Phono preamp settings questions

[subfire91]

Hello guys,

i need your input on some adjustments on my phono preamp.

I have a Project phono S3 B and Project X8 turntable with an Ortofon Blue fitted.

The phono preamp is connected to Denon Stereo Receiver using 1.5m Van Den Hul 502 cable rated at 75pF/m.

i would like to ask what do you recommend 50 or 150 pF resistance and 40 or 45dB of gain ?

Regarding 50 vs 150pf and 40 vs 45dB of gain i dont see any difference in sound quality (putting aside the 45dB is obviously louder) but thats may be because being relatively new to the "sport" and also because of my untrained ears .

Thank you in advance

 

[JRowland]

The Ortofon 2m Blue specs between 150-300 pF.
Cable - 108 pF
Table 20-25 pF
Either setting works at 180 ish on the 50 pF setting and 280 ish on the other. I believe the way high I can’t hear at 53 years old personally range is all that is barely affected.

I always go with the lowest gain I can select to hit whatever volume I need no matter the device pretty much.

 

[DVDdoug]

If you don't hear a difference, don't lose sleep over it.

More capacitance tends to boost the highest-highs a bit. Too-little capacitance tends to roll-off the highs.

... If you "know a little" this is counter-intuitive because parallel capacitance normally tends to make a low-pass filter, reducing high frequencies. But the capacitance along with the pickup's inductance makes a resonant filter that usually resonates a bit above 20kHz. More capacitance brings the resonant frequency down to where it more-affects (and boosts) the high frequency audio range.

So... I had it backwards back in the vinyl days. I thought lower capacitance was better, but in fact there is an optimum.

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Generally, you can simply adjust the gain to make the loudness from the turntable about the same as your other sources, or to compensate if you just "feel like" you've got too much gain or too little gain. Different cartridges have different output levels and different recordings have different loudness so you can use whatever setting you like.

Or, higher gain usually means more noise so if you can hear preamp noise (him, hiss, or whine) you may want to try to lower setting. (The signal-to-noise ratio from the record isn't affected since the signal and record noise are amplified together.)

 

[JP]

but in fact there is an optimum.

A good example of the interplay between the LC resonance and RC filter, and finding optimum.

@subfire91 there are a couple 2M Blue measurements in the cartridge library. Looks like closer to 150pF will be optimal, though the resonance looks to be north of 15kHz, hence why it's probably not that audible. Note that a lot of manufacturer capacitance specs, particularly of the last decade or so, don't usually meet with reality.

 

[subfire91]

thank you all very much for your help. i will go with 45dB gain and 50pF at the phono and see how it goes

 

[Nick_Sukhov]

there are a couple 2M Blue measurements in the cartridge library. Looks like closer to 150pF will be optimal

-6 dB to -10 dB @ 20 kHz can NOT be optimal, I think. It seems to me better way to use higher input resistance and lower capacitance - see my attached screenshot

 

[JP]

More often than not it is a material mistake to dismiss the mechanical system's impact on response. I was looking at actual measured response, not models of only the electrical system.