Packburn 325 Owner's Manual - page 5
SOME USERS OF THE PACKBURN AUDIO NOISE
SUPPRESSOR
Customers are telling us -
“Simple to use…just sit back and listen!”
“Good hiss, pop and click elimination!”
“Improved musical clarity!
“The controls are easy to operate!”
“Preserves the original sound – serves archival purposes
well”
And for those who have returned their Packburn machines
for upgrading to the model 325 performance level * -
“The blanker and continuous noise suppressor are more
effective even on LP records.”
“There is less low frequency rumble on older records
including vertical-cut records.”
* Consult factory for details
APPLICATION NOTES
78s:
The success of the Audio Noise Suppressor is most
spectacularly demonstrated with noisy 78 rpm disks, as these
present a continuous stream of ticks, pops, etc. the
suppression of which is immediately demonstrable. The same
applies to excessively ticky, scratchy or dirty 45s and long play
disks. You can instantly hear how the Switcher reduces the
crackle. Next you can turn on the Blanker and hear the major
role that it plays in eliminating or reducing noise from
scratches and cracks. Then you can adjust the Continuous
Noise Suppressor for the final improvement. You can even
operate the TEST switch and hear the effect of choosing the
noisier groove wall.
45s and long play disks. You can instantly hear how the
Switcher reduces the crackle. Next you can turn on the
Blanker and hear the major role that it plays in eliminating or
reducing noise from scratches and cracks. Then you can adjust
the Continuous Noise Suppressor for the final improvement. You
can even operate the TEST switch and hear the effect of
choosing the noisier groove wall.
Long Play and Stereo Disks: The improvement of these
requires more patient observation if they have not been abused,
as these have only occasional and pops, some of which,
however, can reproduce as loud as a pistol shot. The Blanker
reduces the pistol shots to innocuous thumps. Lesser noises are
turned into slightly noticeable thuds when they are not totally
eliminated. The Continuous Noise Suppressor effectively and
unnoticeably reduces the hiss.
45s and polystyrene long play records, with their higher hiss
level, are nicely served by the Continuous Noise Suppressor.
Acetates: These can range from worn and deteriorating disks
to extremely quiet, mirror-surfaced beauties. The Audio Noise
Suppressor handles the difficult ones like bad 78s, the good
ones like fine long playing disks.
Vertical-cut Recordings: This includes acoustical disks and
cylinders and electrical broadcast transcriptions. Both the
Switcher and Blanker have a major effect in reducing transient
noises from broadcast transcriptions. With acoustical disks and
cylinders the Blanker plays the major role in reducing the
transient noises. The Switcher can be turned up slightly for some
assistance in the noise reduction. The Continuous Noise
Suppressor can be applied to good effect in reducing the
remaining hiss.
78 Transfers to tape or long playing records: Many tape
copyists and record producers mistakenly transferred 78s with
the RIAA curve, which reduced surface noise but also took much
of the life out of the sound of a voice or instrument. In playing
back from such a source, one can restore the treble equalization
and then use the facilities provided by the Audio Noise
Suppressor to suppress the noises in the proper manner.
Analog Master Tapes and Film: The Continuous Noise
Suppressor is very successful at unobtrusively reducing the hiss
level of analog master tapes or copies thereof.
CDs: We claim no applicability of the Audio Noise Suppressor
to CDs mastered from original digital tapes. However, CDs
derived from 78s, from old movie sound tracks or from master
tapes that antedate the introduction of encode/decode noise
reduction devices all are instances where the Audio Noise
Suppressor has a role to play, whether on the part of the CD
producer or the consumer. If the producer chooses to ignore
what the Audio Noise Suppressor can do to improve his
product, the consumer can do it on his or her own!
Broadcast reception in general can benefit from use of the
Continuous Noise Suppressor if there is audible hiss, whether
the source of the hiss is in the program material or in the
conditions of the reception. Broadcasts of historical material, if
equalized with the RIAA curve (as it often is) can be corrected
and transient noises can also be suppressed.
Regarding copies, In general: The Blanker has to be relied on
to provide whatever transient noise suppression is to be
achieved. However, it must be recognized that recordings
processed into long playing disks or into radio broadcasts are
subject to equalization, compression and limiting and probably
are also several copying generations removed from the original.
All of these circumstances can tend to soften the leading edge of
a noise transient with the result that the detectability of the noise
transient by the Blanker circuit is lowered. Thus, as a general
rule, the Transient Noise Suppressor will be at its most effective
when it can be applied to the original recording.
The Continuous Noise Suppressor will not be affected in the
same way. It will just have more to do.
Carefully made stereo tape transfers of a monophonic disk or
cylinder—especially a digital tape—can provide good results,
as the Switcher can be employed and there should be no
appreciable degradation of the noise transients that would
reduce the effectiveness of the Blanker.
Record Restoration: Application of the Continuous Noise
Suppressor is best deferred to the final stage of processing by
those doing record restoration. In such applications, one would
use the Transient Noise Suppressor at the start. After filtering,
equalization, volume expansion, adding reverberation, etc., one
can then use the Audio Noise Suppressor a second time, this
time by-passing the Transient Noise Suppressor and using only
the Continuous Noise Suppressor.
Quadraphonics — Surround Sound — Ambience Systems
— Electronic Reverberation: The spatial illusion of these
systems is seriously degraded when pops and "pistol shots"
disclose the presence of the ambience loudspeakers. With the
Audio Noise Suppressor one can even play 78s without any loss
of the spatial illusion.