[Law87]

hey guys, I recently purchase a Mad Dog along with it I purchase a Nuforce MMP for portable amp (I really need it to be portable) it push the sound to really loud level (I never go pass 50% on my device), but it doesnt sound "full" to me, the bass seems like its holding up ok but its not punchy. so my questions is, what do you look for when your Amp is not giving your headphone enough juice (bass, mids and treble)? how do you look at Amp spec and determine if its good for your headphone, TIA all.

 

[jseaber]

  hey guys, I recently purchase a Mad Dog along with it I purchase a Nuforce MMP for portable amp (I really need it to be portable) it push the sound to really loud level (I never go pass 50% on my device), but it doesnt sound "full" to me, the bass seems like its holding up ok but its not punchy. so my questions is, what do you look for when your Amp is not giving your headphone enough juice (bass, mids and treble)? how do you look at Amp spec and determine if its good for your headphone, TIA all.

 
Purely considering power, you need to look at four specifications:
 

1. Headphone Impedance (ohms)
2. Headphone Sensitivity (dB/mW)
3. Amplifier Output Voltage or Power at your headphone's impedance (V or mW)
4. Amplifier Output Impedance (ohms)

 
 
1) Make sure amplifier output impedance is less than (Headphone Impedance)/8
 
2) Check needed power to reach desired volume. Most agree that 110dB is a painful listening level, and 115dB is thoroughly excessive. Decide the maximum volume level you expect, then insert your headphone's sensitivity into the equation or chart below.
 
Required Amplifier Power = 10^((Volume - Sensitivity)/10)
 
 
...or here's that equation in a convenient lookup table:
 

Headphone Sensitivity db/mW)	Volume, 110 dB	Volume, 112.5 dB	Volume, 115 dB
85	316.2	562.3	1000.0
86	251.2	446.7	794.3
87	199.5	354.8	631.0
88	158.5	281.8	501.2
89	125.9	223.9	398.1
90	100.0	177.8	316.2
91	79.4	141.3	251.2
92	63.1	112.2	199.5
93	50.1	89.1	158.5
94	39.8	70.8	125.9
95	31.6	56.2	100.0
96	25.1	44.7	79.4
97	20.0	35.5	63.1
98	15.8	28.2	50.1
99	12.6	22.4	39.8
100	10.0	17.8	31.6
101	7.9	14.1	25.1
102	6.3	11.2	20.0
103	5.0	8.9	15.8
104	4.0	7.1	12.6
105	3.2	5.6	10.0
106	2.5	4.5	7.9
107	2.0	3.5	6.3
108	1.6	2.8	5.0
109	1.3	2.2	4.0
110	1.0	1.8	3.2
111	0.8	1.4	2.5
112	0.6	1.1	2.0
113	0.5	0.9	1.6
114	0.4	0.7	1.3
115	0.3	0.6	1.0
116	0.3	0.4	0.8
117	0.2	0.4	0.6
118	0.2	0.3	0.5

 
 
 
An amplifier is capable of cleanly driving your headphones as long as its rated power meets or exceeds the above value at the headphone's impedance. Obtaining output power information from a manufacturer is the challenge.

 

[Law87]

   
Purely considering power, you need to look at four specifications:
 

1. Headphone Impedance (ohms)
2. Headphone Sensitivity (dB/mW)
3. Amplifier Output Voltage or Power at your headphone's impedance (V or mW)
4. Amplifier Output Impedance (ohms)

 
 
1) Make sure amplifier output impedance is less than (Headphone Impedance)/8
 
2) Check needed power to reach desired volume. Most agree that 110dB is a painful listening level, and 115dB is thoroughly excessive. Decide the maximum volume level you expect, then insert your headphone's sensitivity into the equation or chart below.
 
