Esoteric Sound Re-Equalizer Owners manual

OPERATING MANUAL

FOR

REK-O-KUT

RE-EQUALIZER

PRICE: $5.00

INSTRUCTIONS FOR OPERATION OF REK-O-KUT RE-EQUALIZER

INTRODUCTI ON:

Modern preamps are designed solely for today's microgroove, RIAA equalized recordings. In the 1950's,
they included sw itches providing seve ral diffe rent RECORD COMPENSATIONS. The more expe nsive
units had two switches labeled TURNOVER and ROLLOFF. Turnover refers to the bass boost that must
be applied to compensate for the diminishment of bass during record cutting to avoid crosscutting of the
grooves. Rolloff refers to the treble loss to compensate for high frequency boost applied during record
cu tting. T he be nefit of the la tter is a reduction of sur fa ce no ise du ring play.

Before 1954, there were a variety of recording characteristics, such as AES, LP, NAB and FFRR. Most
were used fo r a brief period, say between 194 0 and 19 54. Before 1940, most re cords were cut flat with
only a low frequency turnover below from 300 Hz to 800 Hz. This also applied to broadcast transcriptions
and Vitaphone-type recordings used before sound-on-film. So, if you play a pre-WW II 78 rpm record
through a modern preamp, you are actually effectively playing it with a scratch filter whose cutoff begins at
2200 Hz. This accounts for the lack of highs and slightly muffled voices experienced with these records.

One way of dealing with the equalization problem is to use a graphic equalizer, but it is very difficult to get
acc urate resu lts by this method. Another way of dealing w ith the record com pensation problem is to
modify your modern stereo preamp with an equalization switch for both RIAA and other compensations,
but it may spoil the cosmetics of your $1800 preamp.

There is also the problem of what to do with recordings of vintage discs made off of modern RIAA phono
amplifiers. They will suffer from the frequency response distortion caused by the RIAA amplifier and they
cannot be played through the phono input of a properly equalized preamp.

The RE-EQUALIZER solves this. It is used after the RIAA phono stage, and connects to the system like a
comm on graphic equalizer. It will then compensate any signal source for proper equalization. The RE-
EQUALIZER allows the use of any phono a mplifier an d will no t degrade th e per fo rmance of any
audiophile unit.

CONNECTION:

The RE-EQUALIZER should be con nected to
the stereo system just like any other auxiliary
sound processing component. De-clickers,
such as the Packburn 323 or Esoteric Sound
SURFACE NOISE REDUCER, must alw ays
precede the RE-EQUALIZER. If tape
recording is not used, connect the RE-
EQUALI ZER in the tape monitor path. If tape
recording is desired, connect the RE-
EQUALIZER in the tape monitor path (Fig. 1)
and use a "Y" connector to feed its (or
associated equipment's) output to an unused
"Aux" inp ut. Tape p laybac k will be via this
"Aux" input. W ith the tape monitor switched in,
you will hear via your speakers the sound that
is being processed.

If your preamp/amp/receiver does not have a
separate "Aux" input, eliminate the "Y"

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connectors and connect directly into the recorder, and connect the recorder's output to the amp's "Tape
In." Then for no rmal listening of Re-E qualized or otherwise pr ocesse d sound monitor the tape recorder. If
the tape recorder has a "Monitor" switch, it must be in "Source" to do this.

CONTROLS:

The front panel has three controls: Turnover, Rolloff, and Bypass. The Turnover has eight positions:
FLAT, 300 Hz, 400 Hz, RIAA, Lp, and 700 Hz. The Rolloff also has eight positions: FLAT, -5 db, -10 db,

-12 db, RIAA, and NAB. The BYPASS switch provides a hard wire connection from input to output with no
intervening circuitry. When switched to “IN,” the two inputs are connected together providing mono
operation. This reduces some noise and facilitates recording.

Turnover (FLAT) - Can be used with acoustical 78 rpm records and cylinders. Then use graphic EQ for
best sounding bass. Acoustic recording bass compensation is highly subjective. Suggest you use 300.

Turnover (3 00 Hz) - This is used for Columbia brand and manufactured electrical 78 records, London
FF RR 78s, B BC broadcast tran scrip tions, many pre -WWII re cord s & transcr iptions , early Wester n Elec tric
products. Also, it is useful for improving bass on acoustical records.

Turnover (400 Hz))(AES) - Some post-WW II 33s, 45s, 78s using the AES characteristic.

