### Cartridge GAIN calculations - What is the decibel offset of .3 mV vs. .65mV

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#### undertow

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##### Cartridge GAIN calculations - What is the decibel offset of .3 mV vs. .65mV
« on: 23 Feb 2018, 05:28 pm »
Okay....

So I have 2 MC cartridges I am trying to calculate the real output db difference on output not the final voltage.

I have used the gain calculators, and tried converting, but not getting the results.

1st cart. is going to be a .3 mV thru a 60 db phono amp, which equals - 300 mV output, or less than a half volt when amplified hitting the main preamp.

2nd cartridge is a .65 mV going thru the 60 db phono amp which equals - 650 mV output or just over a half volt.

What should the perceived db difference be here? Half the power cart. should be what? About 3 db weaker, 6 db weaker, 9 db weaker?

I am trying to get a reasonable ballpark difference in real sound output because it will cost a pretty penny to get the low output cart. Re-tipped in this case.

I need about a 5 or 6 db system drop because the .65 mV cart. does have a little to much where the Preamp volume does not allow a lot of "Travel"... I have plenty of gain overall no doubt so I want to make sure to get a good solid "Softening" of the volume acceleration using the lower output cart. if I have to spend to get it tipped.

Obviously I can't just test it to find out because I don't have another working low output to test this before sending it out and spending on it and then finding out I don't truley solve the issue.

I am sure it will drop a bit, I have had many before, just not sure in this case it will be MUCH of a drop even with half the power going into 60 db.

If I only shave it barely with 1 or 2 db then I might have to take a a different approach here instead of trying to drop the cart. power back.

Thanks for the help guys, I just can't find the right calculation or way to convert online with this metric.

#### undertow

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• Posts: 882
##### Re: Cartridge GAIN calculations - What is the decibel offset of .3 mV vs. .65mV
« Reply #1 on: 23 Feb 2018, 06:44 pm »
I think i have the answer... doubling of the voltage source should be equivelant to a 6 db difference in this case on paper... in the real world with differences in setup and equipment might be a bit different result, but we should be close.

Thanks anyway