Are U.S. stereo LPs recorded with RIAA curves — verification based on technical documents and engineer testimonies

Are all U.S. stereo LPs recorded with RIAA curves?

Question answered on this page: Were all U.S. major-label stereo LPs recorded with RIAA curves after 1958? Or were different EQ curves used by different labels?

Introduction: two different acts

Before getting into the subject, there is an important distinction to make.

• Switching curves and comparing sounds to find your preference — this is one of the pleasures of record playback. Listening with the sound you prefer is a personal choice.
• Identifying that "this record was recorded with XX curve" — this is a separate act that requires historical and technical verification.

This page deals with the latter: which curve was in fact used for recording.

Answer: U.S. stereo LPs were recorded with RIAA curves

Let me state the conclusion first. Stereo LPs by major U.S. labels since 1958 have been recorded with RIAA curves.

This is confirmed by multiple independent lines of evidence.

Evidence 1: design of stereo cutting equipment

When stereo LPs were introduced to the U.S. public in 1958, the entire recording system used for cutting in the United States (the stereo cutter head and recording amplifier combination) was designed with RIAA recording characteristics as the standard.

To produce stereo LPs, it was necessary to install this new cutting equipment. In other words, the entire recording system was updated to an RIAA-based design at the point when stereo LPs were produced.

To cut a stereo disc with a curve other than RIAA would have required special measures to deliberately circumvent the equipment design, and no record of such measures has been found.

(→ See Pt.19)

Evidence 2: cutting engineers' testimonies

Several cutting engineers have testified that RIAA curves were used in their own facilities.

• A mastering engineer at Capitol testified: "Capitol's mastering used RIAA curves. That's all."
• A cutting engineer at Decca (UK) (1957–1972) testified: "There is no such thing as the FFSS curve. FFSS is a marketing term; Decca used RIAA."
• A mastering engineer at Columbia reported, after inquiring with senior engineers, that "the switch to RIAA was completed for all releases by 1955."
• Another veteran mastering engineer at Columbia testified: "Absolutely, positively, no Columbia curve was used in the stereo era."

(→ See Pt.20)

Evidence 3: Columbia's internal documents

An internal document prepared by William Bachman, Columbia's Director of Electronics and Research, has been discovered. This document contains the following:

• A graph showing the similarity between the Columbia curve and the RIAA curve
• A note that manufacturing variation was greater than the difference between the two curves
• A statement that "the RIAA curve is ideal for reproduction of Columbia LPs, and a gradual transition to RIAA should be implemented"

The document is undated, but has been identified as having been filed between the 1955 and 1956 memos.

Also, an article in the August 28, 1954 issue of Billboard reported that at that time less than half of Columbia's mastering equipment had been converted to RIAA, and that it would take another six months to complete the transition of all equipment.

Meanwhile, the CSL (Columbia Standard Level) test disc, distributed by Columbia to radio stations beginning in February 1955, bears the label inscription: "Columbia Standard Characteristic: as per R.I.A.A - N.A.R.T.B. industry norm."

These indicate that Columbia's transition to RIAA was completed in the first half of 1955, or at the latest in the second half of 1955.

Evidence 4: Rudy Van Gelder's equipment records

Rudy Van Gelder's studio, which handled recording and cutting for jazz labels such as Blue Note, Prestige, and Impulse!, introduced RIAA recording equipment (Gotham PFB-150WA) in early 1955.

Van Gelder himself stated his use of RIAA characteristics in an article he contributed in October 1955.

Blue Note and Prestige records differ only in label artwork; cutting was all done in the same Van Gelder studio, using the same equipment.

(→ See Pt.19)

(→ Rudy Van Gelder's cutting equipment and EQ curves)

So why does the "non-RIAA curve" theory exist?

Despite the above evidence, there is a claim that "most U.S. stereo LPs are recorded with non-RIAA curves." Typical arguments for this claim are as follows.

1. "Verification" by aural comparison

When you switch curves on a variable-EQ phono equalizer, the sound changes. And sometimes one setting sounds "better" than another.

However, changing the EQ curve is a change in frequency response and phase response. It is physically natural for the sound to change, and "the sound changed" does not mean "the recording curve has been identified."

(→ Can you hear a difference when you change the EQ curve?)

2. "Recommended curve" lists by label

Several tables on the Internet assign the "correct EQ curve" to each label. However, comparing these tables reveals cases where different curves are recommended for the same label.

For example, one table recommends "AES" for a given label, another recommends "NAB," and yet another recommends "Columbia."

If these tables were based on objective measurements, the recommendations for the same label should match. The fact that they disagree suggests that these tables reflect subjective choices based on aural preferences.

3. Confusion between "recommended playback settings" and "recording curves"

The "recommended settings by label" lists that appeared in 1950s magazine articles were guides to recommended settings on the playback side (in effect, "it is easier to listen with these settings"). They were not records of the curves used at the time of recording. There are cases where these two have been confused.

Supplement: what this page does not claim

This page does not negate the following points.

• It is historical fact that multiple EQ curves existed during the pre-RIAA period (before 1954). Before RIAA was established, each label used its own curve (→ The History of Phono EQ Curves: In a Nutshell)
• During the monaural LP transition period (1954–1958), some records may have remained on non-RIAA curves. The timing of transition varied, especially among independent studios (→ When did each label switch to RIAA?)
• It is physically natural that changing the EQ curve changes the sound.
• Listening with the sound you prefer is a personal choice.

Summary

That U.S. stereo LPs (1958 onward) were recorded with RIAA curves can be confirmed by multiple independent sources: the design of the cutting equipment, engineer testimonies, internal company documents, and equipment records.

On the other hand, the claim that they were recorded with non-RIAA curves is based solely on aural comparison, without reference to primary sources (recording equipment specifications, cutting engineers' testimonies, or label technical documents).

Switching curves and comparing sounds is one of the pleasures of record playback, but "what sound do you prefer" and "what curve was used in the recording" are two different questions. We hope this page helps in making that distinction.

← Back to FAQ