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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
viridian's avatar
viridian
5,372 posts
 

Don, sorry for your challenges.

So the first list refers to the four gain settings of your phono stage and the overload margins for each one. The second set has an asterisk, but you don't provide the info attached to it. 

At any rate the sensitivity is the amount of input signal from your cartridge needed to achieve a pre determined output signal. Usually 2 or 3 volts.

IMHO, the 1mV output of your cartridge is kind of a tweener. I would try both the 40db setting, and if noise, or diminished dynamics was an issue, I would move up to 64db, and pick whichever sounded better. You will do no damage by using either one, it is strictly the sound quality that you prefer that should guide your choice. Good luck!

no_regrets OP
563 posts
 

@viridian 

Thank you for your quick reply!

I think the 40dB will seem quite anemic with my cartridge, but I’m hoping the 64dB will be just what it needs. 
 

My concern is if the 1mV will overdrive the phono amp or not. 
So with the 5.7mV maximum input, you feel that I will have plenty of dynamic headroom and I wouldn’t overdrive or clip the phono amp?

Do you have any idea how much headroom I would have with the 1mV going into the 64dB input?  I remember that we should try to have at least 20+dB of overload margin.  
 

I truly appreciate your help!

best wishes,

Don

tablejockey
4,108 posts
 

From the  Benz Micro site:

"The ZH at .7mV, is ideal for tube phono stages in the 50-60dB gain range.'

https://benzmicro-northamerica.com/benz-micro-ruby/

Determining what sounds right to your ears won't damage anything.

 64db choice isn't  far out of suggested range.

 

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