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M2Tech
EVO PHONODAC TWO
DXD-DSD A-TO-D AND D-TO-A CONVERTER – PHONO PREAMP
REVISION P
A – JULY 2016
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9.3.1. CCIR/IEC for 9.5cm/s and 19cm/s (3¾ ips and 7½ ips) and CCIR/IEC for
38cm/s (15 ips) (IEC1 and IEC3)
CCIR (Comité Consultatif International pour la Radio) was an European Committee similar
to NAB. They proposed an equalization for reel-to-reel tape recorders which was adopted
by most European manufacturers. It has been said by many that the CCIR equalization is
better than the NAB one. Anyway, the choice of one or the other standard is only an option
when recording, as some tape recorders have both equalizers. For playback, the choice
depends on the standard used to record the tape. For the record, all commercial pre-
recorded tapes available on eBay or other auction sites are made using NAB.
9.3.2. NAB for 9.5cm/s (3¾ ips) and NAB for 19cm/s (7½ ips)
NAB proposed two equalization curves for tapes, one for 3¾ ips (curve B) and one for 7½
ips (curve A), plus an amendment for 15 ips which, anyway, was suggested to avoid (7½
ips was the preferred speed for tape recorders used in broadcasts). The EVO PHONODAC
TWO offers both curve A and curve B.
9.4. Acquiring with equalization
When no equalization curve is used, then the clip indicator turns on right before clipping
(that is, when the input signal is equal or higher than the reference level set in the menu).
Should the input signal further increase its amplitude, the ADC saturates. User should
avoid getting the clip indicator turn on at any time during acquisition.
When an equalization curve is used, then the clip indicator may not be consistent with the
VU-meter in the recording software, as the latter indicates the signal level downstream the
equalization, while the clip indicator works on the signal at conversion level (that is, before
the equalization). User should then pay attention to both the clip indicator and the VU-
meter in the recording program. As a general rule, ADC clipping may occur when using
equalization at a VU meter levels such as -2/-3dB. Clip may be acceptable when it
happens from time to time, for very brief time lapses and it's mostly related to record's
"clicks" and "pops".
9.5. Interfacing a cartridge or a tape head
The EVO PHONODAC TWO has an input impedance which can be set to any value between
10 Ohms and 50,000 Ohms by means of a knob on the back panel. This value range
accommodates virtually every source, from line-level ones (47k-50k), to MM cartridges
(47k typically), to medium/high-output MC and moving-flux cartridges (around 15k), to low-
output MC cartridges (10 to 2k). Tape heads also may need a specific impedance loading.
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