For Robbie wattage

[daveb91]

P=E^2/R

30 volts 4ohm
P=30^2/4
P=900/4
P=225 WATTS

2 ohm
P=900/2
P=450 watts

25 watts is not always 25 watts change your load watts go up.

[xjoewhitex]

P=E^2/R

30 volts 4ohm
P=30^2/4
P=900/4
P=225 WATTS

2 ohm
P=900/2
P=450 watts

25 watts is not always 25 watts change your load watts go up.

wattage for what?

[narfdanarf]

This is why people prefer Optima batteries for car stereo applications.

[narfdanarf]

Optima batteries will supply voltage at approx. 14.4 volts, and a lot of amps will put out more power at 14.4 volts than at 12 volts.

One thing about amps now is that pretty much all good amps will run 2 ohm mono now, and most audiobahn will run 1ohm just fine.

[RobbieNelson]

One thing about amps now is that pretty much all good amps will run 2 ohm mono now, and most audiobahn will run 1ohm just fine.

Why is that good? BTW... if the car is running the battery becomes a load, the alternater is what it powering the car.

[xjoewhitex]

One thing about amps now is that pretty much all good amps will run 2 ohm mono now, and most audiobahn will run 1ohm just fine.

Why is that good? BTW... if the car is running the battery becomes a load, the alternater is what it powering the car.

in a way but if you have a bad battery and it dies while you are driving So does Your car. So in a way isnt it Series connection With 2 Supplys? battery- Motor - alt - Battery?

[narfdanarf]

It is good because it gives more versatility to a setup. One of the reasons they came out with dvc (dual voice coil) subs is because it allowed you to wire the sub at a 2 ohm level. This is good because you could then achieve the min. resistance (most power) out of an amp/sub combo with only one sub.

So now, because of this versatility, a lot of manufacturers make there subs dvc with two 4ohm voice coils. If you had two of these subs the only ways you could wire them would be 16 ohm, 4 ohm, or 1ohm. With this in mind, it takes a lot more amplifier to run 1000 watts at 4ohm than 1000 watts at 1ohm.

For example, you could power one sub 500 watts with a 2ohm amp and another sub 500 watts with a 2 ohm amp butt it would be a lot cheaper to power both subs 1000 watts with a 1 ohm capable amp.

I am kind of sick and tired so I hope this makes sense. I tried to explain :roll:

[Feedman]

I understand.... 8)

[RobbieNelson]

With this in mind, it takes a lot more amplifier to run 1000 watts at 4ohm than 1000 watts at 1ohm.

Why is this? You didn't explain.

Side note: Why do power companys distribute power at high voltage and low(relatively) current and not visa-versa?


For example, you could power one sub 500 watts with a 2ohm amp and another sub 500 watts with a 2 ohm amp butt it would be a lot cheaper to power both subs 1000 watts with a 1 ohm capable amp.

Why not drive them with one amp at 4 Ohms?


I am kind of sick and tired so I hope this makes sense. I tried to explain :roll:

I'm not mad at cha'. Just learning/explaining. Remember: when we argue, other people listening in(lurking) learn from it. I learn myself from these type of educated arguing. It's good for the mind. Or would you rather discuss "What exactly is rice?"? LOL :lol:

[xjoewhitex]

Or would you rather discuss "What exactly is rice?"? LOL :lol: what are you trying to say.... 8)

[Feedman]

That is definatly true. Arguing or what I like to call creative discussion, stimulates the mind. Good conversation guys...keep up the good work... 8)

[daveb91]

Robbie I dont know how I said it what I meant was my Orion hcca225 amp is a 2x25 amp but is bridgable down to 1/4ohm stereo. High current amp.

[daveb91]

Side note: Why do power companys distribute power at high voltage and low(relatively) current and not visa-versa?



