Understanding Audio Amplifiers

Maymyvetteliveforever

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I'm old school so I'm trying to grasp the concept of 1 to 2000 watt amplifiers these people have in there cars today. Although mine isn't on the road yet, I remember 25 years ago the GM 120 amp Pioneer I have was so loud I had to turn it down for fear of busting an ear drum at times. What amazed me is it was so clean even at 3/4 volume, it was difficult to find a speaker that would carry the volume without blowing out. Now a days I'm hearing 1500 watts of power...... if the GM 120 Pioneer amp (back then) had 10 times that watts at 1200 watts you would be able to hear it about 10 miles away....plus where would you find a car speaker to match it? I just don't get it.
 
Simply speaking I bet they are liars.....there was a thing years ago where the Japs were lying about the power of their home elctronic gear, so the feds clamped down on it....but forgot to mention CAR audio....

so the lies continued....it really killed them in home audio for a while, but of course they recovered....

typical audio amps back when ran at about 50% efficiency today maybe 60-70%? anyway, that means a KW in a car would need 200 amps.....

so very simply, they are not a KW in power....not by any conservative standard of measure anyway....

PEAK dynamic power....well maybe....but not RMS both channels driven...


:crutches:
 
RMS power versus a BS rating where you add everything, it's like with stickers and 10 HP upgrades for your engine, install 50 of those and supposedly you have added 500 HP....
 
typical audio amps back when ran at about 50% efficiency today maybe 60-70%? anyway, that means a KW in a car would need 200 amps.....

so very simply, they are not a KW in power....
not by any conservative standard of measure anyway....
:crutches:

Not sure I understand the statement in bold, can you simplify please?


With all being said, how do you now compare apples to oranges, or do we even bother. Next question, would the 25 year old GM 120 Pioneer amp be compatible with today's head unit that now has additional wiring for sub/s and or is this amp even worth keeping due to it's age?

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Volts times amps= power in watts....a KW is Kilowatt, just like a power rating for a electric iron or whatever in your house....1000 watts.....

same thing, but with a GREAT efficiency rating of say 70% for losses in the power amp....given off as HEAT, which is why those heat sinks are there....
the cooling fins....you get into consuming 1500 watts to generate 1000 into the speakers....well, if you do that we take 1500 and divide by lets say 13.5 volts as a decent level with engine running....giving us 111 amps under a best case scenario.....if you double that with two amps that's my rounded off 200 amps...

we ain't got alternators that can do that very long, not and run the car too....

getting into Leece Neville type territory, like a fire truck and a alt the size of a basketball or larger even....sometimes two of them....they have the room for that, a vette DONT.....

NOW, here is where it gets interesting....the kids drive these over rated amplifiers with going directly off the battery sometimes....and so they get a lot of 'punch' power, sometimes even using a HUGE size capacitor on the main power line,, the 12 volt feed....it's a help too....

so YES it is possible to generate a KW worth of power into the speakers for an instant, but that is into the woofers ONLY, second off, that instant is for about .1 second....100 milliseconds.......hardly a honest power rating for any amp....steady on for ten minits is a more honest rating....when trying THAT, those amps will blow up......literally, smoke, fire, heat, whole thing...:gurney::evil:


No sense in getting all techy on you.....but I"m a olde tyme elect tech from WAY back, with an equally olde tyme stereo hobby, mostly home systems...
Decades ago I had a friend with another '60 vette, much like mine....he put a very nice stereo in it, with custom dash and 8 track player system, before any factory ever heard of it....made from old 'spot pack' systems the disc jockeys used in radio stations for playing commercials...known in the trade as 'spots'....
 
Thanks for the explanation mrvette, although I'm embarrass to say that I may have to read it a few more times to better understand it.
 
Thanks for the explanation mrvette, although I'm embarrass to say that I may have to read it a few more times to better understand it.

Maybe I don't tipe the best, I type as in conversation/talking, it's the way I think, as I don't tipe papers and admin/bureaucracy for many years now....count 3 decades....

;):rofl:
 
There is no problems with your grammer what so ever, it's the electronic side of it that I'm trying to grasp. I guess I should be more audio tech savy. Give it time I'll learn.

Thanks again mrvette sir!
 
There is no problems with your grammer what so ever, it's the electronic side of it that I'm trying to grasp. I guess I should be more audio tech savy. Give it time I'll learn.

Thanks again mrvette sir!

Sir, hell, everytime someone calls me sir or MR. I turn around looking for my father....and he passed in '86....

hit some search online for elementary electronics/electricals if they not too heavy these daze trying to sell something...

maybe try Radio Shack, they used to have some elementary electrical/electronic primers cheep....dunno about today...call/ask/online??

library maybe? if they still exist??

:bump:
 
Amps have a couple of different ratings. One is the RMS power level. RMS stands for root mean square (its an engineering/math thing). Basically this is the constant power level - the level of power the amp can put out continuously. The other rating is peak power. Most amps can put out much more than the RMS rating but only for short periods of time. Most people like to quote the peak level because it sounds more impressive. I'm much more impressed by sound quality.

Marketing may also have something to do with power ratings. I don't know if all manufacturers rate their amps according to industry standards. I'm guessing not.