Turnover (500 Hz)(RIAA) - Mos t post- 1935 US 78 s, bro adca st tran scriptions a nd als o for Orth oaco ustic
and NAB transcriptions.

Turnover (500 Hz, modified)(LP) - For early Columbia and some other LPs.

Turnover (7 00 Hz) - Used mostly by RCA for early RCA-Victor 1950s LPs and 45s, 1931 vintage Victor
LPs. Helpful with acoustic records provided there is a sharp rum ble filter.

Rolloff (0dB)(FLAT) - For aco ustic al records and all early (pre -1938) electrical 78s a nd transc riptions. A
low-pass (scratch) filter is useful in conjunction with this setting.

Rolloff (-5 dB) - This is for a -5 db drop at 10 KHz. Used for some post-1938 78's, FFRR 78s, or to soften
noise on early recordings.

Rolloff (-10 dB) - Used for some post-1938 78s, early LPs, such as RCA andLondon.

Rolloff (-12 dB)(AES) - This is used for some post WWII records employing the AES characteristic.

Rolloff (-13.7 dB)(RIAA) - For most modern records.

Rolloff (-16 dB)(NAB) - For early Columbia LPs and all NAB and Orthoacoustic transcriptions.

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REC OMMENDED SETTINGS (see tables):

These are re commendations , but not written in stone. As doc umentation of recording curves is difficult to
track down, some experim entation may be called for. Be particularly observant of matrix numbers
surrounding the label area and record labels for dating records.

Tables for record compensation settings were published in most early hifi magazines (“Dialing You Discs”
in High Fidelity) but are often fallacious. Th ese turn up occas ionally and may be consulted. In
"Conversations With Toscanini," by B. H. Haggin, many subjective suggestions are given for playback of
Toscanini discs.

HINTS ON USE:

One advantage of the RE-EQUALIZER is the ability to use it on tape recordings of vintage records made
with RIAA equalized preamps. Do not trust all transcription and record labels. Also, many small recording
company and radio station engineers seemingly didn't understand the technology and often employed no
pre-emphasis on recordings labeled as NAB. This has been found to occur even on discs cut in the
1960's! Many pre-WWII radio shows which were recorded with flat highs were re-syndicated again in the
late 40's and 50's. As original masters were normally used, the re-release will require a flat Rolloff even
though the label states NAB or Orthoacoustic! This is also true for post-WWII 78s. Play LP reissues of
78s, as on RCA Bluebird, with the Flat Rolloff position and you will be in for a pleasant surprise.

You may find many discs that do not fit the tables or are ambiguous. For these, you will have to let your
ear be your guide. Western Electric, Columbia, and non-US com panies tended to use 300 H z Turnover.
Listening to the material will often suffice to impress you whether to use 300 Hz or 500 Hz. Once the low
end is determined, try various Rolloffs. Almost all early electrical recordings were recorded with flat
response. If noise proves a problem try more than the recomm ended Rolloff.

Whe n playin g olde r or ab used recor ds tha t require les s Rollo ff, i.e., F lat, -5, -8, a sig nifica nt increase in
noise level will often be noticed due to surface noise. In these cases, a high frequency, lo-pass, hi-cut, or
"scratch" filter is recommended. Don't forget that when playing a flat cut record with an RIAA preamp, you
are actually effectively using a scratch filter that is some 13.7 db down at 10 KHz. With these types of
records, with let's say a 7.5 KHz scratch filter and the RE-EQUALIZER set to F LAT , you will b e gain ing in
highs between 2.2 KHz and 7.5 Khz. Although the scratch filter is employed, its use with the RE-
EQUALIZER may result in significantly more highs than with a standard RIAA preamp and no filter.

W hen playing vertical-cut records, such as Edison or Pathe, switch one pair of leads (non-earth ground) of
a stereo cartridge used for play. If not done, the channels will largely cancel when the RE-EQUALIZER is
switched to “IN,” resulting in very low volume.

Most comm ercial, pre-RIAA records h ad matrix numb ers that were of larger, often cursive fonts, and were
raised from the surface. Their characters appeared to be made with punches. Most RIAA discs had
smaller, more Arial fonts and appeared to be etched into the surface. You can use a toothpick and
magnifying glass to help determine this.

LONDON/DECCA OLDE R MATRIX LOND ON/DECC A NEW ER M ATRIX

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