NAB Values for Tape Playback

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hagtech

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NAB Values for Tape Playback
« on: 6 Feb 2013, 08:03 pm »
I always get a lot of requests for modifying a CORNET2 or BUGLE for use as a tape head preamplifier.  What are the values for NAB equalization at 15ips?  Well, I finally had a moment to dig into this...

From what I can find there is a bass pole at 50Hz and a treble zero at 3.183kHz.  The EQ is very similar to the RIAA of a phonostage, but with just one section.  I chose to do the EQ in the first stage.  Overall gain should go up a bit.

CORNET2: Set R205 = 1k and remove R213 and C204. 

BUGLE: Set R10 = 14.3k and R14 = 226 ohms.  R8 = 0 (jumper).  Remove R13 and C2.  Copy in other channel.

I have not actually tried out these values, they are based on calculations and theoretically will get you close.  If anyone tries this, please comment on your results.

jh