TRACE ELLIOT 715 - Additional Information; Power Amplifiers and Anti-Clipping; Combo Unit Specifications

ADDITIONAL INFORMATION
POWER AMPLIFIERS
The power amplier sections within these Trace Elliot products are high efciency advanced designs. They
are designed to withstand rigorous use and include protection for over-temperature, over-current and short-
circuits.
Although designed to run comparatively cool, the high power versions do contain fans. These blow cool air
from the outside across critical components and back out through the vents. Therefore, the vents on the front
and rear or sides of these units should not be obscured. Please bear this in mind if you intend to rack-mount
or ight-case your amplier.
ANTI-CLIPPING CIRCUIT
To prevent prolonged power amplier clipping which, apart from sounding highly offensive, is the easiest
way to destroy speakers, the power amp sections are immediately preceded with a two-stage circuit to control
the signal level from the preamp. The rear panel of each amplier will show two RMS power ratings, one
for transients and the other for steady-state signals. The circuit is inactive until the power level reaches the
lower rating. At this point the rst stage of signal amplitude control is applied. This works like a fairly slow
compressor that is relatively unobtrusive and will gently control the signal level to keep it from clipping the
power stage. To catch transients, a second stage is applied at the higher power level. Between the two stages
the signal level is controlled to keep clipping to a minimum without the circuit being too audible in affecting
dynamics. The 12 Band products incorporate a valve as part of this circuit.
COMBOS
Various combinations of preamp, power amp and speaker congurations are available within the range. The
particular combination of your unit will be marked on the front panel.
All the amplier sections are designed to deliver their full rated power into 4 ohms. Therefore a combo tted
with a 4 ohm internal speaker will deliver the full power into its own enclosure. Although capable of driving
extension cabinets, the connections on the rear mean that the user has to disconnect the internal speaker before
connecting to an extension cabinet.
Combos tted with an 8 ohm internal speaker will deliver approximately 50% – 60% of the rated power into
their own enclosure. Connecting to an 8 ohm extension cabinet will bring the overall impedance down to
4 ohms and will therefore deliver 100% of the rated power. The connections on the rear of these combos
allow an extension cabinet to be connected while keeping the internal speaker connected. This arrangement
is ideal for using the combo on its own at rehearsals, recording sessions and smaller gigs, then connecting an
extension cabinet, such as a 1518 or 1028H, to give more power when required at larger gigs.
Combos tted with switchable high frequency horn attenuation (e.g. 715X, 1215, 1210) benet from the user
being able to set the horn on full, half or disconnected. The setting will depend on playing and music styles,
preamp settings and personal choice.
On 12 Band units, when using the VALVE drive at high DRIVE settings it is advisable to experiment with the
setting of the horn attenuation. Generally for more traditional warm or overdriven bass tones the horn should
be set low or off.
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