impedance confusion

when you looks ot buy an amp, you run into mainly either 2ohm or 4ohm. i have scatterd knowledge, so i know less ohms is less resistance. amps push about double the watts at 2ohms, so its cheaper t buy 2ohm system. but what would be the advantages of 4ohm system or 2ohm.

only thing i see is power.

[2ndGenTeg]

Ohms law states that a circuit with half the resistance will see twice the power. So from an economical standpoint, running your setup with a lower esistance will result in better efficiency for your money.

The drawbacks: More resistance means cleaner sound. Lower resistance means more strain on your components.

Personally, I'm running everything at 4 ohms- super clean sound, and my amplifiers are happy. It costs more- I pretty much had to buy an extra amp- but I think it's worth it.

You could also go down to one ohm mono on a capable amp. If you turned the gain down, it shouldn't be too tough on the amp. With the gain up, though, you could put too much strain on it and toast it.

Decisions, decisions...

u mean there is sound quality difference between 2 and 4ohm? i guess that Image Dynamics should have made their chameleon component set 4ohm instead of 2ohm

[2ndGenTeg]

Kinda. Remember that a lower impedence also means more power. More power (to an extent, as long as it's clean) means better sound. So there's a trade off. In general, all other things being equal, higher impedence means cleaner sound.

but 100 watts RMS at 2ohm and 100 watts at 4ohm will both sound the same. so the impedance shouldn't really matter unless you just want more power. right?

[2ndGenTeg]

Wrong. 4 ohm will be cleaner, assuming that you didn't turn up the gain to compensate for higher impedence, but rather using a stronger amp.

say you have a JL 300/2 running you speakers. it should make the same power as from 1.5-3ohm, since it has a regularted power supply. so no matter what the impedance the speaker is..it will make the same power with the same voltage and input voltage. can you explain how the higher ohm speaker will sound better than the lower ohm speaker when indeed they are getting the same power? i would love an explanation

[2ndGenTeg]

Remember that the speaker is little more than a cone whose movement is controlled by electric impulses, which creates sound. Impedence is a circuit's resistance to the flow of electrons. When the impedence is higher, there is more resistance to movement. Resistance to movement means that the flow of electrons will be more susceptible to changes in momentum, meaning tighter speaker response. It's difficult to explain.

Compare it to suspension on a car. A stiffer suspension will be equivalent to a higher impedence- more resistance to movement, quicker return to neutral, and much tighter response. Softer suspension would be equal to a low impedance- less resistant to a change of momentum, slower return to a neutral position, mushier response.

And FYI: 300 watts at 4 ohms on the JL amp will NOT be equivalent to 300 watts at 2 ohms. That automatically regulated power supply is something of an automatic gain control. When the impedence is turned up, so is the gain. The efficiency is turned down, as is the quality of the power. The JL amp has the capability to produce 600 watts at 2 ohms, but its design keeps things simple for those who don't want to go to the trouble of figuring out impedence loads and power output.

i doubt you'll notice a difference in sound quality though. 4ohm will have less distortion, but its inaudible, so it shouldn't really matter if you're going with 4 or 2ohm. you're not going to notice a sound quality difference, so why not just go with 2ohm when you're going to get more power anyways.

Originally posted by GSteg
i doubt you'll notice a difference in sound quality though. 4ohm will have less distortion, but its inaudible, so it shouldn't really matter if you're going with 4 or 2ohm. you're not going to notice a sound quality difference, so why not just go with 2ohm when you're going to get more power anyways.

it does depend on the amp though, most amps will have a much higher SNR driving 2 than 4 or 8. The voltage drop across 2 ohms is much smaller than higher impedance drivers, with less of a drop the same noise will come across as a larger signal(thus the higher SNR). Granted it's not audible, but to an RTA you can tell the difference.

most amps nowadays noise signal ratio are rated at least 90db, that anything above that is inaudible, even to RTA'a.. 90dB is such a high number already...100dB can't be heard differently.

also it depends on what frequency and how much watt the N/S ratio was rated at. with the same power at 2 and 4ohm, i don't think you can hear the difference. it's like racing in the quarter mile. 14.07 seconds and 14.02 seconds feels the same, and no one can really tell the difference which one is faster, but the 14.02 is technically faster.

