Headphones...which is easier to drive, 40 ohms or 600 ohms?

[vinyl addict]

I've read mixed comments regarding which is easier to drive. Some say that a headphone with 35 ohms is harder to drive than one at 600 ohms. I was auditioning some cans at a store and a Grado SR1 was "louder" than a Sennheiser HD650 (using the same amp and source).....I'm confused

 

[Mercuttio]

Generally speaking, a can with lower impedance is easier to drive.

*moron typo editing*
Grados are easier to drive than Sennheisers
*moron typo editing*

There are plenty of exceptions though. The K701 (though having a lower impedance) is sometimes harder to drive than the HD650, when I tried them next to each other. K701 at the same volume level on the knob wasn't pumping out nearly as much sound.

 

[vinyl addict]

Quote:

Originally Posted by Mercuttio Generally speaking, a can with lower impedance is easier to drive. IE Sennheisers are easier to drive than Grados.

Okay...the Grado SR1 has a rated impedance of 32 ohms, the Sennheiser HD650 is 300 ohms. As stated, the Grado was louder with the volume at the same level so how can your statement be true? Is this one of those exceptions as well?

 

[Mercuttio]

Quote:

Originally Posted by vinyl addict Okay...the Grado SR1 has a rated impedance of 32 ohms, the Sennheiser HD650 is 300 ohms. As stated, the Grado was louder with the volume at the same level so how can your statement be true? Is this one of those exceptions as well?

I'm sorry, I'm talking about the number "35" being lower than "300." That's the way this usually works here. The higher that number, the more power you will need to drive the headphone to full potential or higher volume. Now, a quick note: just because something can drive the HD650 to be loud doesn't mean it is properly driving it. You need to listen for dynamics and control within the music. A properly driven headphone will display these things.

You mean an RS1, right? There isn't an SR1 Grado.

 

[skudmunky]

Quote:

Originally Posted by Mercuttio Generally speaking, a can with lower impedance is easier to drive. IE Sennheisers are easier to drive than Grados. .

did you really mean that?

 

[vinyl addict]

Quote:

Originally Posted by Mercuttio I'm sorry, I'm talking about the number "35" being lower than "300." That's the way this usually works here. The higher that number, the more power you will need to drive the headphone to full potential or higher volume. Now, a quick note: just because something can drive the HD650 to be loud doesn't mean it is properly driving it. You need to listen for dynamics and control within the music. A properly driven headphone will display these things. You mean an RS1, right? There isn't an SR1 Grado.

oops...I meant RS1. Thanks for your comments, I hope I'm not the only person here that learned something today...good to know

 

[Mercuttio]

Quote:

Originally Posted by skudmunky did you really mean that?

Oh, hahaha! No wonder! Nice big fat typo. I'll edit that for clarity. Sorry for the confusion!

 

[slinger1182]

Umm I had the same question when I was new around here.

knowing that R (impedance/resistance) = V (voltage) / I (current), it would seem that higher the impedance, higher would the voltage to drive it. So higher impedance phones would be more difficult to drive. Hence RS-1 would sound louder than HD650 at the same volume setting. However, as the impedance drops lower and lower, the current required would start to get higher to drive them and hence making those headphones difficult to drive again so as to require a high current amp to drive them.

 

[gdg]

Current is the issue when discussing the ability to drive a speaker or headphone (not Voltage). Another way to look at it is an issue of "power". Since P=IR^2 one can see that the higher the resistance/impedance the lower the amount of current required ot produce a given amount of power. The formula should be interpretted as I=V/R and there is an "inverse" relationship between current and impedance/resistance. The best amps in the world are able to supply enormous amounts of current into a given impedance. The lower the impedance the higher the amount of current required. Low impedance speakers are a challenge for cheap amps that can't supply the currrent and are generally harder to drive. Likewise with headphones. You kids need to learn some physics/engineering basics.

 

[sidewinder]

So that's why my Senn 435 doesn't sound great with my portable amp (output current in neutral: about 35mA; 2 9V batteries).

