SMART Phono ReMastering Equalizer

SMART Phono ReMastering Equalizer^TM

Model RME 1950

Today's modern audiophile equipment can sometimes be frustrating to owners of old records, especially when their collection includes many old 78's or old Lp's. Almost all modern preamps are designed solely for today's microgroove, RIAA (Recording Industry of America Association) equalized recordings.

In the 1950's, almost all high-end phono preamplifiers included selector switches having several different "record compensation options." Occasionally, on the more expensive units, this function was divided among two switches labeled "Turnover" and "Rolloff." Turnover refers to the bass boost that must be applied in the preamp to compensate for the purposeful diminishment of bass during record cutting to avoid crosscutting of a groove to an adjacent groove. Rolloff refers to the treble loss the preamp must provide to compensate for high frequency boost applied during record cutting process. The benefit of the latter is a reduction of surface noise during playback.

Until 1954, there were a variety of recording characteristics applied to records as they were being cut, such as AES, LP, NAB and FFRR. Actually, most of these compensations were used for a relatively brief period, between 1940 and 1954. Before 1940, most records were cut flat with a low frequency turnover of 6 dB per octave below 300 Hz to 800 Hz. This also applied to broadcast recordings (transcriptions) and motion picture Vitaphone type recordings used before sound-on-film. Therefore, if you play a pre-WWII 78 rpm record on 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. Of course, after 1954 all records were recorded to the RIAA characteristic for uniform record compensation on all modern phonographs.

One way of dealing with the equalization problem is to use a graphic equalizer, but it is very difficult to get accurate results by this method. Another way of dealing with the record compensation problem is to modify your modern stereo preamp with an equalization switch for both RIAA and compensation curves used in early recordings. The later requires a thorough knowledge of filter circuitry and electronics.

There is also the problem of what to do with tape recordings made from modern RIAA compensated phono curves. They will suffer from the frequency response distortion caused by the RIAA curves and they cannot be played through the phono input of a special or antique record amplifier.

Because of these problems, the ReMastering Phono Equalizer was designed. It follows the RIAA phono amplifier and is connected to the system like a high level graphic equalizer would be. It will then compensate any signal source for correct equalization. The ReMastering Phono Equalizer permits the use of any phono preamplifier and will not degrade the performance of any audiophile system.

CONNECTION:

The ReMastering Phono Equalizer should be connected to the stereo system just like any other auxiliary sound processing component. De-clickers, such as the SAE 5000 or Burwen TNE 7000 always precede the ReMastering Equalizer. If tape recording is used, connect the ReMastering Phono Equalizer in the tape monitor path. If tape recording is desired, connect the ReMastering Phono Equalizer in the tape monitor path and use a "Y" connector to feed its (or associated equipment) output to an unused "Aux" input. Tape playback will be via this "Aux" input. With 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" connectors and connect directly into the recorder or, and connect the recorders output to the amps "Tape In.'' Then for normal listening of Re-Equalized or otherwise processed sound, monitor the tape recorder. If the tape recorder has a "Monitor" switch, it must be in "Source" to do this.

When connecting to a computer sound card to make CD transfers, connect both outputs from the RME1950 directly into both high level inputs of the sound card. A CD must have two channels even though the material being recorded is monaural.

If you are using a Laser Turntable with a high level output option, then connect the LT audio outputs directly to the RME1950 inputs using a quality stereo cable. This version of the LT has built-in RIAA correction. If you are using an LT with low level outputs then a preamplifier must be used. The outputs of the preamp are connected to the inputs of the RME 1950.

CONTROLS:

The front panel has three controls: Turnover, Rolloff, and Bypass. The Turnover has six positions: FLAT, 300 Hz, 400 Hz, RIAA, Lp, and 700 Hz. The Rolloff also has six positions: FLAT, -5 dB, -10 dB, -12 dB, RIAA, NAB.

The BYPASS switch provides a hard wire (stereo) connection from input to output with no intervening circuitry. When the switch is in the "IN" mode both output channels from your preamplifier are summed together for a mono output on both channels of the RME1950. The signals now pass through the filters and you may select the setting you desire.

Turnover (FLAT) - Use this setting for most acoustical 78 rpm records and all cylinders.

Turnover (300) - This is used for Columbia brand and manufactured electrical records, London FFRR 78's, BBC broadcast transcriptions, many pre-WWII records & transcriptions, early Western Electric products.

Turnover (400) characteristic - Some post-WWII 33's, 45's, 78's using the AES recording curve.

Turnover (RIAA) - Most post-1935 US 78's, broadcast transcriptions and also for Orthoacoustic and NAB transcriptions.

