all about ohms

[kastonie]

I basically understand the math behind hooking up subs to amp, and how much wattage the subs will get @ the number of ohms, but what i dont understand is the relationship of ohms to sound quality. If there is any relationship at all...if anyone knows about this, please inform me.....does the sound quality diminish at lower ohms....because basically i dont care about how loud my subs can be heard outside my car, i just want clean, tight bass that i can enjoy inside my car....

[sntnsupermen131]

the lower the ohms, the harder your amp has to work
thus, its harder for the amp to control the speaker(equaling worse sound quality)
but to tell you the truth, if you can hear the difference, id be surprised
the biggest thing about sound quality is the THD(distortion)
lower the number, the better
-Cody

[Airplay355]

the ohm of a speaker does not reflect its sound quality. ohms are a measure of resistance. you will be stressing your amp if it is incapable of powering the speaker. ohms and clean tight bass do not effect eachother. if you have a 4 ohm driver and an amp capable of powering 4 ohm loads then you are fine. if you have a 4 ohm driver and your amp is only capable of powering down to 8 or 6 ohm loads then you will be overworking the amp and most likely sending it into protect mode or frying it because of the excess heat.

clean tight bass will be a result of a good amp, a good driver, and a good source. not a driver with a lower or higher amount of ohms.

[Jstas]

Originally posted by Airplay355
ohms and clean tight bass do not effect eachother.

That is incorrect. The lower the impedance of the circuit, the harder it is for the amplifier's power supply to control power output that controls the movement of the speaker. Even if the amp is rated at 1 ohm, it will still play cleaner at 2 ohms than it would at 1 ohm. The same goes for 4 and 8 ohm loads respectivly. The 8 ohm load may not make the most power but it will be the most accurate impedance load as far as the amp is concerned.

To demonstrate this, take a pencil and hold it by the writing end between your index finger and your thumb. Hold the palm of your hand over the eraser end. Now, wiggling your thumb and index finger, bounce the eraser between your hand and a table or desktop. Pretty easy to control the movement of the pencil, correct? Now, move your hand farther away from the table top. Gets harder, don't it? Now take you hand away and move the pencil away from the desktop, in mid-air. Now try wiggling the pencil with no impedance to it's mid-air progress. Gets really freaking tough without your hand and the table top to influence directional change, doesn't it?

The amplifier does the same thing with the sine waves that the output signal is traveling in. The power supply has to switch between a peak and valley at whatever cycle the frequency is playing at. The wider the amplification band, the wider the swing of the switching is. Reducing impedance widens that band and makes it more difficult for the power supply to effectivly switch along the signal curve.

I realize the term "switch" may not be an accurate term to describe the functioning of the power supply but, without going into detail, it's simple and gets the point across.

So yes, impedance can directly affect sound quality, even if the amplifier is rated at that impedance level.

[Airplay355]

then maybe i misunderstood, i thought the issue was can you judge the quality of a speaker by its ohm rating and thats y i said that. i completely agree with you, maybe i just worded things wrong. the point im trying to get across is that you cant judge the sound of the speaker by its ohm rating.

[Jstas]

No, you're right, you can't. There is so much more to a speaker than it's ohm rating. The only purpose an ohm rating serves in choosing equipment is by telling you what amplifier you should be buying to achieve your desired result.

[PoweredByDodge]

here's a question that expounds on the topic... and gives you two something more tangible to work with. (since i think the question has been answered for the original poster)...

ok... now... if I have two amplifiers made by the same company, same class (lets say AB), with basically the same type of design, same type of components, and one is rated at 500 x 1 bridged at 4 ohms... the other is rated at 500 x 1 bridged at 1 ohm.

then i have two subs to be mated to these amps... again, basically the same sub, same company, same parts, both single voice coil, everything is identical except the voice coil material / length / or whatever other voice coil characteristic they choose to change for the sake of differing the impedance... one is a 4 ohm sub, the other is a 1 ohm.

so -- which would sound better... would they be identical? ... would there be ANY difference, however miniscule - even if it is unnoticeable by the human ear??

I've got a few ideas floating in my skull, but nothing really concrete enough to answer my own topic... responses from the peanut gallery??

[Airplay355]

i would answer but u seem to conceited to be worth the time, pc

and by the way, if its unnoticeable to the human ear the who cares, unless u buy subs for your dog. its what you hear that matters.

