 Mar 2007 22:53
On Mar 16, 10:40 am, z28com <z28com.2nj...(a)no-mx.forum.carstereos.org>
wrote:
> D.Kreft;670998 Wrote:
>
>
>
> > Why do I share this story with you? Basically to point out that there
> > are some not-so-subtle differences between amps, and that just
> > because an amp may seem pretty expensive for the amount of power it's
> > rated to deliver (IIRC, the PPI was about 2x the price of my
> > Soundsteam), it can really pay off in terms of the enjoyment you can
> > get out of the system. So buy the nicest small amp that you can
> > afford--don't be suckered into buying a cheap-O amp because it has
> > bigger numbers--you'll actually save more money in the long run if you
> > *DO IT RIGHT THE FIRST TIME* and *DON'T HAVE TO KEEP UPGRADING*.
>
> > -dan
>
> WELL SAID!!!!
>
> I have been trying to tell people this for years. I spent the first 10
> years trying to save money by buying cheaper amps and speakers and it
> just isn't worth it. I got tired of trading up.
>
> --
> z28com

Thanks, Dan and z28com. This is the kind of advice I'm looking for.
Like you, I don't want to waste my time with shoddy equipment. I also
share your opinion about adolescent marketing gimmicks and look for
intelligent, functional design. I'll keep you posted.

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