Specifications

division in this and all other 'scope photos. At 1 kHz,
separation measured an impressively high 55 dB fas
opposed to Mclntosh's conservatively guaranteed
45 dB) while at the frequency extremes of 100 Hz
and 10 kHz we measured 37 dB and 35 dB respec-
tively. In Fig. 7, the sweep mode was changed, so
Fig. 7 —Crosstalk components, 5 kHz,
Mclntosh MX 117 Tuner-Preamp
the listener to enjoy reception of marginally quiet
signals while still benefitting from the interstation
muting feature. We meaured an alternate channel
selectivity of 80 dB for this sample. SCA rejection,
under conditions of a modulated 67 kHz SCA sub-
carrier injected at 10% of total modulation of the
main carrier was a very satisfactory 60 dB below re-
ference output level while stereo sub-carrier product
rejection was in excess of 65 dB.
While it is not our practice to spend too much time
testing the AM sections of AM-FM tuners (most of
them are simply so poor in performance that they are
not worth bothering about), we do, as a matter of
course, measure at least the frequency response of
the AM tuner sections. As can be seen in Fig. 8, we
were pleasantly surprised to find absolutely flat re-
sponse down to 20 Hz (most AM tuners tend to roll
off bass severely below 50 to 100 Hz or so). And
while response to 3.5 kHz may not seem like "hi-fi"
reproduction to most listeners, it is actually better
than the response obtained from most of the AM
sections of combination AM-FM tuners or receivers
that we measure in our laboratory.
that this time the sweep was linear, from 0 Hz to 50
kHz, with the lightly visible scale corresponding to 5
kHz per horizontal division. The tall spike at left is a 5
kHz output from the modulated channel. Contained
within that spike is the representation of the oppo-
site (unmodulated) channel output, while to the right
of these are various cross-talk products at harmonics
of 5 kHz as well as any residual 1 9 kHz or 38 kHz
sub-carrier output products. All of these extraneous
output products were at least 60 dB or better below
the desired reference output level. Note, too, that se-
paration at the relatively high 5 kHz frequency was
approximately 40 dB (the difference in "height" bet-
ween the two spikes at 5 kHz-one within the other--
at the left of the display). Muting threshold for this
FM tuner was set to 1 7 dBf (3.9 uV), an ideal signal
level for this type of muting circuit, since it allows
Fig. 8 —Frequency response, AM section,
Mclntosh MX 117 Tuner-Preamp
Preamplifier and Control Section Measurements
Mclntosh Laboratory has chosen to publish their
specifications relating to the audio portions of the
MX 1 1 7 in a way that pre-dates the new IHF/EIA
Amplifier Standards, whereas in our lab we adhere to
the newer standards. Since this would make it diffi-
cult to compare published specs with measured re-
sults, we decided to make both types of measure-
ments. In that way, those interested in comparing
results with those obtained for other products where
the IHF/EIA standard was used will be able to do so,
while those wishing to compare results with Mclntosh
published specs can do so as well. IHF/EIA phono in-
put sensitivity measured 0.45 mV. This corresponds
to almost exactly 2.2 mV as claimed by Mclntosh for
the higher 2.5 volt output. As for the high level in-
puts, 50 mV of signal was required to deliver the
43
Fig. 9 —Range of equalizer controls,
Mclntosh MX 117 Tuner-Preamp