Tannoy ellipse Owner's Manual - page 12
4.4:
ACTIVE CROSSOVER
The integrated active crossover, which splits the input signal into LF and HF separate amplification channels, has been designed
using a dedicated computer simulation program. The result is an unconventional topology giving optimum electronic transfer
functions, i.e. achieving the desired target response when combined with the acoustical responses of the LF and HF units in the
actual cabinet.
Thanks to the advantages of the Dual Concentric principle, filters with low phase variations in the overlap frequency range can
be used without the detrimental effect on the spatial dispersion that occurs with conventional multi-way speakers. As a result
the group delay can be maintained practically constant over the whole frequency range, essential to provide a good transient
response and an accurate stereo image. Such a degree of optimisation and accuracy in matching the crossover to the drive unit
cannot be achieved passively, without inducing significant loss of sensitivity and resulting in highly inconsistent performance due
to the variations in the impedance of the drive units.
4.5:
BASS PORTS
Ellipse monitors have bass ports located on the front baffle. You should keep the back panel of the monitors at least 150mm
(6") away from the nearest wall surface to avoid the monitor coupling with the surface and increasing the bass response in a
manner that results in a bass light mix.
If you cannot avoid being close to the wall or if you're using a separate subwoofer, you may wish to consider plugging the port
tubes with closed cell foam-rubber plugs supplied. Because the ports aren't needed if the monitors are coupled to the wall or
are being used with a high pass filter, you won't be losing any bass performance and you can improve the mid-bass response
by plugging the ports.
4.6:
SENSITIVITY CONTROL
The sensitivity control on the rear panel provides input gain adjustment, and it may seem strange that you turn it clockwise
towards a negative figure (-10dB) or anticlockwise towards a positive one (+4dB). That's because it tells you the nominal signal
level needed to drive the system to full power at each end of the range. We kept the conventional operation of a volume control
- it gets louder when you go clockwise - but resisted the temptation to calibrate from 0 - 11. The sensitivity control allows the
monitor to be used with any professional or semi-professional equipment, with a balanced or unbalanced output signal. See
section 3.4, Setting the Level.
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That's a fairly common arrangement in integrated active near field monitors, because it's great for making best use of available
amplifier power and conferring some protection to the LF driver, but what if you want to be aware of what's going on below
the turnover frequency of the LF hi-pass? The downside of this kind of alignment is that you may be working with signals in the
mix that have subsonic VLF content. In a conventional passive speaker and external amplifier set-up, you'd know about it because
of the excessive slow cone movement that would be pretty obvious to see.
This kind of unwanted VLF content saps amplifier power and can cause damage to whatever speakers out in the world will be
reproducing the track. It can happen on dialogue, music or whatever - think about a spoken "P" causing trouble because of
inadequate pop-shielding, a subway train passing under the studio during a big symphonic moment and no-one noticing, or
even a drum loop sampled from warped vinyl. There are plenty of subsonic signals waiting to disrupt your work, but you don't
want to impose a blanket remedy by inserting a 50Hz hi-pass filter on the entire mix.
That is where the VLF indicator in the Ellipse comes into play - any sub 20Hz signals above an innocuous level will cause the
LED indicator to flash yellow on every positive and negative half cycle of the offending signal component. You may want to look
into eradicating the problem at source, but at the very least, you can set about finding which track is culpable and filter it out.