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  5. Owner's Manual

Packburn 325 Owner's Manual

Manual is about: AUDIO NOISE SUPPRESSOR

Summary of 325

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    Electronics inc. Audio noise suppressor model 325 owner’s manual packburn is registered in u.S. Patent and trademark office rev 10-1.

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    Electronics inc audio noise suppressor model 325 a single-ended noise suppressor designed to eliminate or reduce noises due to imperfections in and damage to sound recordings in all analog audio media and their digital reproduction, including cylinder, disk, film wire and tape recordings, both monop...

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    Noises first. In the case of recordings containing no transient noise, such as analog master tapes and copies thereof, the continuous noise suppressor will be the only one needed. The continuous noise suppressor is a variable low- pass filtering circuit that responds in accordance with the nature of...

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    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 w...

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    Audio noise suppressor model 325 technical specifications designed for professional installations and for quality home sound systems outfitted to interface with 600 ohm balanced line systems or with the more customary single-ended hi fi systems; provided with xlr professional connectors as well as w...

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    1 table of contents foreword pg: 3 installation of the audio noise suppressor 4 controls (front panel description) 7 getting started 12 technical principles of operation 15 suggestions for optimum processing of historical recordings 17 vertical cut records (edison diamond disc, hill and dale) 20 rec...

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    2.

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    3 foreword packburn electronics, inc. Has been in business for over 25 years, inspired by the late richard c. Burns. What got the company running was dick’s passion for historical sound recordings and inventive playback equipment that would rescue musical nuances in a safe and effective manner from ...

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    4.

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    5 installation of the audio noise suppressor a. The turntable a stereo cartridge needs to be used even for monophonic phonograph records. If a monophonic record is played back using a monophonic cartridge, the first noise reduction stage (switcher) won’t operate to remove noise. For those using the ...

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    6 (d) install a pair of passive equalizers between the preamplifier and the audio noise suppressor. For an example of a design, refer to installation of a passive equalization network ahead of the audio noise suppressor on p. 25. C. Equipment following the packburn a u d i o n o i s e suppressor: si...

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    7 front panel controls 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1 l - left input level 11 power - packburn on/off 2 r - right input level 12 mode - selects how input signals to be processed 3 input level - adjusts meter readings 13 tns – transient noise suppressor (switcher and blanker) on...

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    8 power provides line voltage to the packburn. When in the off position, the left input is directly fed to the left output and also the right input is directly fed to the right output. This means that even when the packburn is not powered, your audio system will have signal continuity. Ans (audio no...

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    9 b. Mode switch this switch determines how the packburn is to process the input signal. In the st (stereo) position, the packburn treats the input as having two different musical signals and so feeds stereo to the l and r outputs. When the switch is set to all of its other positions l (left), r (ri...

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    10 test is normally kept in the off (‘0’) position. This switch provides a way to check the effectiveness of the switcher. In the off position the quietest input signal is always selected by the switcher for playback, whereas in the ‘1’ position the nosiest signal is always selected! The comparison ...

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    11 normal for them to respond to louder passages of music. A 3:00 control setting is a good starting place for most records in fair condition. For 78 rpm records with hiss or long playing records with scratches, higher settings are often beneficial. E. Continuous noise suppressor controls (low, rate...

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    12 getting started 1. Install the packburn between your pre-amp and the stage of your audio system to which the pre-amp was connected. Don’t connect the packburn to the line voltage just yet. 2. Preset these controls as shown : power input level bal. Output level mode turnover rolloff tns test switc...

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    13 5. Turn on just the switcher (noise reduction stage 1) mode tns test switcher blanker cns ans bal. (switcher) rate mon or ver 1 0 1 ← 0 0 1 > > > > the switcher applies only to the mon and ver modes. Stereo records not having much stereo imagery to sacrifice may be played in mon. Stereo recording...

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    14 7. Turn on just the cns (noise reduction stage 3): mode tns cns ans (cns) rate low (cns) rate l r mon ver st 0 1 ← 1 > > > > select as desired. Tns overrides the switcher and blanker switches. Start at the 8:00 (full counter-clockwise) position. Select a quiet passage of music. Adjust low as you ...

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    15 technical principles of operation a. Mode switch in all settings of the mode switch except the st (stereo) setting, the lower frequencies of the left and right input signals to the packburn are mixed below 300 hz turnover at a 6 db/ octave slope. This pretty much eliminates the rumble component. ...

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    16 c. Blanker impulse noises on records are characterized by a high amplitude and a short duration. Their duration is so short that it is chiefly by virtue of their high amplitude that they are perceived as acutely as they are. Thus, a device that will limit noise impulses so that the amplitude does...

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    17 suggestions for optimum processing of historic recordings a. Cleaning optimum reproduction of a phonograph record requires that it be clean. We are not able to recommend one cleaning method or product over another but in general whenever cleaning “caution” is the rule. If the record appears to ha...

