Improving on a Revox B77 frequency curve

[lcsaszar]

The equalization rule. During sound storing at tape, highs are inceased and during playback attenuated, to enhance signal/noise ratio. Same as RIAA but with different objectives and frequencies.

https://es.m.wikipedia.org/wiki/National_Association_of_Broadcasters

https://www.tapeheads.net/threads/vintage-r2r-tape-equalization.47579/

It is not completely same principle. During recording, the head current is kept constant, i.e. the frequency response of the recording chain is flat.
At playback, the head output is falling at -6 dB/octave, which is equalized. The time constant where treble boost kicks in is defined by IEC or NAB. This is the point where gap width is comparable with 1/2 wavelength, causing loss. And there are some minor equalizations at the extremes of the audio band due to head physical characteristics (low frequency ripple) and high frequency loss caused by the bias.

 

[Osvaldo de Banfield]

Thankyou. I noted that there are differences. I read some books years ago. But I explained it quickly and easily to not confuse the OP with too many garbage.

And are of no importance to solve the guy's issue.

 

[Audio>X]

6. should go after 7. isn't it?

No, but I did forget to write between 6 & 7 > to adjust record-head azimuth - WOOPS 😕