Turnover (700) - Use with some early electrical 78's and some 1931 vintage Victor Lp's. Also, it is useful for improving bass on acoustical records. Provided there is a sharp rumble filter.

Rolloff (FLAT) - For acoustical records and all early (pre-1938) electrical 78's and transcriptions. A low-pass (scratch) filter is useful in conjunction with this setting.

Rolloff (-5) - This is for a -5 dB droop at 10 kHz. Use for some post-1938 78's, FFRR 78's and BBC transcriptions or to soften noise on early recordings.

Rolloff (-10) - This is for a -10 dB droop at 10 kHz. Use for some- post-1938 78's, early Lp's. such as London & RCA-Victor.

Rolloff (-12) - This is used for some post -WWII 33's, 45's, and 78's employing the AES characteristic.

Rolloff (NAB) - For early Columbia Lp's and all NAB and Orthoacoustic transcriptions.

These are recommended, but not written in stone for setting the ReMastering Phono Equalizer to accurately play back various records. As documentation of recording curves is difficult to track down, some experimentation may be called for.

Tables for record compensation settings were published in most early HiFi magazines and some books. These publications may be found occasionally and should be consulted. An example of one such article, "Conversations With Toscanini," by B. H. Haggin are given many subjective suggestions for the playback of Toscanini discs.

Overlaid plot of various curves

Various settings of the Turnover and Rolloff filters

One advantage of this ReMastering Phono Equalizer is the ability to not only to be used with phono records, but on tape recordings of vintage records made with RIAA equalized preamps.

Be skeptical of all transcription and record labels. Many pre-WWII radio shows, recorded with flat highs, were re-syndicated again in the late 40's and 50's. Because the original masters were normally used, the re-release will require the flat Rolloff even though the label states NAB or Orthoacoustic! This is also true for post-WWII 78's. An example is RCA-Victor 78’s of Glenn Miller, which was originally recorded in the 30's on Bluebird or Victor. You will find that a Rolloff of “FLAT” or “-5” is satisfactory. Many of the compensator settings specified in various old tables would have stated that -10, or the AES setting was the proper Rolloff to use. Try playing many Lp reissues of 78's, as on RCA Bluebird, with the “Flat” Rolloff position and you will be in for a pleasant surprise.

Many small recording companies and radio station engineers apparently didn't understand recording and playback curves and often employed no pre-emphasis on recordings but labeled them as NAB. This is a common occurrence even on discs cut as late as the 1960's!

You may find many discs that do not fit the tables or discs that do but for whom the table is ambiguous. On these, you will have to let your ear be your guide and try to determine if the manufacturer could have been Western Electric, Columbia, or non-US. These often used 300 Hz Turnover. Listening to the material may suggest you use 300 Hz or 500 Hz. Once the low end is determined try various Rolloff positions. Almost all early electrical recordings were recorded with flat response. If noise proves a problem try more than the recommended Rolloff.

When playing older or abused records that require less Rolloff, i.e., Flat, -5, -10, a significant increase in noise level will often be noticed due to surface noise. In these cases, an external high frequency, lo-pass, hi-cut, or "scratch" filter is recommended. An excellent product for this purpose is the ELP model LHF-3 filter offered on this website. Don't forget that when playing a flat cut record with an RIAA preamp, you are actually effectively using a scratch filter that is 13.7 dB down at 10 kHz. On these types of records, with a 7.5 kHz scratch filter and the ReMastering Phono Equalizer set to Flat, you will find an increase in highs between 2.2 kHz and 7.5 kHz. Although the scratch filter is employed, its use, in combination with the ReMastering Phono Equalizer, will result in significantly more highs than with a standard RIAA preamp when not using the filter. These suggestions are where you are using the RME1950 for real time playback of a record.

Vertical cut records, such as Edison Diamond, or Pathé, and others, require that you switch one pair of leads (non grounded) of the cartridge. If this is not done the channels will cancel each other with the RME1950 is switched "IN". This is because there is no lateral motion of the needle (side to side) only vertical (up and down).

If you are truly concerned about the playback accuracy of the original material, and want to preserve the sound, it is best to use the proper compensation curves and treat the noise with "noise reduction" software after a transfer to a digital medium. Most large pops and clicks are best removed manually with a wave editing program. Small clicks, hiss, and background "frying" can be effectively removed with specialized noise reduction software programs.

Switchable 120 VAC, 60 Hz. and 240VAC, 50 Hz line AC operation. We cut the power plug off the line cord when we ship to other countries. You must install the proper plug for your country. We do not stock all the various power plugs used around the world.

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Please inform us of any errors that you find in the equalization tables. Your contribution will assist in keeping the list accurate and current.