Valve Itch phono

[Salas]

50k Zo 820k Zin

http://www.diyaudio.com/forums/analogue-source/73211-inverse-riaa.html

Also remember I don't use "lost constant" in my RIAA filters, so factor that in when measuring

 

[merlin el mago]

Wich one post 1?

Wich factor have I to use?

 

[Salas]

EC8010's #2. It also has the Neumann constant so don't pay attention to beyond 20kHZ compliance with ours

 

[merlin el mago]

The inverse RIAA is the attached?

 

[merlin el mago]

Noted is EC8010's #2

 

[merlin el mago]

Salas my signal generator has an output of 600 ohms how to scale 22R for 75R oscillator or 47R for 50R oscillator?

 

[Salas]

EC8010 wrote in #8 that its about having 2197 Ohm before the RC networks. So don't have 2K1 and the 22R/47R choice, have 1597 and your generator

 

[merlin el mago]

Thanks Salas. I have problems sourcing 6n2 1% capacitor. 1597R in place of 22R or 47R or in place of 2K1 + 22R or 47R?

 

[stajo]

In place of total ie 2K1 + 22R or 47R

 

[Salas]

In place of both in series total

 

[merlin el mago]

I have problems sourcing 6n2 1% capacitor & 1597R 0,1%

 

[Salas]

Athens & Stockholm moved to same time zone

 

[Salas]

I have problems sourcing 6n2 1% capacitor & 1597R 0,1%

Make combinations

 

[stajo]

Athens & Stockholm moved to same time zone

Finally

 

[merlin el mago]

Very usefull for resistors:

Reverse engineered resistor calculator resistor pairs - search of R1 and R2 with known total resistance iteration resistor calculation - sengpielaudio Sengpiel Berlin

 

[merlin el mago]

127R + 1k47 = 1597R 0.1%

 

[merlin el mago]

1n5+4n7 = 6n2 1% PS

 

[Joao@AltheaMusica]

Salas my signal generator has an output of 600 ohms how to scale 22R for 75R oscillator or 47R for 50R oscillator?

use a very 2 stage measering amplifier - high Z-in and low Z-out - and place the inverse RIAA between the 2 stages. It should not be impoosible to make such an "Inverse-RIAA-measurement-tool" with low noise and low distortion op-amps like AD 7xx series.

This is all you should know to do this - it's only using of basic design principles and good measurement tool like ARTA.

 

[merlin el mago]

A very usefull calculator by Jim Hagerman for loading

Hagerman Technology LLC: Cartridge Loading

Thanks to Jim now I understand why the MM needs different resistor loading depending the inductance of the cartridge & the capacitance of the tonearm cable.

 

[merlin el mago]

Salas now I'm using 7N7 tube in place os 6SN7 are electrically the same only change the socket loctal in place of octal, have I to change something because these 7N7 are really 9-10mA instead of 8mA