Hiss on Phono

[Sandeepmenon]

For a level frequency response the load definitely needs to be set to high. I am using an Ortofon A90 and ended up with voltage level set at 7.7mV to avoid clipping on the LPs I checked it with. That is over double what I had expected, unlike digital max recording level on LPs is not a fixed quantity!

I have a background noise level of around -80dB with these settings, and about -60dB on the run in groove of a clean LP.

Thank you Frank. I have updated the settings and currently playing around to get the right voltage level set! You mentioned in an earlier thread that you have the Ortofon T3000 SUT which has a 30db gain so wouldn't the output voltage from the SUT be 8.54mV given that the A90 is rated at .27mV? Wanted to understand what the starting point should be for trying out the voltage levels in my scenario. Apologies if I am getting some of the basics wrong

You are quite right about the gain, my mistake.

OTOH the limiting factor here is that what is taken as 0dB on an LP is nominal 5cm/sec at 1 kHz, and records exist modulated a fair bit more than this, and with varying level content with frequency (and often scratches some of which give huge output) whereas digital 0dB is the maximum level possible, all bits on.

That means setting the gain to avoid clipping the ADC is a hit and miss affair. Generally I go for a safety margin when recording microphones since 24-bit is way more than needed. On the Devialet phono input I have not 'finalised' my gain setting yet either! Maybe I never will. Adjusting with each LP to avoid clipping is probably the only way to iterate to a suitable setting.

Thanks. I have settled for 5.5mV for now. Do need to tweak it for some very "loud" records though!