Mesa/Boogie Subway TT-800 Owner's Manual page 6

pecially drawn to the story of the 400/400+ models. It became clear that there were additional paths and evolutions that these amps
might have taken had the technology available today been available back then, by combining Randall's classic tube circuitry with
newer technology and manufacturing techniques to create what we think is the best of both worlds. The SUBWAY TT-800 combines
a true 2 channel preamp (a classic "BOOGIE CHANNEL" preamp and a "SUBWAY CHANNEL" preamp) along with our rock solid
800 watt, 2 ohm capable class D power amplifier into a bass amp full of the features that are expected by the top players of today.
The SUBWAY TT-800 is hand built in Petaluma, CA. with the world's finest materials.
OVERVIEW: FRONT PANEL
The SUBWAY TT-800 begins with the front panel input section, which is comprised of the INPUT jack, MUTE switch and HIGH/LOW
GAIN switch. The INPUT jack feeds a high impedance J-FET input "buffer amplifier" which provides appropriate loading for all active
and passive pickups (including most piezo types). The MUTE switch silences the signal from the INPUT jack to the SPEAKER output,
HEADPHONE output and both DI outputs for silent tuning with a tuner connected in line with the instrument or to the TUNER OUTPUT
jack. The HIGH/LOW GAIN switch sets the gain of the input stage, allowing better scaling of the input stage for more precise control
of levels as well as to improve the performance when intentionally overdriving the gain stage circuitry. Also present are the DEEP and
BRIGHT switches, something that was common to some versions of the Bass 400/400+ and Subway models. Indicator (tally) LEDs
are provided for all switched functions. Both channels share a common 12AT7 (or 12AU7) vacuum tube GAIN stage (V1A and V1B),
splitting from this point to feed each channel's respective circuitry.
BOOGIE CHANNEL:
with some of today's most requested features. One concept is the first tube gain/buffer stage (V1A & V1B), common to both channels,
which also drives the pre-eq DI output. A feature pioneered in the Subway series is the precision variable HIGH PASS FILTER, which
blocks unwanted sub-sonic signal, as well as being useful for specific tone shaping functions (especially related to preamp overdrive).
Another feature is the all tube gain stage (V2A and V2B) which directly drives the BOOGIE TONE STACK EQ. Historically, this is the
basic eq/tone stack that Randall has favored going back 50 years, updated with a new mid shift control, and is in part responsible for
the more aggressive voicing of this classic "old school tone" channel. The output feeds a fully buffered pre-channel "master volume"
effects loop (more on this later), channel "master volume", channel switching and output drive circuitry.
SUBWAY CHANNEL:
D-800+ and the WD-800. Of course the variable HIGH PASS FILTER is provided which, similar to the WD-800, directly drives the
tube gain stage (V3A). This is followed by an active Baxandall EQ which consists of LOW and HIGH FREQUENCY shelving bands
plus a sweep mid band. The Subway channel retains the voicing similarities of the D-800, D-800+ and WD-800 models, but with
some subtle differences as well. The output of the EQ section feeds a fully buffered pre-channel "master volume" effects loop (more
on this later), channel "master volume" control, channel switching section and the output drive circuitry.
MASTER SECTION:
"amplification solution" and not just a bass amp. Each effects loop can operate as a standard series effects loop but can also function
as a signal insert point, allowing an external preamp (pedal or rack mount) to be substituted in place of an on-board preamp via the
EFFECTS RETURN jack. These return inputs allow the signal to follow the channel switching and post eq DI routing, so that any
combination of onboard preamps and external preamps may be used seamlessly, the balance between either of the return inputs
may be adjusted via the channel "master volume" controls. Using the onboard preamps, the combination of positions between the
input GAIN and CHANNEL MASTER volume, along with the signal strength from your bass (which is also affected by your playing
style and touch) allows for a wide range of tones and feel, from shimmering clean to overdriven and everything in between. Another
unique feature is the power amp overdrive symmetry control which modifies how the output tube emulation works by altering how
the signal enters and exits the soft clipping portion of the circuitry. As in the WD-800, there is POWER AMP DAMPING control, but
unlike the WD-800, this function is tied directly to the impedance selector switch on the back and automatically tracks the speaker
impedance just like in a tube amp's output transformer. What is POWER AMP DAMPING you might ask? This damping function fine
tunes the inherent looseness/tightness of the power amp which gives more bounce to the feel and makes the amp a little bit more
interactive with the speakers. By integrating it with the impedance selector switch, it's performance remains more consistent from 8
ohms all the way down to 2 ohms.
This channel takes original concepts from Randall Smith's Bass 400/400+ designs and combines them
This channel takes much of its inspiration from our popular Subway series, with elements from the D-800,
The master section of this amp contains some unique features that make this model stand out as an
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