Creek T-40 Owners manual

CREEK T40 FM TUNER
GETTING STARTED – Quick Instructions

1. Carefully unpack your T40 from its box. Don’t throw the box and packing away – in the unlikely
event that you may need to return your T40 to the factory for service, the specially designed
packaging will prevent damage in transit.

2. Check that the voltage of your mains electricity supply (house current) is the same as that stated on
the rear panel of the T40. If you are in any doubt please contact your dealer. Permanent damage
to your tuner may be caused if it is connect to a mains supply of the wrong voltage.

3. Attach a mains plug to the end of the 3-core mains supply lead, if one is not already attached. Make
sure that the coloured wires are connected to the correct terminals in the plug. If you are in any
doubt, please consult your dealer. Permanent damage to your tuner (or to you) may be caused if
the plug is incorrectly connected to the cable. Plug in to a convenient socket (receptacle).

4. Connect the audio output of the T40 to the “TUNER” or “RADIO” input of your amplifier. There are
two sets of outputs on the rear panel of the tuner –

¦Two phone (RCA) sockets, left and right, providing low level output (100mV)
¦One 5-pin DIN socket providing medium level stereo output (350mV)

Use whichever is more suitable for your amplifier, or the connecting leads you have. It won’t
matter which you use for now – no damage will occur either to the tuner or to the rest of your
equipment if you use the wrong one, but the sound may be either distorted or too quiet. This is
covered in more detail later in the handbook.

Note: A short lead is provided in the tuner packaging with a DIN plug at each end for
connecting the DIN output on the T40 to the “TUNER” input on our companion amplifiers
CAS4040 and CAS4140.

If stacking the two unis ALWAYS stand the amplifier on top of the tuner, not the other way up. This
is to allow adequate airflow to the heat-sinks at the rear of the amplifier for cooling, and avoids
‘cooking’ the tuner in the amplifier’s heat.

5. Connect an aerial (antenna) to the aerial socket or terminals on the tuner’s rear panel. There are
screw terminals provided for ribbon type cable, and a socket for a 75 ohm co-axial cable. Aerials,
Signals and Noises are covered in more detail later in this handbook, but please note that
however good a Tuner may be, it is only as good as the signal it receives. Good Signals mean Good
Aerials. The CAS3140 will perform better than most tuners using only a cheap indoor aerial, but you
will not benefit from its full capability unless you and your tuner are treated to a good quality aerial
installation.

6. You should now have your CAS3140 connected to an aerial of some kind, a suitable amplifier (and
loudspeakers) and plugged into the mains supply. As a precaution against damage to your
loudspeakers (or your ears) make sure that the Volume control on the amplifier is turned to a low
setting. You can now switch on the amplifier, and select the Tuner or Radio input with the selector
switch.

7. On the CAS3140 make sure that the four push-button switches on the left of the front panel are in
the ‘out’ position. (This is the normal operating position for these switches.)

8. Press in the power switch on the right end of the front panel. The Frequency Display in the centre of
the panel should now have green numbers showing, and the other indicator lights may also be lit.
Don’t worry if they aren’t – that comes next.

9. Turn the Tuning knob on the right of the display until the frequency of a local broadcast programme
is displayed. If you don’t know the frequencies of any local broadcasts, then go to Step 11 below.

10. The Tuning Indicator above the tuning knob should now be lit and, if you turn up the volume control
on the amplifier, you should now be able to hear the broadcast. If so, then move straight to 15
below. If the Tuning Indicator is not lit, then the station you have chosen may not be strong enough,
or you may have selected the frequency incorrectly.

11. Turn the tuning knob slowly to tune along the FM band and you should fid a station which is strong
enough to light the indicator, and be audible. If you are now listening to a broadcast, go to 15 below.

If not, check that all four switches at the left of the front panel are in the ‘out’ position and that the
Input selector of the amplifier is correctly set to the Tuner input, that the TAPE MONITOR switch (if
provided) is in the ‘Source’ or ‘Normal’ position and that the volume is sufficiently loud.

12. Again tune slowly through the band and watch the Frequency Display. You should see that it gets
brighter and dimmer as you tune, and the Tuning indicator (and possibly the Stereo indicator above
the ‘mono’ switch) lights as the display gets brighter. If this is not happening, then check the aerial
and its connections thoroughly, and try again. If the various indicators still fail to respond, go to 14
below.

