Treble - Mesa/Boogie TransAtlantic TA-15 Owner's Manual

FRONT PANEL: Controls & Features
expect the same type of response you would find with these heavier sounds as you would from a 100 watt amp. The TA-15 is indeed
mighty in its class... but those little EL84's can't handle massive amounts of both preamp gain and huge low end like an amp running
the larger octal-based 6L6 or EL34 type power tubes. Running the GAIN control high in the 15W and 5W Modes in perfectly fine to
do, it just won't keep the attack very focused... especially as you increase the playing loudness.
NOTE - CHANNEL 1: In Channel 1 the VOLUME control is both the front end (GAIN) control and the playing loudness or "master"
control as well. We wanted to pay tribute to these sounds in the most reverent way and there was no master volume control on the
original amplifiers - so as you turn up the VOLUME control in CHANNEL 1 - you are adding (gain) saturation AND turning up the
playing volume. Purists have long identified with this "no master" scheme - citing its more urgent response, clarity and dynamic touch
sensitivity. We agree with these observations to some degree – for these types of circuits – but there is little doubt that the trade-off
for this stripped "no-master" approach is difficult to overlook when it comes to the flexibility department.
So we gave you a choice by including a cool new feature for this type of circuit. When you need the old-school response of the original
"no-master" scheme and the gain versus volume issues that inherently arise from this scenario are not a problem... crank it up and
Rock!
But for those times when you do need control over the gain and saturation independent of the playing volume... pull the CUT control
out and... problem solved, you now have a MASTER volume control! The CUT is preset to about 1/3 of the way on (rolling off just a
little top end) and the same pot now functions as a fully independent MASTER volume control.
Again...Pushed In, the CUT/PULL MASTER control functions as a CUT control (rolling off high frequencies as you increase the
control clockwise - almost like a reverse PRESENCE control). Pulled Out, the CUT/PULL MASTER control becomes an inde-
pendent MASTER volume.
This "mod" to the original "vintage" architecture greatly enhances the flexibility of both NORMAL and TOP BOOST Modes and allows
you to use them for many more sounds and footswitchable scenarios. It opens up the landscape for these sounds to be applied in
new ways and allows them to interface to the modern world of sounds and yet retain their expressive charm and harmonic identity.

TREBLE:

This control, while being the second most powerful control in the preamp, is very simple to operate... and when you've
dialed in a little too much, it's easy to tell right away. The TREBLE controls how much of the high frequencies in the preamp will be
blended in to the signal. This is another control to use in the middle ranges to produce the best balance of tone and
noise. The TREBLE can bring in unwanted noise (hiss) when set to the extreme high end of its range (3:00 – 5:30)
so avoid setting the TREBLE this high whenever possible.
Like the GAIN, the best sounds are found with the TREBLE in it's middle range where an equal blend of highs from
here are mixed in with the lows from the BASS (and GAIN). If you need things brighter in CHANNEL 1 - try leaving
TREBLE BASS
the CUT control set low (9:00 – 7:00). The top end that comes from there comes later down the line in the signal
path - closer to the power section - and will produce less likelihood of noise and task the preamp tubes less.
Very high settings of the TREBLE control will increase the likelihood of microphonic tubes to start making noise and begin ringing or
feeding back. It just adds too much top end into the signal path early and this is then amplified again and again making any sensitive
1.25 A
SLO
BLO
tubes show their weaker side. This will be most critical in TOP BOOST in Channel 1 and both HI 1 and HI 2 in Channel 2 where the
CAUTION!
higher gain present will put more scrutiny on the preamp tubes.
TUBE GUIDE
4 x 12AX7
A T
In the TOP BOOST Mode of Channel 1 and the HI 1 Mode of Channel 2 you may find that the TREBLE wants to be set a bit lower LL UBE
2 x EL 84
than in some of the other modes and it is not uncommon to find it set below11:00 for many great sounds... especially solo tones.
NORMAL TWEED
HI 1
TOP BST HI 2
25W 25W
FT
SW
15 15
PULL
CUT / MASTER
5W 5W
T A
RANS TLANTIC
A
MPLIFIER ®
TA-15
CAUTION: CHASSIS SURFACE MAY BE HOT!
(Continued)
GAIN TREBLE BASS
WARNING!
PATENTED
H P , CA
ANDBUILT IN ETALUMA
PAGE 8
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™
POWER
STANDBY
MASTER
SPEAKERS
6,621,907
7,173,488
8 OHM 4 OHM
7,602,927
ON
ON