brutus BX1500D

[Randy Savage 5,000+ posts]

Different amps have different efficiencies...Loyd said it will be around 70%...which is right around where a lot of Class D amps pull...

 

[bigbassman Premium Member]

yes.. its best to use exact efficiencies, but from my knowledge on amplifier design, I made an educated estimate on the efficiency of this amp (within 5%)

all amps are different, but efficiencies differ a bit less than most would guess..

ohm's law rocks //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Loyd L.

 

[spyd3r 10+ year member]

My point exactly.

And thats not ohms law my friend. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif Its a power law which Ohm did come up with, but that is not the name. Using a simple power equation I=P/V or i^2=P/R does not exactly give you even a rough idea what the amp draws.

Im a second year eletrical/computer engineering major, and we have only studied simple amplification theory and manufacturing..and your way isn't even close in giving you the max drawn current.

You would have to know the exact parameters of the amp (ie. an interenal resistance seen by a DC power source) to even begin calculating ideal specs.

Since its a power amplifier.....you would have some extensive DC, AC, AC node, characteristics to analyze using measured resistance values of resitors...inductor coils...caps. transistor loops...and so on . Then after you calculated all the loop equations you will be able to come up with a peak current draw.

And where in the world did you get the 30% efficiency???? What a bogus thing to say...did you design this amplifier that you know how effiecient it is?

In the real world the max current draw will be not over 140 amps. No calculations just an educated guess.

Best way to determine the max draw is to emailthe tech. (John) at Hifonics and get him to email you a test sheet for that amp.

BTW:

Not trying to sound negative towards you bassman, but thats a pretty silly thing to say that you came up with the max draw by using a power equation. Just trying to clear up a little eletrical stuff w/o being technical is hard for you to understand the amount of calcualting goes into figurng amps out. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[bigbassman Premium Member]

you should read a bit harder.. I didn't say 30% efficient.. I said 70% efficient, total amp, at full power.. that's accepted avg for a switching power supply amplifier.. total amp.. meaning power in to power out.. its not dead on, nor was it meant to be..

and btw.. I wasn't going for an EXACT current draw... but within the varibles I stated, mine will be close...

email hifonics, and you'll get a current draw spec.. from a test bench.. that means extremely stable voltage.. which will not represent IN CAR PERFORMANCE....

1600 / 14.4 + 30% = 144 amps, which would make your guess correct... but you WILL NOT.. repeat once more.. WILL NOT ACHEIVE THAT VOLTAGE IN CAR WITH THE AMP AT FULL POWER..

* I=P/V is a derivative of ohm's law, and while not exactly correct, is refered to as such for ease of understanding..

here's one for the road...

JBL 1200.1 JBL techs rated it as having 114 amps of current draw at full power

it was tested in the jan. 2000 issue of Car Stereo Review (now CSRME) Ken C. Pohlmann test it as producing 1378 watts at 14.4 volts..

It was also tested to be 73.6% efficient at full power...

lets do my math...

1378 / 14.4 + 26.4% = 120.9 amps

well gee golly.. my INCORRECT//content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif method which took all of 25 seconds, got me to within 6.9 amps of the ACTUAL TESTED CURRENT DRAW, DONE BY THE PEOPLE WHO DESIGNED THE **** AMP //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

you go ahead and do your method.. I'll take mine, and have the rest of the night to look at ****.. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

goodbye //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Loyd L.

 

[spyd3r 10+ year member]

Well no use to fret over something like max current draw.

As long as you realise that your really rounding off the actual numbers..a bit //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif .

I've read alot of your post and you seem very knowledgebale with car audio. So kudos for that , and you weren't wrong either. Just some people have different ways of doin things. Seems silly that I pointed out such a small thing as a few amps.

The point here is that the amp will draw as much as any other class D amp will at that power level( ~140A-180A //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif ).

So unless you have a high output alt or something...don't expect to drive around town w/o your lights dimming a bit. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[Randy Savage 5,000+ posts]

Originally posted by bigbassman you go ahead and do your method.. I'll take mine, and have the rest of the night to look at ****.. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

We really didn't need to know this...

 

[Biohazard 10+ year member]

thats only if the amp is at 1 ohm right? so if it were at 4 ohms wired then it would draw significantly less current correct?

 

[bigbassman Premium Member]

Originally posted by Biohazard thats only if the amp is at 1 ohm right? so if it were at 4 ohms wired then it would draw significantly less current correct?

of course.. because it only does 450-500 watts at 4 ohm.. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Loyd L.

 

[KurupT 10+ year member]

blah, just go with the old school gen vi colossus //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif old school rules!!

 

[limitkid7 5,000+ posts]

hi //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[MaXiMa 10+ year member]

what do u think would drain more power. 2 BX1500D's or 1 audiobahn 2300HCT amp. from what bigbassman says the BX1500D pulls a 180 amps at full power so that is 360 amps with both of them at full power.

 

[Miller 10+ year member]

I'm confused. Isnt the whole purpose of fuses to cut off power after a certain amount of amps so that the amp isnt overlouded with power? If the amp has 2 60 amp fuses, that means 120 amps max. So how could it have a max of 180 amps or whatever was said above? Wouldnt the fuses blow??

 

[MaXiMa 10+ year member]

ya i thought so too. but these guys really know what they are tlakin about. although maybe it could possibly pull 180 amps if the fuses werent there. and can some one answer my question 2 posts up please.

 

[MaXiMa 10+ year member]

come on guys throw me a bone on these questions

 

[Miller 10+ year member]

hey if you guys claim it can only make those watt claims at 180 amps or so and the amp is only rated for 2 60 amp fuses, then does this mean it doesnt put out 1500 watts? Is it an over rated amp?