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parafeed headphone amplifier

Checks and Setup

There is nothing to setup and adjust for the TORPEDO! Parafeed Headphone Amplifier. However, the TORPEDO! is a true, high-voltage tube amplifier and there are several precautions that should be observed prior to plugging the amp in and turning it on.

  1. Make certain that the PCB and the case are as clean as you can get them. Ensure that solder flux, untrimmed leads, and metal chips/powder within the case and case slots have been thoroughly cleaned. Any of these items could potentially cause a disastrous short.
  2. Ensure that the safety ground is thoroughly connected to the case.
  3. Ensure that you've installed the fuse in the IEC inlet.
  4. Ensure that that the case lid is on top and screwed to the endplates. Ensure that the tubes are secure in their sockets and are not contacting the sides of the case tube holes.
  5. Identify either a power strip or an outlet that will let you cut power to the amp. In case of a short or over-heating, you may not want to turn the amp off with the power switch. The case could be shorted, too.
  6. Have a DMM handy with an earth ground available for one of the probes.
  7. After following the precautions listed above, apply power to the amp by either turning on the power strip, or flipping the switch at the IEC inlet. Do not touch the amp case at this point!
  8. Upon power on, you'll note that the two biasing LED's will come on first, followed by the tubes glowing, then finally - the four LEDs in the CCS sections will light up. The amplifier is pretty much powered-on and ready to go at this point.
  9. Without touching the case yet, use your DMM to see if you can measure voltage between the earth ground you selected earlier and the case of the amp. Try several points just to be sure.
  10. If you read zero or near-zero voltage, then the case is OK to touch and you can proceed with testing the rest.
  11. Turn the amp off, apply a signal source, and turn the amp back on. Wait for the final four LEDs to light and the tubes to glow.
  12. Find an old pair of headphones (ones you won't mind blowing up if the worst happens) and plug them in. With the music source active, slowly apply volume to the headphones.

Some final precautions:
  • Never change tubes with the amp powered on!
  • Never power up the amp with the case lid off!
  • Never operate the amp without the safety ground connected!

If everything checks out, enjoy your TORPEDO!

file last changed:Tuesday, December 27, 2011 6:00:00 AM
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