Sound Performance Lab GOLDMIKE MK2 2485 - Manual (Page 18)

18 GoldMike MK2
Solid state and tube stages
The solid stage preamp section is based on a fully discrete,
balanced instrument amplifier and operates 12 single transis-
tors in class A mode. A sophisticated circuitry ensures a nearly
constant frequency response at any gain level. With an impres-
sive slew rate of more than 200V/µs the solid stage is capable to
amplify highest frequencies and fastest transients with almost
no distortion, which is crucially important to achieve a realistic
sound experience. Coupling condensers were used as spar-
ingly as possible to avoid their inherent disadvantages such as
diffuse sound, slurring and loss of dynamics. To eliminate DC
artifacts, these are replaced by servo circuits operating outside
of the audio signal paths.
An op-amp subsequently converts the instrument amplifier’s
output signal into an unbalanced one, which is then fed to the
tube. Here an additional +6 dB tube amplification is added,
switchable to +12 and +18 dB with the Tube Amp function.
The tube type—a Sovtek® 12 AX7 LPS—was also selected after
extensive measurements and listening tests. This tube type
outclasses the standard 12 AX 7 by far and delivers an open,
transparent sound, excellent noise values and is especially reli-
able. An impedance converter adapts the tube’s high-imped-
ance signal to the following stages.
Output Stage
The output stage can drive very long connections (depending on
cable capacities, up to several hundred yards). The max. output
level is at +26 dBu, allowing plenty of headroom to drive subse-
quent converters.
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