[PoweredByDodge]

i'm too conceited? -- ain't that just the truth.

and as far as who cares -- i do, and anyone else who's just interested in audio for the sake of audio is/might be.

there has been talk from some that the 1 ohm setup i described above would not be as sonically/electrically 'perfect' as the 4 ohm setup. reasons differ...

i was just looking for some good talk on the topic, as i really have not gotten as much info on the topic as i'd like to have.

anyway - thanks for nothing.

[TrappedUnder Ice]

Actually...both amps wont normally have similar specs. There are some..but not many...that run similar at 4ohm vs. 1ohm...even if the amp is designed that way

A one ohm stable amp normaly will have lower damping factor and higher THD...wich could effect sq! Take into effect that the 1ohm amp will put a tighter current draw from the electrical system wich could even effect overal SQ

just some thoughts...

PBD conceited??? thats a good one!:p

[Airplay355]

sorry for the hostility, the peanut gallery remark threw me off. i thought u were asking me to test my knowledge or something only then to disagree. i'm sorry for jumping to conclusions

[sntnsupermen131]

but lets say that the 1 ohm amp is really good vs. a crappier 4 ohm amp where damping, thd, and so on were the same
in that case, i would think that they would perform the same...
b/c really, damping is how good an amp can control the sub, so if it stays the same, then should it not sound the same?
and thd is the amount of distortion, if they were the same for both amps, audible or not, they would sound the same
but otherwise, like thomas said, many factors change for the worse when ohms drop
but is there an audible difference b/t a 8 ohm and 2 ohm sub?????
-Cody

[Airplay355]

if all your talking about are ohms, and we arent considering any other things the there would be no audible difference. the 2 ohm sub would be harder for the amp to drive though. so if you were testing them both on the same amp, the 8ohm sub would stress the amp less and would most likely sound better on the same amp then the 2 ohm sub. even if the amp was stable down to 2 ohms, there would still be less stress on the amp.

[bikezappa]

There is NO relationship between Ohms and the quality of the sound.

Start with Ohms Law.

E=IR, which is Voltage =Current times Resistance

Voltage is measured with Volts
Current is measured by Amperes
Resistance is measured by Ohms

Also,

W=IE, which is Wattage=Current times Voltage

Wattage is measured by Watts

and with some algerbra substitutions

W=I times I times R=IIR

or

W=E times E divide by R=EE/R

You can measure the watts that are powering any speaker if you know the resistance or impedance of the speaker (2 to 10 ohms)and can measure the volts from the amplifier to the speaker with a voltmeter.

Quality is not in any of the equyations.

What is quality?

Tougher question to answer.

My definition: Quality is a good blend of the romantic and the classical. Or a blend of form amd function.

All off the above replies are voodoo science in my opinion.

Just my $0.02

[TrappedUnder Ice]

thats right and wrong. thier is no direct relationship between ohms and sq...however the design of the amp and what ohms it runs at...does effect bottom of the line sq. ... so more to say indirectly ohms effects sq.

cody...yes...your point is well taken. A 1ohm us amp would be much better then say a 4ohm MTX amp

[PoweredByDodge]

so basically...

if (even tho not very likely, but if) two amps were identical at 1 ohm and 4 ohms, one being X wattage at 1 ohm bridged, the other X wattage at 4 ohms bridged, and hooked to two identical 1 and 4 ohm subs... they would perform for all apparent reasons the same?

... makes sense i guess.

the only way it would really matter would be if you had an amp that was supposed to be driven at 4 ohms, then drove it at 1 ohm, and thus dropped its otherwise "nice" specs down to shittyness. (at least that's what i've gathered from what y ou guys said).


well... that's somewhat refreshing... buying a 1 ohm amp and sub isn't any bad thing as long as it has performance ratings (assuming they're accurate ratings) are good.

common thought (or at least what some people have been saying to me on and off) is that a 1 ohm amp and 1 ohm sub, regardless of quality will not be as good sonically or electrically as a 4 ohm amp/ sub combo.

half of me 'believed' that line... half of me didn't...

thanks guys :)

[sntnsupermen131]

i doubt it would be audible though...
if the measured THD of one amp AT 2 ohms was less than lets say .05
and the damping factor was still good...
then i doubt you would hear a difference b/t the amp above(the one i made up...) and a 4 ohm amp with thd thats less than .05 and the same damping factor
so while it might be a difference, it would not be an audible difference...at least to a human
this is interesting though...never really thought about it
-Cody

