Hi Again!

I want to replace my 10 year old Sony Head Unit (35W x 4) with
something more powerfull - I am looking to power two 6 x 9's that are
rated at 60 W RMS, and two (yet unpurchased) 4" speakers (it's all my
car will hold without substantial modding). I do not plan on getting a
separate amplifier. If I were to get a head unit that puts out 60W x
4, do I need 60W RMS front speakers? I really want to fully power the
6 x 9s because I have no sub and they are in speaker boxes on the rear
dash (so the base isn't too great to begin with). Most of the 4"
speakers I've seen take 100W max and 20W RMS; would a 60W x 4 Head Unit
blow those little 4" speakers? Basically, I would LOVE if you guys and
gals could recommend specs. on a head unit so that I can power the 6 x
9's and not blow small front speakers (also, any recommendations on the
front speakers I need to buy would be appreciated).

Thanks so much.

-Bob

Don't be misled by the manufacturer's ratings. No head unit that I'm
aware of can deliver 60 watts per channel. The vast majority of the
"30wrms per channel" head units bench at around 15-18 watts per channel
prior to the onset of clipping. There are a rare few that bench up into
the 20's, and those guys heat up like a mother. I can't even imagine a
60's.

On Tue, 8 Mar 2005, Bob wrote:

Hi Again!

I want to replace my 10 year old Sony Head Unit (35W x 4) with
something more powerfull - I am looking to power two 6 x 9's that are
rated at 60 W RMS, and two (yet unpurchased) 4" speakers (it's all my
car will hold without substantial modding). I do not plan on getting a
separate amplifier. If I were to get a head unit that puts out 60W x
4, do I need 60W RMS front speakers? I really want to fully power the
6 x 9s because I have no sub and they are in speaker boxes on the rear
dash (so the base isn't too great to begin with). Most of the 4"
speakers I've seen take 100W max and 20W RMS; would a 60W x 4 Head Unit
blow those little 4" speakers? Basically, I would LOVE if you guys and
gals could recommend specs. on a head unit so that I can power the 6 x
9's and not blow small front speakers (also, any recommendations on the
front speakers I need to buy would be appreciated).

Thanks so much.

-Bob

"Bob" wrote in message
oups.com...
Hi Again!

I want to replace my 10 year old Sony Head Unit (35W x 4) with
something more powerfull - I am looking to power two 6 x 9's that are
rated at 60 W RMS, and two (yet unpurchased) 4" speakers (it's all my
car will hold without substantial modding). I do not plan on getting a
separate amplifier. If I were to get a head unit that puts out 60W x
4, do I need 60W RMS front speakers? I really want to fully power the
6 x 9s because I have no sub and they are in speaker boxes on the rear
dash (so the base isn't too great to begin with). Most of the 4"
speakers I've seen take 100W max and 20W RMS; would a 60W x 4 Head Unit
blow those little 4" speakers? Basically, I would LOVE if you guys and
gals could recommend specs. on a head unit so that I can power the 6 x
9's and not blow small front speakers (also, any recommendations on the
front speakers I need to buy would be appreciated).

Thanks so much.

-Bob


When a HU says it puts out 60 watts x 4 it REALLY only puts out about 25-27
watts RMS. My Alpine claims to put out 60 watts x 4 but it actually puts
out 27 watts X 4 RMS.

You are probably not going to blow most aftermarket 4" speakers with this
type of HU. Also, as my first installer told me 20 years ago, your speakers
will first "cry for help" before they blow. If they are distorting a lot,
just reduce the volume. You can also install an in-line passive high-pass
x-over on those 4" speakers to reduce the amount of bass they are getting.
These are simple and cheap ($2.00) capacitors that can be bought at Radio
Shack and install in line with your speaker cables.

Actually, what you will probably find is that your HU is not powerful enough
for your 6x9's. 27 watts RMS is really not much if your goal is any kind of
loud (or moderately loud) bass. I would recommend getting an amp to drive
your 6x9's, and let your HU drive those 4" speakers.

MOSFET

Thanks for the advice. If I get an amp to power the 6 x 9's, what
wattage output should I look for (my speakers: 240 Watts Max. Music
Power (60 Watts Nominal))?

Also, do I need crossovers for the 6 x 9s, and should I use powered or
unpowered? I have heard that some amps have crossovers built in, and I
know that my 6 x 9s have a "Built-in Crossover (-12dB/oct. HPF/MID)
(-6dB/oct. HPF/TWT)" (pioneer).

I do not want to spend a ton of money (my car is a P.O.S. and I don't
live in the nicest neighborhood). I was warned about older cars having
bad alternators and things like that; my car is a '90 Toyota Camry with
160K miles - is this somthing to watch out for?

I appreciate you Pros taking time to help me.

-Bob

"Bob" wrote in message
oups.com...
Thanks for the advice. If I get an amp to power the 6 x 9's, what
wattage output should I look for (my speakers: 240 Watts Max. Music
Power (60 Watts Nominal))?

50-75 watts RMS per channel would be perfect to drive your 6 X 9's. Even a
100 watts RMS amp would do fine. Don't worry about the numbers matching
up, a little more power than needed is almost always a good thing.

Also, do I need crossovers for the 6 x 9s, and should I use powered or
unpowered? I have heard that some amps have crossovers built in, and I
know that my 6 x 9s have a "Built-in Crossover (-12dB/oct. HPF/MID)
(-6dB/oct. HPF/TWT)" (pioneer).

The "built-in" crossovers in your 6 x 9's are for the little midrange and
tweeter. But if your 6 x 9's are your only source of bass (no subwoofer)
then I would not recommend any other crossover as you do want want to
eliminate any of your bass.

I do not want to spend a ton of money (my car is a P.O.S. and I don't
live in the nicest neighborhood). I was warned about older cars having
bad alternators and things like that; my car is a '90 Toyota Camry with
160K miles - is this somthing to watch out for?

I appreciate you Pros taking time to help me.

-Bob

Thanks again, MOSFET. I've seen you all over this board - you (and
several other regulars) really know your car audio!

I will probably buy a 2 channel amp (after reading over posts in the
multi-channel amp topic) that puts out 70 - 100 W RMS per channel. I
will not be getting crossovers for the rear speakers, but I will get a
pair of "in-line passive high-pass x-over"s for the front 4" speakers.


More questions:

1. Any specific recommendations for an amp under $300?
Brand/model/suggestions? Please remember, I know very little about
this stuff.

2. When I get the high-pass crossovers, what should be the cutoff
frequency?

3. Once I get the amp, I understand that I run RCA outs from the HU to
the amp input, then run the amp output directly to the rear 6 x 9s. I
also need to run power to the amp, and I need to ground the amp. Where
can I ground the amp, and where can I power the amp? (do I literally
run wires from the battery to the amp?)

-Bob