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Amp recommendations for Audeze LCD-2 - Page 464

post #6946 of 7570

Signal = voltage in voltage based amps

Signal = current in current mode amps.

 

When voltage amps drive HP, current is generated by V=IZ where Z= impedenace.

Current is function of voltage with respect to phase.

And magnetic flux is in phase with current, not with voltage.

Because magnetic flux = H is only function of current. This means that only current generates magnetic flux, and voltage can be generated without any current for example open circuit having maximum voltage but zero current that generates no magnetic flux.

 

Of course voltage generates magnetic flux in relation to impedance=Z, but a phase amount delay.

 

Sorry for my adoption of math.

Especially impedance Z is function of frequency, when it approaches to resonance the phase will delay or advance in 90 degrees.

 

Because all these relations, voltage amplifier drives by voltage signal and HP responds only to current, so that there is a phase difference between signal generator ( driver) and signal producer (HP) due to impedance that depends on frequency. The higher the frequency, the larger the phase difference between driver (AMP) and driven (HP).


Edited by Joong - 12/4/13 at 4:05pm
post #6947 of 7570
Quote:
Originally Posted by Joong View Post

Signal = voltage in voltage based amps
Signal = current in current mode amps.

Yes, I know.
Quote:
When voltage amps drive HP, current is generated by V=IZ where Z= impedenace.

You mean I = V/Z.
Quote:
Current is function of voltage with respect to phase.

The phase of what?
Quote:
And magnetic flux is in phase with current, not with voltage.

And why does that matter? Whether you drive the headphone from a current source or a voltage source, for a given current through the headphone, you'll have a given voltage across the headphone. I = V/Z, V = IZ.
Quote:
Because magnetic flux = H is only function of current.

Yes, just as voltage is a function of current.
Quote:
Of course voltage generates magnetic flux in relation to impedance=Z, but a phase amount delay.

But the impedance of an ortho, such as the LCD-2, which is what this thread is about, is virtually purely purely resistive. So you may just as well use R instead of Z.
Quote:
Especially impedance Z is function of frequency, when it approaches to resonance the phase will delay or advance in 90 degrees.

As I said, the LCD-2sare virtually resistive.

And even if you are talking about a resonant circuit, at resonance, phase is 0 degrees and Z is purely resistive. You only get a 90 degree lead or lag when the load is PURELY reactive, i.e. pure inductance or pure capacitance. When there is any loss, such as resistance, the lead/lag will always be less than 90 degrees.

se
post #6948 of 7570

The people that recommended the Lyr with the LCD2's are old new's when there weren't any V100/V200's or the Burson stuff on the market. Things have changed greatly over the past 2 years. 

post #6949 of 7570

The voltage phase is actually signal phase in Voltage based amps.

The actual HP is a motor that responds only to current.

This means that original sounds lacks or advances with respect to actually produced sounds.

 

This phase difference is well related to V=IZ, so that this may not be equal to usual jitter, but there is certainly phase difference between driver and driven.

 

The LCD-1/2/3 or any orthors, must have inductive to produce or interact with DC field of magnet array.

There is no conductive trace that have 100% resistive only.

 

Of course the orthors has much less inductive than dynamic ones, so that orthos requires lots of current than those of dynamic phone, in order to compensate the lack of inductance through which magnetic flux is generated.

 

I generally agree that for the audio signal band there is not much appreciable inductance as you mentioned.

However, these crazy headfiers consider that any tiny amount of electric quantity might be controlled by expert like the founder of Bakgoon, for example.

 

He considers seriously an comfortable in several pico seconds jitter, and he tried to correct it by current mode amps. Amazing!!! He simply had been inspired by that fact that the turn table got several hundred kilograms to prevent the rotational speed variation of the turn table by gaining weight that much. That turn-table example was parallel with modern jitter concept, which pushes the DAC with superior jitter control by considerable effort.

I am also one among them crazy people.

 

As you mentioned, the phase difference between voltage based amps and HP will be negligible when we consider very tiny amount inductance. But when we consider signal as voltage, and sound as current of magnetic flux; there is jitter like action is always there.

 

That is something like the piston motion as resistive component of impedace, whereas crank acts as jittering reactive comp.

Therefore due to the length of piston rod ( resistive) much longer than the crank ( reactive) there is no way v-amp signal delaying or advancing for 90 degree, but very tiny amount that bothers headfiers here.


Edited by Joong - 12/4/13 at 4:54pm
post #6950 of 7570
Quote:
Originally Posted by Joong View Post

I am also one among them crazy people.

Then I'll not waste my time trying to discuss the physics with you.

se
post #6951 of 7570
The audiophiles' concerns might not be measured by physics, but by the limit of human brain's sensing capability.
Therefore there is always some argue.
Nice talking was it.biggrin.gif
post #6952 of 7570
Then don't bring any physics into the discussion. And don't speak of the brain's sensing capability unless you have something to back it up other than some audiophile said so.

se
Edited by Steve Eddy - 12/4/13 at 6:14pm
post #6953 of 7570

Steve Eddy takin' 'em to school, again. :deadhorse:

post #6954 of 7570
Quote:
Originally Posted by Steve Eddy View Post

Then don't bring any physics into the discussion. 

