VAC Renaissance 30/70 - Manual (Page 10)

8
TIPS & ADVICE
A Word About Feedback
One rear panel control is provided by which controlled amounts of loop negative feedback may be introduced. The
settings are as follows:
Labelled Comments
0 no global feedback at all
2 2 dB negative feedback
3 3 dB negative feedback
4 4 dB negative feedback
5 5 dB negative feedback
6 6 dB negative feedback
A given amount of feedback reduces the sensitivity of the amplifier by that amount. For example, when switching from
0 dB to 2 dB of feedback, you will need to turn your preamplifier up 2 dB to achieve the same volume.
As small amounts of feedback are introduced, the sound will tend to tighten up and be more controlled. At the same time,
the frequency response of the amplifier/loudspeaker combination will change. With dynamic speakers, 0 dB is often
satisfactory, and excessive amounts will dry and brighten the sound too much. With highly reactive loudspeakers, such
as electrostatics, more feedback may actually produce a more open, airy sound.
There is no "optimal" setting for this control in an engineering sense. While feedback improves static damping and
lowers some forms of distortion, it also weights the relative balance of distortion components to a higher order. In other
words, there's a little good and a little bad about feedback. Listen, and use the setting that provides the best overall
subjective performance of your system.
For further information please read the Tips section entitled Tuning Your System.
A Word About Grounding
The Renaissance amplifier is designed to be used with a three prong power cable. The ground pin connects directly to
the chassis, while the audio ground couples to the chassis as determined by the GROUND switch. In the DC position, the
audio ground ties directly to the chassis. In the AF position, audio and radio frequencies ground information is
referenced to the chassis, but DC is blocked. In the RF position, only radio frequency energy is bled to the chassis, and
audio signals "float". Each of these positions will sound different and may produce different noise floors. The correct
setting depends on how the rest of your system is grounded. Try each, and use the setting that produces the best sonic
performance. Retest the settings any time you change a component in your system or change any power wiring.
Please note that some power line "conditioners" or "enhancers" do unusual things with the power line grounds, and may
thereby create noise and sound quality problems.
For further information please read the Tips section entitled Tuning Your System.