[flocchini]

As much as I would like an AC motor controller how about a Headphone amp?

[hagtech]

Yeah, I had been thinking about that too.  The Cymbal was originally started as a headphone project.  But I just couldn't converge on the right way to design it.  

On the other hand, the "Oboe" is in the works.  It is an opamp based preamplifier housed in the BuglePro box.  I figure 3 or 4 inputs, balance & volume controls, and a headphone output.  Probably using a TI buffer chip.  One big board with circuits and ac power supply.  Might jam Bugle style phono stage in it too.

Anyway, that's probably the only headphone amp for awhile.  Wondering if I should add a remote control option.  Could add a bit to the cost.

jh

[GarMan]

Jim,

I can't imagine there being a huge difference between a pre-amp and a headphone amp.  The output would certainly need to deal with a differenct load.

How difficult do you think it would be to modify the Clarinet design so that it also provides headphone capability with the flick of a switch?

Gar.

[ricksc]

A key additional feature of headphone amps is crossfeed to simulate speaker listening rather than the extreme stereo separation that you get with headphones. This makes a huge difference to me, eliminates headphone fatigue.

Rick

[hagtech]

A headphone amp needs a power gain.  Linestage has sufficient voltage drive for most headphones, but not enough current or power.  It would require a lower impedance output.  I think some headphone amps just use cathode followers.  Didn't like that approach myself, prefer a transformer.  But hey, more than one way to skin a cat.

Don't think a Clarinet could be modified too easily.

My present thinking is to use a power amplifier with a low impedance output pad.  In my shop, I use a modified 100W Hafler into a 100/1 ohm resistor divider.  The 100 ohm load is easy on the amplifier, yet gives a reasonable 1 ohm drive to my 32 ohm Grados.  That's a DF of 32.  And the headphones don't have a nasty impedance issue or much back EMF.  The Hafler does what it is best at, providing large signals with low distortion.  The small signal and crossover glitches are reduced by a factor of 100.  I'll do the same thing in my upcoming OBOE preamplifier (solid state like Bugle).  

There's always the Bottlehead and Singlepower headphone amps.

jh