[WarriorAnt]

Are there any Class A headphone amps?  I have a Class A amp in my speaker rig and I love it but I don't know that much about headphone amps.  

 

[baka1969]

The Schitt Asgard, the Matrix M Stage, the easy-to-find Gilmore Lite, the HeadAmp GS1, Luxman has a couple, the Beta22 are a few of the amps biased into Class "A". Then there are tube offerings. Read around and you'll see there are more than a handful to choose from. Being an amp that is Class "A" doesn't necessarily guaranty an exact sound as all the amps I've mentioned sound differently. So decide what you're after and do some research. Good luck.

 

[Uncle Erik]

Yes, quite a few, if not most, headphone amps are in class A.

 

[dan1son]

The reasons for NOT running in Class A are usually related to power consumption.  Class A power amps always draw full power and produce full heat.  Doesn't really matter for minimally powered headphone amps, might as well bias em into Class A (unless they're battery powered of course...).
 
All of that said, most "lower end" opamp based headphone amps are not biased into Class A.  The higher end DIY amps can be, Pimeta, PPA, etc.  Discrete headamps are probably Class A.

 

[Uncle Erik]

dan1son, you're right about class A drawing a lot of power.

The good news is that if you're running class A under 1W (like most headphone amps) the inefficiency isn't so bad.

Now, if you want 100W of class A for speakers, you're going to draw plenty of power. Not to mention generating plenty of heat.

This is one advantage of headphones.

 

[WarriorAnt]

Quote:

dan1son, you're right about class A drawing a lot of power.

The good news is that if you're running class A under 1W (like most headphone amps) the inefficiency isn't so bad.

Now, if you want 100W of class A for speakers, you're going to draw plenty of power. Not to mention generating plenty of heat.

This is one advantage of headphones.

 
I have a Krell KSA 150.  It's a Class A, runs 150W.    It needs a 20 amp line and it runs extremely hot.  Sounds great though.  After I originated this thread I realized headphone amps don't need to produce a lot of power and so most likely Class A would not be a problem.  I like Class A for the excellent slew rate and the clarity of the leading edge of the signal.  
 

 

[Armaegis]

Heh, who needs to heat your home in the winter when all you need to do is play music on your speakers 24/7?

 

[WarriorAnt]

Actually that's what I did.  I live in the desert now so I have to sell the amp.  Can't be running that think when it's 115 outside!

 

[melomaniac]

Quote:

Now, if you want 100W of class A for speakers, you're going to draw plenty of power. Not to mention generating plenty of heat.

 This is one advantage of headphones.

 
but with the bel canto or wyred4sound amps that run ice power, you can put a kilowatt to work and generate almost no heat at all. sounds good too!

 

[scottiebabie]

correct me if im wrong but dont all AB amps run in class A upto 2x bias current or thereabouts. in speakerland thats meaningless but for headphones, it basically means class A power for most of the time.

 

[WarriorAnt]

Class AB amps have a slower slew rates thus blurring the leading edge of the signal.   

 

[Uncle Erik]

Class AB also inserts some distortion where it crosses over in push-pull. The signal changes hands between two devices and there's a little distortion when that happens.

 

[ford2]

Quote:

 
but with the bel canto or wyred4sound amps that run ice power, you can put a kilowatt to work and generate almost no heat at all. sounds good too!

Ice power is a marketing name for a T amp.

 

[melomaniac]

Quote:

Ice power is a marketing name for a T amp.

@ford2, no you got that exactly backwards.
 
- anyway, back on topic: the culture of efficiency has brought us ergonomics, fordist scientific management, outsourcing, mass lay-offs, six sigma, and lean hierarchies - yet it remains an observable fact that in some cases (and it's up to you to decide whether to generalize from here), the kind of inefficient (even wasteful) solution, like pure class A amplification, yields more satisfaction. sure, environmentalists and engineers can agree at least for this once that class A puts out more heat than sound - but it's great sound. unfortunately, a century of training in terms of efficiency has left too little room for concerns about quality.

 

[Frihed89]

All SET amps run all-Class A. Many Woo and all Eddie Current tube amps are SETs.