[sntnsupermen131]

bikezappa...according to ohm's law youre right...but ohm's law is not the only thing that were talking about
you have to take into account the designs of amps, speakers, etc
speaking of which
would a 2ohm speaker have to work harder than an 8 ohm speaker?
i really doubt it, but would it?
-Cody

[Airplay355]

the speaker wouldnt work harder but the amp would

[sntnsupermen131]

thats what i was thinking
but heres another question:
If a SVC sub is lighter than a DVC sub, then a SVC would be easier control...
hence, would a SVC sound better than a DVC?
-Cody

[MTXMAN]

back to what vinnie was asking.... i'm going with two brands i'm familiar with here...
Diamond Audio TDX 10" subs come in both dual 2ohm and dual 4ohm vc configurations...
US Amps has both the 1000x and 1000 which are identical in specs with the exception that one runs at 4 ohms and one runs at 2...

If you had a dual 4 ohm vc TDX bridged to run at 2 ohms off or the US Amps US1000
and...
a dual 2 ohm vc TDX bridged to run at 4 ohms of of the US Amps 1000x

they should be sonically identicle the specs would be the same for both the amps and subs, as long as you tested the rms watts of each amp to make sure that they were close to eachother... so debate solved, it depends on specs alone and what type of configuration you desire to run, however in some setups you would be better off with a higher ohm load...

[Stoney3678]

Ok guys, here it is.
Give me a break.... so you're telling me an 8ohm sub with an 8ohm stable amp would sound the same as a 1 ohm sub with a 1 ohm stable amp. That's like saying a V6 mustang runs the same quater as a SVT cobra........
sq aside... the 1 ohm sound will be the rediculous sounding thing you hear coming from chevrolet caprices, etc with their ported boxes and a 4000watt pyle amp pushing a 15............
an 8 ohm sub would be something you'd not hear outside the car..... you want to talk about resistance...and ohms law. Ok we have 1 ohm.... therefore nothing is against it, it's like the f'n tank of speakers, because it's just blasting away not paying attn to anything. the 8ohm speaker is thinking to iself "damnit, I have all this stuff on top of me, i'm gonna go ahead and take a step back... and make some really audible goodness" and it does.

IF there isn't any diff, then why the hell produce a 1 ohm speaker...or 8 ohm speaker, screw the entire equation and just produce a SPEAKER.... give me a break.
Don't forget the fact that every setup is different, let's say you put a 8 ohm sub in a spacecraft hanger... well it might sound good, you put the same size 1ohm sub and it may sound like my asshole......

The main thing i wish, is that I could somehow get my car audio system to sound as good and balanced as my home audio system. But I have my doubts....
Anyway....don't forget that my opinion is completely different than yours :P
Regardless, I would love to have an 8ohm setup all around... but hence I havn't found, nor would I have the funds for an 8ohm setup, so i have to settle for a BS 4ohm setup...

And, has anyone noticed their system sounds different everyday? Maybe it's because of the atmosphere... the pressure changes... remember specs are made in lab conditions, you take your system to denver and it may sound fine... then drive to florida and it may sound completely different, hahaha, ever think about that?

[PoweredByDodge]

stoney - you're wrong...

learn more about car audio, then come back, we'll chat. until then, have some coffee.

to the rest of you guys... bass on.

[Stoney3678]

hrmm... you caught me off guard there man... I'm in college right now, sorry if I sound like too much of a kid.... but I'm learning atm and there's just something a little empty about your argument. umm...

[sntnsupermen131]

dude...umm
where to begin...
lets say you have 3 4ohm subs and a 1 ohm stable amp
what do you do?
you hook them up to a 1.33 ohm load
does this sound like absolute crap?
umm...NO
and then u go and say well you cant even hear an 8ohm sub outside your car
i dunno about you guys, but i failed to see where we were talking about anything besides SQ
i could go on...but its 1:50 in the morning and i have to wake up at 6:30...and i still need to check my mail...among other shit
-Cody

[TrappedUnder Ice]

Personally...If you had 2 us amps..and run runs at 1ohm and other at 4ohms...both put out the same power...I'd opt for the 4ohm for sq. It may be audible...it may be not...but I'd know in the back of my mind...Ive done everything to try insure the best "possible" sounding system to "My" ears

Sq is the desire for true reproduction at respectable levels - everyones level is diff!.

with that said I Usually will not opt for anything less then 4ohms in my vehicle...now my wifes tahoe..thats diff...I'll be running the autotek at 2ohms mono :rolleyes:

[kastonie]

SOMEBODY GET THE SCIENTIST IN HERE

[sntnsupermen131]

i dunno, i think if the specs are good enough at 2 ohms, then i see no problem with running a 2 ohm setup
-Cody

[PoweredByDodge]

scientist?

