1 ohm amplifier

I am thinking of opgrading the bass section of my sound system. I love low frequency bass in fact right now i'm running at 30-35 hz but i realised that i need more power to produce loud bass at this frequency. The best way to maximize power output of an amplifier is to decrease the frequency. My plan is to wire 2 dual coil subs at 4 ohms per coil in parallel. However with 1 ohm the current draw from the vehicle will be tremendous. How can i minimize dramatic current draw effects from such a system and how i can supply such an amp with enough power to work at it's max or close to it.

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Prodigal Son

nouseforaname wrote:

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if you run a 1 ohm stable amp, you shouldn't have any problems with current draw. as long as your amp is rated at the ohm load you want to acheve, then it shouldn't dram any more amps than a 4 ohm amp.

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Thats not quite right. A one ohm stable amp is quite often high current and draws more amperage than a standard 4 ohm stable amp. List more info such as vehicle subs current amps deck current box and we can help out more from there

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

ok i currently have a boss bv6500 dvd player, soundstream bx-10 digtal bass reconstruction processor, profile pm50 4 band parametric equalizer (with 30 Hz low pass filter), Power Acoustik PCNC-2.0F 3.0 Farad Digital Capacitor. Currently i'm running 2 Rockford Fosgate P210S4 10" Punch Stage 2     Rockford Fosgate P210S4 10" Punch Stage 2 wired in parallel (2 ohms) to a Power Acoustik LT980/2 -- 2-Channel Amplifier and already the current draw is dimming everything in my car very badly when i turn up the volume in my 1991 mitsubishi galant. I am looking to upgrade my bass to 2 Kicker 05S12L54     Kicker 05S12L54 -- Dual 4 Ohms 12" L5 Solo-Baric S12L5 Kicker S12L54 and a Hifonics BXi 2006D     Hifonics BXi 2006D -- Brutus Series Class D Monoblock Amplifier (2000 watts RMS @ 1 ohm • 1500 watts RMS @ 2 ohms • 650 watts RMS @ 4 ohms). I was told that for 1 ohm apllication the ground wiring must be perfect with 0 guage wire. I also noticed that most 1 ohm stable amps don't have any fuses so i'm assuming this may make them easier to fry. Hope this information is enough. Thanks

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Prodigal Son

They have fuses, they may be inside the amp. Before you do anything to "upgrade your bass" you have to upgrade your charging system. You can install anything you want but without the juice its useless and won't perform to whats its rated or even close. Read the above sticky on upgrading the big 3 before you spend any money on higher power equipment. FYI the capacitor can aid in headlights dimming they add more of a draw on your already starving charging system....

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nouseforaname wrote:

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ok, the last 1 ohm stable amp i had ran LESS amps than the 4 ohm amp i ran. i know that may be a little hard to understand for some people, but it can happen. i'm a 12 year install veteran so yes i know how to check for things like that and it can be done.

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ABSOLUTELY wrong. If you are seeing a class A/B amp with an equivalent output rating as a Class D amp, and the Class A/B has fuses that are the same size or smaller than the Class D amplifier, one of two things ABSOLUTELY MUST be happening: 1: The Class A/B is OVERRATED, or 2: The Class D is UNDERRATED. There is NO WAY any class A/B amp can be more efficient than ANY Class D amplifier. Class A/B has a theoretical MAXIMUM efficiency of 66%, and that's THEORETICAL. Usually 50% is more the norm. A Class D amplifier has a theoretical maximim efficiency of 92%. Again theoretical, typically 85 or so percent efficient. You do the math. A 1000 watt amplifier is NOT a 1000 watt amplifier. You may be a 12 year veteran installing electronics, but I am a 21 year veteran in electrical and electronics theory from a military background. No, it can't be done. You CANNOT overcome Ohm's Law. In fact, you can't even BEND Ohms Law...

bazzgazm wrote:

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one thing you'll see is class a-b amps have better efficiency than they used to.

so getting a 4 ohm stable 2 channel amp that can create 1000 watts @ 4ohm mono will often consume less current than a class d monoblock @ 1ohm 1000w.

so if you series/parallel 4 voice coils @ 4ohms each you will do what you need to max out a good 2 channel 4ohm mono stable bridgeable amp.

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If the output is 1000 watts, it does not matter WHAT the load is to acheive that output power. The input/output ratio will actually become worse as you load the amplifier down. This happens with Class A/B and Class D amplifiers. Their efficiency gets worse the more you load them, meaning that you will have more heat wasted per output watt provided.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

So what exactly are class A/B and class D amplifiers and now i've noticed digital amplifiers- What exactly are they and what are their ups and downs? Thanls for the posts really learning alot here.

