Full past revision history of this site — all changes older than the "Recent updates" shown on the top page
Past revision history
What you'll find on this page: A full chronological list of all changes made to the lower-level pages (In a Nutshell, FAQ, Research Notes) of this site that are no longer shown in the "Recent updates" section on the top page.
For the latest updates, see the "Recent updates" section on the top page.
- May 17, 2026
- ✏️ What a 46-issue close reading of 'Dialing Your Disks' (1950s High Fidelity) reveals — Added figure (close-up of Prestige PRLP-200 back cover with the RIAA curve marking)
- ✏️ Rudy Van Gelder's cutting equipment and EQ curves — what the equipment records and his own testimony tell us — Added figure (close-up of Blue Note BLP-5058 back cover with explicit RIAA marking, one of the earliest Blue Note LPs to do so)
- ✏️ How generative AI is used in producing this site — what AI handles, and what it does not — Added a description of the cross-review pattern (parallel independent advice from a separate-context Codex and Claude Code instance). Added two items to the quality control list ("early course-correction on drift" and "cross-checking AI-written descriptions against the actual diff"). Added a new section "External observations" presenting Anthropic
/insightsautomated analysis as a third-party view. Expanded the site structure description at the top from "two layers" to "three layers", reflecting that the post-Pt.0–25 Liner Notes series is also co-written with generative AI - ✏️ What sources did I use for this research? — an overview of primary sources over two years — Added figure (patent document Fig.3+4+5 showing the Orthacoustic recording equalizer response)
- ✏️ How did listeners actually play records before RIAA unification — casual listeners, audiophiles, and professionals — Added figure (LIFE magazine, July 26, 1948, Dr. Goldmark with 101 LPs)
- ✏️ What was the Columbia LP curve (500C-16) — its technical characteristics, adoption history, and transition to RIAA — Added figures (Billboard, June 26, 1948; a Columbia 7-inch Microgroove record 3-102; and Billboard, August 28, 1954, p.62)
- ✏️ Are U.S. stereo LPs recorded with RIAA, or with per-label EQ curves? — At the end of the "So why does the 'non-RIAA curve' theory exist?" section, added a note that audible differences come from the recording chain upstream of cutting (microphones, program EQ, mixing, tape, engineer's decisions, mastering) rather than from EQ curves, with links to related FAQs. Added partial bolding to the concluding sentence
- ✏️ When did major U.S. labels move to the RIAA curve — a list based on verifiable documents — Merged the "Independent studios" table into the main label table (added Blue Note, Prestige, Contemporary / Good Time Jazz as label rows so readers can find labels in a single list)
- ✏️ Are there reliable references for EQ curves — research-based resources and criteria for evaluating source reliability — Added figures (Definitions section of Powell 1989, Audacity Plugins source list)
- May 16, 2026
- ✏️ What EQ curves were used before RIAA, and why were there so many — Added figures (the 1949 NAB vertical recording curve and the 1951 AES Standard Playback Curve)
- ✏️ What was the Sapphire Group — the gatherings that broke down industry secrecy and paved the way for standardization — Added figures (1946 photo of the first Hollywood Sapphire Group meeting and the 1948 Audio Engineering article announcing the formation of the AES)
- ✏️ When did the standards documents change their wording for the time constants from LCR to all-RC? — Added figures (the 1949 NAB standard's notes page and the Broadcasting Telecasting article reporting the 1953 NARTB revision)
- ✏️ When was the RIAA curve established — years of pre-history leading up to January 29, 1954 — Added figures (the RIAA recording/reproducing curves graph and the 1953 Broadcasting Telecasting article on the momentum toward a recording-standard revision)
- ✏️ Are U.S. stereo LPs recorded with RIAA, or with per-label EQ curves? — Added Evidence 7 (design and owner's manuals of consumer stereo amplifiers, with tabulation from the August 1964 issue of Audio Magazine). Added the CSL test disc label to Evidence 3 and the Bell 3030 schematic to Evidence 7. Added AES E-Library links to Evidences 5 and 6
- May 15, 2026
- ✏️ Can a playback EQ perfectly cancel a cutting EQ? — Adjusted the paragraph order at the start of §2
- May 13, 2026
- 🔔 Newly published: Are LCR and RC phono equalizers fundamentally different?
- ✏️ When did the standards documents change their wording for the time constants from LCR to all-RC? — Tidied up the Read further section, replacing placeholder references with sister FAQ links.
- 🔔 Newly published: Can a playback EQ perfectly cancel a cutting EQ?
