FAQ on phono EQ curves — basics, history, audibility, and practical playback
Phono EQ Curve FAQ
Questions about EQ curves, answered one topic at a time. Each page can be read independently.
If you're just getting started
- What is phono equalization?
- What is the RIAA curve?
- Read the history in brief (In a Nutshell)
- Are all U.S. stereo LPs on the RIAA curve? (a frequently asked question)
- Where is the RVG sound made? Recording- and mastering-stage sound shaping (a frequently asked question)
1. Fundamentals
2. History
2.1 Birth of the LP and the Battle of the Speeds
- Who invented the LP?
- Why did lateral-cut become the standard rather than vertical-cut?
- What was the "Battle of the Speeds"?
- Why did Columbia and RCA Victor release separate formats if their engineers were cooperating?
- What was the Columbia LP curve?
- What EQ curves existed before RIAA?
2.2 Standards and standardization
- The first-ever recording standard — the 1942 NAB
- Why was the 1942 NAB standard defined as a curve with a ±2 dB tolerance rather than in time constants?
- Why did the U.S. and Europe use different EQ curves?
- When was the RIAA curve established?
- Why did RIAA become the standard?
2.3 People, places, and technological evolution
- How did listeners play records back then?
- What was the "Sapphire Group"?
- Stokowski and Bell Labs: the experimental recordings
- What equipment did Rudy Van Gelder use for cutting?
- What cutting curve did Rudy Van Gelder use before installing his Gotham (1953 to early 1955)?
- What was "Dialing Your Disks"? What can it tell us, and what can't it?
- How did record playback technology evolve?
- What is hot stylus recording?
3. Sound and perception
- Can you hear a difference when you change the EQ curve?
- Are there records where you can hear the difference between recording curves with your own ears?
- EQ curve vs. mastering — which determines the sound?
- Where is the RVG sound made? Recording- and mastering-stage sound shaping
- Somethin' Else 3-way LTAS — measuring the processing newly added at the RVG Edition stage
- What factors besides the EQ curve affect the sound of a record?
- Listening tests vs. documentation — which should you trust for identifying EQ curves?
4. Practical playback
- How should I play pre-RIAA records?
- When did each label switch to the RIAA curve?
- What EQ curves were used on mono LPs from 1948 to 1958?
- What curve should I use for 78 rpm records?
- Do I need a variable-EQ phono equalizer?
5. Commonly confused points
Topics frequently conflated in popular discussion, sorted out against primary sources.
6. Standards and implementation deep dive
Technical detail of LCR vs RC in standards documents and in circuit implementation. Focused on differences of notation and implementation within the same target curve.
- When did the standards documents change their wording from LCR to all-RC?
- Are LCR and RC Phono Equalizers Fundamentally Different?
- Can a Playback EQ Perfectly Cancel a Cutting EQ?
Sources, methods, and about this site
- Is there a reliable EQ curve reference?
- What sources did I use for this research?
- How is generative AI used in producing this site?
→ Read the history in brief (In a Nutshell)
Revision History
- June 1, 2026: Expanded the RVG-related FAQs from two existing entries to four. Split off the pre-Gotham discussion from "What equipment did Rudy Van Gelder use for cutting?" into a new FAQ "What cutting curve did Rudy Van Gelder use before installing his Gotham (1953 to early 1955)?", added to "People, places, and technological evolution". Split off the recording- and mastering-stage sound shaping from "Somethin' Else 3-way LTAS — measuring the processing newly added at the RVG Edition stage" into a new FAQ "Where is the RVG sound made? Recording- and mastering-stage sound shaping", added to "Sound and perception" and also linked from "If you're just getting started"
- May 13, 2026: Restructured the FAQ overall into seven sections. Added "If you're just getting started" at the top. Split History into three subsections (Birth of the LP and the Battle of the Speeds / Standards and standardization / People, places, and technological evolution). Added two new sections "Commonly confused points" and "Standards and implementation deep dive". Added two new FAQs ("Are LCR and RC Phono Equalizers Fundamentally Different?" and "Can a Playback EQ Perfectly Cancel a Cutting EQ?") to "Standards and implementation deep dive"
- May 11, 2026: Added "Where is the RVG sound made? A 3-way LTAS of Somethin' Else" to the Sound and perception section
- April 30, 2026: Added "Are there records where you can hear the difference between recording curves with your own ears?" to the Sound and perception section
- April 29, 2026: Added "When did the standards documents change their wording from LCR to all-RC?" to the History section
- April 28, 2026: Added "What was Dialing Your Disks? What can it tell us, and what can't it?" to the History section
- April 15, 2026: Moved "The first-ever recording standard — the 1942 NAB" and "Why was the 1942 NAB standard defined as a curve with a ±2 dB tolerance rather than in time constants?" from Fundamentals to the History section
- April 15, 2026: Added "Why was the 1942 NAB standard defined as a curve with a ±2 dB tolerance rather than in time constants?"
- April 15, 2026: Added "Why did Columbia and RCA Victor release separate formats if their engineers were cooperating?"
- April 10, 2026: Added "How is generative AI used in producing this site?"
- April 10, 2026: Added "The first-ever recording standard — the 1942 NAB" and "Why did lateral-cut become the standard rather than vertical-cut?"
- April 9, 2026: Added "What sources did I use for this research?"
- April 8, 2026: Initial publication