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Prodigal Son

nouseforaname wrote:

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whatever. guess my THEORY is bad.

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Yes, your theory is bad.

~wirewise~

It was the "whatever" comment that encouraged me :)

The thing to remember in this forum is that there is a lot to learn from a lot of members here no matter how long you've been installing mobile electronics.

~wirewise~

Im gonna speak in generalizations here so remember this isnt written in stone. A A/B amp is often used to run full range speakers and/or speaker sets. The amps are not as high effeciency as a class D amp but have a lower distortion rating. They are also generally availible in 2 and 4 channel configurations although there have been single channel as well as 5,6,7,8,9 channel versions. A Class D amp is generally used to run subwoofers. They are more efficent than your standard A/B amps but have a higher distortion rating. This is generally not audible in a subwoofer so it doesnt matter. Generally a class D amp is a single channel or "mono Block" amp.

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

Raven, what did they use to run subs BEFORE class d technology came out?? Class AB amps. And yes I know you were just generalizing.

Class AB amps were the norm for along time. I still use class AB for my subs in my current set up

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

ohms law
CURRENT = square root of power/resistance.
bend that!

bazzgazm wrote:

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ohms law
CURRENT = square root of power/resistance.
bend that!

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What the hell does that mean? And I am asking because there is much hostility in that, and it's aimed directly at me...

If you look at what you just wrote, it is a mathematical formula. Can you bend mathematical formulae? No, that's why the USE them... there is no "ummmmm... maybe I can do this with it... fudge a little here, and it'll still come up with the right answer" so you just stuck your own foot in your own mouth.

Now, if you'd like to defend your statement, I'll listen to whatever you have to say.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

I didnt get that either so I just left it alone man

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

If your mathematical formula is
current = square root(power/resistance)
then when resistance is cut in half, current is doubled.
hence the idea of the high current amplifier
now, if you read most test reports from independant companies on class a/b amplifiers, many reliable, decent amps are now 55-60% Efficient @ their 4ohm mono load
now when your class d's (90% in real life.. @ 1/3 power maybe) then you will see more likely 70-75%
now calculate your 4ohm load vs. your 1ohm load.

THAT'S your defense?

OK... Let's do that, shall we?

I dont care about the load... 1000 watts out is 1000 watts out. We agree on that, right? 1000 watts into 4 ohms just requires a higher output voltage to achieve than it would at one ohm. Anybody on this board should know that. (NO offense intended to those of you who don't, or possibly don't understand)

What I am referrring to is EFFICIENCY. How effectively does the amplifier, and all of it's associated circuitry (including power supply DC-DC conversion, and output stages), transfer 1000 watts of energy to the load. How much heat is wasted?

A Class D amplifier, and I'll use your worst case number of 70%, OK? (This'll be like running it at a 1 ohm load...)

1000/.70=1428.6 watts INPUT
1428.6/14.4=98.75 AMPS IN
428.6 watts blown off in the heatsink as wasted heat.

Now, your Class A/B, and I'll give you the benefit of the doubt again, and use your BEST case scenario of 60%... (This'll be like running it at a 4 ohm load)

1000/.60=1666.7 watts INPUT
1666.7/14.4=115.74 AMPS IN
666.7 watts blown off in the heatsink as wasted heat... 55% MORE wasted energy in a Class A/B amplifier, and that is comparing a WORST case Class D to a BEST case Class A/B.

I will also give you the benefit of the doubt that both amplifiers are loaded optimally... I don't care, again, about the speaker impedance... The lower the impedance, the less efficient any amplifier will run. Those numbers above will not likely change much, relative to each other, and the input currents will only get higher, as the efficiency decreases across the board... Also, as every amplifier will have component tolerance variations, these are not necessarily EXACT numbers, but again, all the formulae above are sound, well known, and proven. Was I able to bend any laws? Didn't think so...


:::::EDIT:::::

I forgot I wanted to add this example, earlier...

Now, going back to my earlier statements of previous posts, IF you have a Class A/B amplifier with, say 100A worth of fusing, (to go with the above example of the Class D amplifier, at 98.75A input) how much output power can it REALLY make, on a continuous basis? Let's do the math, shall we?

14.4*100=1440 watts IN
1440 watts in, * 60% efficiency = 864 watts out.