But it doesn't take much to get some serious power levels. I'm finishing up a stereo install in my '73. Dash speakers powered by the head unit which is rated at 22 watts RMS per channel. That's a total of 44 watts. My amp is a 120 watt RMS per channel 4 channel amp. The kick panel speakers will be powered by two of the channels and the other two will be bridged to power a single small subwoofer. So, my simple system has 524 watts of RMS power. But the peak power rating for my system is 1300 watts. Quite a difference.

If I had purchased a separate amp for the subwoofer and used the 4 channel amp for the 4 main speakers, I would have needed another 240 watts of RMS power to match the subwoofer to the rest of the system. Subwoofers are generally not nearly as efficient as main speakers and need a lot more power to drive them so that is also why you hear of very large amps. Two 15" subwoofers that are not efficient might need an enormous amp to drive them.

I didn't need 120 watts for my kick panel speakers. I wanted an amp small enough to fit in the jack compartment which meant I needed a Class D amp. Class D amps run much cooler and are much smaller than the other class amps but are also a lot more expensive. I sized the amp to power the subwoofer but because my amp is more than I need for the kick panel speakers, I set the gain control on those two channels lower than normal to prevent blowing those speakers. My system sounds great and I haven't even added the subwoofer yet.

Crutchfield has some good educational information on their website: http://www.crutchfield.com

Kinda long winded. Hope I did you some good.

DC
 
Thanks DC3 for taking the time to give another perspective. I seems the more it's explained to me the more I understand. I guess in a way I'm trying to figure out whether these (2) GM 120 and GM 40 amps are worth savings. My other thought is whether they will connect to the new head units that are available...... 25 years later, and if not...which I assume is the case, can they be adapted to connect.

Thanks again guys.
 
Thanks DC3 for taking the time to give another perspective. I seems the more it's explained to me the more I understand. I guess in a way I'm trying to figure out whether these (2) GM 120 and GM 40 amps are worth savings. My other thought is whether they will connect to the new head units that are available...... 25 years later, and if not...which I assume is the case, can they be adapted to connect.

Thanks again guys.

If they have RCA inputs, they would likely work. It gets more iffy if they have speaker level inputs. Some head units don't have speaker level outputs, RCA only and you can't marry the two without some type of adapter. RCA is the preferred method for best sound.

Don't know how your amps would compare sound wise to the new stuff. Hell, they might sound better. Are they 2 or 4 channel amps? Is the 120 a per channel watt rating or something else. I couldn't make out the text on the nameplate in the photo you provided.

The large heat sinks make me think they put out a lot of heat so you would want good airflow if you install them. If they don't have gain controls (think of it as a volume control), you would want to make sure your speakers can handle the maximum output of the amps. If they do have gain controls you can match the amplification to your speaker ratings.

DC
 
I got the following photo's off the net, I have two of the GM 120's and one of the 40 amps. As you can see no rca jacks, just plain ol old school.

Pioneer4.jpg


Pioneer5.jpg


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I can't see the end where those wires are coming in/out of them, there should be two inputs on there about 3/8 round with hole in the middle....red/wh is the typical color code on plastic in the middle....the pin is about 1/8 diameter....

the speakers could be on a plug or just screw terminals, saying +- on them....

the heavy typical red/black wires are the main power to your alt or battery....the yellow/maybe white? wire is the signal from the head end unit to turn on/off for the power amp....

most of the higher power amps, even the old ones, used a nice power supply design that eliminated any alternator whine in the speakers due to main power routing....among other advantages.....it's purpose was to jack up the voltage available to drive the speakers with....not doing that would severely limit the power available at just 12 volts, even assuming 100% efficiency which is not the case....so the net affect to you is wiring the power amp to the alt direct is a good thing, and the head end/source/preamp/equalizers should go across the battery, as they draw almost no current...

course then you have to turn it on/off individually....not via the ignition switch like factory....

:clobbered:
 
Most big systems today run a number of power hungry sub-woofers. Low frequency reproduction with ground pounding power!
 
I got the following photo's off the net, I have two of the GM 120's and one of the 40 amps. As you can see no rca jacks, just plain ol old school.

I did a google search for the Pioneer GM 120. I found out there was an issue with the input level which made the amp best suited for a compatible Pioneer head unit. Apparently it could work with other head units depending on the output level. No RCA jacks means speaker level inputs. My gut tells me you would be better off with a modern amp. I wish I could help more but I just don't know enough about these amps.

DC
 
My gut tells me you would be better off with a modern amp. I wish I could help more but I just don't know enough about these amps.

DC
Thanks for trying DC3, I also did a search and read some members did do the swap over which was somewhat confusion but in the end they made it work. I'm just not sure I'd want to attemp that same mod. It would be a real waste to throw out three Pioneer amps though.
 
My gut tells me you would be better off with a modern amp. I wish I could help more but I just don't know enough about these amps.

DC
Thanks for trying DC3, I also did a search and read some members did do the swap over which was somewhat confusion but in the end they made it work. I'm just not sure I'd want to attemp that same mod. It would be a real waste to throw out three Pioneer amps though.

Old ET like me is mildly curious about them....IF you decide to pitch them, don't, I will PP you the postage to send them cheep to me, and if then I can't do anything with them either....to the recycle scrap metal bin they do....son in law collects that shit on his trailer for trips about twice a year....several hundred bux/trip.....copper/brass/aluminum/steel/ any metal...

:nuts:
 
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