Preamp as Headphone Amplifier?

hi Neutral,
Head-fi.com says that mostly todays amps/pre-amps dont have a good headphone stage mainly because the manufacturers are hardly concerned about the headphone out and try to save on the manufacturing costs by compromising heavily at headphone output stage. Cant really blame them. Though there are few amps/pre-amps which do have decent headphone amp (NAD being one of them) still they are just ok....nothing really worth considering.

That's sad Abhi,
I doubt a headphone requires more than 2W/ ch. And nothing justifies poor quality just to save a few dollars. What's worse - very few people will buy a headphone amp and they will simply think that headphones have no potential!

I dont know what to say....may be we in India are not very much exposed to the concept of headphone amp but in other places people are well aware of the needs of a headphone and the utility of a headphone amp so the manufacturers (who are mostly foreigners) dont exactly realise our mentality.

You asked :

1. How good is the headphone amplifier that comes in-built into preamps and integrated amplifiers?

2. Is it capable of delivering clear vocals and bass extension on high impedance professional headphones like Sennheiser or Beyerdynamic?

First for all, what IS a Headphone amp ? Its a mini power amp. Also just as there are amps that complement certain speakers, dito for Headphones and their amps.



Your 1st question is probably answered best as 2 questions :
1. a Almost ALL integrated amps and power amps that have a heaphone socket, does not have a Head Phone amp at all ! Its just a resitor from the speaker terminals to the Headphone socket.

1.b A pre amp, yes would ALWAYS have a seperate HP Amp- built in if it did have a HP socket.

If I was a Pre amp manufacturer, I would not waste money buliding in a Headphone amp, that would probably not be used by over 50% of all the customers, and even worse, the few that do have serious headphones, may or may not complement the specific HP amp design.

2. You refer to 'professional headphones like Sennheiser or Beyerdynamic.'
So you ARE refering to serious sound and SERIOUS money ( US $ 500 + ).

Having spent that much money, a separate HP amp, will Certainly give you Good returns. ( They will probably call for another US $ 500 investment ! )

Now dont forget to add the cost of the interconnects from your Pre amp or CD player to the HP Amp.

Another option is a pair or Electrostatic HPs like STAX, which have their own HP amp unit, which also provides the High Voltage, to the 'cans'.

These will give, IMHO FAR greater transparency, delicacy, deatil, and speed, though the bass is somewhat different from what you are used to listning from a box ( speakers or Dynamic HP enclosures ).

You could buy the entry level STAX "Earspeakers" with energiser, in S'pore for approx Rs 27K after bargaining ....

Listen, listen and listen before you buy.

Heard the new (video ) ipod with its own earbud speakers, with earbud sponge jacket, playing 192K and better mp3 ?

I like it.. and you can walk and excersise with it, unlike a Headphone based system.

Life is FULL of compromises...

Thanks Amp Nut,

For the education. Never knew that a resistor was all that was needed to get a headphone output.

Re Price of headphones: I guess most people wouldn't go beyond $200 for a disposable item. After all, the HPs are for night listening, and we all have high-end speakers for regular listening.

Re the Stax: Do they have two cords, one for the signal and the other for a power supply / built-in battery. Are they power guzzlers? From what I understand, they must be considerably larger than even full-sized headphones.

The Power ( High Voltage ) + Signal are ( now ? ) integrated on a single, flat Ribbon Cable, from the Shelf unit to the Head Phone.

The Extension cable too is a single ( Round but Not Coax ) cable with multiple wires in it.

The power supply is rated at 12 V 5 Amp, so it guzzles as much juice as some laptops... but nothing an auto battery cant handle

Oops ! Forgot to answers yr 2nd Q :

The phones are the same size as regular cans, maybe a bit thicker, but the fit and extended comfort level is great.

Funnily, I seem to feel the need to scratch my ear sometimes, I suspect the high polarising Voltage, gets the hair in my Ear canal doing a standing ovation !

Any other STAX usersd with the same 'feel ? '

Some more Gas on why a dedicated HP Amp will serve better than a 100 Watt power amp feeding cans thru a resistor.

Just look at the typical Power Amp (PA) design compromises.

1. The PA is designed for LARGE Voltage swings ( 28 V RMS for 100 Watts into 8 Ohms ) and Large Output current ( Tens of amperes ).

In contrast, a HP Amp would be Great doing about 6 V to 8 V RMS... even that would be tooo much.

2. The lower current and voltage permit more refined semi conductors to be used ( think of a Race car instead of a dumper truck ) in the HP amp, compared to a power Amp.

3. The HP amp needs to deliver SMALL signals, VERY well, Cross over distortion, and noise shot into your ear from 2 inches away would be rather noticable.

The Head Phone Amp can therefore be designed with its Output stage running in Pure Class A, without in-ordinate power consumption.

4. The Low Voltage swing of the HP amp means less gain required between input and output, and more ( inherently ) linear circuits can be used.

And ofcourse the high ( certainly higher than the HP impedence ) series resistor will yield a VERY poor Damping factor. The Amp + Resistor will therefore have very poor control over the HP driver diaphram ...

Guess Im getting toooo tech ...