Trappedunderice = AMD engineer
Jstas = Lockheed Martin electro-dude

we've got scientists...

and i'm God by day, EE student by night...

far as the 8 ohm car setup... its not prudent... you've got to ramp up voltage so much that its just not doable.

In a house, you've got lots of voltage, but not much current (110 Vrms AC @ about 14-15 amps before u blow the breaker... cut that down via a transformer and you may get a useable 20 volts (or better if you've got an amp with a great transformer) DC and the equivelant of about 40 or 50 amps at MOST)... so high voltage, low current setups are what is great -- 8 ohms.

In a car, you've got assloads of current and jack squat voltage (14 volts, but the sky is the limit for current, however since most people dont like buying alternators, lets say 100 -150 amps... that can be racked up higher with the addition of batteries / alternator replacement)... and hence, low V, high current setups are "gooder"...

what's that mean? lower impedances for speakers. --- 4 ohm, or 2 ohm speakers are the way to go for loud boomin sound quality.

The difference between 4 and 8 is not even worth getting into -- its not going to be anything to worry about.

1 and 4 however is more of a gray area...

my final thought on the topic was along the lines that as much as you can have two amps that are identical - one driving at 1 ohm, one at 4 ohms, with the same damping factors and slew rates at their rated outputs, a 1 ohm sub would not provide the "guardrail" that a 4 ohm would... just wonder if when you get down to those low frequencies with low impedances if it really makes a difference.

were we talking about a 1 ohm tweeter versus a 4 ohm tweeter, i wouldn't even question the thought that, if built properly, the two could sound / perform identically.

[Stoney3678]

cool man, thanks for actually putting a real post up. My post was rather lacking seriousness if you couldn't tell.... I was just wondering when someone was going to back it up with some real stuff. Because ohms are great to talk about, but seriously there are so many other relating factors when you're speaking about car audio... or any audio for that matter. I'm glad you actually brought up the idea of volt/current because that is an annoying issue, if there wasn't any difference between house/car energy it would be great, pricing of car audio amps would most likely go down, due to how simply they could be made.
Good thing about car audio is it's only getting better. Compared to home audio it's still a baby, and it's developing well.

I have a quick opinion question, I don't have a lot of experience with different types of sub boxes. I'm sure there's a forum on here about it, but my issue is this.
If i went from a sealed box to a ported box (amp power not chaning) would the result be a much more filling,sort of 'floppy' bass as opossed to tight responsive bass? And what does a band pass box do anyway?

[Airplay355]

poted boxes result in flatter respones and then a quick roll off ( speaking in terms of a graph) a seal box gives more an arc or parabolic graph. ported boxes also allow for more spl with less work from the driver, that would in turn result in less work on ur amp. some people like the way sealed subs sound better though. its about ur preference i guess.

[disneyjoe7]

PoweredByDodge


Must if not all amps you guys & gals are playing with don't use the 14 volts in their amp output sections. Amps use a power supply that takes the 14 volts and brings that up to say + & - 25v or more. You could never get more then say 10watts RMS (1000w PMP) using 14 volts directly.




Quote

>>In a car, you've got assloads of current and jack squat voltage (14 volts, but the sky is the limit for current, however since most people dont like buying alternators, lets say 100 -150 amps... that can be racked up higher with the addition of batteries / alternator replacement)... and hence, low V, high current setups are "gooder"...<<

[sntnsupermen131]

a ported box--
contrary to what airplay is saying, if you want to talk in terms of graphs, a sealed box is going to be more of a straight line, while a ported box is going to arc in certain frequencies, being louder in those frequencies
a bandpass is going to arc even more in certain frequencies, but cuts a lot of frequencies out all together
some subs are designed for use in ported only, some subs are designed for use in sealed, some can be used in both
a very well designed ported box can give you a 3db gain across almost all frequencies that a sub is played at
a poor designed box will still be louder, but only at certain frequencies, and can be very punchy
but ported boxes are much bigger than sealed boxes...generally
im not talking about like 2 completely difft. subs, cuz im sure i can find a ported box thats smaller for one sub than a sealed box for a completely difft. other sub
but if you look at a sub that can be ported and sealed, the amount of space the sealed needs is less than the ported
which is why i like sealed
its a lot easier to deal with, if i had a trunk, id probably get a ported, cuz i can make a box that doesnt need to fit any type of dimensions, but i have a truck and the box fits under my back seat, so sealed is the way to go for my application
-Cody