 

Zing !!  

 

Although I thought you were going to say something a little more insulting when you started with "And don't speak of the brain's sensing capability unless you have ...".  Actually, almost feel a little let down now that I think about it ...  ;)

post #6955 of 7570
Quote:
Originally Posted by NinjaHamster View Post
 

 

Zing !!  

 

Although I thought you were going to say something a little more insulting when you started with "And don't speak of the brain's sensing capability unless you have ...".  Actually, almost feel a little let down now that I think about it ...  ;)

 

Sorry to have let you down. But I'd like to think you'd feel even more let down if I got myself banned. :D

 

se

post #6956 of 7570

Guessing, but I'd assume that headphones uses some kind of equalizing filter at the input to tweak the signature. That filter might not behave as intended if you replace the voltage driver with a current driver. In normal filters for instance the first pole will be removed by doing this.

post #6957 of 7570
Quote:
Originally Posted by DrNope View Post

Guessing, but I'd assume that headphones uses some kind of equalizing filter at the input to tweak the signature. That filter might not behave as intended if you replace the voltage driver with a current driver. In normal filters for instance the first pole will be removed by doing this.

I'm not aware of any headphones that have any response shaping equalization built into them. I'm pretty sure there's probably something out there that does, but everything I've seen has the driver driven directly.

Nor am I aware of any loudspeaker or headphone driver that's designed to be driven by a current source. Everything assumes it will be driven by a voltage source.

If you look at the impedance plot of a typical dynamic driver, whether loudspeaker or headphone, you'll see that it peaks at the driver's resonant frequency. This is where the driver is working most efficiently compared to above and below this frequency. And as was mentioned previously, it's current through the voice coil that produces the magnetic field that interacts with the driver's magnets and causes the diaphragm to move.

So now when you drive it with a voltage source, because Ohm's Law says that current is equal to voltage divided by impedance, and since impedance is highest at the resonant frequency, there will be less current flowing in the voice coil at that frequency. Which makes sense because where it's most efficient is where you need less power to get the same amount of output.

But drive that same driver from a current source, and everything gets turned upside down. Because a current source wants to drive the same amount of current through the load regardless of the impedance, when you get to the peak of the impedance curve, which again is where the driver is most efficient, there will be much more current flowing through the voice coil compared to driving it with a voltage source and as a consequence, the output of the driver will be much greater. It's the same as if you used a voltage source and used EQ to give it a peak in the response at the resonant frequency.

In other words, if you start out with a driver that has a flat response when driven from a voltage source, as you transition to a current source, the frequency response starts to look like the impedance curve with a peak at the resonant frequency (as well as at high frequencies where the voice coil inductance starts coming into play). When Nelson Pass began experimenting with current source amplifiers to drive single driver loudspeakers, he had to add networks to compensate for this and avoid peaks in the low frequency response.

This isn't an issue with orthos though due to their flat impedance. But with dynamic drivers, they're designed to be driven from a voltage source.

se
post #6958 of 7570
I'm looking for a new headphone amp for my LCD 2.2's, just wondering what some of the best headphone amps are in the following price ranges:

$500-$1000
$1000-$1500
$1500-$2000

Three of the ones I am considering in each range are the Woo Audio WA7 Fireflies, Schiit M & G combo & Burson Conductor. what do you guys think is the best bet for the LCD-2 in those price ranges?
post #6959 of 7570
Quote:
Originally Posted by goldendarko View Post

I'm looking for a new headphone amp for my LCD 2.2's, just wondering what some of the best headphone amps are in the following price ranges:

$500-$1000
$1000-$1500
$1500-$2000

Three of the ones I am considering in each range are the Woo Audio WA7 Fireflies, Schiit M & G combo & Burson Conductor. what do you guys think is the best bet for the LCD-2 in those price ranges?

Sounded good from my burson soloist. Can probably find one for around $700 on the FS forums. I think those are still en vogue these days.

Also sounds good from my dacmini.
post #6960 of 7570
Quote:
Originally Posted by goldendarko View Post

I'm looking for a new headphone amp for my LCD 2.2's, just wondering what some of the best headphone amps are in the following price ranges:

$500-$1000
$1000-$1500
$1500-$2000

Three of the ones I am considering in each range are the Woo Audio WA7 Fireflies, Schiit M & G combo & Burson Conductor. what do you guys think is the best bet for the LCD-2 in those price ranges?1

 

1. Audio GD NFB10.33

2. Burson Soloist, Violectric V200, Schiit Mjolnir

3. I don't have an answer for #3 because I don't believe amps should cost that much.

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