So it can be stepped down. Use a stepdown transformer the voltage lowers and the current raises. If they distribited it with high current and low voltage the conductor would be massive. You ever see a Tesla coil? nothing like arcing million volts through you (at extremely low current and high frequency) :twisted:

[narfdanarf]

What I was getting at ( I think) was that 4 ohms is more resistance than 1 ohm (obviously). It takes a much larger and more expensive amp to run 1000 watts at 4 ohm than at 1 ohm. IE....you could take a amp that was High current capable that would normally only be 250 watts at 4 ohm. and it could run 1000 watts at 1 ohm.




amp "A"
low current amp, max output of 1000 watts at 4ohm price $500.00


amp "B"
high current capable amp, 250 watts @4ohm, 500 watts @2ohm, 1000 watts at 1 ohm price $300.00

[dysturbed_90dx_4dr]

You guys are also forgeting Amps pulled by the stereo system being a factor. This is why cars with big sound systems have so many electrical problems. With my saturn i was running over 1000watts Max (about 6-700RMS depends) That pulls a hell of alot more than the 60 amps maximum the alternator is producing. That means what your alternator produces isn't enough for your system to use so it turns to the battery for more power till it is run down. because of this alternators have to work twice as hard to recharge the battery as well as produce the next bass note and run your car. This causes your alternator to die young.

Amps = watts/volts
I=P/E
1000watts / 14.4 volts = 69.4amps

Consider my new system
1500watt HiPhonics Brutus + 500.4 JL Audio = 2000watts
2000watts / 14.4 volts = 138 amps


Anyone who builds a system that needs more than your stock alternator can produce needs to upgrade the alternator first not the battery. Batteries are just the backup and a bandaid for your cars electrical system basicly.

I have a Optima Yellow top in my car right now which is recommended for car audio cause it's a deep cycle battery which you will find that all good car audio batteries are deep cycle.

From Optimas website
"Starting applications in high-accessory vehicles/High Cycling Applications. Vehicles with computers, extra radios, electronic components, lights, winches, etc. will create excessive amperage drain that can damage a starting battery. Recommend the OPTIMA Yellow Top to provide fast recharging and longer life due to its' ability to cycle over 300 times.

Each OPTIMA Yellow Top Deep Cycle Battery is rated at 120 minutes of Reserve Capacity at a 25 Amp draw. This means if your alternator stops making charge your battery can run your car for a short time "

And the Yellow top is the only one coverd by optimas warrenty if used for car audio. The Red top isn't.

Dysturbed

[daveb91]

You guys are also forgeting Amps pulled by the stereo system being a factor.
Dysturbed

We werent forgetting we just werent talking about that. :) Also talking about bandaids on stereos how about the guys who put 10 1 farad caps on there stereos because they say they arent getting enough power. The cap is not there for that purpose its there to stablize the supply voltage.

[dysturbed_90dx_4dr]

yeah a 2nd battery is a much better option than adding capacitors. I mean a cap can help you somewhat with the light dimming issue but it doen't actually give you more power it just holds the power for your big hard bass it then recharges. It still draws from the battery and alternator even if the cap is there.

Dysturbed

[RobbieNelson]

If they distribited it with high current and low voltage the conductor would be massive.

True. Also you have less losses in the conductor itself. P=R X I^2 (often refered to as "I squared R losses" ... So, the higher the current the more power you lose through resistive elements(cables, terminals, transistors). So a high current amp will be less efficient than a lower current amp.

[RobbieNelson]

What I was getting at ( I think) was that 4 ohms is more resistance than 1 ohm (obviously). It takes a much larger and more expensive amp to run 1000 watts at 4 ohm than at 1 ohm. IE....you could take a amp that was High current capable that would normally only be 250 watts at 4 ohm. and it could run 1000 watts at 1 ohm.

You haven't given any scientific/engineering explanation as to why this is the case. The power devices(transistors) in the amps still have to handle 1000W, regardless of high or low current.




amp "A"
low current amp, max output of 1000 watts at 4ohm price $500.00


amp "B"
high current capable amp, 250 watts @4ohm, 500 watts @2ohm, 1000 watts at 1 ohm price $300.00

I'm not saying you're a fibber, but getting actual prices for actual amps would be nice.

[narfdanarf]

"Amp A" MTX Thunder 942
4ohm 700 watts max
height- 2.1"
width- 9.75"
length- 17.8"
price - $599 at Crutchfield

"Amp B" Audiobahn A8000t
2ohm 800 watts max <---more power
height- 1.85"
width- 9.85"
height- 11.85"
price - $330 at Crutchfield


Although they are high priced, I used prices from Crutchfield because they still carry both amps wereas we do not anymore.All of the specs I got directly off of the manufacturer websites, I suppose I could provide links butt I am starting to get bored of this. Granted they are two different amp manufacturers but both manufacturers are similar in quality, size, and price.