Required Amplifier Power = 10^((Volume - Sensitivity)/10)
 
 
...or here's that equation in a convenient lookup table:
 

Headphone Sensitivity db/mW)	Volume, 110 dB	Volume, 112.5 dB	Volume, 115 dB
85	316.2	562.3	1000.0
86	251.2	446.7	794.3
87	199.5	354.8	631.0
88	158.5	281.8	501.2
89	125.9	223.9	398.1
90	100.0	177.8	316.2
91	79.4	141.3	251.2
92	63.1	112.2	199.5
93	50.1	89.1	158.5
94	39.8	70.8	125.9
95	31.6	56.2	100.0
96	25.1	44.7	79.4
97	20.0	35.5	63.1
98	15.8	28.2	50.1
99	12.6	22.4	39.8
100	10.0	17.8	31.6
101	7.9	14.1	25.1
102	6.3	11.2	20.0
103	5.0	8.9	15.8
104	4.0	7.1	12.6
105	3.2	5.6	10.0
106	2.5	4.5	7.9
107	2.0	3.5	6.3
108	1.6	2.8	5.0
109	1.3	2.2	4.0
110	1.0	1.8	3.2
111	0.8	1.4	2.5
112	0.6	1.1	2.0
113	0.5	0.9	1.6
114	0.4	0.7	1.3
115	0.3	0.6	1.0
116	0.3	0.4	0.8
117	0.2	0.4	0.6
118	0.2	0.3	0.5

 
 
 
An amplifier is capable of cleanly driving your headphones as long as its rated power meets or exceeds the above value at the headphone's impedance. Obtaining output power information from a manufacturer is the challenge.

Thanks for the reply, I'm still trying to figure it all out. When an amp driving a headphone louder but not necessarily better in term of sound quality does that mean the amp is not putting out enough mW?

 

[jseaber]

 
Thanks for the reply, I'm still trying to figure it all out. When an amp driving a headphone louder but not necessarily better in term of sound quality does that mean the amp is not putting out enough mW?

 
Your Mad Dogs need a fair amount of power. It's possible for an amp to improve output power compared to your audio source, and still lack sufficient power for your headphones.
 
 
It looks like power of your amp is only published as "80mW @ 16 ohms". Mad Dogs are rated about 50 ohms and 90 dB/mW, so they need roughly 316mW based on the above calculations. So, more power could be useful.

 

[Law87]

   
Your Mad Dogs need a fair amount of power. It's possible for an amp to improve output power compared to your audio source, and still lack sufficient power for your headphones.
 
 
It looks like power of your amp is only published as "80mW @ 16 ohms". Mad Dogs are rated about 50 ohms and 90 dB/mW, so they need roughly 316mW based on the above calculations. So, more power could be useful.

Thanks again, I looked at the jds cmoy but found no spec regarding power, do you think its enough power to drive the headphone?

 

[jseaber]

 
Thanks again, I looked at the jds cmoy but found no spec regarding power, do you think its enough power to drive the headphone?

 
Power output with the cMoyBB will be no higher than your current amp. You'll need to look at stronger amps.

 

[yong_shun]

Volume, 110 dB

Purely considering power, you need to look at four specifications:

1. Headphone Impedance (ohms)
2. Headphone Sensitivity (dB/mW)
3. Amplifier Output Voltage or Power at your headphone's impedance (V or mW)
4. Amplifier Output Impedance (ohms)

1) Make sure amplifier output impedance is less than (Headphone Impedance)/8

2) Check needed power to reach desired volume. Most agree that 110dB is a painful listening level, and 115dB is thoroughly excessive. Decide the maximum volume level you expect, then insert your headphone's sensitivity into the equation or chart below.

Required Amplifier Power = 10^((Volume - Sensitivity)/10)


...or here's that equation in a convenient lookup table:

Headphone Sensitivity db/mW)	Volume, 110 dB	Volume, 112.5 dB	Volume, 115 dB
85	316.2	562.3	1000.0
86	251.2	446.7	794.3
87	199.5	354.8	631.0
88	158.5	281.8	501.2
89	125.9	223.9	398.1
90	100.0	177.8	316.2
91	79.4	141.3	251.2
92	63.1	112.2	199.5
93	50.1	89.1	158.5
94	39.8	70.8	125.9
95	31.6	56.2	100.0
96	25.1	44.7	79.4
97	20.0	35.5	63.1
98	15.8	28.2	50.1
99	12.6	22.4	39.8
100	10.0	17.8	31.6
101	7.9	14.1	25.1
102	6.3	11.2	20.0
103	5.0	8.9	15.8
104	4.0	7.1	12.6
105	3.2	5.6	10.0
106	2.5	4.5	7.9
107	2.0	3.5	6.3
108	1.6	2.8	5.0
109	1.3	2.2	4.0
110	1.0	1.8	3.2
111	0.8	1.4	2.5
112	0.6	1.1	2.0
113	0.5	0.9	1.6
114	0.4	0.7	1.3
115	0.3	0.6	1.0
116	0.3	0.4	0.8
117	0.2	0.4	0.6
118	0.2	0.3	0.5

An amplifier is capable of cleanly driving your headphones as long as its rated power meets or exceeds the above value at the headphone's impedance. Obtaining output power information from a manufacturer is the challenge.

