Convert cartridge output voltage to db gain

Thanks for the input so far. Well I assumed it was a gain issue because I have to turn the volume knob up to around 2 o'clock to get satisfactory listening levels. When I play CD's, the volume knob is around 10 o'clock for the same listening level. In my old preamp/amp setup, I did have to turn the phono up louder than the CDP, but it wasn't as drastic. Phono was about 11 o'clock, CD around 9 o'clock.

FWIW, previous amp was 75 wpc, the amp section in my current integrated amp is listed as 80 wpc.

Sidssp, the phono stage is solid state, and was not noisy in my old preamp/amp setup. It does seem like surface noise, but my cartridge, speakers, and phono stage have not changed. I sold my preamp and amp (both tubed), bought an integrated amp, then I noticed the change. CD's play with no noise issue. The integrated amp has a tube line stage and tube power amp sections.

Kal, where would I find V1 and V0?

Cheers,
John

My cartridge is low enough, about .35mV that to get it to sound the same as the CD player the volume has to be turned up. Paul Marks, the phono preamp creator said it was a matter of the gain of the phono preamp combined with the cartridge output that made it necessary. A slightly higher one, .65mV was mentioned, would obviate that necessity.
So some part of it is the gain issue, but not the noise issue.

Actually, the equation is: db = 20Log10(Av), where Av is the voltage gain (Vout/Vin). Vin is the input signal (your cartridge output of 0.24mv) to the phono stage. Ultimately you want a line level of 0.5 to 1.0v from the phono stage's output to match the same same level from the CD Player.

If you are aiming for 0.5v output from the phono stage, Av = (0.5v / .24mv) = 2083.3 Plug this into the "db = " equation and you have a db value of 66db, needed by the phono stage to achieve that 0.5v signal into the line stage.

So, by that calculation, he has adequate gain in the phono stage despite his protestations. As I said, it is the noise level, not the gain that needs to be addressed.

Since he is turning up the gain (reducing attenuation) in the in the integrated amp to attain the same (subjective) output with the same phono stage, I suspect the input stage on the new integrated.

Kal

Ok, thank you for the responses. That does explain the volume difference to some extent. According to John's calculations, my phono stage has an output of 0.5V, while my CDP has an output of 2.5V. So, I'm guessing (since I can't find my old sceintific calculator) that I would need a cartridge with about a 2.0 mV output with 66 db of gain to make a closer match to the 2.5 V output of my CDP.

Is this correct? Or as Kal suggest, I should try changing the preamp tubes in the integrated amp? (1 12AX7, 1 12AU7)

Cheers,
John