18V/32Ohm = 0,56A

In case of my Koss KSC75, it does get more juice and thus sounds better.

18V/60Ohm = 0,3A

But still, it needs 300mA to sound 'optimal', is that correct?

 

[nikongod]

Quote:

Originally Posted by sidewinder So that's why my Senn 435 doesn't sound great with my portable amp (output current in neutral: about 35mA; 2 9V batteries). 18V/32Ohm = 0,56A In case of my Koss KSC75, it does get more juice and thus sounds better. 18V/60Ohm = 0,3A But still, it needs 300mA to sound 'optimal', is that correct?

what do you mean "output current?" at idle, there should be NO output current, or voltage. the amp may use current in its-self (class a bias and whatnot) but it should not put out current.

the koss's have a higher impedance. you may like the results of adding a small resistor to the senn's. as another thought the sound signature of thoise headphones may just not be for you.

 

[trains are bad]

Quote:

Originally Posted by gdg Current is the issue when discussing the ability to drive a speaker or headphone (not Voltage). Another way to look at it is an issue of "power". Since P=IR^2 one can see that the higher the resistance/impedance the lower the amount of current required ot produce a given amount of power. The formula should be interpretted as I=V/R and there is an "inverse" relationship between current and impedance/resistance. The best amps in the world are able to supply enormous amounts of current into a given impedance. The lower the impedance the higher the amount of current required. Low impedance speakers are a challenge for cheap amps that can't supply the currrent and are generally harder to drive. Likewise with headphones. You kids need to learn some physics/engineering basics.

This is somewhat correct, however voltage IS an issue. In the real world you are often working with a finite rail voltage (say 9v in the case of a portable amp). If I'm not mistaken this is why car speakers are traditionally 4ohm instead of the common 8 ohm of house speakers.

Impedence matching is really what you are concerned about, it's not as simple as saying that one or the other extreme is easier to drive.

 

[MatsudaMan]

Quote:

Originally posted by gdg Current is the issue when discussing the ability to drive a speaker or headphone (not Voltage). Another way to look at it is an issue of "power". Since P=IR^2 one can see that the higher the resistance/impedance the lower the amount of current required ot produce a given amount of power. The formula should be interpretted as I=V/R and there is an "inverse" relationship between current and impedance/resistance. The best amps in the world are able to supply enormous amounts of current into a given impedance. The lower the impedance the higher the amount of current required. Low impedance speakers are a challenge for cheap amps that can't supply the currrent and are generally harder to drive. Likewise with headphones. You kids need to learn some physics/engineering basics.

Dude,
Wow, it's pretty obvious that you have some "basic" physics/engineering knowledge. I'm impressed. Doesn't mean you have to rub it in and be pretentious about it (ie. your last sentence). I could just imagine you pushing up your glasses while you were writting it.

 

[Audiofiler]

Quote:

Originally Posted by Mercuttio Generally speaking, a can with lower impedance is easier to drive. Grados are easier to drive than Sennheisers There are plenty of exceptions though. The K701 (though having a lower impedance) is sometimes harder to drive than the HD650, when I tried them next to each other. K701 at the same volume level on the knob wasn't pumping out nearly as much sound.

yup..all about current, load balancing, and impedance with cans, amps, and sources..

Merc hit the nail right on the head though..

Quote:

Originally Posted by Mercuttio There are plenty of exceptions though. The K701 (though having a lower impedance) is sometimes harder to drive than the HD650, when I tried them next to each other. K701 at the same volume level on the knob wasn't pumping out nearly as much sound.

I have the k701, it requires a lot of juice to push them...

One thing as a sidenote that the OP may notice with his/her RS-1's, is that they go much louder than most phones out of identical source/amps and volume level...this attributed in part to its low imp...as stated above

 

[trains are bad]

Quote:

P=IR^2

Actually, power is (I^2)(R). I will give you the benefit of the doubt and assume it was a typo. And the following sentence where you explained how...oh wait.

You really should get some engineering/physics basics.