Phono Amp Spec’s

I think you got most of the info you need already, but let's put it in context.  An amp has a maximum output level it can provide. Think of it as an electrical volume.  The larger the amplification factor -- (multiplies the input signal to get output, for example 1V input with 2X gain (amplification) means 2V output) -- the smaller the input must be so the output is not exceeded.

So this is stable of "gains" whcih is the amplification factor expressed in decibels.  At various gains they provided the largest output voltage in mV it can handle. You cna look up your cartridge's output max and make sure it is lower (bro not too much or the volume will be low).

Phono amps are a tradeoff of gain, noise, and overload all the time. Drove me nuts until I got my few recipes.

To put real numbers on this, one listing is 40dB, which is 100X.  The maximum input they list is 90mV (0.09V). We can then infer the overload output level is 0.09 X 100 = 9V. 

I agree with the other @retiredaudioguy…your preamp jumps from 40 to 64 dB while your cartridge’ sweet spot is in the middle. I have used Pro-Ject PhonoBox DS3B and it has a 55 dB setting. They make a TubeBox version as well.

Thank you everyone for your help and recommendations!

@itsjustme 

I appreciate you trying to put some numbers on this!

To take this another step further….

Im considering the Accuphase C-47 phono amp. 
From their manual, it states the following information…

Input Sensitivity for 64dB of gain = 1.26mV for 2V output @ 50 Ohms 

Maximum Input voltage for 64dB of gain = 5.7mV

Maximum Output Level .01% THD 20-20k hz = 8.0 V

I have read that you should strive to have at least 20dB of overload margin across the frequency range. 
 

Are you able to estimate what the overload margin expressed in dB would be if my cartridge output is 1mV going into their 64dB MC input with the specifications they listed above?

Here is their link. 
https://www.accuphase.com/cat/c-47_e.pdf

Thank you so much for trying to help me better understand!

Best wishes to you all,

Don

Nice phono! Wouldn’t the maximum input voltage listed in the Accuphase lit be the point just below overload? Says 5.7mV at 64db gain. 20db above 1mV would be 10mV.

Perhaps the KAB cartridge calculator will be of help, there is also a general chart at the bottom showing the appropriate gain for a 1mV cartridge. You can also play around by changing any parameter and recalculating. Good luck.

https://www.kabusa.com/pregain.htm

To complicate things further, Bob's Devices makes a 1:5 SUT which would lift the nominal output to 5mV and allow you to go straight into the MM phono gain. Unfortunately for more money of course.

Hi Don,  Pretty busy so wont do the arithmetic but to help you along:

20dB margin = 10X margin. 

64 dB of gain is 1500X

So calculate backwards

hope the is helpful