13. If the Indicators are changing as you tune, but you still cannot hear anything, then carefully check
the connections between the T40 and your amplifier, and that the input to which the T40 is
connected is the one selected by the Input Selector. If all appears correct and there is still silence,
then:

14. If you are still unable to hear any broadcast, call your dealer for help. If you have a knowledgeable
friend to help you, then please ask them to read this Handbook first, as the functions of the controls
on the CAS3140 are very different from most other tuners. There is a detailed description of the
operation of the T40 in the CONTROLS and FUNCTIONS section later in this Handbook.

15. You should now be listening to a radio broadcast through your T40 and you can now get a feel for
some of the various automatic functions it provides. Tune slowly through the FM band, and notice
how the tuner remains silent until the Tuning Indicator lights. Your T40 tuner will normally only let
signals through to the amplifier if they are of adequate audio quality. You will also see that the
brightness of the Frequency Display varies as you tune. The brightness of the display is proportional
to the strength of the received signal – the brighter the display, then the stronger the signal. This
allows you to choose the strongest station to get the best possible reception in areas where there
are more than one station broadcasting the same programme.

So now you can tune your T40 to a station broadcasting some pleasant music, and settle down in a comfortable
chair to read the rest of this Handbook……..

The next section gives a Technical Background to FM broadcasting and reception to help explain the operation of
the features of the T40. If you don’t want to go into this much detail at this stage, then skip straight through to the
section on CONTROLS and FUNCTIONS that follows, which explains the operation of the T40 in detail.

SIGNALS, AERIALS AND NOISES

FM stands for Frequency Modulation, a method of transmitting radio signals. Generally FM is broadcast on VHF
(Very High Frequencies), in the range 88 to 108 MHz (megahertz), although the limits of the band vary from
country to country.

AM stands for Amplitude Modulation, another method of radio transmission, generally used in the LF, MF and HF
bands (Low, Medium and High Frequencies), in the range 150 to 3,000 kHz (kiloHertz). These bands used to be
called Long, Medium and Short Wave, and measured in terms of wavelength in meters, from 2000m to 100m.

Band width is a term which describes a range of frequencies, so that the generally accepted bandwidth of human
hearing is from 20Hz to 20kHz. In audio to transmit audio signals and reproduce them with reasonable fidelity or
quality it is therefore necessary to transmit a sizeable portion of this 20kHz bandwidth, an generally for FM radio
the upper limit is set at about 15kHz as a reasonable compromise between transmitted radio bandwidth and
received audio bandwidth.

Without getting too deeply involved in the technicalities of radio, we can say without too much oversimplification
that, for a given received audio bandwidth there is no difference in quality between AM and FM. However, there is
an enormous difference between the amount of radio bandwidth needed by the two different systems.

With AM, the signal is transmitted by varying or modulating the amplitude of the transmitted radio carrier wave.
The modulation process creates signals on both sides of the carrier frequency, called sidebands, which are equal
to the modulating bandwidth. So to transmit our 15kHz of Audio we need 30kHz of Radio, and to transmit BBC
Radio 4 on 200kHz Long Wave we would use a portion of the band from 170kHz to 230kHz, or practically the
whole band! For this reason the transmitted audio bandwidth on broadcast AM is significantly restricted to well
below 5kHz or so, and this is why AM is thought to be lo-fi, not because AM is inherently an inferior transmission
medium, but because AM broadcasts are transmitted that way, so that enough stations can have a fair share of
the available bandwidth.

With FM, the signals are transmitted by varying or deviating the carrier frequency to either side. The amplitude of
the carrier remains constant, and it is its frequency that changes to carry the audio. The bandwidth used to carry

an FM signal carrying our 15kHz of audio is dramatically greater than for AM, because the maximum deviation of
the carrier to either side of its normal frequency is proportional to the maximum amplitude of the audio being
transmitted, so the limitation on radio bandwidth is imposed not by the audio frequency range but by its dynamic
range. For good fidelity of reproduction, dynamic range Is an equally important factor to bandwidth, and our FM
system will need something like 300kHz of radio bandwidth to transmit our 15kHz audio signals, or equivalent to
nearly one third of the Medium Waveband. To use FM for good quality broadcasting it is therefore necessary to
transmit at frequencies high enough to give enough bandwidth for each channel, hence VHF.

