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The Truth About The RIAA Response

The number of people who know the true frequency response of a magnetic cartridge is very few.

The Brüel & Kjær response plots are equalised so you could (wrongly) assume the cartridge output is flat.

The real response should plot upward at 45 degrees from the left.

The rising response is +6dB/octave, which is +20dB/decade. It is an a.c. generator, who's output rises with frequency.

Now, if we look at the frequency response plot of an RIAA phono preamp, what do we see?

We see two downward slopes, one ending at 500Hz and the next starting at 2122Hz. These are at a rate of -6dB/octave, which is -20dB/decade.

But why two slopes?

The cartridge only needs a single downward slope to equalise its single rising slope!

...making it flat.

What else could there be?

Well, if you subtract one from the other the residual implies that the record has a frequency response that has a step in it.

The residual appears to be flat from about 50Hz to 500Hz, then falls 12dB before reverting to flat from 2122Hz upwards.

And if you look at the residual going left from 50Hz, you'll see it rising.

So does that mean the record has a frequency response with bass boost, and shelving down in the midrange? It surely does!

Now you know the true frequency response of a RIAA record, and its nothing like what everybody else explains, because they didn't take the simple steps of understanding what are easily proved by some simple subtraction.

But say you don't believe me, and you think I could be lying. What other evidence is there?

Low budget record players used rochelle salt cartridges (crystal cartridges) and some used lead-zirconium titanate, otherwise known as ceramic cartridges - and no EQ!

I'll not link to Roger Russel's site because it isn't https, but he vouches that these cartridges are flat output, something which I've known since around 1975.

If RIAA records had the output you're told about all over the web, then via one of these cartridges, they'd have no bass and only screechy treble, but millions of people (provided they're still alive) would soon put you right.

If you could still use one of those old record players you'd find them a bit "bassy" simply because of that shelving down in the midrange.

No, the cartridge that gives out no bass and only screechy treble when played into a line (flat) input, is the magnetic cartridge, simply because it has the rising response of +6dB/octave, which is +20dB/decade.

So why are there so many websites at the top of the search results that say the opposite?

Simple, Larry Page and Sergey Brin forgot to insert a "Hitler filter" in their algorithm. What's that? You know, tell a big lie and repeat it so often that it becomes the truth... LOL