Sorry I know this is an old post but something I wish to clarify:
1. For impedance, the equation is (Amplifier Output Impedance) < (Headphone Impedance/8) right?
2. Why there is a need to divide the headphone impedance by 8?

 

[Harold999]

the bass seems like its holding up ok but its not punchy

.

Signs of an impedance mismatch are recessed mids i.c.w. pronounced lows.
What you describe is the opposite, so it could be that you are used to a sound which wasn't neutral, and now your new amp is.

 

[junki]

First you have to know what you like and what you don't like about the sound of your headphones of choice.

Besides the obvious "does this amp output enough current to drive my headphones" which can easily be determined from the amplifier's specs coupled with an introductory knowledge of Ohm's Law (99.9% of audiophiles proudly embrace their ignorance of the technical drivers of the products they use), amps can supplement certain aspects of your headphones to a limited, usually subtle extent. These aspects are the psychoacoustic sensations of the sound, such as sound stage, smoothness vs. bite, speed / attack / slam, separation and layering, and such. So, second, you'll need to get a good grasp on what these terms mean and how they relate to your headphone of choice, so you can digest impressions more productively.

As an example, the MCTH delivers a signal that for one reason or another sounds airy and expansive to a number of careful listeners. This, when paired with a headphone that has a peculiarity with its sound stage (like the HD600/650 or Focal's lineup which have relatively intimate stages, or the HD800 which has a very large stage) can either help alleviate or further augment this aspect of the sound.

I say the above in retrospect because it's pretty difficult to know for sure whether a pairing sounds nice without trying it firsthand. Hindsight is always 20/20.

An amp will not alter the frequency response of your headphones.

 

[yong_shun]

First you have to know what you like and what you don't like about the sound of your headphones of choice.

Besides the obvious "does this amp output enough current to drive my headphones" which can easily be determined from the amplifier's specs coupled with an introductory knowledge of Ohm's Law (99.9% of audiophiles proudly embrace their ignorance of the technical drivers of the products they use), amps can supplement certain aspects of your headphones to a limited, usually subtle extent. These aspects are the psychoacoustic sensations of the sound, such as sound stage, smoothness vs. bite, speed / attack / slam, separation and layering, and such. So, second, you'll need to get a good grasp on what these terms mean and how they relate to your headphone of choice, so you can digest impressions more productively.

As an example, the MCTH delivers a signal that for one reason or another sounds airy and expansive to a number of careful listeners. This, when paired with a headphone that has a peculiarity with its sound stage (like the HD600/650 or Focal's lineup which have relatively intimate stages, or the HD800 which has a very large stage) can either help alleviate or further augment this aspect of the sound.

I say the above in retrospect because it's pretty difficult to know for sure whether a pairing sounds nice without trying it firsthand. Hindsight is always 20/20.

An amp will not alter the frequency response of your headphones.

Can further explain about the Ohm's law? I know they are some governing equations behind the matching of amp and headphone but it is still confusing to me. I don't mind you bombard me with equations. I am an engineer by training and wish to know more about this. Thank you

 

[junki]

Can further explain about the Ohm's law? I know they are some governing equations behind the matching of amp and headphone but it is still confusing to me. I don't mind you bombard me with equations. I am an engineer by training and wish to know more about this. Thank you

Things to keep in mind:

1. Voltage is a function of resistance and current. For a given voltage potential in a circuit, higher resistance means lower current, and vice-versa.
   
2. Power (watts) is a function of voltage and current. For a given power intake, less current draw means higher voltage potentials, and vice-versa.
3. Impedance is more or less resistance.

For a DAC > amp > headphone setup, power is more or less the constant in your signal chain. Let's take a look at a couple of scenarios.

