"dave" wrote in message
m...
On 03/17/2014 02:53 PM, William Sommerwerck wrote:
wrote in message
...

Once the playback EQ has been set, it doesn't need adjustment.
In fact, most tape decks //don't// have adjustable playback
EQ! The curve is standardized.

Dolby B dynamically adjusts the curve slightly. Are you trying to
calibrate with a compander running at the same time? When all
else fails use your ears, after listening to your favorite source
material on the same speakers. At 1+7/8 ips it's a miracle they
work at all.

Let's back up. Dolby B does not modify playback EQ. This is fixed.

The OP wanted to trim the playback EQ. But on most decks, this is impossible.
* So that brings the discussion to its logical conclusion.

If you're simply /measuring/ the playback response, then of course the noise
reduction should be shut off.

* When I bought an Otari MX 5050 many years ago, I noticed that the playback
response, using an MRL tape, was off. Looking at the schematic, I discovered
that the playback EQ had the wrong resistor value. I changed it to the
theoretically correct value -- and the response flattened out to what it
should have been. Naturally, the people at Otari told me I didn't know what
the hell I was talking about.