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How do headphone amplifiers differ from speaker amps?

bravomail

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#21
Magni is a speaker amp, converted into a headphone amp. And ppl tried to use it as speaker amp. Though the founder complained that "speakers are much more reactive than headphones", and of course said that your warranty is void. :) I'm with the guy on this. Use speaker amps for speakers. At least good amps will have overload protection relay.
 

Sal1950

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#22
There's nothing magical about headphone amplifiers. They are a product segment dreamed up by the 'separate everything into an individual box crowd', tell them it's so much better and charge lots for the inconvenience.
Amen, Just a reflection of the audiophoolishness that crept into the headphone listening market over the last decade or so.
 

k9gardner

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#23
In theory, there's no difference between a headphone amplifier and a loudspeaker amplifier.
...
S.
Maybe I'm going off on a tangent here, but what about the difference between the front-panel headphone output of a "speaker amp" and the output of a dedicated headphone amp? Am I going to hear something different through the headphones?
 

twsecrest

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#24
Maybe I'm going off on a tangent here, but what about the difference between the front-panel headphone output of a "speaker amp" and the output of a dedicated headphone amp? Am I going to hear something different through the headphones?
Most speaker amplifiers and receivers and A/V receivers use the speaker amplifiers to also drive the headphone jack. the stuff that needs to be done for the speaker amplifier to drive headphones causes the headphone jack to have a high output impedance (Ohms), so low Ohm headphones
(>150-Ohms?) do not sound right plugged into speaker amplifiers/receiver/AVreceivers, headphones that are in the 250-Ohm to 600-Ohm range do better. a few higher priced A/V receivers do come with a dedicated headphone amplifier.
 

daftcombo

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#25
Most speaker amplifiers and receivers and A/V receivers use the speaker amplifiers to also drive the headphone jack. the stuff that needs to be done for the speaker amplifier to drive headphones causes the headphone jack to have a high output impedance (Ohms), so low Ohm headphones
(>150-Ohms?) do not sound right plugged into speaker amplifiers/receiver/AVreceivers, headphones that are in the 250-Ohm to 600-Ohm range do better. a few higher priced A/V receivers do come with a dedicated headphone amplifier.
I think you messed up.
Some <150-Ohms headphones might have their frequency response curve affected.
 
OP
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garbulky

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Thread Starter #26
Maybe I'm going off on a tangent here, but what about the difference between the front-panel headphone output of a "speaker amp" and the output of a dedicated headphone amp? Am I going to hear something different through the headphones?
The front panels of speaker amps sometimes use their own speaker amp output to the headphones. To reduce noise and power they use a dropping resistor which can increase the impedance. This can cause variations in interactions with the headphones. So in that aspect, it's not the same. Of course there's nothing stopping using an actual separate headphone amp inside the speaker amplifier to power it.
The Emotiva A-100 is a godo example. its default mode is a dropping resistor which raises impedance to 220 ohms and reduces noise. They state that this resistor can cause variations similar to "vintage gear". Their direct drive mode involves inserting a jumper to bypass it unleashing the full power of the amp with a much lower impedance but at the expense of increased noise. So with the wrong combo, in direct drive mode you can get audible hiss, and in stock mode you can get uneven driving of the headphone drivers.
 

twsecrest

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#27
I think you messed up.
Some <150-Ohms headphones might have their frequency response curve affected.
To me a 150-Ohm headphone is a bit of a gray area, it's not the desired impedance for plugging into receivers, but the impedance issue will cause headphones to have a bloated (louder, less detailed) bass and some might like the louder bass.
I would rather plug my 150-Ohm HD58X into a receiver, over my 250-Ohm or 600-Ohm DT770/DT880/DT990 headphones.
 

sergeauckland

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#28
Maybe I'm going off on a tangent here, but what about the difference between the front-panel headphone output of a "speaker amp" and the output of a dedicated headphone amp? Am I going to hear something different through the headphones?
The front panels of speaker amps sometimes use their own speaker amp output to the headphones. To reduce noise and power they use a dropping resistor which can increase the impedance. This can cause variations in interactions with the headphones. So in that aspect, it's not the same. Of course there's nothing stopping using an actual separate headphone amp inside the speaker amplifier to power it.
The Emotiva A-100 is a godo example. its default mode is a dropping resistor which raises impedance to 220 ohms and reduces noise. They state that this resistor can cause variations similar to "vintage gear". Their direct drive mode involves inserting a jumper to bypass it unleashing the full power of the amp with a much lower impedance but at the expense of increased noise. So with the wrong combo, in direct drive mode you can get audible hiss, and in stock mode you can get uneven driving of the headphone drivers.
Pretty much this. A headphone only amplifier has to provide a few volts into an impedance of anything from a few ohms upwards. A loudspeaker power amplifier has to provide volts into an impedance of anything from a few ohms upwards. So much is the same, but the main difference is in the 'few' above. For headphones, 2 - 3 volts is enough to blow you head off (depending of course on the headphone's impedance and sensitivity), whilst for most loudspeakers, it need something like 10x that many volts. That's why most integrated amplifiers just stick a few hundred ohms in series with the headphone output, and drive it from the normal loudspeaker output. A few actually have a separate headphone driver amp that doesn't have the few hundred ohms in series. The problem with resistance in series with the headphones is exactly the same as resistance in series with loudspeakers, in that it modifies the loudspeaker's / headphone's frequency response. That might be a Good Thing, but generally is not, and is certainly different to what the designer intended. One can use a loudspeaker power amp without series resistance for headphones, but there's firstly the risk of damage, both to headphones and ears, from excessive loudness, and the increase in noise, as the normally quiet noise of a power amp into loudspeakers is much more noticeable into more sensitive headphones.

As someone who only uses headphones in extremis, I'm not too fussy about what I drive them with, but for those poor unfortunates who do use headphones regularly, then a dedicated amplifier with a very low output impedance is the technically better choice.

S.
 
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