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Phono Preamp Gain

Hi all,

I am in the process of getting a new cartridge and I want to make sure the output voltage is a good fit for my system. First off here's what I'm working with:

VPI Prime
Schiit Mani (30dB, 42dB, 48dB, 59dB gain options)
Prima Luna Dialogue Premium Integrated (239mV input sensitivity using KT88 tubes) (S/N ratio 81)
JBL L100

My question is what do I use for Vout in this equation to calculate the correct gain to choose on the Schiit Mani phono preamp??


20log(Vout/Vin)


Using the input sensitivity of the integrated and the output voltage of the  Soundsmith Otello ES Moving Iron Cartridge I get 

20log(.239V/.00212V) = 41dB gain

Is this correct?
My main issue is I dont know if my assumption to use .239V is correct.

Cheers



nmo25
peterf6
74 posts
 
I tried all the recommended MM levels on my Schiit Mani and Freya with a Grado MM. Two levels sounded good. One was a better match for being similar to my digital rigs channel, so I'm using that. (I should note there was a distortion before the unit and cables burned in, so if yours is a new set up, do a burn in on the Mani).
tablejockey
3,851 posts
 
"I’m not sure if the JBLs are anywhat of a good match for the Primaluna but I got them for dirt cheap at an estate sale so they are staying for a while."

nmo25- I bet the JBL's will sound good, if you like the "vintage sound"

Vintage sound to me is not overly detailed, overall presentation leaning on the warm side. There shouldn't be any lack of bass with the JBL's.

You might be able to fine tune the JBL's tone with the 2 gain tubes on the PL.


panzrwagn's avatar
panzrwagn
506 posts
 

@tablejockey re: "There shouldn't be any lack of bass with the JBL's." You might want to edit that to say 'mid-bass' as the L100 starts rolling off steeply around 55Hz. It's also a high-Q design with a peak of 6dB or more so an octave above the port tuning frequency. Low bass was never a capability. 

ozzy62's avatar
ozzy62
3,013 posts
 

I am using a SS Carmen II, which is the same output voltage as your cart. (2.12 mV) and running it into an SPL Phonos using the 46 db gain setting. Works great, plenty of headroom without overloading. I'm using a passive (Hattor Audio) preamp so no extra gain there.

 

lewm
12,809 posts
 

You cannot really extrapolate from one system to another to estimate the needed phono stage gain, especially if the line stage is passive. But amplifier input sensitivity, and speaker efficiency also play important roles. Anyway, the OP cannot break anything by trying different gain settings. And it seems likely that somewhere between 42 and 46d B gain is going to be ideal.

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