Is it the EQ curve or mastering that determines the sound of a record — from the perspective of the entire signal chain

Which determines the sound, the EQ curve or the mastering?

Questions answered on this page: Is it the EQ curve that determines the final sound of the record, or the mastering as a whole?

The EQ curve is only one element of the signal chain

The sound etched on a record is the result of a long signal chain from recording to cutting. The three parameters of the EQ curve (turnover, high-frequency pre-emphasis, and bass shelf) are only one part of this entire chain.

The signal chain from recording to cutting includes, for example, the following elements:

1. Microphone selection and placement — different models have different frequency responses
2. Mixing console — EQ, pan, and level adjustment for each channel
3. Tape recorder recording characteristics — tape type, recording speed, bias settings
4. Tape playback characteristics — playback head condition, azimuth adjustment
5. Cutting equalizer — this is where the EQ curve settings are applied
6. Cutterhead characteristics — different frequency response for different models
7. Additional processing during cutting — low-pass filter, limiter, etc.

The EQ curve is item 5 in this list.

Same curve, different sound

Even if it is the same label from the same era, if the engineer and studio are different, the sound of the record can be very different.

This is natural. Every element of the above signal chain except the EQ curve is different. Identical EQ curves do not guarantee that the final sound will be identical.

The recording tape and the cutting tape already sound different

The tapes used for cutting records are often not the same as the master tapes from the recording studio. They are adjusted in sound pressure and bandwidth balance for cutting, and already sound different from the master tape.

This can actually be heard on CD reissues. For the same album, CDs mastered from the cutting tape and CDs mastered from the original master tape often have a very different sonic character.

An important point here is that the cutting tape does not contain the disc recording EQ (such as RIAA). The tape is played back and sent through the disc recording EQ into the cutting amplifier; only at that point is the EQ-processed signal engraved onto the disc.

In other words, the sonic difference between the cutting tape and the master tape that can be heard on CD reissues has nothing to do with the disc recording/playback EQ — it is the result of the engineer's "sound shaping." Put another way, the sound engraved on the record may already be different from the master tape before the EQ curve is even applied.

(→ See Pt.24)

Conversely, cases where the difference is slight even though the curves are different

The difference between the Columbia LP curve and the RIAA curve was, according to Columbia's own internal documents, smaller than manufacturing tolerances (disc-to-disc variation) (personally, I find this a little hard to fully accept, but…).

In other words, "different curve names" do not necessarily mean "large audible differences."

Limitations of searching for the "right" curve

Trying to reach the "right sound" by changing only the three parameters of the EQ curve is tantamount to trying to control the end result with only one element of the entire signal chain. It has limitations in principle.

This does not negate the value of studying the history of EQ curves. Rather, the history of recording is not the history of EQ curves alone but the history of recording technology as a whole.

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

→ The History of Phono EQ Curves: In a Nutshell

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