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RE: PAS 2, Lost high freq w/ mod

There are parts on the selector switch which are in the original RIAA equalization scheme. They need to be removed, because the Curcio modification has all of the equalization parts on the circuit board.

The original Dynaco design had equalization parts on the selector switch because it provided for the preamp to be used with either a moving magnet/iron phono cartridge, or a tape head without a gain stage. To do this it had to be switched between RIAA phono equalization and NAB tape head equalization. It also had a provision (the SPECIAL input) for use of the phono stage as a flat amplifier for use with microphones.

Most users only use phono in their systems, so most modifiers wire the phono input directly to the input of the PAS phono stage without provision for those alternate uses of the phono stage, thus removing switch contacts from the signal path. But in any case if you do the Curcio RIAA modification...or any of the others...those equalization parts need to be removed from the selector switch. Also, the wiring that goes to/from the switch to change equalization among RIAA, NAB and flat, needs to be eliminated.

Follow the instructions from Curcio...or anyone else...to the letter.

GP49

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