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Vintage threads from the first ten years

Guitar headphone amp

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10/22/1999 1:30 PM
Dan Harris	Guitar headphone amp Hi- has anyone tried making a tube-based "Rockman"? I put together a nice little guit/bass preamp to use in my recording studio to directly drive a channel strip on my console. Does anyone have any hints about adding a headphone driver stage? Would I need an output xfmer?

10/22/1999 1:43 PM

Dan,

You'll find some headphone amp circuits on some of the sites I posted in your other question.

The two common ways to drive headphone would be OTL cathode follower, from say, a 12AU7, or with a small OT as you suggested.

For guitar, I'd probably first try the cheesiest OT I could find, and hope that it's limited frequency response would get me most of the way towards shaving off that "direct to the board" sizzle. ie. compensated output.

Perhaps find an old plastic tabletop AM/FM radio, and salvage the really tiny OT you're likely to find inside.

... Whit

10/22/1999 4:14 PM
JoeA	You might try this website also... http://www.headwize.com/projects/index.htm

10/23/1999 12:19 AM
Dan Harris	Thanks for your help- These are some great and informative sites!

10/23/1999 5:53 AM

Proceed with caution

There are a few things that warrant against a tube-based headphone amp.

1) Do you really want high voltage that close to your head?

2) What people like best about tubes is how they distort when you push them. What audiologists like least about them is how you destroy your hearing when you push them. Anything that doesn't sound good unless you punish your ears is probably technology to avoid.

10/23/1999 7:02 AM

Mark,
A low wattage stereo tube amp like the Harmon Kardon A300 or Dynaco SCA-35 makes a great headphone amp, and has a controllable volume. I wire a headphone jack right to the speaker 8 ohm taps, with a 100 ohm resistor on the positive side, and a stereo pot for volume.

The high voltage stays in the amp, nowhere near the headphones. The max volume is nowhere near where my modern sony home stereo amp would max out if someone accidently cranked the volume knob up.

Ted

10/23/1999 10:45 AM

Mark,

Good point about building a potential electroshock therapy module. I had this conversation with Steve M. a while ago, and I think we agreed that transformer output was preferred to an OTL design because of the high voltage isolation protection. Most of the OTL designs tap off the cathode, which lowers the risk somewhat, but some sort of short in the tube still has the potential to rearrange one's aggressive tendancies and make them a useful member of society once again.

And I still think that a cheap OT would provide some sort of desireable tone modification too...

...Whit

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