Originally posted by 2ndGenTeg



And FYI: 300 watts at 4 ohms on the JL amp will NOT be equivalent to 300 watts at 2 ohms. That automatically regulated power supply is something of an automatic gain control. When the impedence is turned up, so is the gain. The efficiency is turned down, as is the quality of the power. The JL amp has the capability to produce 600 watts at 2 ohms, but its design keeps things simple for those who don't want to go to the trouble of figuring out impedence loads and power output.

300 watts at 4ohm WILL be the same as 300 watts at 2ohm. the gains are no way changed. if they are, then why would JL even pu on a gain knob? what the amp does is the amp detects the ohm and regulates the rail voltage so the amp would have enough power to put out that much of watts at 1.5-4.0 ohm

[Accord Man]

Originally posted by GSteg
300 watts at 4ohm WILL be the same as 300 watts at 2ohm. the gains are no way changed. if they are, then why would JL even pu on a gain knob? what the amp does is the amp detects the ohm and regulates the rail voltage so the amp would have enough power to put out that much of watts at 1.5-4.0 ohm

Nope, on any of those JL amps, 300w @ 4ohms and 300 @ 2ohms will not sound the same.
2ndGenTeg's idea is right on the money.. its something like an auto-gain.. Like you said, it detects the impedance and sets the voltage (fully variable switching)..

Originally posted by Accord Man
Nope, on any of those JL amps, 300w @ 4ohms and 300 @ 2ohms will not sound the same.

to human ear..you cannot tell if it's 2 or 4ohm. simple as that. the difference in distortion is so little that is inaudible.

Originally posted by Accord Man

2ndGenTeg's idea is right on the money.. its something like an auto-gain.. Like you said, it detects the impedance and sets the voltage (fully variable switching)..

i thought he meant the gain knob

[Accord Man]

Originally posted by GSteg
to human ear..you cannot tell if it's 2 or 4ohm. simple as that. the difference in distortion is so little that is inaudible.

probably not.. I didnt read thru the whole thread..

I thought this was about if there would be a difference or not..



notice that on a good SQ system (with good components, obviously..) theres a good chance you'll hear the difference.. You may not hear the noise, but the reproduction wont be as faitful.

There is a reason for SQ amp builders to make them with a thd of less than 0.003!!!

[Accord Man]

Originally posted by GSteg
i thought he meant the gain knob

LOL, proabably not..

Imagine having an amp with no outboard gain controle..
:o

Originally posted by Accord Man

There is a reason for SQ amp builders to make them with a thd of less than 0.003!!!

anything less than 1% of THD should be inaudible, especially with the car's acoustics.

http://www.eatel.net/~amptech/elecdisc/thd.htm

Originally posted by Accord Man
LOL, proabably not..

Imagine having an amp with no outboard gain controle..
:o

that means less work for me to do (adjusting the gain)

[Accord Man]

Originally posted by GSteg
anything less than 1% of THD should be inaudible, especially with the car's acoustics.

http://www.eatel.net/~amptech/elecdisc/thd.htm

the problem with THD, is that its not only about noise..
any distorsion (deformation--negative) of the sound is accounted for..


so in an SQ setup, you will hear it.. I know what I'm saying may sound crazy to you.. but its the truth.



Wow, everyone one in the Audio forum is trying to test me today..

If you beleive that THD and S/N ratio's are really important then you should thank the marketing departments at amplifier companies. Now 99.9% of amps have ratings in those two catagories that are to good to be audible.

Most people are hard pressed to hear a few percent distorition on a test tone and more distortion can be masked in music.
GsTeg has already brought up a resource that might help you better understand the issues at hand.

[Accord Man]

Originally posted by Tchad
If you beleive that THD and S/N ratio's are really important then you should thank the marketing departments at amplifier companies. Now 99.9% of amps have ratings in those two catagories that are to good to be audible.

Most people are hard pressed to hear a few percent distorition on a test tone and more distortion can be masked in music.
GsTeg has already brought up a resource that might help you better understand the issues at hand.

THD and S/N ratios arent everything, but they are elements that need to be considered in conjunction with the rest of the factors at play.

As you raise the volume the distorsion becomes more and more apparent (partly because the components are approaching
they're max capacity and partly because your hearing becomes more sensitive to what it hear.)

For most people, it wont matter.. But for those who are serious about SQ car audio.. it will..

