[LazyListener]

@castleofargh
 
I wasn't implying any conclusions, or stating that power is the sole cause.  I'm fully aware of correlation vs causation.  I was simply stating my limited observation, and also from what I've read of most others' observations - that more powerful amps, when paired with higher impedance cans, tend to produce a fuller, rounded sound vs weaker amps that tend to produce a thinner, leaner sound.
 
I got the impression from your posts that you think power output has no effect on sound quality.  Is that correct?  I apologize if I misunderstood your posts.
 
My personal theory on the matter is that lower frequencies require more power to produce a certain SPL, whereas higher frequencies require less power to produce same SPL.  Therefore, weaker amps are tuned to sound loud by using more of that power for higher frequiencies and less power for lower frequencies.  The idea is to make it sound loud, not necessarily balanced.  Amps with more power on tap are tuned to sound more balanced because there is plenty of power to go around for the entire frequency spectrum.  Just a theory.  Manufacturers want their relatively weak amps to sound loud, as louder amps sell more than quieter amps.

 

[lugnut]

 
I just went to Moon Audio, added a set w/ Dragons to my cart and went to checkout. No mention of out of stock.

Wow, this is my last post about this. I never said they were discontinued, just found it interesting that their add for the Senn. hd 650 said "out of stock, discontinued".
I don't know anything about dragons it was the headphones in question.
 
https://www.moon-audio.com/sennheiser-hd-650-headphones.html

 

[Krutsch]

  Wow, this is my last post about this. I never said they were discontinued, just found it interesting that their add for the Senn. hd 650 said "out of stock, discontinued".
I don't know anything about dragons it was the headphones in question.
 
https://www.moon-audio.com/sennheiser-hd-650-headphones.html

 
I hear you... just about every time I post something I'm sorry I did.

 

[lugnut]

   
I hear you... just about every time I post something I'm sorry I did.

No problem on my end.

 

[Dulalala]

@castleofargh


I wasn't implying any conclusions, or stating that power is the sole cause.  I'm fully aware of correlation vs causation.  I was simply stating my limited observation, and also from what I've read of most others' observations - that more powerful amps, when paired with higher impedance cans, tend to produce a fuller, rounded sound vs weaker amps that tend to produce a thinner, leaner sound.

I got the impression from your posts that you think power output has no effect on sound quality.  Is that correct?  I apologize if I misunderstood your posts.

My personal theory on the matter is that lower frequencies require more power to produce a certain SPL, whereas higher frequencies require less power to produce same SPL.  Therefore, weaker amps are tuned to sound loud by using more of that power for higher frequiencies and less power for lower frequencies.  The idea is to make it sound loud, not necessarily balanced.  Amps with more power on tap are tuned to sound more balanced because there is plenty of power to go around for the entire frequency spectrum.  Just a theory.  Manufacturers want their relatively weak amps to sound loud, as louder amps sell more than quieter amps.

I don't think the power output of the amp varies for different frequencies. I'm pretty sure it's constant-ish to what you set it at with the volume knob. Don't quote me on this though I could be wrong.

 

[LazyListener]

I don't think the power output of the amp varies for different frequencies. I'm pretty sure it's constant-ish to what you set it at with the volume knob. Don't quote me on this though I could be wrong.

Maybe I didn't explain it well enough.  I've read somewhere, long time ago, that low frequencies draw more power from an amp to create a certain volume level, whereas high frequencies require much less power to achieve the same volume level.  Therefore, weak amps tend to sound thinner and leaner (with high impedance cans) because there is not enough power to adequately move the driver to reproduce those low frequencies with any real authority (SPL level).  Yet, those weak amps can still sound pretty loud in the middle and higher frequencies that don't require much power to reproduce.  Introduce an amp with moderate to high power output, it can adequately move the driver to reproduce low frequencies with ease, while still having plenty of power left for the high frequencies, thereby sounding more full.  Again, just a theory, based on what I've read about low frequencies requiring much more power to reproduce at same SPL levels than high frequencies.