[PoweredByDodge]

Originally posted by disneyjoe7
Must if not all amps you guys & gals are playing with don't use the 14 volts in their amp output sections. Amps use a power supply that takes the 14 volts and brings that up to say + & - 25v or more. You could never get more then say 10watts RMS (1000w PMP) using 14 volts directly.

the amp output section has a voltage dependant upon the output power...

say you've got a 250 x 2 stereo amp @ 4 ohms (1000 x 1 bridged @ 4) --- assuming a plain jane sine wave input of 1k Hz, you're looking at 250 watts / roughly 4 ohms = 62 = V^2 ... so that's just under 8 volts.

yup.. 8 volts rms roughly.

1000 x 1 at 4 ohms.... 1k / 4 = 250 = V squared.... take the root and you're down to 16 volts. 16 is a bit more than 8. and so we see the great variance, even within an individual amplifier. assuming the speaker stays the same, as you increase volume, you're bumping up voltage, not current. (different frequencies cause the speaker to have a reactance which will change its general impdeance... so a 4 ohm speaker might "act" like 2 ohms at 10 hertz... or "act" like 6 ohms at 20,000 hertz... but in gereral its AROUND 4 ohms at most frequencies.

as far as the power supply goes... that is what i was actually talking about.

in a car, you've got a conditioned 12 - 14 volt power supply from the battery to the amp. the power supply will ramp that up to whatever the output stage needs. the output transistors don't actually supply the JUICE for the speakers.... the power supply does. your output stage is (in its most disgustingly basic sense) a valve through which the energy of hte power supply is channeled, shaped into an AC wave (from its raw DC form) and then spit out the speaker terminals.

in the home environment, you can feesibly have a 25 +++ volt power supply... i haven't ripped apart a home amp in a while... and i'm nowhere near as enlightened with them as car amps, but, i would surmise you can, if you really wnated to, squeak 30 to almost flirting with 40 volts DC power supply out of a 110 volt AC wall outlet with sufficient current to drive an 8 ohm speaker through the output stage.

[PoweredByDodge]

oh and as far as the ported box thing -- cody is dead on right -- a sealed box will 99.999999% of the time give you the flattest curve possible with any subwoofer... a great sub should have a dead flat line between say 30 and 90 hertz... trailing off by a bit from there and then a hard line down after.

[Airplay355]

how can you have a flat curve?

http://www.stryke.com/pics/AV12MKIIvented.gif sorry this is the only website i could think of with graphs. its not as smooth and parabolic as the sealed one. it drops off more rapidly but has higher spl at lower frequencies.


http://www.stryke.com/pics/AV12MKIIsealed.gif this one is sealed and has a more parabolic graph, with a longer and smoother roll off.

you can flatten the response of a ported sub with an equalizer if it really pisses u off that much

[PoweredByDodge]

well now i know where you're coming from -- take a look at a more SQ oriented sub....

http://www.imagedynamicsusa.com/website/tech/data_sheet_idq10d2v2.html

between 10 and 90 hertz, for the sealed enclosure - there is only a 4 db "rise" in the middle...

for the subs u were showing us, there's a 39 db difference!!!

yikes!!!!! that's the furthest thing from "flat" i've ever seen.

a good sub will stay around the same sensitivity level throughout its playable frequency range (say 10 to 100 hertz for a sub)

in the case of the IDQ i showed you above -- it is at about 90 when its at 10 hertz.... peaks up at 94 around 50-ish hertz... and hten drops to like 89 or 90 around 100 hertz. that's a whole lot better than the sub you posted with 76 db's at 10 hertz and peaking at 115 db's around 70-ish hertz, and then falling off a bit at 100.

flatter is better.

polk is pretty flat in general... the momo's probably aren't as flat as the IDQ's, but the momo is a goddamn fine sub with a pretty flat frequency response -- that is why is plays so many different kinds of music SO WELL. you can throw it in a sealed box, set your gain, and forget about it-- u dont have to play with it and reset it to a different gain / bass boost for every different type of music BECAUSE it is so flat.

[TrappedUnder Ice]

The wheels on the bus go round and round

[Airplay355]

powered by dodge-

i agree with everything u said, a sub should have a flat graph, i was just using those subs because i couldnt think of another site with graphs on it.