- May 11, 2026
- ✏️ Rudy Van Gelder's cutting equipment and EQ curves — what the equipment records and his own testimony tell us — Separated "The 'RVG sound' is not about the EQ curve," "Measuring the 1958 Somethin' Else," and "The cutting EQ curve and sound shaping are separate matters" into a new FAQ Where is the RVG sound made? A 3-way LTAS of Somethin' Else. This FAQ now ends at the "Connection to the EQ curve debate" section with a pointer to the new FAQ
- ✏️ Rudy Van Gelder's cutting equipment and EQ curves — what the equipment records and his own testimony tell us — Expanded the LTAS comparison of the 1958 Somethin' Else recording to a 3-disc comparison (Capitol/Blue Note 1987 McMaster / RVG Edition 1999 / Analogue Productions 2009) and expanded the figures to 5. Confirmed via the 3-disc comparison that the centering processing was newly added at the RVG Edition CD 1999 stage. Organized Steve Hoffman's interpretation of LP cutting master stage sound shaping and tabulated its correspondence with the 3-way LTAS. Added quotes from Van Gelder's own 2012 JazzWax interview (interviewer Marc Myers): the joint work with Alfred Lion, control of the entire recording chain, and his own description of the lacquer master process
- 🔔 Newly published: Where is the RVG sound made? A 3-way LTAS of three Somethin' Else CDs
- May 6, 2026
- ✏️ Rudy Van Gelder's cutting equipment and EQ curves — what the equipment records and his own testimony tell us — Expanded the "RVG sound is not about the EQ curve" section into a two-stage structure (session recording stage / mastering stage). Added Hackensack studio acoustics, the Telefunken U47 close-miking strategy, Billy Taylor's piano-recording testimony from Skea 2002, and the construction of the Englewood Cliffs dedicated studio in 1959 (designed by David Henken) with its contrast to Hackensack (RVG Legacy) to the session recording stage. Added quotes from Van Gelder's own testimony (1995 Audio Magazine interview by James Rozzi; 2005 All About Jazz article by Chris M. Slawecki). Added an LTAS comparison (author's analysis) of the 1958 Somethin' Else recording as a table and figures
- April 30, 2026
- 🔔 Newly published: Are there records where the same source is cut with multiple EQ curves on one disc?
- ✏️ When did the standards documents change their wording for the time constants from LCR to all-RC? — Tidied up the Read further section.
- April 29, 2026
- April 28, 2026
- April 27, 2026
- ✏️ Why the RIAA curve became the industry standard — technology, politics, and economics — Added McKnight (J. Audio Eng. Soc. 30(4), p.244, April 1982) account at the end of Factor 2, noting that AES and RIAA — separate organizations — adopted the same characteristic in the same year as a symbol of cross-industry consensus-building
- ✏️ When was the RIAA curve established — years of pre-history leading up to January 29, 1954 — Added McKnight (J. Audio Eng. Soc. 30(4), p.244, April 1982) account in the standardization-timeline section, noting that AES TSA-1-1954 and the RIAA's 1954 standard adopted the same characteristic in the same year and that the "Bulletin No. E1" name and revision dates were assigned retrospectively
- ✏️ (In a Nutshell Part 2) How did unification finally happen? — From the postwar era to the birth of the RIAA curve (1942–1954) — Added McKnight (J. Audio Eng. Soc. 30(4), p.244, April 1982) account at the end of §4 "Three standards, one curve," noting that AES TSA-1-1954 and RIAA adopted the same characteristic in the same year and that the "Bulletin No. E1" name was assigned retrospectively
- April 19, 2026
- ✏️ What is phono equalization (phono EQ)? — the EQ process essential to record playback — Added note on the 1956 Saturday Review description
- ✏️ What EQ curves were used before RIAA, and why were there so many — Added Burke's account from the 1956 Saturday Review book (five playback curves a domestic control unit should provide, plus the equalizer-as-necessity truism)
- April 18, 2026
- ✏️ Why did the U.S. and Europe use different EQ curves — the divergence in turnover frequencies and its background — Corrected the date of A.E. Barrett's (BBC) remark on NAB pre-emphasis from 1949 to 1947 (source: NAB Recording Standards Meeting, Audio Engineering, October 1947)