 

[Me x3]

 
Maybe I didn't explain it well enough.  I've read somewhere, long time ago, that low frequencies draw more power from an amp to create a certain volume level, whereas high frequencies require much less power to achieve the same volume level.  Therefore, weak amps tend to sound thinner and leaner (with high impedance cans) because there is not enough power to adequately move the driver to reproduce those low frequencies with any real authority (SPL level).  Yet, those weak amps can still sound pretty loud in the middle and higher frequencies that don't require much power to reproduce.  Introduce an amp with moderate to high power output, it can adequately move the driver to reproduce low frequencies with ease, while still having plenty of power left for the high frequencies, thereby sounding more full.  Again, just a theory, based on what I've read about low frequencies requiring much more power to reproduce at same SPL levels than high frequencies.

Well, it's not a good theory.
Most dynamic headphones like the HD650 need less power at the bass to play at the same dB SPL as the rest of the spectrum.
You might be able to find warm cheap awful sounding amps/chips. I've plugged my HD650 into a very low grade smartphone once (Samsung Galaxy Y) and it sounded full. Blurry and lowish fi, but warm and full. Same would apply to the output on some entry laptops.
 
On the other hand, the original Magni I had at that time was significantly cooler and clearer overall despite being much more powerful.
 
You'll find bright/cool powerful amps and also low powered warm amps. It's not a matter of power.

 

[steffanan]

Well, it's not a good theory.
Most dynamic headphones like the HD650 need less power at the bass to play at the same dB SPL as the rest of the spectrum.
You might be able to find warm cheap awful sounding amps/chips. I've plugged my HD650 into a very low grade smartphone once (Samsung Galaxy Y) and it sounded full. Blurry and lowish fi, but warm and full. Same would apply to the output on some entry laptops.

On the other hand, the original Magni I had at that time was significantly cooler and clearer overall despite being much more powerful.

You'll find bright/cool powerful amps and also low powered warm amps. It's not a matter of power.

hold on there, he's totally correct that lower frequencies require more power on any speakers at all. I mean, you can't get around the physics of how this stuff works.you're physically fighting against a spider, and surround suspension, the further you want that speaker to move, the more power it's going to require to overcome that physical restriction. There are other factors at play additionally like efficiency curves and varying resistances at different frequencies, and I don't know anything else about the debate you two are in, but I don't like seeing his super valid statement get shut down inaccurately. I know a ton of open backed headphones that require a great amplifier in order to gain some low end extension.

 

[raybone0566]

The 650's need roughly 2volts(5.7 peak to peak) to reach reasonable listening levels. I'd imagine you could pull up a PDF on the amp your interested in & see if it can swing that voltage.

 

[dbkelly]

The 650's need roughly 2volts(5.7 peak to peak) to reach reasonable listening levels. I'd imagine you could pull up a PDF on the amp your interested in & see if it can swing that voltage.

Looking up the specs for the DF 1.2, the Black and the Red, the outputs are 1.8, 1.2 and 2.1 volts respectively.

 

[Me x3]

hold on there, he's totally correct that lower frequencies require more power on any speakers at all. I mean, you can't get around the physics of how this stuff works.you're physically fighting against a spider, and surround suspension, the further you want that speaker to move, the more power it's going to require to overcome that physical restriction. There are other factors at play additionally like efficiency curves and varying resistances at different frequencies, and I don't know anything else about the debate you two are in, but I don't like seeing his super valid statement get shut down inaccurately. I know a ton of open backed headphones that require a great amplifier in order to gain some low end extension.

No, that's not correct mate. It wasn't a valid statement.
Here you have the accurate explanation. If you have any doubt, feel free to ask.
 
Have a look at HD650's frequency response:


The frequency response plot is created by feeding the headphone with a set of tones of varying frequency at constant voltage.
As you can see here, for a given voltage 100Hz tone (bass) will sound as loud as 1000Hz tone (midrange) and both will sound louder than the treble (say 6000Hz tone)
So you need more voltage to make the treble sound as loud as the midrange and bass.
 
What does power means?
Power is related to Voltage and the Impedance of the load where the Voltage is applied.
 
Power = V x V / R
 
Now let's take a look at HD650's impedance plot:

 
As you can see, the impedance is higher in the bass.
 
Going back to the Power formula:
Power = V x V / R
 
For a given voltage, higher Resistance (read impedance at certain frequency) means lower power requirement.
Since you need the same voltage for the bass and mids, the bass need less power than the mids.
 
In other words, HD650's drivers are much more efficient in the bass region. Same applies to most open back dynamic headphones.

