Why is SQ better at 4 or 8 ohms compared to 1 or less?

[VWBobby 10+ year member]

I've never been able to find a definite answer on this.... Can someone please explain how this works? I think it has to do with dampening and more or less the speaker having a "cushion" when run at 4 or 8 compared to 1?

I have heard of people driving 250-watt amps down to 0.25 Ohm to get around 1000-watts but they never mentioned how it sounded doing it. I have also run many 2 to 8 ohm setups and didn't notice any difference that I could attribute to the load.

//content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif

Thanks in advance!

-Bobby

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[Cruzer 10+ year member]

Im not sure if its noticable to the ear the difference, but i think its just easier on the amp to run at 4 ohms which means it can put out cleaner signal, power, and sound.

i could be wrong, its just a guess. either way i doubt its noticeable to the ear

 

[power-fanatic07 5,000+ posts]

Less THD at 4 ohms than at 1 ohm unless you are running an amp that has constant power (CP) like a JL slash or RF CP.

 

[VWBobby 10+ year member]

Ahh... That makes sense. Most of the amps I've owned/run were .05% or less, so the distortion would be minimal at 2 compared 4/8.....but if it was driven down much lower it would probably be clocer to 0.5, 1% or more?

 

[Haunz 10+ year member]

As far as I am concearned its the other way around. More power/headroom ~ Better SQ. Differences in THD and damping should no be audible. And even if THD did become audible, you can always turn down the gain...

I have heard of people driving 250-watt amps down to 0.25 Ohm to get around 1000-watts but they never mentioned how it sounded doing it.

Very few amps can handle .25ohm loads for daily listening...

 

[VWBobby 10+ year member]

It was for competition use on a Lanzar amp of all things.

I agree about the More Power = Headroom = SQ. I usually size my amps at least 1.5x larger RMS than my speakers can handle and rarely play at anything more than 50-60% volume to avoid distortion. Most amps aren't designed to be run more than about 80% continuous.

 

[gunz4me2 10+ year member]

Some amplifiers perform VI Limiting out the wazoo at lower impedance loads and that will adversely impact sound quality by introducing artifacts into the output side. With that said, if the amplifier was competently designed as a high current low impedance product, it shouldn't suffer from this issue.

If you want to take it to the other extreme, some class D amplifiers designed for low impedance use DO NOT like 8 or 16 ohm loads at all.

 

[LiveAudio911 10+ year member]

Actually there is no difference Sub wise or quality on different Ohm loads..

What makes the difference is the Amp.. the reason it does change is because the amp gets too hot running at the lower loads.. because not enough power.. gain set incorrectly.. overheating- heat in general or not enough power.. so on so forth..

The amp causes the signal to clip.. thus the Sub reproduces a clipped -flat signal..

So with all things equal with the correct amp.. with the correct power going to it.. you wont notice a difference..

 

[rsgladwin85 10+ year member]

Actually there is no difference Sub wise or quality on different Ohm loads..
What makes the difference is the Amp.. the reason it does change is because the amp gets too hot running at the lower loads.. because not enough power.. gain set incorrectly.. overheating- heat in general or not enough power.. so on so forth..

The amp causes the signal to clip.. thus the Sub reproduces a clipped -flat signal..

So with all things equal with the correct amp.. with the correct power going to it.. you wont notice a difference..

That statement is and isn't correct. The lower impedance does force the amp to run hotter, but that in itself isnt what causes a loss of "sound quality". As electronic components run hotter and hotter, they become less efficient, therefore not providing as solid of a signal.

Example: An amp running at 300w RMS at 4ohms runs at 86% efficiency, meaning it will supply the same signal quality and strength 86% of the time. Bumped down to a 2ohm @ 1200w RMS load you might get say a 70% efficiency rate. Same general principle for any power source. The more load on it, the hotter it gets, therefore the less efficient its signal.

 

[VWBobby 10+ year member]

Ok, so it sounds like the ohm load has more to do with how efficient the amp can run = cooler to an extent. If the amp is happy and running cool, it will produce good clean sound. It also sounds like you have to keep your ohm load in the same range as the amp was designed, be it 4 or 8 ohm otherwise the amp doesn't respond to the load properly (8 or 16 ohm on an amp designed for 4). Its probably similar to running a sub/speaker in a box that is too large or too small, the "cushioning" effect the load has must have an effect on the output stage of the amp (how the transistors are actually operating).

Thanks for the help! This is exactly the type of info I was looking for. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Buck 5,000+ posts]

Good thread //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[jda 10+ year member]

Most amps are built for low distortion at a set pipe size (4-8 ohm usually) - components are selected that meet this criterion. If you slow down, or speed up, that pipe, then distortion goes up because the components are not in their optimal range. It is a price point issue since likely few people would spend 10-20K on an amp that used components so high in quality that they would have very little distortion no matter the pipe size - I doubt that most of these components actually exist.

As mentioned above - heat has an effect also.

 

[Wingman0121 10+ year member]

I haven't heard a better-sounding subwoofer amp than the USA-2000X which puts out max power at 4 ohms mono.

Sometimes an amp can take advantage of impedance rise if it puts out good power at higher impedances than say, 1 ohm.

 

[smgreen20 10+ year member]

Example: An amp running at 300w RMS at 4ohms runs at 86% efficiency, meaning it will supply the same signal quality and strength 86% of the time. Bumped down to a 2ohm @ 1200w RMS load you might get say a 70% efficiency rate. Same general principle for any power source. The more load on it, the hotter it gets, therefore the less efficient its signal.

You lost me.
An amp 86% efficient doesn't mean it will supply the same signal quality and strength 86% of the time. It means that the current that the amp is drawing from the electrical system, 86% of it is in form of musical output power, and the remaining 14% is dispersed in heat.

Example: If an amp is drawing 100 amperes of current, 86% of it went to the amplification of the music in watts/power, and the remaining 14 amperes of current went in heat, sense no amp on the market can be 100% efficient.

Unless I miss-understood you????

 

[VWBobby 10+ year member]

Where it gets really interesting is when you have Bash amps with the energy reclaiming technology. As far as I can tell, the slight voltage produced by the cone moving back in can charge some capacitors to use as reserve power for the next excursion. This is how they exceed the 90-95% efficiency, by recycling the power fed back into the amp from the cone/coil movement. Of course music is an AC signal so the amp is usually pushing just as much as its pulling on the cone.