Will someone explain to me what ohms are?

i'm sure a search on wiki, google, or here could enlighten you. more ohms means more volts are needed for the headphones to reach a certain decibal level. in general headphones with high ohms (senn, beyer) and harder to drive than headphones with lowers ohms (grado, ath).

What I don't understand is that an electrical engineer once told me that with some amps, the higher the ohms the easier they are to drive???

ohms are an expression of impedance. They're named after a guy named Ohm. Ohm's Law is a very basic building block of electrical theory.

The nominal impedance of a headphone - expressed in ohms, and generally referred to at a specific frequency - is only half the story, if that.

The big question is efficiency. A very inefficient 8 ohm voice coil system won't get as loud as a very efficient 600 ohm voice coil system.

Generally, yeah, your average 600 ohm cans need a higher volume level to sound as loud as your average 32 ohm cans. But there are notable exceptions.

120ohm isodynamic drivers frequently need a higher volume level than 600 ohm voice coil dynamic drivers. Hybrid cans like the K340 have a nominal impedance around 400 ohms but need more than most 600 ohm cans for the same loudness level -- I'm not even talking about eargasm level here.

Usually, people will tell you that these cans are "hard to drive".

The K1000 is another good example, its 120 ohms, but its massively inefficient, so It needs a lot of power. Same for the Ergo AMT, its a very low 4 ohms, but still needs a lot of power.

well.... v = iR
and P = Vi >> i^2 *R
according to this equation, more power is needed with higher ohm (unit for resistance)
Unless I made a huge mistake on this...

But to be true, by looking at ohms of a phone can not give you exactly how easy it is to drive it, I think there are some other factors that are involved in how easy it is drive a headphone

and OP, seriously, please do more research before you post a question. I am pretty sure you will get your answer on web site.

the k1000 has a sensitivity of 74dB. i think that is the lowest i have seen for a headphone (um. . . earphone or ear speakers). very inefficient.

Oh geeze. One of these days we need a sticky thread on ohm's law, efficiency, sensitivity, and what that means to you.

Lets start with the basic presumption of Ohm's Law: You Get Nothing For Free.

When you create an electrical potential across a load, the impedance of that load - how much the load impedes the flow of electricity - defines how much electricity is drawn from the source.

Thus, a low-impedance load draws more current from the amplifier than a high-impedance load. This is unavoidable, force-of-nature, 'canna break the laws of physics cap'n' stuff.

If the source doesn't have a lot of current sourcing capability, this can have a number of ill effects.

Large trasients - like a bass note - can fall flat before they reach their peak if the source runs out of current before it can finish servicing the pulse.

Increased current draw on some kinds of amplifiers can slow down their slew rate, causing the amplifier to slur the sound slightly.

The upside is that you don't need many volts to make the air move around the driver.

A high impedance load presents a very easy load to the source, but because less current is being drawn across it, if we presume that all other properties of the driver are the same, it requires more volts to move the air around the driver.

Your home stereo system has volts to spare. If anything the headphone jack was an exercise in limiting the volts on the output. It's not uncommon for a home stereo type system to be able to swing about 80 volts.

Your computer's sound card can probably only swing about 5 volts. Often as little as three.

Portable devices can generally swing three or less.

So, if you plug 600 ohm DT-990's into your iPod, it's not going to make much noise. If you were going to get an amp, you'd want one that can swing plenty of volts (say, two 9v batteries) but it doesn't need much current - a simple cmoy will do just fine.

If you plug your 32-ohm grados into your ipod, they'll get plenty loud, but they may sound slurred and distorted at high volume due to the difficult load they present to the little headphone amp.

Curiously enough, the ipod shuffle will handle it better than a full size ipod, since it appears to have a switch-mode headphone amp rather than a linear amp. If you were to look at the output on an oscilliscope, the full-size ipod will start out to service a large transient nice and clear, and then just give up. The shuffle makes it all the way across, but there's little squigglies on the top of the wave 'cause the output transistors are switching on and off at frequencies much higher than you can hear.

Also, correct me if I'm wrong here, when you need a high voltage to drive the cans, just because you got it to the same volume level, doesn't mean it's driven correctly either.

Example? Run some cans out of your ipod, then run them out of home home reciever. Your sound will sound fuller (amplification coloring aside), because you have major voltage and power running to the headphone jack, versus the power coming from a AAA or 9V battery.

My 250 ohm Beyers opened up like a flower when I ran them through a home system...they sounded fine under a GV5, but nothing can compare to a home rigs power and ability to drive headphones with authority...

Eh, yes and no.

Columbs are columbs, any way you slice 'em.

A different source may have cleaner power - and you are essentially listening to the power supply anyway.

It may introduce less distortion, or just more pleasing distortion. 2nd order harmonics make people swoon.

'synergy' between amps and output devices is a subject i decline to discuss, but it does exist, like chocolate and peanut butter - sometimes two things go better together than apart.

Why is it that in general headphones that are lower in Ohms are easier to drive, whereas, speakers with higher Ohms are eaier to drive?

i've been curious about this topic as well and after reading and searching the forums as well as google, i'm still unsure what effect different impedance has on the sound produced by a headphone driver. take the DT990s. other than different power requirements, how would they be perceptibly different if they were 60ohms instead of 600ohms? why have different impedances? are there implicit advantages and disadvantages aside from how easy they are to drive?

I'm sorry if this was already said in the thread cuz I only read about half of it, but do ohms have a direct correlation to sq or spl? I think its the lower ohms = higher spl (except for certain instances) is that right?