• You're using a certain popular high impedance Sennheiser can. Your headphone impedance is really high and has high variance across the frequency domain, so for any given voltage potential from your amplifier to your headphone, your headphone draws, relatively speaking, little current (#1). So what does it mean to put power into your Sennheisers if it doesn't draw much current? Amplified voltages (#2). A tube (in tube amps) and FET based transistors (in some solid states) are high resistance components, which means they draw little current (#1). The amplifier outputs a certain amount of power, and if the amplifier uses these high resistance, low current components, the amplifier is mostly amplifying voltage. This is one of the reasons why tube amplifiers work well with Sennheisers.
• You're using a low impedance planar headphone. Your headphone impedance is low, so for any given voltage potential from your amplifier's headphone out, your headphone draws, relatively speaking, more current (#1). So what does it mean to drive (ala put power into) your planar headphone if it draws current and has low resistance? Amplified current (#2). Bipolar transistors in some solid states are low resistance components, which means they draw higher amounts of current (#1). The amplifier outputs a certain amount of power, and if the amplifier uses bipolar transistors (OPA1612 for example), the amplifier is amplifying current. This is one of the reasons why solid state amplifiers or hybrid valve amplifiers with a transistor-based output stage work well with planars.

 

[yong_shun]

Things to keep in mind:

1. Voltage is a function of resistance and current. For a given voltage potential in a circuit, higher resistance means lower current, and vice-versa.
   
2. Power (watts) is a function of voltage and current. For a given power intake, less current draw means higher voltage potentials, and vice-versa.
3. Impedance is more or less resistance.

For a DAC > amp > headphone setup, power is more or less the constant in your signal chain. Let's take a look at a couple of scenarios.

• You're using a certain popular high impedance Sennheiser can. Your headphone impedance is really high and has high variance across the frequency domain, so for any given voltage potential from your amplifier to your headphone, your headphone draws, relatively speaking, little current (#1). So what does it mean to put power into your Sennheisers if it doesn't draw much current? Amplified voltages (#2). A tube (in tube amps) and FET based transistors (in some solid states) are high resistance components, which means they draw little current (#1). The amplifier outputs a certain amount of power, and if the amplifier uses these high resistance, low current components, the amplifier is mostly amplifying voltage. This is one of the reasons why tube amplifiers work well with Sennheisers.
• You're using a low impedance planar headphone. Your headphone impedance is low, so for any given voltage potential from your amplifier's headphone out, your headphone draws, relatively speaking, more current (#1). So what does it mean to drive (ala put power into) your planar headphone if it draws current and has low resistance? Amplified current (#2). Bipolar transistors in some solid states are low resistance components, which means they draw higher amounts of current (#1). The amplifier outputs a certain amount of power, and if the amplifier uses bipolar transistors (OPA1612 for example), the amplifier is amplifying current. This is one of the reasons why tube amps usually don't work well with planar headphones.

Thanks for such detailed explanation.

So to summarise for high impedance (resistance) headphone, it draws less current because of ohm's law, V=IR.
A high resistance component will amplify the voltage to supply the power to the power hungry headphone? (This part is a little confusing to me)

 

[junki]

So to summarise for high impedance (resistance) headphone, it draws less current because of ohm's law, V=IR.
A high resistance component will amplify the voltage to supply the power to the power hungry headphone? (This part is a little confusing to me)

Yes. That is all true.

High impedance headphones and dynamic transducers in general respond to voltage amplification better than current amplification.
Low impedance headphones and planar transducers in general respond to current amplification better than voltage amplification.
An amplifier's headphone out will output some milliwatts of power, but whether that power is made up mostly of current or voltage potential is dependent on the amp's topology, its output stage, as well as the headphone that's connected to it.

@jseaber feel free to correct me on any of this.

 

[yong_shun]

Yes. That is all true.

High impedance headphones and dynamic transducers in general respond to voltage amplification better than current amplification.
Low impedance headphones and planar transducers in general respond to current amplification better than voltage amplification.
An amplifier's headphone out will output some milliwatts of power, but whether that power is made up mostly of current or voltage potential is dependent on the amp's topology and output stage as well as the headphone that's connected to it.

@jseaber feel free to correct me on any of this.

Cool! This impressed me a lot. Never know about this. Thank you!