Now, is that a 1000 watt amplifier? Short and simple answer? No. So, to reiterate, the Class A/B amplifer, CALLED a 1000 watt amplifier is simply over-rated, isn't it? It's NOT a 1000 watt amplifer.

Please read my posts, regarding choosing an amplifier, if you have any further questions regarding this...

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

if the resistive load on an amplifier has nothing to do with current draw then i should just quit installing.
I wonder why it is when you try to run a 4ohm stable amp @ 1ohm mono that the amp overheats and the fuses blow?
if the same 40 amps is being drawn through the power wire from the alternator to create the 40x13=520*.6=312watts at 1ohm, as the same as 4ohm.. then? I'm really lost? please explain this theory you corrected me with.
when resistance is cut in half, current consumption doubles.
that's simple

bazzgazm wrote:

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I wonder why it is when you try to run a 4ohm stable amp @ 1ohm mono that the amp overheats and the fuses blow?
if the same 40 amps is being drawn through the power wire from the alternator to create the 40x13=520*.6=312watts at 1ohm, as the same as 4ohm.. then? I'm really lost? please explain this theory you corrected me with.

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If you have, for your example, an amplifier that is one ohm stable, and it can produce 312 watts into that one ohm load, into 4 ohms, it will only produce (around) 78 watts, NOT 312 watts. It's NOT the same 40 amps into a 4 ohm load... It's more like 10 amps.

Input current consumption doubles, because you are trying to produce MORE OUTPUT POWER. When you halve the load, yes, you WILL pull more power on the input side, but that is because you are not ONLY making X watts anymore, your are making (or trying to make) X*2 watts...

WHEN two different amplifiers are producing IDENTICAL OUTPUT POWERS, in my example above, 1000 watts, the LOAD MEANS NOTHING... it is inconsequential. The output power is 1000 watts, whether it is into 4 ohms or a dead short... 1000 watts is 1000 watts, and 1000 watts out, in the case of Class D requires 1400 watts in, and in the case of Class A/B, requires 1700 watts in - WHATEVER THE LOAD. The efficiency of the amplifier is still maintained based on its topology, and Class A/B will ALWAYS be less efficient than a Class D.

In ANY ONE GIVEN amplifier, in order to produce 1000 watts, an amplifier must make X voltage at Y current. The power supply does this on the power supply rails. If you halve the load, ON THAT SAME AMPLIFIER, now the power supply must try to make Y*2 current, to maintain X voltage. It can't do this without demanding more INPUT power from the battery. Because the voltage from the battery does not change, it must demand more CURRENT... Twice as much, to be exact. That is why the fuses blow... Because you are trying to make more power than the input fuses, provided by the manufacturer to keep the amplifier operating in a safe range, will allow. IF you were to increase the current capacity of the input fuses (don't do it, but IF) the power supply will continue to try to make the necessary power, until A: the protection circuitry stops it from running away, or 2: the amp overheats to an untimely DEATH... i.e. ya let the smoke out.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

While trying to avoid what may sound like some serious ass kissing, I would like to second everything that haemphyst has said so far in this thread, this dude knows his stuff. From everything I have learned as an electrical & electronic engineering student, I would say that it is entirely correct and the arguements that some people are making are not based on the solid, basic physics and maths arguements such as those above, and can definately learn something from them.

OK so you guys are saying that when the lower the resistance the greater the current draw from the vehicle and it's basically imparative that the electrical system of the vehicle be upgraded. So running at 1 ohm will almost definitely (considering i want to run at over 1000 W power) have to change my alternator and 3 wires (big 3). This is important to me cause i like to pre-plan my sytem thoroughly before i invest in it. Thanks again i've been learning so much from you guys. THANKS!

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Prodigal Son

Well, yes and no.... You look at the amplifier specs, and whatever load you are putting on the amplifier, the specs will tell you the amp will make this much power @ that load. That is the important number, NOT what the amp is loaded with. You take THAT number, then determine how much currrent the amplifier will pull from the car... This means you need to decide FIRST which woofers you are planning on using, and then, WHAT load you can produce from those woofers to present to the amplifier.

So, yes, if you are running 1000 watts, then you need to figure approximately 100A for a Class D amplfier, and approximately 115A for a Class A/B amplifier.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Prodigal:

There's been some ammusing back and forth in this thread.

For a good place to -start- learning more, check out https://www.bcae1.com/

It helped me tremendously when I came here to hang out with people that really know what they're talking about, like haemphyst.

Good luck with your system. I would personally never consider running a 1-ohm load unless you're dying to compete, but I also listen to old folks music most of the time.

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New Project: 2003 Pathfinder