- ✏️ The first-ever recording standard — the 1942 NAB and its revisions (1949, 1953 NARTB, 1964) — Expanded the 1949 revision section in four layers based on close reading of Broadcasting Telecasting (1948–1949): the two-layer approval flow (RRSC executive committee → full committee on April 9, 1949 → NAB Board of Directors on April 14–15, 1949) with the April 7 open meeting; primary-source backing for the disc-curve carry-over (March 28, 1949 "reaffirmed a majority" quote; April 18, 1949 composite-groove study quote); the trade-press silence in the second half of 1949 (May–June follow-up gap, July Portsmouth engineering-department downgrade, November consolidation of standing committees, absence from year-end reviews); and the Howard → McNaughten engineering-director turnover three to four months after adoption
- April 17, 2026
- ✏️ Why so much disagreement about EQ curves, especially in Japan? — Minor revision of the summary; added link to the FAQ page on EQ curve references; updated the series link to point to the research-notes page
- ✏️ What is the RIAA curve? — the analog record EQ standard established in 1954 — Minor revision of the summary
- ✏️ How generative AI is used in producing this site — what AI handles, and what it does not — Changed the list of models used into a bullet list and added Claude Opus 4.7
- ✏️ Are U.S. stereo LPs recorded with RIAA, or with per-label EQ curves? — Minor revision of the summary
- ✏️ Do you need a variable-EQ phono equalizer? — decision criteria by collection type — Minor revision of the summary
- April 16, 2026
- ✏️ (In a Nutshell Part 2) How did unification finally happen? — From the postwar era to the birth of the RIAA curve (1942–1954) — Added a new subsection to §3 on the vocabulary shift from graph to time-constant definitions (AES 1951 "impossible task" and Moyer 1953 "curve alone" primary-source quotes)
- April 15, 2026
- ✏️ (In a Nutshell Part 1) Why wasn't there a unified standard from the start? — From the birth of electrical recording (1925) to the NAB standard (1942) — Added primary-source context on the 1942 NAB standard's background — ten equalizer settings in use, the RRSC's charge to "minimize adjustments on the reproducing system," and Smeby's acknowledgment of the diversity of existing characteristics. Corrected the adoption date to March 19–20, 1942 per the NAB Engineering Handbook (1945, 3rd Edition)
- 🔔 Newly published: Why did the 1942 NAB standard use a ±2 dB tolerance curve, not time constants?
- 🔔 Newly published: Columbia and RCA Victor shared information through NAB, Sapphire, and AES — so why incompatible formats?
- April 14, 2026
- ✏️ What is the hot stylus — the technology that transformed recording quality and helped standardize EQ curves — Added figures
- ✏️ Who invented the LP — the contributions of three key figures and how to read their conflicting accounts — Added figures
- ✏️ What was the Battle of the Speeds — Columbia LP vs RCA Victor 45, how it was resolved, and its connection to EQ curves — Added figures
- ✏️ How record playback technology evolved — the interplay of stylus pressure, disc materials, and recording characteristics — Added figures
- ✏️ Stokowski and Bell Labs experimental recordings — how a conductor and engineers pioneered high-fidelity recording — Added figures
- ✏️ What is phono equalization (phono EQ)? — the EQ process essential to record playback — Added figures
- ✏️ What is the RIAA curve? — the analog record EQ standard established in 1954 — Added figures
- ✏️ Rudy Van Gelder's cutting equipment and EQ curves — what the equipment records and his own testimony tell us — Added figures
- ✏️ How generative AI is used in producing this site — what AI handles, and what it does not — Updated the description of the Codex / Claude Code role split and quality control practices to reflect the current workflow
- ✏️ When did major U.S. labels move to the RIAA curve — a list based on verifiable documents — Added figures
- ✏️ Why lateral-cut rather than vertical-cut became the standard — the commercial outcome and the 1938 physical justification — Minor wording fixes; added figures
- April 13, 2026
- ✏️ The first-ever recording standard — the 1942 NAB and its revisions (1949, 1953 NARTB, 1964) — Inserted the recording frequency-characteristic chart from the 1942 NAB standard paper (Chinn 1942, Broadcast Engineers' Journal) and the lateral-cut recording chart from the 1953 NARTB standards document. Both visually show that the graph definitions carried a ±2 dB tolerance band
- ✏️ The first-ever recording standard — the 1942 NAB and its revisions (1949, 1953 NARTB, 1964) — Noted that the 1942 graph definition carried a ±2 dB tolerance, citing the Fig. 1 / Fig. 2 captions of Smeby's paper
- ✏️ The first-ever recording standard — the 1942 NAB and its revisions (1949, 1953 NARTB, 1964) — Reflected the following from the contents of NAB Reports 1941-1942. Precised the 1941 RRSC timeline (May 23 → June 13 → June 26 → August 20 → October 23), added four direct NAB Reports quotes (task definition, "ten different equalizer settings," "highly controversial subject," wartime deferral), introduced a new subsection on the October 23 main-committee adoption, and connected the graph→time-constant section to the 1942 rationale. Minor wording fixes elsewhere