 

[Cedric Yong]

Whats a good portable amp to pair with the HD6xx/HD650?The only reason i need a portable amp is because I like to listen music in a silent corner when I'm outside.My budget is around 150usd-ish.Please help,thanks in advance

 

[DavidA]

Whats a good portable amp to pair with the HD6xx/HD650?The only reason i need a portable amp is because I like to listen music in a silent corner when I'm outside.My budget is around 150usd-ish.Please help,thanks in advance

I can use my Fiio X3ii to drive the HD-650 to a good listening level and its decent but will not be as nice as a bit behind dedicate desktop amp like the BH Crack

 

[steffanan]

No, that's not correct mate. It wasn't a valid statement.
Here you have the accurate explanation. If you have any doubt, feel free to ask.

Have a look at HD650's frequency response:




The frequency response plot is created by feeding the headphone with a set of tones of varying frequency at constant voltage.
As you can see here, for a given voltage 100Hz tone (bass) will sound as loud as 1000Hz tone (midrange) and both will sound louder than the treble (say 6000Hz tone)
So you need more voltage to make the treble sound as loud as the midrange and bass.

What does power means?
Power is related to Voltage and the Impedance of the load where the Voltage is applied.

Power = V x V / R

Now let's take a look at HD650's impedance plot:



As you can see, the impedance is higher in the bass.

Going back to the Power formula:
Power = V x V / R

For a given voltage, higher Resistance (read impedance at certain frequency) means lower power requirement.
Since you need the same voltage for the bass and mids, the bass need less power than the mids.

In other words, HD650's drivers are much more efficient in the bass region. Same applies to most open back dynamic headphones.

Ok, so you're suggesting that a higher resistance in a particular frequency range makes it in practice, louder? Cause think about how amplifiers respond to higher resistance. It is similar to putting a smaller lightbulb somewhere in your house where there was previously a larger bulb. Let's not forget that a voice coil is a simple electrical consumer and the resistance is our key to understanding what quantity of electricity that will be consumed within a circuit. Plus, I'm curious how you are saying most open backed headphones are more efficient in the lower frequency ranges, do you believe that open backed headphones are typically bassier than closed back headphones?

 

[Me x3]

Ok, so you're suggesting that a higher resistance in a particular frequency range makes it in practice, louder?

Me x3: No, louder or not at a particular frequency range relative to the others will depend on the frequency response. I'm saying that for a given voltage the higher the impedance at that frequency, the less power needed. This comes from the fact that for a given voltage, higher load resistance means less current drained from the amplifier, and thus less power is required.

Cause think about how amplifiers respond to higher resistance. It is similar to putting a smaller lightbulb somewhere in your house where there was previously a larger bulb.

Me x3: From the amplifier's perspective, a high impedance load is an easy load because it will drain little current. It's well known stuff in the speaker world were 4 Ohm low sensitivity speakers can be really hard to drive, while higher impedance speakers are normally easier loads. Consider the following example: both AKG K702 (67 Ohm) and Beyerdynamic DT880 (250 Ohm) need 0.3 Vrms to sound at 90dB @1kHz. Since the AKG has a relatively low impedance it will drain a big amount of current from the amplifier while the 250 Ohm Beyer will drain very little. That's why despite both needing 0.3 Vrms for 90dB, the AKG needs 4 times the power required for DT880 (250)

Let's not forget that a voice coil is a simple electrical consumer and the resistance is our key to understanding what quantity of electricity that will be consumed within a circuit.

Me x3: Sensitivity expressed in dB/V and resistance are both important when it comes to understand how much power a headphone needs at given frequency. Higher resistance means less current flow, that's correct, but dynamic transducers on an acoustic enviornment are more than just a voice coil so there are other variables involved besides resistance (or impedance). Two headphones with the same impedance can have different power requirements and that's why sensitivity is key in the analysis.

Plus, I'm curious how you are saying most open backed headphones are more efficient in the lower frequency ranges, do you believe that open backed headphones are typically bassier than closed back headphones?

Me x3: No, I don't think most open back headphones are bassier. Being bassier or not depends on the frequency response. Most open back dynamic headphones (with voice coils) have a bump in the impedance vs frequency plot centered at the bass region, just like HD650. This is called the 'main driver resonance' and it's the region where the driver is most efficient. Being more efficient is not the same as sounding louder, being more efficient means requiring less power to achieve the same loudness.