SWR Baby Blue Head Manual

Baby Blue Head
GENERAL DESCRIPTION AND DATA
The Baby Blue (head only) was designed and developed for the discerning professional bass player in need of a superior
small bass head for studio and small venues.
The precision electronic section is entirely hand-built and employs everything from vacuum tubes for the preamp section to
discreet solid state components for the power amplifier. Each individual component was selected for reliability and accurate
reproduction of the signals from both electric and acoustic instruments. The features were selected with an emphasis on
studio applications and for use in live settings where a very true signal is needed. By using just the power switch and
volume controls, we believe you will experience the cleanest and most transparent sound you have heard out of your
instrument. The Aural Enhancer and Tone sections are designed to bring out the "character" of the individual musician and
their instrument without altering or masking their inherent qualities and/or techniques.
We truly hope that this "instrument" helps bring out the best in your playing and adds to the enjoyment of your profession.
We would like to sincerely thank all the musicians and engineers that helped us with this project and especially Walter
Becker, Neil Stubenhaus, Phil Chen, Keith Jones, Jimmy Haslip, Michael Rhodes, Phil Lesh, Dan Schwartz, Dann Glenn and
Dwayne "Smitty" Smith.
SPECIFICATIONS - ELECTRONICS
Note: All measurements were taken with a line voltage of 120VAC.
Maximum power at 1KHz under clipping: 120 Watts RMS @ 8 ohms, 160 Watts RMS @ 4 ohms
Power Amp Distortion (1KHz)
0.02% THD, 100 Watts RMS @ 8 ohms
0.03% THD, 100 Watts RMS @ 4 ohms
Intermodulation Distortion @ 8 ohms, 100 Watts RMS, 60/7KHz, 4:1, =0.05%
Frequency Response (power amp): -3db at 10 Hz and 22KHz
System Distortion
(Gain and Master Volume full, enhancer and tone controls set flat,
1KHz): 0.5% THD
Sensitivity (for full output @ 8 ohms, 1 KHz)
Passive/Active Input Jack = 10 millivolts
Active Input Jack = 50 millivolts
Input Impedance
Passive/Active Input Jack = 800K ohms
Active Input Jack = 60K ohms
Effects Return Jack = 27K ohms
Output Impedance
Effects Send Jack = 100 ohms
Line Out Jack = 100 ohms
Tuner Out Jack = 100 ohms
Headphone Jack = 100 ohms
Signal to Noise Ratio
unweighted -72db
(7 millivolts typical, mostly hum)
Equivalent Input Noise: 2.5 micro-volts
FRONT PANEL FEATURES
PASSIVE/ACTIVE
This input can and should be used if your instrument has passive electronics (no built-in preamp). Some pickups such as
EMG, etc. employ batteries for operation and will work perfectly using the Passive/Active input. Technically speaking, this
input should be used if your instrument has an output voltage of 1 volt RMS or LESS. Consult your owners manual or ask
the manufacturer if you are unsure.
NOTE: If you hear a small amount of distortion and neither the Preamp Clip LED or Power Amp clip LED are activated, try
using the Active Input Jack. Some built-in preamps such as those made by Bartolini can be used in the Passive/Active
input.
If you would like to overdrive the first TUBE stage, this can be accomplished by using a preamp between your instrument
and the Passive/Active input. To obtain optimum sound when trying this, make sure the Preamp clip LED is not activated.
If this occurs, turn down your Gain Control. The first preamp stage is NOT monitored by the Preamp clip circuit for this
reason.
ACTIVE INPUT
The Active input jack should be used with instruments having a built-in (on board) preamp that will produce signals over 1
Volt RMS. Known basses that should use the Active input only are Kubicki X-Factor and some Ovation Electrics. Some
really "hot" pickups installed in your instrument may find the Active input more compatible. The best judge is your own
ears. If you are using KEYBOARDS (such as a Roland D-50, etc.) with the Baby Blue, we have found the best input to be