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Discussion Starter · #1 ·
I searched the forum but could not find the answer. Does anyone know what the factory radio wattage output is from the headunit per channel??
Thanks
Alan
 

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quickturbo said:
I searched the forum but could not find the answer. Does anyone know what the factory radio wattage output is from the headunit per channel??
Thanks
Alan
It suppose to be a 200 watt HU so I would think it is 50x4 at 2 ohms.
 

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gm4life said:
It suppose to be a 200 watt HU so I would think it is 50x4 at 2 ohms.
if anything, thats max, not RMS. or it could be for the :quoties: sub :quoties: amp too
 

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Manufacturer-stated ratings like "200 Watt Stereo" and the like are always purely hype used for marketing, and in no way reflect the true real-world output. 200W at 50% distortion, maybe. If the mfrs published the true RMS rating of their factory units nobody would want them.
 

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Hummina said:
if anything, thats max, not RMS. or it could be for the :quoties: sub :quoties: amp too
Good point, I should have said system watts not HU. But like everything is listed as MAX output.
 

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Discussion Starter · #8 ·
I have a factory sales flyer and it says its 200 watt but I think that's peak wattage with the head unit and the factory amp. I was hoping someone would know off the to of there head. Its not a real big deal I was hooking up a line out converter and it had 2 different inputs for different wattage head units. Its only temporary until I can buy a Phreddy_Aus Kit.
 

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quickturbo said:
I was hooking up a line out converter and it had 2 different inputs for different wattage head units.
What are the two options?

I believe that 200W advert does include the 80W sub amp, so that means 120W max for the head unit, which isn't any more than most head units.
 

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Lothar34 said:
What are the two options?

I believe that 200W advert does include the 80W sub amp, so that means 120W max for the head unit, which isn't any more than most head units.
correct and that is peak power not RMS... so 30 x 4 for the front(door and dash tweeters together) and side speakers. 40 x2 for the rear shelf subs


It's certainly enough to piss off a neighbor of mine though...bitched about not turning my stereo down before i pull in the driveway...:fawkdance
 

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Flashpoint said:
correct and that is peak power not RMS... so 30 x 4 for the front(door and dash tweeters together) and side speakers. 40 x2 for the rear shelf subs

That is 30x4 at 2 ohm, so 15x4 at 4 ohm peak. Usually RMS is 1/2 of peak, so 7.5x4 RMS at 4 ohm. That is really crappy!!!
 

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Let's play.

Assuming:

1. The amp is not a switching amp nor uses a switching power supply....
2. The amp is a bridged amp
3. The battery voltage is 13.8V and that is what is available to the amplifier

13.8 x 2 = 26.8V (peak to peak)

Assuming the amp can get within two diode drops of the rails (1.2V per rail)

26.8V - 1.2 -1.2 = 24.4V Peak to Peak

RMS = .707 x Peak-Peak/2 or .707 x 12.2V or 8.625V RMS

Assuming the output stage can deliver all the current needed (since current moves a speaker not voltage):

Power = ExE/R
P = (8.625V x 8.625V)/8 ohms or 9.3W RMS into 8 ohms
18.6W RMS into 4 ohms
37.2W RMS in 2 ohms

It's possible the amps are bootstrapped and you can gain up to 25% more power so 46.4W RMS into 2 ohms for each channel. I am assuming a purely resitive load and not a complex load like a speaker but this is close enough for goverment work....

Odds are the spec is peak to peak inverse IHF music power at 1000 hertz (it's a joke meaning the amp is so loosely rated as to be meaningless).

I can see where they loosely rate the system 200W at 2 ohms if we include the subwoofer amp. From a traditional sense it's rated in the 55W at 8 ohms.
 

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The chip used in the headunit is a TDA7454:
http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/7/TDA7454.shtml
RMS 30W x 4 @ 2ohm, 1%THD

In the sub amp, there are two TDA7396s:
http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/7/TDA7396.shtml
RMS 45W x 1 @ 2ohm, 10%THD (at 1KHz, the subs should be crossed over well below that)

The "max" power for all those is 390W. So I guess Pontiac really was correct to claim 200W.


What gets me though, is that I don't see anything resembling a crossover in the subwoofer amp. There are a couple inductors in there, but they're connected straight to the fuse, so those have to be for the power supply. Were we wrong about those subs being crossed over? Did anybody ever check, or did we all just assume that they were?

Also, the capacitor on the tweeters (the ones in the dash and the coax pair) is 10uF. At 2ohms, that would cross them over at 8000Hz. That's pretty damn high. I can only figure they did that because the impedance of the woofers at that frequency would be high enough that it wouldn't overload the amp up in the range where both speakers are being driven. I can't believe I left those damn tweeters in the dash for so long...
 

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Lothar34 said:
The chip used in the headunit is a TDA7454:
http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/7/TDA7454.shtml
RMS 30W x 4 @ 2ohm, 1%THD

In the sub amp, there are two TDA7396s:
http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/7/TDA7396.shtml
RMS 45W x 1 @ 2ohm, 10%THD (at 1KHz, the subs should be crossed over well below that)

The "max" power for all those is 390W. So I guess Pontiac really was correct to claim 200W.


What gets me though, is that I don't see anything resembling a crossover in the subwoofer amp. There are a couple inductors in there, but they're connected straight to the fuse, so those have to be for the power supply. Were we wrong about those subs being crossed over? Did anybody ever check, or did we all just assume that they were?

Also, the capacitor on the tweeters (the ones in the dash and the coax pair) is 10uF. At 2ohms, that would cross them over at 8000Hz. That's pretty damn high. I can only figure they did that because the impedance of the woofers at that frequency would be high enough that it wouldn't overload the amp up in the range where both speakers are being driven. I can't believe I left those damn tweeters in the dash for so long...

I remember someone putting a full range speaker on the output of that amp and said they get no highs out...so... I dunno. :confused:


If you have a battery (or power supply) and a HU to feed it, hook a full range you have laying around (if you have one) and see?
 

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Alright I just cut up a bunch of wires from a dead ATX power supply because they fit perfectly on the pins in the stock amp.

I wired it up to a head unit I have sitting around and the thing wouldn't power up. I opened it and it's getting voltage (only 9.3VDC) and it's getting the signal from the head unit but it wouldn't come on. I guess 9.3V isn't enough to power it up, even though the head unit worked fine. Maybe I'll have to find a real 12V power supply and not use a computer PS...

I was gonna check to see where the crossover point on the amp was, if there was one.

I know I have a couple laptop power supplies at work that will put out 14V @ 3A. I should be able to get by with one of those if it's just for a couple minutes to test it.
 

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Well I found a 12V 3A power supply here in my apartment and tried that, but no luck.

I wonder if I messed something up when I took the thing apart and put it back together? Looking at the datasheet, it should be turning on. I'm giving it what it wants and I don't think any of the protection scenarios are true. This sucks 'cause now if I want to test it I'd need to take my car apart so I can get to the output wires.

I guess I could just let it go. I probably won't end up needing it anyway.
 

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is there an actually amp in the car that i can get access too, and if there is can someone tell me where it's located?
 
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