Alpine 7873 Installed....No need for an amp??
12-27-2001, 06:16 PM
#12
Registered User
Join Date: Dec 2001
Location: encino
Posts: 1,792
Likes: 0
Received 0 Likes
on
0 Posts
Well, im sure you guys are excited to see the instal, BUT NOT AS MUCH AS ME
i just was at my friends shop and they are booked solid for a few weeks. so unfortunately i have to wait
but i will try to take as many pics as i possibly can during the process so you guys can get a good idea of what is involved. so stay tuned.........
i just was at my friends shop and they are booked solid for a few weeks. so unfortunately i have to wait
but i will try to take as many pics as i possibly can during the process so you guys can get a good idea of what is involved. so stay tuned.........
01-02-2002, 04:17 PM
#13
Registered User
My Alpine CDA 7876 is essentially the same as the CDA 7873. Both are rated for 60 Watts x 4 and both actually put out (according to Alpine) 27 watts rms per channel.
I found that with just front speakers, with the top down, I had to turn up the volume high enough that I had serious distortion. After I added Lucid's rear speakers, I was able to get the full potential from the deck. Now, sometimes, I don't like the low end distortion at high volumes, but I can filter that out.
I love the combination of CDA-7876 (or 7873) plus upgraded front speakers plus Lucid's rear speakers. Upgrading the door wire will get you absolutely nothing. I did it and I know.
To get the full potential from the CDA 7873, you have to put in a hefty power cable direct to the battery and a heft ground cable. If you just wire the CDA 7873 to the Honda harness, you're crippling the head unit. It says that in the Alpine installation instructions and it makes sense to me.
Barry in Sheridan, Wyoming...
I found that with just front speakers, with the top down, I had to turn up the volume high enough that I had serious distortion. After I added Lucid's rear speakers, I was able to get the full potential from the deck. Now, sometimes, I don't like the low end distortion at high volumes, but I can filter that out.
I love the combination of CDA-7876 (or 7873) plus upgraded front speakers plus Lucid's rear speakers. Upgrading the door wire will get you absolutely nothing. I did it and I know.
To get the full potential from the CDA 7873, you have to put in a hefty power cable direct to the battery and a heft ground cable. If you just wire the CDA 7873 to the Honda harness, you're crippling the head unit. It says that in the Alpine installation instructions and it makes sense to me.
Barry in Sheridan, Wyoming...
01-03-2002, 12:34 PM
#14
Just a note for you guys with head units that advertise "peak' power ratings.
1. There is no agreed upon definition of "peak power".
2. RMS power is defined, well-known, and easily tested and confirmed.
3. Unless a head unit has an internal switch-mode inverter power supply (I've never even heard of one with this), it is impossible to get more than 23 watts RMS into 4 ohms if you have a 13.5 volt power source. And the 23 watts assumes no wire resistance, no PC board resistance, and no voltage drop through the amplifier output transistors, all 3 of which are impossible.
4. Head unit manufacturers do not usually test actual head units as they would be installed in a car to determine RMS power ratings. They usually use the amplifier chip manufacturer's application data as the rating for the amp.
5. The chip manufacturer tests their IC amplifier power output like this:
a. Connect the power supply directly to the amp IC pin, with no other wires in the middle.
b. Connect the load (4 ohm resistor) directly to the IC pin with no wires in between.
c. Artificially cool the amp IC so it doesn't overheat, and see how much power it puts out.
As an example, I just bought a Sony MP450, which has in big writing right on the front of the unit "50 Watts X 4". But if you read the book it says "19 watts RMS". When tested on a bench with 13.5 volts input, you can actually get 15-16 watts out of this thing, which is about as good as you will see in real life.
The other clue is to look at the head unit fuse. On the Sony it's only a 10 amp fuse, so how do you get 200 watts (50 W x 4) from a unit that only consumes 135 watts (10 amps x 13.5 volts)?
It won't happen, unless Sony re-writes the laws of physics.
1. There is no agreed upon definition of "peak power".
2. RMS power is defined, well-known, and easily tested and confirmed.
3. Unless a head unit has an internal switch-mode inverter power supply (I've never even heard of one with this), it is impossible to get more than 23 watts RMS into 4 ohms if you have a 13.5 volt power source. And the 23 watts assumes no wire resistance, no PC board resistance, and no voltage drop through the amplifier output transistors, all 3 of which are impossible.
4. Head unit manufacturers do not usually test actual head units as they would be installed in a car to determine RMS power ratings. They usually use the amplifier chip manufacturer's application data as the rating for the amp.
5. The chip manufacturer tests their IC amplifier power output like this:
a. Connect the power supply directly to the amp IC pin, with no other wires in the middle.
b. Connect the load (4 ohm resistor) directly to the IC pin with no wires in between.
c. Artificially cool the amp IC so it doesn't overheat, and see how much power it puts out.
As an example, I just bought a Sony MP450, which has in big writing right on the front of the unit "50 Watts X 4". But if you read the book it says "19 watts RMS". When tested on a bench with 13.5 volts input, you can actually get 15-16 watts out of this thing, which is about as good as you will see in real life.