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    18 elliptical styli although with louder reproduction of the ticks. Since the packburn audio noise suppressor suppresses the ticks, some owners have found that the conical stylus is optimum in those cases where harmonics greater than about 7 to 8 khz are not present (early acoustical recordings, for...

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    19 center playback, surface uneveness and by signal components introduced by tracking error and tracing error including "pinch effect". Listening to the vertical component can be a valuable diagnostic procedure: turn the mode switch to ver, rotate (switcher) rate fully counter-clockwise, and switch ...

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    20 vertical-cut records a. Switcher vertical-cut records such as pathe and other hill and dale discs, edison cylinders, and edison diamond discs differ fundamentally from lateral-cut records in that the signal is recorded in the bottom of the groove rather than on the two sidewalls. Thus there are n...

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    21 recommendations for preserving perishable media a. First generation media first generation media with limited life expectancy are often transferred in as close to their original forms as possible to non-perishable, often digital media for archiving. The packburn’s mode switch settings l, r, mon a...

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    22 compact discs - tape - broadcasts a. Compact discs cds derived from 78s, from old movie sound tracks or from master tapes that antedate the introduction of encode/decode noise reduction devices are some examples of where the audio noise suppressor has a role to play. Re-equalization of the signal...

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    23 c. Film recordings, wire recordings although we do not have experience with processing either of these media, the blanker should be able to reduce transient noise and the cns should be able to reduce continuous noise. For film whose audio track is monaural, the switcher might have a role to play ...

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    24 the vu meters the vu meters are, strictly speaking, peak reading meters. They are connected following the input level and turnover controls but preceding the balance (bal) control. The purpose of the meters is to assure that the audio noise suppressor is not overloaded. Bal has no effect on the m...

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    25 optimizing other components in your audio system a. Pre-amplifier ahead of the packburn the frequency response of the left and right signals from the pre-amplifier ahead of the packburn need to match for the switcher is to operate to best advantage. 1 set the treble and bass controls on your pre-...

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    26 c. Phase monitoring oscilloscope the cathode ray oscilloscope is a valuable tool for accurately aligning a stereo system used to play back monophonic records or stereo tapes of monophonic records into the audio noise suppressor. Setting the phase monitor oscilloscope: 1. Adjust the input signals ...

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    27 alignment of a tape recorder playback head is most accurately accomplished by pre- recording simultaneously in both channels a series of oscillator tones starting at the low frequency end of the audio spectrum..

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    28 trouble - shooting procedures 1. There is no output signal. Power is 1 (on), and ans is 1 (engaged.) make sure the cables are not crisscrossed, i.E., the one that feeds signal to the packburn has been connected to the l and r input receptacles and the one that feeds signal from the packburn has b...

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    29 4. There is no setting of the balance control that produces a good null. The mode switch is in ver and a monophonic record is being played. The equalization curves of the two input signals being provided to the audio noise suppressor are matched. The audio noise suppressor is provided with profes...

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    30 8. There is not much frequency meter action even though the cns switch is ‘1’ (on) and cns rate is fully clockwise. This could be an indication that the record is especially hissy, or that the high frequency levels in the signal to the audio noise suppressor have been unduly exaggerated. This cou...

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    31 equalization settings traditionally, the inherent equalization curves used for cutting electrical recordings have been specified in terms of a “bass-turnover frequency” and “treble pre-emphasis.” it is intended that the playback equalization curve be the inverse of the equalization curve used dur...

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    32 c. Equalization curves by name name turnover (hz) rolloff (db) published setting nearest packburn setting published setting nearest packburn setting aes 400 400 12 12 ffrr (1949) 250 250 5 6 ffrr (1951) 300 300 14 14 ffrr (1953) 450 500 11 12 lp/ col 500 (lp) lp 16 16 nab 500 500 16 16 orthophoni...

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    33 but may offer a better starting place. Some use a rolloff of 5 db to reduce surface noise. F. Records made between 1925 and 1955 set the turnover and rolloff per the following tables. The need for equalization curves for playback of electrical records has never been controversial but there is sti...

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    34 records made between 1925 and 1955 turnover (t) and rolloff (r) settings 78 ↓ t r 78 ↓ t r 78 ↓ t r banner perfect inconclusive odeon (early) (pre 1947) 300 300 0 8.5 vitaphone (motion picture) 300 950 0 18.5 blue bird 800 10 mercury 400 12 brunswick (rare) (early) (1946-) 1000 500 300 8.5 0 16 m...

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    35 45 ↓ t r 33 ↓ t r 33 ↓ t r columbia 500 16 colosseum 400 lp 12 16 oxford 750 16 decca 750 16 columbia lp 16 odeon 300 8.5 mercury 400 12 concert hall 400 lp lp 12 16 8.5 parlophone 300 8.5 mgm 500 12 cook 500 12 period 500 16 rca victor 800 10 philharmonia 400 12 coral 400 12 polydor 300 8.5 decc...

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    36 input/ output schematic and block diagram for models 323 aa, 325 electronics inc. P.O. Box 226, syracuse, ny 13215 usa ph. 315-476-9121.