Phono Amp Spec’s


Hello 

Can someone please help me understand the following…

*Maximum Input Voltage
64dB = 5.7mV
70dB = 2.9mV
34dB = 180mV
40dB =  90mV
 
I would be using a Benz Micro Ruby ZH moving coil cartridge with this phono amp.  
It’s output is rated at .7mV@3.54cm/sec which I believes equates to .998mV @ 5cm/sec.  
 
1.  Am I understanding this correctly, that my roughly 1mV cartridge would be fine going into this 64dB MC input?
 
2.  Is there a way to know what would the dB overload margin would be with 1mV @1khz as well as the low, mid, and high frequencies going into this 64dB MC input?
 
Secondly,
I’m concerned about over driving/clipping the phono amp.
 
* Input sensitivity
64dB = 1.26mV
70dB =   .63mV
34dB = 40mV
40dB = 20mV
 
1.  Can you please help me understand how the input sensitivity of 1.26mV for the 64dB MC input relates to my Benz Ruby ZH with a roughly 1mV output.  
 
What exactly should this mean to me?
 
After suffering 5 major strokes, my memory of many things have been lost. So, if anyone could please help me better understand how the above spec’s would affect me, I would truly appreciate it. 
 
Best wishes,
Don
 
 
 
 
no_regrets

If you are contemplating a new Phone Stage, I can recommend the Sutherland Duo.  There are other Sutherland options in various price ranges; given the impedance of the Benz ZH the "Loco" Sutherlands are probably not right.  In reviews their phono stages are noted for having large headroom.

The Duo (and 20/20) offers five gain settings (40, 46, 52, 58, and 64 dB) and five loading options (100, 200, 475, 1k, and 47k ohms).

The 52dB or 58dB with 475 ohms would seem to be a good match.

Upscale Audio (e.g.) offers 60 day auditions.

I have the Duo, paired with the Koetsu Rosewood Platinum and am delighted with the sound.

Best wishes to you.

 

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.