The link GSteg supplied is great, I read thru that whole site a couple of years ago.. You should listen to the audio sample thats on there..

On my PC, I have a 4.1 THX approved speaker system.. And at low volumes I hear the noise..

I'm curious, have you guys ever been to an SQ type competitions?

I have put my reply inside the quote.

Originally posted by Accord Man
THD and S/N ratios arent everything, but they are elements that need to be considered in conjunction with the rest of the factors at play.

> Right. If you can tell the difference between a sound to noise ratio of 90 and 105 you are have better ears than me for certain. Same with THD.

As you raise the volume the distorsion becomes more and more apparent (partly because the components are approaching
they're max capacity and partly because your hearing becomes more sensitive to what it hear.)

> I doubt that this is due to the amp unless you have set your gains incorrectly. I suspect that your components are near to their limits, ie past thier linear thresholds.

For most people, it wont matter.. But for those who are serious about SQ car audio.. it will..

> Only to their eyes and brains, not their ears.

The link GSteg supplied is great, I read thru that whole site a couple of years ago.. You should listen to the audio sample thats on there..

> I have listened to similar samples. You have good ears if you hear 1% distortion. But even a $140 profile amp has a THD of .07%. Does it make the amp good? Not IMO, but its not the THD that makes it bad.

On my PC, I have a 4.1 THX approved speaker system.. And at low volumes I hear the noise..

> Are you saying that its even audible at low volumes?

I'm curious, have you guys ever been to an SQ type competitions?
> No, but typicly they are not the best source of facts about audio.

[Accord Man]

* my replies...

Originally posted by Tchad
THD and S/N ratios arent everything, but they are elements that need to be considered in conjunction with the rest of the factors at play.

> Right. If you can tell the difference between a sound to noise ratio of 90 and 105 you are have better ears than me for certain. Same with THD.
*I'm a classical pianist, I've playing for about 14 yrs.. Its possible that my ears are a little more capable of detecting minute details than the average man (I'm not saying your an average man/woman, but maybe you havent havent taken the time to listen carefully?!)

As you raise the volume the distorsion becomes more and more apparent (partly because the components are approaching
they're max capacity and partly because your hearing becomes more sensitive to what it hear.)

> I doubt that this is due to the amp unless you have set your gains incorrectly. I suspect that your components are near to their limits, ie past thier linear thresholds.
*When an amp is close to its max, there will be more noise.

For most people, it wont matter.. But for those who are serious about SQ car audio.. it will..

> Only to their eyes and brains, not their ears.
*umm, if thats what you think..

The link GSteg supplied is great, I read thru that whole site a couple of years ago.. You should listen to the audio sample thats on there..

> I have listened to similar samples. You have good ears if you hear 1% distortion. But even a $140 profile amp has a THD of .07%. Does it make the amp good? Not IMO, but its not the THD that makes it bad.
*.07 is pretty high.. and most companies that produce low end stuff, will over rate their gear..

On my PC, I have a 4.1 THX approved speaker system.. And at low volumes I hear the noise..

> Are you saying that its even audible at low volumes?
*Well, its a roughly 400w rms system.. And with the Sound Card controles set so that I can turn the knob all the way up.. before maxing out.
And at the volume set to around 20%, I can clearly hear the 1%..


I'm curious, have you guys ever been to an SQ type competitions?
> No, but typicly they are not the best source of facts about audio.
*Maybe not to learn, but to listen..

> I doubt that this is due to the amp unless you have set your gains incorrectly. I suspect that your components are near to their limits, ie past thier linear thresholds.
*When an amp is close to its max, there will be more noise.

Perhaps more noise, but its doubtful that it is due to the amp.

Well I tried not to bring this up, usually leads to more confusion, but here it is. A certain person Richard Clark has a challenge that is worth $10,000 to anyone that can tell the difference in the way two amps sound (at the same volume driven linearly, crossovers ect. bypassed). You can take that Profile amp and a brax amp, if you can really tell the diffence you can walk away with 10K, but many people have tried and failed, and everyone averages out to pure guessing. In one case someone actually planned a vacation with his wife using the winnings... however lets say the vacation never happened. Thousands of people have taken the test no one has gotten over 8 before incorrectly repsonding.
This is why I believe that s/n ratio's and THD ect are NOT important factors in choosing an amp (agian within reason). All amps are not created equal, but all amps will sound the same, when properly matched.
I am sure you'll have questions, so feel free to ask.