I am sure you could come up with two different amps that disprove me too, because there are always exceptions to the rule.And, I'm not saying that this is the rule, this is just what I have deduced from installing amps at work.You say that they should be the same size(transistors) and they very well may be, however for some reason or another amps of the type "a" variety are larger/more expensive.

[Feedman]

I'm not saying you're a fibber, but getting actual prices for actual amps would be nice.

*dead* 8)

[daveb91]

Most of the low current amps are bigger because of the wasted space inside them heat sinks that are not effective. High current amps on the other hand have nice beefy pwr supplies with better, larger caps higher rated resistors and more elaborate filtering circuits. Also some lower scaled amps have crossover networks built in which most of the time are passive which the coils and caps take up more room also.

[RobbieNelson]

"Amp A" MTX Thunder 942
4ohm 700 watts max
height- 2.1"
width- 9.75"
length- 17.8"
price - $599 at Crutchfield

"Amp B" Audiobahn A8000t
2ohm 800 watts max <---more power
height- 1.85"
width- 9.85"
height- 11.85"
price - $330 at Crutchfield


"Amp C" Audiobahn A8002t
4ohm 800 watts max
height- 2"
width- 12"
height- 11"
price - $350 at Crutchfield

And Amp B is bigger than Amp C according to Crutchfield.

It's 20 bucks more, but it's 2 channel.

2Ohm? This conversation started with dave stating that his amp could handle a 1/4 Ohm load. That's alot more extreme than 2Ohm.

[RobbieNelson]

Most of the low current amps are bigger because of the wasted space inside them heat sinks that are not effective.

High current amps are inherently less efficient. There will be more power lost in the amp due to high current resistive losses. Did you miss the whole power company high voltage transmission lines note.


High current amps on the other hand have nice beefy pwr supplies with better, larger caps higher rated resistors and more elaborate filtering circuits.

Uhhhh... where did that logic come from?


Also some lower scaled amps have crossover networks built in which most of the time are passive which the coils and caps take up more room also.

We're talking Low Current and High Current... not low-end/cheap and high-end/quality.

[daveb91]

So you werent talking size? :?

[daveb91]

Most of the low current amps are bigger because of the wasted space inside them heat sinks that are not effective.

High current amps are inherently less efficient. There will be more power lost in the amp due to high current resistive losses. Did you miss the whole power company high voltage transmission lines note.


High current amps on the other hand have nice beefy pwr supplies with better, larger caps higher rated resistors and more elaborate filtering circuits.

Uhhhh... where did that logic come from?


Also some lower scaled amps have crossover networks built in which most of the time are passive which the coils and caps take up more room also.

We're talking Low Current and High Current... not low-end/cheap and high-end/quality.

The first two quotes were commenting on size of a high current amp and reg amp and the last quote WAS talking about hig and low current amps the most high current amps dont have built in crossover circuits because they are commonly used in competition which most use external crossovers.

[xjoewhitex]

im so confused.. :?

[daveb91]

yeah one guy always makes things confusing! :shock:

[dysturbed_90dx_4dr]

So dave you got a old "Cheater" Orion? And that is what they called them too. Those amps are golden in competion i know.
It's a shame they don't label amps like that anymore:)
75x2 is the label on the amp. LOL yeah right and the amps makes almost 1500watts RMS @ 1/2 ohm. HCCA was the bomb.

Dysturbed

[RobbieNelson]

So dave you got a old "Cheater" Orion? And that is what they called them too. Those amps are golden in competion i know.
It's a shame they don't label amps like that anymore:)
75x2 is the label on the amp. LOL yeah right and the amps makes almost 1500watts RMS @ 1/2 ohm. HCCA was the bomb.

Dysturbed

This backs up my High Current Amp origin theory.

[daveb91]

2x25 not 2x75 225HCCA the smallest one.

[kmfdmk]

Points towards ebay:

If you're looking for one ebay has a few:

http://search.ebay.com/HCCA-amp_W0QQsok ... 1QQfromZR8 (http://search.ebay.com/HCCA-amp_W0QQsokeywordredirectZ1QQfromZR8)