Bass Clip Threshold Control (Bass Clip Thrsh Db); Phase Rotator In/Out - Orban OPTIMOD-FM 8200 Operating Manual

I-7
OPTIMOD-FM 8200 V3.00 UPGRADE MANUAL ADDENDUM
clipping distortion. If it does, you will need to back off the control in question and/or
back off the control.
Final Clip
If you turn up the control for Band 1 (below 100 Hz), you may wish to turn down the
control by an equal amount. This will preserve the relationship
Bass Clip Thrsh dB
between the bass multi-band clipper and the final clipper.

Bass Clip Threshold Control (Bass Clip Thrsh dB)

The 8200 uses Orban's patented multi-band distortion-cancelling clipper system to
achieve a low peak-to-average ratio without creating audible distortion due to clipping.
The bass clipper is part of this system. It is embedded in the multi-band crossover so that
harmonics created by clipping are rolled off by part of the crossover filters. The
threshold of this clipper is ordinarily set between 4dB and 6dB below the threshold of
the final clipper in the processing chain, depending on the setting of the LESS-MORE
control in the parent preset upon which you are basing your full control adjustments.
This provides headroom for contributions from the other four bands, so that bass
transients don't smash against the final clipper and "shut it down," momentarily blocking
any other program material and causing a sound similar to very hard pumping. The bass
clipper also protects against overt intermodulation distortion between the bass and higher
frequency program material.
Some 8200 users feel that the bass clipper unnecessarily reduces bass punch at its factory
settings. To accommodate these users, Version 3.00 software makes the threshold of the
bass clipper a user-adjustable control. The range (with reference to the final clip
threshold) is 0 to –6dB. As you raise the threshold of the clipper you will get more bass
but also more distortion and pumping. Be careful when setting this control; do not adjust
it casually. Listen to program material with heavy bass combined with spectrally sparse
midrange material (like a singer) and listen for IM distortion induced by the bass'
pushing the midrange into the final clippers. In general, unless you have a very good
reason to set the control elsewhere, we recommend leaving it at the factory settings,
which were determined as a result of exhaustive listening tests with many types of
critical program material.

Phase Rotator In/Out

The multi-band limiter receives the output of a three-pole phase rotation circuit. This has
a flat frequency response but a phase response that is nonlinear with frequency. Its
purpose is to make voice waveforms symmetrical, which minimizes clipping distortion
and makes voice (particularly live voice from microphone feeds) sound cleaner.
The downside of the phase rotator is that it subtly reduces the clarity and definition of
music. While this is unlikely to be heard on the vast majority of consumer radios, many
people listening with audiophile-quality gear will be able to perceive it. We therefore
have provided the ability to bypass this circuit, leaving only the phase rotation intrinsic
to the crossover topology in the multi-band limiter. This residual phase rotation is