- ✏️ The first-ever recording standard — the 1942 NAB and its revisions (1949, 1953 NARTB, 1964) — Strengthened the rationale for the graph→time-constant shift with Moyer 1953 and Roys 1968. Added a direct Smeby quote on why the 1942 standard used graph form. Added Boegli (April 1953) on conditions just before the NARTB revision
- April 12, 2026
- ✏️ Key terms in phono EQ curves — turnover, time constants, curve notation, and more — Added note on Japanese "SP record" terminology
- ✏️ What was the Battle of the Speeds — Columbia LP vs RCA Victor 45, how it was resolved, and its connection to EQ curves — Added the design philosophy of the New Orthophonic curve (Moyer 1957)
- ✏️ What is the RIAA curve? — the analog record EQ standard established in 1954 — Added note on RIAA standard document circulation date (June 1954)
- ✏️ What EQ curves were used before RIAA, and why were there so many — Added a brief reference to Moyer 1957 (at least eight recognized characteristics; parameter ranges)
- ✏️ What EQ curve should you use for 78 rpm records — an honest look at an open question — Strengthened the description of European 78 rpm records with Copeland 2008; added the Decca ffrr exception
- ✏️ How did listeners actually play records before RIAA unification — casual listeners, audiophiles, and professionals — Added note on RIAA standard document circulation date (June 1954)
- ✏️ (In a Nutshell Part 2) How did unification finally happen? — From the postwar era to the birth of the RIAA curve (1942–1954) — Added note on RIAA standard document circulation date (June 1954)
- ✏️ The first-ever recording standard — the 1942 NAB and its revisions (1949, 1953 NARTB, 1964) — Added the 1953 NARTB standards book and the 1964 NAB standards book (ed. Hess) as primary-source citations
- April 11, 2026
- ✏️ How record playback technology evolved — the interplay of stylus pressure, disc materials, and recording characteristics — Added Pierce & Hunt's findings on vertical compliance; minor wording fixes
- ✏️ Why the RIAA curve became the industry standard — technology, politics, and economics — Added Moyer (1957) "eight characteristics" and "compromise" citations to Factor 2
- ✏️ What sources did I use for this research? — an overview of primary sources over two years — Added Copeland (2008) to technical references and Moyer (1957) to trade magazines
- ✏️ What sources did I use for this research? — an overview of primary sources over two years — Added Japanese-language resources section
- ✏️ Why did the U.S. and Europe use different EQ curves — the divergence in turnover frequencies and its background — Added CCIR background and Copeland (2008) bibliographic details
- ✏️ Why lateral-cut rather than vertical-cut became the standard — the commercial outcome and the 1938 physical justification — Added quantitative distortion data from Pierce & Hunt 1938 (p. 169)
- April 10, 2026
- ✏️ When was the RIAA curve established — years of pre-history leading up to January 29, 1954 — Clarified the significance of the June 1954 RIAA standard document; added post-approval transition details from "The Curve That Conforms" (1954)
- 🔔 Newly published: How generative AI is used in producing this site — what AI handles, and what it does not
- ✏️ Are U.S. stereo LPs recorded with RIAA, or with per-label EQ curves? — Added primary sources (Westrex 1958 quotation in Evidence 1, new Evidence 5 on the standardization process and Evidence 6 on playback equipment), with tone adjustments
- 🔔 Newly published: Why lateral-cut rather than vertical-cut became the standard — the commercial outcome and the 1938 physical justification
- 🔔 Newly published: The first-ever recording standard — the 1942 NAB and its revisions (1949, 1953 NARTB, 1964)
- April 9, 2026
- ✏️ (In a Nutshell Part 1) Why wasn't there a unified standard from the start? — From the birth of electrical recording (1925) to the NAB standard (1942) — Added "rolloff" terminology for the playback inverse characteristic; added context on recording technology as trade secrets
- ✏️ Why the RIAA curve became the industry standard — technology, politics, and economics — Added Boegli (1953) citation to Factor 2
- ✏️ Reading guide for the blog series 'Things I Learned on Phono EQ Curves' (25 parts plus a prologue) — Added link to research sources FAQ in the reading guide
- ✏️ Why so much disagreement about EQ curves, especially in Japan? — Expanded "The course of overseas debate" section with a concrete example