The other clue is to look at the head unit fuse. On the Sony it's only a 10 amp fuse, so how do you get 200 watts (50 W x 4) from a unit that only consumes 135 watts (10 amps x 13.5 volts)?
It won't happen, unless Sony re-writes the laws of physics.
01-03-2002, 12:53 PM
#15
Registered User
I basically agree with everything in modifry's post. I'd add one more comment on measured head unit power output. When they say "60 watts x 4" advertised peak power that DOES NOT MEAN 240 watts. It means that ONE AT A TIME each channel could put out 60 watts peak (27 watts rms, whatever...) but not that each of the four channels can put out 60 watts (27 watts rms) at the same time the other channels are also putting out 60 watts.
It's my understanding that the Alpine "60 watt x 4" head units put out a smidgen more power than Kenwood's "50 watts x 4" and the other competition, and this is done by boosting amplifer voltage up to 36 watts and that it depends on a direct connection of the hot lead to the battery and the ground lead to an excellent ground. The battery lead is fused at 20 amps.
Here's Alpine's advertising mumbojumbo: "The Alpine CDA-7876 includes the exclusive "V-Drive" internal amplifier which delivers an incredible 60 Watts x 4 making it extremely powerful as well as versatile."
It's my understanding that the Alpine "60 watt x 4" head units put out a smidgen more power than Kenwood's "50 watts x 4" and the other competition, and this is done by boosting amplifer voltage up to 36 watts and that it depends on a direct connection of the hot lead to the battery and the ground lead to an excellent ground. The battery lead is fused at 20 amps.
Here's Alpine's advertising mumbojumbo: "The Alpine CDA-7876 includes the exclusive "V-Drive" internal amplifier which delivers an incredible 60 Watts x 4 making it extremely powerful as well as versatile."
01-03-2002, 01:03 PM
#16
Registered User
Join Date: Dec 2001
Location: encino
Posts: 1,792
Likes: 0
Received 0 Likes
on
0 Posts
modifry, what you say is true. well, kinda. the old headunits, the ones that were produced more than a fw years ago, used the technology that you speak of. but the new head unit i recently purchased, pioneer DEH P9300, they have introduced a new way of running the self amplifier. not only for a power increase but also for cleaner sound. i may not be a audio guru, but i know when it comes to audiophiles, sony is really not high end, unless you find the few pieces that are really not available in most stores.
so even the seperate amplifiers that are rated at 50 x 4 peak are going to be putting the same 23 x 4 rms, which is what my pioneer is rated at , i believe the same as the alpine. from my understanding, my stock radio, from a 2002 s2000, is rated at 30 watts x 4 peak. so i should see a descent difference sound volume and clarity.
to be honest with you, i believe so much in the headunit, that i am actually keeping the factory speakers (2002 comes with tweeters) , crossing them over with capacitors and running better wiring to them , adding a couple of bass shakers under the seat, and a 10 inch sub fiberglassed into the passenger footwell running off a soundstream amp.
your set up looks clean, but from the past experience i had with convertibles, a sub in the trunk really doesnt sound to great when the top is down, well, not if your inside the car atleast. your work is clean though, and i definately liked the idea of using 2 10 gauge wires, something i might try if i cant anything thicker there. nice job. thankx for the pics. i ll make sure i get you some too
so even the seperate amplifiers that are rated at 50 x 4 peak are going to be putting the same 23 x 4 rms, which is what my pioneer is rated at , i believe the same as the alpine. from my understanding, my stock radio, from a 2002 s2000, is rated at 30 watts x 4 peak. so i should see a descent difference sound volume and clarity.
to be honest with you, i believe so much in the headunit, that i am actually keeping the factory speakers (2002 comes with tweeters) , crossing them over with capacitors and running better wiring to them , adding a couple of bass shakers under the seat, and a 10 inch sub fiberglassed into the passenger footwell running off a soundstream amp.
your set up looks clean, but from the past experience i had with convertibles, a sub in the trunk really doesnt sound to great when the top is down, well, not if your inside the car atleast. your work is clean though, and i definately liked the idea of using 2 10 gauge wires, something i might try if i cant anything thicker there. nice job. thankx for the pics. i ll make sure i get you some too
01-03-2002, 01:06 PM
#17
Registered User
Join Date: Sep 2001
Location: Bay Area
Posts: 938
Likes: 0
Received 0 Likes
on
0 Posts
Not yet, thats one of the next things on the list..
01-03-2002, 01:49 PM
#18
Registered User
Join Date: Nov 2001
Location: Toronto
Posts: 22,863
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by modifry
Just a note for you guys with head units that advertise "peak' power ratings.
...
It won't happen, unless Sony re-writes the laws of physics.
Just a note for you guys with head units that advertise "peak' power ratings.
...
It won't happen, unless Sony re-writes the laws of physics.
01-03-2002, 07:16 PM
#20
Registered User
You only need the remote to program the PAC unit. Mine has been tucked away in the secret compartment since June. So, if you want to save a few dollars, see if you can borrow a remote. If you bought your Alpine locally, your dealer should let you use one for the few minutes it takes to program the PAC unit.