Why, then, is FM used? Well, it has many inherent advantages for transmission of high quality music signals.
Most interference and static tends to be AM by nature, and so an FM receiver can be made to reject this
unwanted AM, and be relatively interference-free. The FM transmitter runs at constant power, and can be
designed to work more efficiently. It is possible to design an FM receiver which detects if it is off-tune, and applies
correction automatically to keep locked to the station being received. This is called Automatic Frequency Control
(AFC). Also F receivers exhibit a phenomenon called ‘capture effect’. If two stations transmit on closely adjacent
frequencies, instead of the receiver detecting both together it will be ‘captured’ by the stronger signal, allowing
clean reception. The ration between the strengths of the two signals need not be very great for this effect to work,
and with the added benefit that VHS signals travel only short distances (the line of sight, more or less) this allows
many stations to share the same channels without interfering with one another. The most important benefit of FM
for Hi-Fi users is that of greatly improved Signal-To-Noise ratio which can be obtained. Again, without getting too
deeply into the technicalities, to transmit information (and speech or music are a form of information) there is a
possible trade-off between three parameters, being rate of information transfer, signal-to-noise, and transmission
bandwidth. In the case of broadcast radio, the rate of information relates to the received audio bandwidth – the
higher the audio frequency we wish to receive, the faster must the modulation take place at the transmitter. To
achieve this fast rate of information transfer with FM we have to use a great chunk of bandwidth, anyway which
means that we can achieve a great benefit in improvement of signal-to-noise performance.

With AM, the weaker the received signal, the weaker also is the recovered audio – eventually the signals just fade
away into nothingness. With FM, however, the recovered audio is independent (to a point) of the received carrier
strength. What happens is that the audio gets noisier with weak signals, eventually disappearing into the noise.
An AM receiver receiving no signals is silent. An FM set under the same conditions produces nothing but (lots of)
noise. Therefore if we make sure that the signal reaching our FM tuner is as big as possible, then we will ensure
that we are receiving as noise-free (and interference-free) a signal as possible, and therefore obtaining the Hi-est
possible Fi. That is why a good aerial system is vital to good Hi-Fi FM reception.

The importance is greatly increased by Stereo. Returning to our simple information theory for a moment, you can
probably see that a stereo signal must contain more information than a mono signal of the same strength. In fact
probably twice as much, since there are now two different signals where before there was only one. Since they
are occupying the same bit of transmission bandwidth as before, and we are now passing information through it at
a faster rate, something in our trade-off must get worse, and it does. In return for our increased information we
lose signal-to-noise performance – the recovered audio gets noisier.

In fact our surmise that two channels in the space of one will mean a factor of two worsening in noise
performance is wildly wrong. Because of the need to make stereo signals compatible with (receivable n) mono
receivers, the extra information to transmit stereo is sent in a clever way, modulated onto a sub-carrier above the
15kHz of mono audio. The combination of this, plus the fact that the mathematics of stereo versus bandwidth are
somewhat more complicated than our surmising would indicate, actually makes for a dramatic increase in noise,
of about 20dB or a factor of 10. In other words, to receive a stereo version of a mono signal requires ten times
more signal at the aerial socket of the tuner to get the same audible noise level. For stereo reception a good
aerial is not a luxury, it is an essential.

Since we have designed the T40 to appeal to those who do not have unlimited resources to spend on their Hi-Fi,
but nevertheless enjoy listening to the highest quality sound possible, we have incorporated several unusual
features to minimise the effects of weak signals. Even so, you will greatly improve your listening pleasure if you
have a good aerial to pull in the signals. Your dealer can advise you on what is necessary for your location, since
VHF reception is variable from place to place. There are also specialist companies who are experts in aerial
installation, and will advise and estimate fairly on your particular needs.

In general if you live within a few Kms of the transmitters then a simple indoor dipole will be fine. Out to about
25Km a 3 or 4-element loft aerial will also be perfectly adequate. Beyond this range it is impossible to generalise.
If you live on high ground, with nothing much between you and the transmitter, then an indoor aerial can give
good results from 80Kms away. Conversely a gasometer or similar large steel structure can completely mask a
transmitter only 3Kms away.

If you live near an airport, or under the path of a busy air-lane then you may experience ‘aircraft flutter’ which is a
rapid fluctuation in signal strength due to reflections of the radio signals from aircraft, and sounds like a fluttering
noise. In severe cases you may see the stereo indicator flashing as the signal varies. It may be possible to point
your aerial at a different transmitter in another direction to overcome this problem, but if there is only one source