- 🔔 Newly published: What sources did I use for this research? — an overview of primary sources over two years
- ✏️ How did listeners actually play records before RIAA unification — casual listeners, audiophiles, and professionals — Added Boegli (1953) and Kendall (1954) citations to consumer amplifiers section
- ✏️ Are U.S. stereo LPs recorded with RIAA, or with per-label EQ curves? — Added section on the "label = curve" assumption
- ✏️ (In a Nutshell Part 2) How did unification finally happen? — From the postwar era to the birth of the RIAA curve (1942–1954) — Corrected the date of the Hollywood Sapphire Group's first meeting
- April 8, 2026
- 🔔 Newly published: (In a Nutshell Part 1) Why wasn't there a unified standard from the start? — From the birth of electrical recording (1925) to the NAB standard (1942)
- 🔔 Newly published: What is the hot stylus — the technology that transformed recording quality and helped standardize EQ curves
- 🔔 Newly published: Key terms in phono EQ curves — turnover, time constants, curve notation, and more
- 🔔 Newly published: Who invented the LP — the contributions of three key figures and how to read their conflicting accounts
- 🔔 Newly published: (In a Nutshell Part 3) What does this history mean for playing records today? — Post-RIAA transition, stereo LPs, and the open questions that remain
- 🔔 Newly published: What was the Battle of the Speeds — Columbia LP vs RCA Victor 45, how it was resolved, and its connection to EQ curves
- 🔔 Newly published: How record playback technology evolved — the interplay of stylus pressure, disc materials, and recording characteristics
- 🔔 Newly published: Why the RIAA curve became the industry standard — technology, politics, and economics
- 🔔 Newly published: Stokowski and Bell Labs experimental recordings — how a conductor and engineers pioneered high-fidelity recording
- 🔔 Newly published: Is it the EQ curve or mastering that determines the sound of a record — from the perspective of the entire signal chain
- 🔔 Newly published: Phono EQ curve history in three parts, in a nutshell
- 🔔 Newly published: Reading guide for the blog series 'Things I Learned on Phono EQ Curves' (25 parts plus a prologue)
- 🔔 Newly published: Why so much disagreement about EQ curves, especially in Japan?
- 🔔 Newly published: Can you hear a difference when changing the EQ curve? — and what that does (and doesn't) mean
- 🔔 Newly published: What is phono equalization (phono EQ)? — the EQ process essential to record playback
- 🔔 Newly published: What is the RIAA curve? — the analog record EQ standard established in 1954
- 🔔 Newly published: What EQ curves were used before RIAA, and why were there so many
- 🔔 Newly published: What was the Sapphire Group — the gatherings that broke down industry secrecy and paved the way for standardization
- 🔔 Newly published: When was the RIAA curve established — years of pre-history leading up to January 29, 1954
- 🔔 Newly published: What EQ curve should you use for 78 rpm records — an honest look at an open question
- 🔔 Newly published: Should you trust listening tests or historical documents to identify EQ curves?
- 🔔 Newly published: What EQ curves were used on 1948–1958 mono LPs — why there is no single right answer
- 🔔 Newly published: Rudy Van Gelder's cutting equipment and EQ curves — what the equipment records and his own testimony tell us
- 🔔 Newly published: How did listeners actually play records before RIAA unification — casual listeners, audiophiles, and professionals
- 🔔 Newly published: What was the Columbia LP curve (500C-16) — its technical characteristics, adoption history, and transition to RIAA
- 🔔 Newly published: Are U.S. stereo LPs recorded with RIAA, or with per-label EQ curves?
- 🔔 Newly published: How should pre-RIAA records be played on modern equipment — sorting out practical options
- 🔔 Newly published: Why did the U.S. and Europe use different EQ curves — the divergence in turnover frequencies and its background
- 🔔 Newly published: Do you need a variable-EQ phono equalizer? — decision criteria by collection type
- 🔔 Newly published: What factors besides the EQ curve affect the sound of a record — an overview of the signal chain from recording to cutting
- 🔔 Newly published: When did major U.S. labels move to the RIAA curve — a list based on verifiable documents
- 🔔 Newly published: (In a Nutshell Part 2) How did unification finally happen? — From the postwar era to the birth of the RIAA curve (1942–1954)
- 🔔 Newly published: Are there reliable references for EQ curves — research-based resources and criteria for evaluating source reliability