5
Overall Stereo Settings: The KBR-3D stereo channel utilizes total attenuation tone controls, thus
if bass, middle and treble are set to “0”, virtually no sound will get through to the power
amp section! This is very versatile but at least one of the tone controls should be set to
“3”.
Bass
Middle Treble
Best signal to noise
2-6
2-6
2-6
Loudest operation
6-9
6-9
6-9
Use lower numbers in quiet settings; use higher numbers at loud venues.
-REAR PANEL CONNECTIONS-
XLR Line Outputs: Signals from the low rotor simulator, the line level inputs, and the full range
stereo channel is sent here. The horn level, as set by the microphone mixer, is also
present (Z out approximately 600 ohms; 70 mV RMS nominal).
Microphone Volume: These two controls mix the rotary channel horn microphones >600 Hz into
the XLR outputs. The level should be set after all parameters on the rotary channel pre-
amp are adjusted. The microphone mixer can be set to zero if external miking is
preferred.
¼” Line Level Inputs: These inputs feed directly to the 100/100 amplifiers and are not affected by
either pre-amp setting. You can connect a mixing board for vocals or any other typical
signal source (420 mV RMS nominal). Volume must be controlled by the signal source.
Dry Rotary Output: This signal is tapped just after the 12AX7EH post-gain control, before the
low rotor simulator volume and bass controls. It provides a line level output to drive
reverbs and other effects where the rotary effect is not desirable. Many “classic” organ
speakers used “non-rotary” reverb in conjunction with rotary sound (420 mV RMS
nominal).
Power Supply: The KBR-3D contains two 100 watt power amplifiers for the full range system
and 45-watt amplifier to drive the horn from>800 Hz. The power supply is capable of
200 watts RMS that is shared between the three amplifiers. Music is almost always
transient in nature and tests have verified the cost/weight effectiveness of this supply in
the KBR-3D. Volume levels requiring sustained 200 watt performance should be
assisted by a PA system, both for hearing protection and for a generally better sound.
Speakers: The KBR-3D utilizes high efficiency 10” 250-watt speakers and 3.5X3.5” Ferro cooled
horns. Reproduction of piano was of primary concern during speaker selection. The
transient nature of piano is one of the best indicators of an amplifier’s performance. The
KBR-3D cabinet angle and speakers provide an incredible 120 degrees of treble
dispersion producing a wide angle of full frequency response.