[Accord Man]

yes.. 1986 GN..
RC's challenge is great.. but it doesnt consider the sound intensity to purtiy relation. Also when I asked him how the test was done, he said its with a single test tone (sine wave). Now why do you think he wouldnt do it with acoustic recordings or even a variety of test tones??

At a moderately low intensity, a Helix will sound pretty close to a Jensen. But turn up the volume, to compensate for an average human's hearing deficiency, and realize the marvels of high fidelity.

If you think the amp doesnt have much to do with the dirtier sound at higher intensities, well you should probably keep thinking.


This thread was originally about 4ohm vs 2ohm configs..
4 ohms is cleaner. And in theory (in reality as well!!)..
You guessed it, 8ohms will be even cleaner!


But enough with the chatting.. Experimentation is the only sure way to go.


Have fun in the lab!

"yes.. 1986 GN..
RC's challenge is great.. but it doesnt consider the sound intensity to purtiy relation. Also when I asked him how the test was done, he said its with a single test tone (sine wave). Now why do you think he wouldnt do it with acoustic recordings or even a variety of test tones??

> You could take a really high power jesen and a 50w brax, and they would sound the same up to the limits of the brax! Dont beleive me then take 10K from RC. Also its not a test tone ! You are asked to compare the amps when they are playing music! Test tones are infact easier!


At a moderately low intensity, a Helix will sound pretty close to a Jensen. But turn up the volume, to compensate for an average human's hearing deficiency, and realize the marvels of high fidelity.
>As above.

If you think the amp doesnt have much to do with the dirtier sound at higher intensities, well you should probably keep thinking.
> Again it comes down to power.


This thread was originally about 4ohm vs 2ohm configs..
4 ohms is cleaner. And in theory (in reality as well!!)..
You guessed it, 8ohms will be even cleaner!

> Whats your reasoning on that one ? IMO it wont matter to our ears! Let me go to RC on this thread "holy cow!!!!!!!!talk about folks commenting on a subject they have no clue about!!!!!!!...............RC"


But enough with the chatting.. Experimentation is the only sure way to go."

[Accord Man]

Originally posted by Tchad
"yes.. 1986 GN..
RC's challenge is great.. but it doesnt consider the sound intensity to purtiy relation. Also when I asked him how the test was done, he said its with a single test tone (sine wave). Now why do you think he wouldnt do it with acoustic recordings or even a variety of test tones??

> You could take a really high power jesen and a 50w brax, and they would sound the same up to the limits of the brax! Dont beleive me then take 10K from RC. Also its not a test tone ! You are asked to compare the amps when they are playing music! Test tones are infact easier!


At a moderately low intensity, a Helix will sound pretty close to a Jensen. But turn up the volume, to compensate for an average human's hearing deficiency, and realize the marvels of high fidelity.
>As above.

If you think the amp doesnt have much to do with the dirtier sound at higher intensities, well you should probably keep thinking.
> Again it comes down to power.


This thread was originally about 4ohm vs 2ohm configs..
4 ohms is cleaner. And in theory (in reality as well!!)..
You guessed it, 8ohms will be even cleaner!

> Whats your reasoning on that one ? IMO it wont matter to our ears! Let me go to RC on this thread "holy cow!!!!!!!!talk about folks commenting on a subject they have no clue about!!!!!!!...............RC"

*when I asked, it was with test tones.. it may not be like that anymore.. When I asked, the conditions were 1 single test tone.
And high fidelity acousitc recordings show imperfections a little more.. Yikes, I quickly read thru the rules and, many things have changed..


*If an amp is rated at 2ohms, then it will be pretty much impossible to tell the difference.. For amps that arent rated at 2ohms, you'll probably hear it. We know that in the car audio world, 4ohms, is the center of reference. When you cut the impedance in half, you're doubling the distorsion (on a McInt that has a .0045 * 2 = .009.. still inaudible.. And the contrary, if you double the impedance you'll have half the distorsion)

*Like I said, its nice to a have learned a whole bunch of things on the net/books, but in the end its real life testing that slices. But education is still very necessary..

*Do you have good speakers hooked up to your cpu?? If so, please tell me you were able to hear the 2khz -- 1% that was injected?!
From where I'm sitting, that sounded pretty obvious..



whoa.. its way past my bedtime..